Taxonomic and Biogeographic Relationships ofthe Island Fox (Urocyon littoralis) and Gray Fox (V. cinereoargenteus) from Western North America

Paul W Collins Department ofVertebrate Zoology Santa Barbara Museum of Natural History, Santa Barbara, CA 93105

from morphometric data whether foxes on Abstract - The purpose of this study is to Tiburon Island should be regarded as a species clarify the biogeographic and taxonomic or subspecies. The assessment of subspecies relationships between two allospecies of fox limits for the island fox is still problematic. (the gray fox and the island fox) and to examine Continued recognition of six subspecies is inter-island phenetic affinities of the island fox. warranted based on the degree of genetic and Island fox populations were compared to 20 morphologic divergence observed between each mainland gray fox populations from western of the island fox populations. The species North America, Mexico and Central America. consists of six subspecies - U. t. catatinae, U. t. Island fox skulls recovered from archeological cle711entae, U. t. dickeyi, U. t. tittoTalis, U. t. sites on the California Islands were compared santacrllzae and U. t. santm·osae. with contemporary island fox populations to determine whether Indians might have played a Introduction role in the dispersal of the island fox. This study is based on stepwise discriminant function Studies of spatially isolated populations have analysis of 28 cranial measurements from 2,200 provided insights into the dynamics of speermens. evolution and dispersal, while also playing a The results demonstrate that the island fox is major role in the development of evolutionary morphologically distinct from the gray fox and theory. In part, this is related to the tendency that it is phenetically closer to present-day for isolated populations to evolve rapidly, both populations of gray fox in California rather phenotypically and genetically, independent of than to gray fox populations in southern the gradual evolutionary changes seen in less Mexico or Central America. Morphological isolated populations. By examining patterns of divergence observed in island fox populations phenetic similarity in insular populations, it on the northern Channel Islands is consistent may be possible to clarify the relative with the islands' spatial distribution and known importance ofvarious random processes such as geologic history, whereas the southern Channel genetic drift, gene flow, founder effect and Island populations show no such concordance. bottlenecking on the evolution of insular Phenetic affinities of subfossil island fox populations. By comparing insular populations material, coupled with the presence of island of a species with those of the nearest mainland fox bone material only in the uppermost levels relative, it may also be possible to determine of archeological sites on the southern Channel whether insular forms are derived or relictual, Islands suggests that Indians probably whether their present patterns of distribution transported island foxes to San Clemente, Santa are a result of single or multiple colonizations, Catalina and San Nicolas Islands. and whether there has been gene flow Based on morphometric data, the generic occurring between populations. status of U?'ocyon is upheld and the genus is The North American genus UTocyon has determined to consist of two species U. traditionally been considered to include two cinereom'genteus and U. tittomtis. It is uncertain recent species: the gray fox (u. cine?'eoargenteus

Third California Islands Symposium 351 Schreber, 1775) and the island fox (u. littoralis the genus U1'ocyon is an ideal subject to study Johnson 1980). Gray foxes probably initially (Vulpes velox) from the San Joaquin Valley of Baird, 1857). Historically, there has been the processes of geographic differentiation of reached one of the northern Channel Islands California also were included in this study for con[-usion about the taxonomic validity of the populations. through chance by rafting or swimming comparison with U1'ocyon taxa. Cranial material genus Urocyon and its two named species. Externally the island fox resembles the gray (Wenner & Johnson 1980). During a period of recovered from island archaeological sites also Recent revisions of the family Canidae have fox but the former is smaller and darker extended isolation they evolved their present were included for comparison with present-day suggested that U1'ocyon be included in Vulpes (Grinnell et al. 1937). Superficially, there is small body size. Eustatic sea level changes U. littoralis samples. (Clutton-Brock et al. 1976) or Canis (Vulpes) little morphological variability among island during the late Pleistocene led to subsequent To reduce heterogeneity in sample sizes and (Van Gelder 1978). The first gray fox known to fox populations, but the species is markedly dispersal, via landbridges, of small-sized island to allow examination of morphologic variation science was described and named as Canis different from the gray fox (Grinnell et al. foxes across the northern Channel Islands within and between samples, specimens were cille1'eo a1'gellteus by Schreber (1775) but was 1937). Taxonomic affinities with tlle gray fox, chain. Indians subsequently transported island grouped according to 28 samples (operational subsequently reassigned to the genus U1'ocyon as well as inter-island phenetic affinities among foxes to the three largest of the southern taxonomic units-OTUs) (Table 1). The by Baird (1857). A second species of gray fox island fox populations, are presently poorly Channel Islands (Norris 1951; Vedder & geographic locations of tlle pooled samples used was described and named by Baird (1857) as understood. Except for original descriptions Norris 1963; Johnson 1972, 1983; Wenner & in tllis study are illustrated in Figure 1. Sample Vulpes (Urocyon) littoralis. Twenty additional (Baird 1857; Merriam 1903; Grinnell & Johnson 1980; Collins 1982,1991). sizes and ta.xonomic designations for each OTU species and subspecies of gray fox and six Linsdale 1930) and the investigations of In this study, I examined patterns of are noted in Table 1 and localities for all adult species or subspecies of island fox were Grinnell & co-authors (1937), there has been morphometric variability within and among the specimens used in the final multivariate analyses subsequently named (Grinnell et al. 1937; Hall no recent effort made to use multivariate two U1'ocyon allospecies (u. cinereom-g-enteus and are listed in the Appendix (copy available on 1981; Fritzwell & Haroldson 1982). As more morphometric techniques to examine the U. littoralis) from western Nortll America. The request from author). Foxes from each of the material became available a number of these biogeographic and taxonomic relationships of biogeographic and taxonomic relationships of seven island populations (including gray foxes taxa were relegated to synonymy with or U1'OCy01Z littoralis. Genetic variability of island the island fox were evaIuated using from Tiburon Island off the coast of Sonora, recognized as subspecies of one or the other of foxes has recently been examined using morphologic variability in 29 cranial Mexico) were treated as separate OTUs, as were the two original species, U. cinel'eoargenteus and standard karyology, allozyme electrophoresis, characters. Univariate and multivariate subspecies with limited geographic ranges or U. littoralis (Grinnell 1933; Grinnell et al. 1937; mitochondrial DNA restriction site analysis statistical techniques were used to compare small sample sizes (Fig. 1; Table 1). Three Hall 1981). There has been no attempt made and genetic fingerprinting (Gilbert et al. 1990; morphologic variability within and among widely distributed gray fox subspecies (townsendi, using multivariate morphometries to assess the Wayne et al. 1991 a, b). populations of present-day island foxes and califo171icus and scottii) with large sample sizes validity of the genus U1'oC)'on or to examine tlle The presence of foxes on six widely prehistoric samples in order to investigate were subdivided into smaller OTUs based on systematics of either of its two named species separated islands off the southern California effects of insular isolation on foxes and to collecting gaps, known taxonomic boundaries U. cinel'eoargenteus and U. littoralis. The coastline has elicited considerable debate over clarify evolutionary and taxonomic relation­ and ecogeographic provinces (Collins 1982). taxonomic status of North American gray how such a poor over-water disperser could ships among the six island fox populations. Taxonomic boundaries used for assigning foxes, therefore, is uncertain. colonize them (Grinnell et al. 1937; Stock This study addresses four primary questions. specimens to OTUs followed the range map for The gray fox is a large, relatively long-tailed 1943; Vedder & Norris 1963; von Bloeker What mainland fox population gave rise to Urocyon in Hall (1981). For the present study, I species, which ranges over most of tlle United 1967; Remington 1971; Case 1978; Johnson island foxes? What do phenetic affinities of treated most Urocyon subspecies as separate States, parts of southern Canada, and most of 1972, 1978, 1983; Wenner & Johnson 1980). present day and prehistoric island fox OTUs because their systematics have not been Mexico and Central America (Hall 1981). At One theory suggests that the present-day populations tell us about their origin and fully reevaluated (Collins 1982). present there are 16 recognized subspecies populations represent a relict form of a pattern of dispersal to the six islands? What Twenty-three cranial and six mandibular (Hall 1981). The island fox, considered a previously more widespread, smaller, role, if any, did Native Americans have in measurements (illustrated in Fig. 2; described diminutive form of the gray fox (Grinnell et al. continental race which reached exposed affecting the present distribution of the island in Table 2) were recorded from each specimen. 1937), occurs only on the six largest of the offshore landmasses via landbridges resulting fox? What is the taxonomic status of the genus All measurements were taken with dial calipers eight islands off the coast of southern from eustatic sea level changes during the U1'ocyon and the species U. littoralis? to the nearest 0.01 mm. Measurements not California with each island presently Pleistocene (Stock 1943; von Bloeker 1967; involving bilateral or midline endpoints were supporting its own subspecies (Hall 1981). Its Remington 1971). A more widely accepted Materials and Methods recorded off the left side of the skull. Since hypothesis holds that the original colonizing multivariate techniques require a complete data distribution across a broad geographical area, A total of 2,207 gray fox and island fox from foxes were similar in size to those on the set, every effort was made to obtain a complete coupled Witll the existence of barriers to gene 20 mainland and seven island samples (Table 1) adjacent mainland, but unique selective series of measurements for each specimen. If a flow, has resulted in Urocyon exhibiting in Central America, Mexico, and western pressures on the islands led to a reduction in left element of a bilaterial measurement was considerable geographic variation. Because of North America (Fig. 1) were examined for size (Grinnell et al. 1937; Vedder & Norris broken or missing then the intact right element this relatively wide distribution and the large geographic variation. A sample of 32 kit fox degree of intraspecific morphological variation, 1963; Case 1978; Johnson 1978; Wenner & was measured. Missing values were estimated

352 353 Table 1. U1'0C)'on and VlIlpcs population samples (OTUs) used in this study. Subspecies designations for each of the samples Table 1. Continued. are based on geographic ranges noted in Hall (1981). See Figure 1 for a map of these population samples. Unless otherwise Number ofSpecimens indicated all localities are in California. Sample Sample Localities No. Code Pooled Male Female Sample Sample Localities Number ofSpecimens U. c. ji-lItel'ClIIlIS No. Code Pooled Male Female 25 FRAT Entire subspecies range (see Hall 1981) 29 21 Ul'0L)'0n littoralis littoralis u. c. glilltelllllillc 1 SMI San Miguel Island 20 17 26 GUAT Entire subspecies range (see Hall 1981) 41 25 U. I. smltm'osac u. c. costlll'icensis 2 SRI Santa Rosa Island 28 31 27 COST Entire subspecies range (see Hall 1981) 5 5 U. I. santm1"lIZaC VlIlpcs vc!ox 7/l1I1.Totis 28 \nJLPES Fresno, Kern and San Luis Obispo Counties SCI Santa Cruz Island 64 64 -l.:!: .-Ul. TOTALS 775 700 U. I. dickcyi 4 SNI San Nicolas Island 45 59 U. I. Cfltalillae 110 100 90 80 70 5 SCAT Santa Catalina Island 21 16 U. I. c!c1llcntae 6 SCLE San Clemente Island 23 16 U. cinel'eoal'gelltells townsendi 7 NCOR Northwestern California and Oregon 24 25 40 8 SFBA San Francisco Bay Area 35 32 9 SINV Sierra Nevada foothills and N. Tulare County 49 27 ,~~~;: MlllUOII.\""""? Sontll nll"npll I. 10 MOSL Coast Range, Monterey-San Luis Obispo Counties 23 23 Sllnl" Cnu I. noonl. U. c. calijornims Snnla Onrbn'.lll,t 11 SSINV Southwestern foothills of the Sierra Nevadas, Sonln 4 Colelln,,!.~ ~snn Tulare and Kern counties. 10 9 tIIeoln,l.

12 SBVC Santa Barbara and Ventura Counties 29 28 CHANNEL ISLANDS 30 30 o 20 40 60 13 LAOC Los Angeles and Orange Counties 30 IIIII II 19 (SUtul" Milos) 14 SDIC San Diego and Imperial Counties 25 28 U. c. peninmlal'is 15 NBCA Northern Baja California, Mexico 19 15 16 SBCA Southern Baja California, Mexico 21 17 U. c. scottii 17 SONORA Sonoran Biotic Province: Sonora Mexico, SE California,

NE Baja California and SIN Arizona 22 51 20 18 MOHAVE Mohave Desert: California (Kern, Los Angeles, San Bernardino,

Inyo and Riverside Counties), southern Nevada and extreme N NINArizona 25 25 19 NAVAJO Navahonian Biotic Province: Northern Arizona, Utah, southern Colorado and northern New Mexico 42 23 +SCALE (Statute Miles) 20 CI-ill-IUA Chihuahuan Biotie Province: Southern New Mexico, SE Arizona, 200 400 800 i Chihuahua, Coahuila, Nuevo Leon, N. San Luis Potosi, 10 N. Zacatecas and Tamaulipas Mexico 53 29 U. cinereoa1'gellteus (spp?)

21 TIBURON Tiburon Island, Sonora, Mexico 110 100 90 U. c. 7l/{/(h'ensis 22 MAD Entire subspecies range (see Hall 1981) 7 4 Figure 1. Map showing the 27 locality samples (OTUs) of U1'Ocyon CillCl'COll1'genteus and U. littoralis used for statistical U. c. lligri1'ostris analysis of morphometric data. Numbers refer to the following samples: (1) SMI, (2) SRI, (3) SCI, (4) SNI, (5) SCAT, (6) 23 NIGR Entire subspecies range (see Hall 1981) 51 52 SCLE, (7) NCOR, (8) SFBA, (9) SINV, (10) MOSL, (11), SSINV, (12) SBVC, (13) LAOC, (14) SDIC, (15) NBCA, (16) U. C. o1'i1/01llus SBCA, (17) SONORA, (18) MOHAVE, (19) NAVAJO, (20) CHIHUA, (21) TIBURON, (22) MAD, (23) NIGR, (24) 24 ORIN Entire subspecies range (see Hall 1981) 18 18 ORIN, (25) FRAT, (26) GUAT, and (27) COST. Acronyms and samples are defined in Table 1 and localities and specimens are listed in the Appendix (copy available on request from author).

354 355 Table 2. Definition ofcranial and mandibular measurements used in this study..Measurements are shown in Figure Character No. Code Name Description ofNleasurement ofNleasurement SKULL MEASUREMENTS 1. NAMW Nasal NIinimum 'Vidth: the minimum distance across the nasal bones at theposterior tlle maximum distance from tllC mandibular notch at tlle base of tlle the premaxillas. Taken perpendicular to the long axis of the coronoid process to the notch in the masseteric line of tlle angular 2. ANAW Anterior Nasal 'Vidth: distance across the anterior most projections (nasal process) of process. nasal bones. DAPMN minimum distance from the notch under the angular process to tlle 3. ROSW Rostrum 'Vidth: distance across the labial margins of Pm2 alveoli. Measured trans 1,er:se posterior margin of the alveolus ofMolar). to the long axis of the skull. RAMW Widtll of tlle minimum distance from tlle posterior margin oftlle alveolus ofMolar) 4. ROSWC Rostrum YVidth breadth across the rostrum at the canine alveoli. Nleasured from Coronoid Process to the mandibular notch. at the canines: labial margins of the canine alveoli. of the Ramus: 5. LYRW Lyre Width: distance across the inside margins of the temporal ridges at MAl'\lH Height of tlle vertical distance from base ofthe subangular notch to tlle superior border fTontal-parietal suture. Coronoid Process of of tlle coronoid. 6. ROSWO Rostrum 'Vidth the least breadth between the orbits at the junction of the lacrimal the Ramus at the canines: fi'ontal suture. TRLLM Tooth Row Lengtll measured from the anterior margin of the canine alveolus to the 7. PORW Postorbital width: the minimum inter-orbital distance measured across the frontal of Lower Mandible: posterior margin ofMolar3 alveolus. immediately posterior to the supraorbital processes. TOLM Total Length of measured fTom tlle anterior margin of tlle alveolus ofI[ to tlle posterior 8. SORW Supraorbital 'Vidth: the maximum inter-orbital distance measured across the frontals tlle Lower Mandible: of tlle process. the supraorbital processes. 9. PALW Palatal width: the maximum width of the palate measured across the palate fi'om by regression analysis using the GLM Statistical Methods: Descriptive statistics anterior labial corners of the MI alveoli. 10. CRAW Cranium Width: the maximum width of the cranium measured across the procedure of the Statistical Analysis System (mean, range, standard deviation, standard temporal suture. (SAS Institute, Inc. 1979). These analyses were error of the mean and coefficient of variation) 11. MASW Mastoid Width: the greatest distance across the mastoid bones perpendicular to conducted using the appropriate intra­ were calculated for all samples and variables long axis of the skull. population (sex/OTU) sample and the variable using tlle MEANS procedure of tlle Statistical 12. ZYGW Zygomatic YVidth: the greatest distance across the outer margins of the zygomatic Analysis System (SAS Institute Inc., 1979), and processes, taken perpendicular to tlle long axis of the skull. most highly correlated with the missing 13. NASL Nasal Length: tlle maximum lengtll of tlle nasals measured along tlle midline of measurement. Estimates were made separately are presented in Appendix I of Collins (1982). nasal suture fi'om tlle anterior tip to tlle posterior most projection. for males and females and were then After calculating descriptive statistics for each 14. MAXL Maxillmy Length: measured from the anterior margins of the eanine alveolus to incorporated into the data sets. Although tllls sample, all linear measurements were posterior most point along the maxillary-fi'ontal suture. teclmique may have biased some measurements transformed to logarithms (loge) to give all 15. MRTL Maxillary Tooth tlle greatest lengtll of tlle left: maxillary tooth row measured at the an­ Row Length: terior margin of the canine alveolus to tlle posterior margin of the more toward the average by excluding extreme variables more equal weight (regardless of their M2 alveolus. values, its overall effect on the study was magnitude) and to make their variances more 16. PALL Palatal Length: measured from the posterior margin of II alveoli to the anterior negligible, since it rarely occurred more than homogeneous across OTUs. All further margin of the notch located at the posterior border of tlle palatine once involving the same measurement within a procedures utilized the loge-transformed bone. particular population sample. Specimens cranial and mandibular characters. 17. BASL Basilar Length: measured from the anterior most inferior border of the foramen magnum (intercondyloid notch) to a line connecting tlle posterior lacking three or more measurements were Ontogenetic variation was examined by most margin of the alveolus ofIl. excluded from further statistical analyses. comparing means of the 29 cranial variables 18. COBL Condylobasal Length: measured from the posterior most projection of the exoccipital Specimens were assigned to one of six age among the four age classes from a sample condyles to tlle anterior most projections of tlle premaxillary bones. classes based on a combination of cranial suture composed of all island foxes (OTUs 1-6). 19. ALPM Alveolar Length lengtll oftlle alveolus oftlle upper carnassial Pm4 along tlle labial margin. closures (Table 3) and molar tooth wear Statistical methods used were one-way analysis ofPremolar4: 20. WBTYP Width between the minimum widtll between tlle ilmer margins of tlle tympanic bullae. patterns. (Fig. 3). Criteria used to age of variance (F-tests) and Duncan's Multiple Tympanic Bullae: specimens in tllls study were based in part on Range tests to test for significant differences 21. TYMW Tympanic'Vidth: the maximum width of the left tympanic measured across the criteria developed by Wood (1958) to age among means and to determine the maximal .tympanic bullae from tlle outer margin of tlle carotid notch to tlle Urocyoll cillereoargellteus. Because of small nonsignificant subsets. To examine the extent tympanic-occipital suture. 22. TYML Tympanic Length: tlle maximum lengtll of the left tympanic measured from the most sample sizes in the youngest and oldest age of secondary sexual variation in U1'OCYOll, the 29 aboral point of the bullae on the suture with the paraoccipital categories, the original six age classes were cranial and mandibular measurements for process to tlle external carotid foramen. reduced to four as follows: juvenile (original males and females were compared for one 23. CRAD Cranium Depth: tlle vertical distance from tlle basioccipital-basi-sphenoid suture to age class 0-1); subadult (age class 2); adult (age island sample (OTU-3) and one mainland tllC fi'ontal-parietal suture. class 3) and old adult (original age class 4-5). sample (OTU-12) using t-tests.

356 357 Table 3. Age categories and cranial and dental criteria used to age specimens. See Figure 3 for an illustration of the molar wear patterns. Criteria follows VVood (1958) with some additions. Age Age ~:~~'~\ No. Name Criterialused to distinguish each age category 0 Juvenile: All sutures are wide open. The adult dentition is newly or partially erupted and in general does not show any wear. (0-5.5 months old) Juvenile-Subadult: Basisphenoid-basioccipital suture nearly closed and basisphenoid-presphenoid suture '~~ ~ open but beginning to close. A V-shaped notch is present between the anterior margin of the presphenoid and the medial ridge of the vomer. The teeth are fully erupted but do not show any wear. All the conules on iVII are sharp with no • indication ofwear. (5.5-12 months old). 2 Subadult-Young Adult: Presphenoid and vomer continuous, no V-shaped gap present. Elongated areas of wear present on the metaconule and protocone. The wear pattern being an area of -... exposed dentine from the apex of the metaconule and protocone toward the ANAW metacone and paracone respectively. These two cusps (metaconule and protocone) ...... still possess their detlnite structures. (25-36 months old). -L'>c Young Adult: Sutures on base of skull closed and completely obliterated. NIl with a narrow band of exposed dentine joining the metaconule and protocone. (37-48 months old). 4 Adult: Sutures on base of skull closed. NIl with a broad band of exposed dentine joining the metaconule and protocone and reaching up to the metacone and paracone. Small patch of exposed dentine on the hypocone. The conules are worn down close to the depth of the interconule space. (49-56 months old). Old Adult: ,Most of the surface of NIl showing exposed dentine. All conules worn down to or below the gum line. This age categOlY has been added for island fox populations.

BASL

~,_.... , .

j o 1 2

TYMW ZYOW

RAMW ... .. 3 5

I ) :/ 6

Figure 2. Skull and mandible of Ul'0L)'0l1 ciucrcofl1'gcntcus illustrating the 29 cranial and mandibular measurements used Figure 3. First upper molar of Ur0L)'on (labial side to the left:) illustrating wear patterns for each of six age categories. Five this study. Acronyms are defined and measurements are described in Table 2. of the six wear patterns are redrawn from Wood (1958). See Table 3 for a description of the specific cranial and dental criteria and terminology used to identity each age categOlY.

358 359 Before the subfossil island fox specimens the intralocality variation, and to insure that the first two canonical variates axes between sexes. Because the majority of the 29 cranial could be used in multivariate analysis of each character used in further multivariate sub fossil and present day samples, and by the characters showed statistically significant geographic variation, it was first necessary to analyses was contributing information useful to pattern of group allocations during the secondary sexual variation across the two determine the sex of each specimen. Since only discriminating between OTUs. classification procedure. samples tested, and because several previous a few of the subfossil island fox specimens To characterize the degree of morphologic studies also have recorded sexual dimorphism possessed both skulls and lower mandibles, divergence among a p1·iori designated samples, in Uroi)'on taxa (Grinnell et al. 1937; Rohde only the 22 cranial characters (Fig. 2) were a series of canonical variates analyses (Cooley Results 1966; Fritzell 1987), all further statistical analyses were run separately for each sex. used for statistical analyses that included & Lohnes 1971) were used. Geographic I. Non-geographic Intraspecific Variation C. IntedoCtllity Chamcter Variation: Two-way subfossil specimens. The sex of each subfossil variation between samples was assessed using A. Intraspecific Ontogenetic Variation: Analysis analysis of variance (ANOVA) detected specimen was determined by means of the stepwise discriminant function analysis of ontogenetic variation in a large sample (417 statistically significant (P :s; 0.0001) differences canonical variates analysis (CVA). A separate procedure of the BMDP Statistical Software specimens) of Uroi)'on littomlis revealed that CVA was run for each island sample with the among the 27 OTUs in all 29 of the cranial (BMDP7M; Dixon 1983). Three separate eight (ANAvV, ROSvV, ROSWC, ROSWO, archaeological specimens recovered from an CVAs were run on different subsets of the characters tested, thus invalidating the null ZYGvV, MA,,'I{L, ALPM, TYMW) of 29 cranial island entered into the CVA analysis for their original data. Sexes were analyzed separately hypothesis of no geographic variation among characters exhibited significant (P:S; 0.05) island of origin as unidentified. These for all of these analyses. To assess generic the 27 OTUs. Because all of the characters differences among character means for tlle four specimens were then evaluated with the affinities of island foxes, tlle first CVA was run showed significant interlocality variation, it was age classes tested. Duncan's multiple range discriminant equation generated from the using four population samples (mainland gray appropriate to use them all in further tests recorded a fairly consistent pattern of reference sample to determine their sex. If the fox, Tiburon Island gray fox, island fox and kit multivariate procedures. However, because ontogenetic variation. With the exception of probability of assignment to a particular sex fox). To examine population affinities of island COBL was actually a combination of BASL ROSVV and ALPM, significant (P < 0.05) was 90% or above, then the specimen was foxes to mainland gray foxes, a second CVA and PALL (Fig. 2), and because COBL did not ontogenetic variation was observed between assigned to that sex and included in further analysis was run which analyzed only the 27 appear to contribute additional information the juvenile-subadult (original classes 0-2) and multivariate analyses; othelwise it was excluded Urocyon OTUs (Table 1). Finally, to examine independent of other included characters, it adult-old adult (original classes 3-4) age classes. from all further statistical analyses. the extent of morphologic divergence among was excluded from all further statistical As a result, young adults (original class 3) The taxonomic value of each character was the six island fox populations, a third CVA was analyses. through old adults (original class 5) were tested in several ways. First, characters were run using all of the island fox samples (OTUs F-ratios resulting from the multivariate selected for further analyses if they contributed 1-6) along with subfossil (archaeological) island pooled for use in all subsequent analyses of analysis of varian·ce (MANOVA) revealed information independent of other included fox specimens. In this analysis, all subfossil geographic variation in Urocyon, while statistically significant differences (P :s; 0.0001) characters (i.e., if they showed a pooled within­ island foxes were entered as unidentified individuals in tlle younger age classes (original for all test criteria, thus rejecting the null group correlation (1' < 0.80) to other included specimens and were classified by the classes 0-2) were excluded from further hypothesis of no statistically significant characters) and if they- showed significant discriminant function. statistical treatment. Consideration of age variation between sexes or between the 27 interlocality variation when tested by two-way The first two sets of CVAs were based on an classes 3-5 as adults in this study generally Urocyon OTUs. Therefore, it was appropriate analysis of variance (ANOVA). Second, analysis of 28 cranial and mandibular characters agrees with Wood's (1958) demarcation of to investigate the dispersion of these samples interaction between sexual variation and while the third set of CVAs only utilized the 22 adults in U. cinereoargenteus. within discriminant space. The MANOVA interlocality variation was tested using a two­ cranial characters (Fig. 2). For the first two B. Sexual Variation: Twenty-six of 29 cranial results revealed that there existed a significant way-multivariate analysis of variance CVAs, canonical discriminant functions were characters in the island sample (OTU-3) (P:S; 0.001) interactive effect between the OTU (MANOVA) of a sample composed of the 27 calculated and group centriods for each sample exhibited significant (P :s; 0.01) sexual and sex differences. This result suggests that Urocyon OTUs. Three criteria (Wilk's lambda, were plotted on the first three vectors. For tlle dimorphism, with males larger tllan females in the amount of sexual dimorphism exhibited in Hotelling-Lawley's trace and Pillais' trace were third CVA tlle centroid for each sample along all but LYRW. Only NAMW, PORW and each of the OTUs may not be equal, which is used to: 1) test the null hypothesis of no with minimum polygons enclosing all TYMW showed no significant difference consistant with tlle results from the t-tests nUl significant variation between populations due individuals in each group were constructed on between the sexes. Twenty-two of 29 cranial for island and mainland samples. to geography; 2) determine if each OTU the first two vectors to illustrate tlle amount of characters in the mainland sample (OTU-12) exhibited the same amount of sexual morphologic overlap among the six present day exhibited significant (P:S; 0.05) differences n. Geographic Variation dimorphism and 3) determine if there was an island fox populations, and to clarify phenetic between the sexes, with males larger than A. Inte1Jpecific Affinities of the Island Fox: In interactive effect between observed sex and affinities of the subfossil island fox specimens. females in all but LYRW and NAMW. Seven tlle first canonical variates analysis (CVA) tlle OTU. The purpose of these analyses was to Phenetic affinities of the subfossil Urocyon characters (NAMW, ANAW, LYRW, PORW, generic and specific affinities of island foxes verify that the interlocality variation of the littomlis specimens were generally recognizable WBTYP, TYMW, DAPMN) showed no were examined. Figure 4 presents a three OTUs was significantly (P :s; 0.05) greater tllan based on the amount of overlap observed on statistically significant size differences between dimensional plot of male and female OTU

360 361 Tiburon Island OTU and the other Urocyon accounted for 87.9% of the morphologic OTUs is probably a result of the small Tiburon variance in males and 86.5 % in females (Table Island sample sizes (male=l, female=3). vVithin 4). Although canonical variates 4-17 are the U1'ocyon OTUs, U. littOTfllis was clearly significant (P :s; 0.01), each provides little divergent in size (CV1), but only slightly additional discrimination between samples; divergent in shape (CV2) from mainland gray axes 4-17 account for the remaining 12.1 % and foxes (Fig. 4). For both sexes the Tiburon 13 .5% of the between sample morphological Island OTU occupied intermediate positions variation Crable 4). Thus, there is little (100%) -4 1!...cinnreoargenteus 0 on the first two axes between the two UroL)'o17 distortion of the phenetic distances observed (Tiburon Island) C') -3 taxa (Fig. 4). between samples when the character space is W The amount of phenetic overlap between the reduced &-om 28 dimensions to only three. I- «- -2 four groups was further assessed through an Canonical variates analysis of both male and II analysis of the proportion of individuals female U1'ocyon samples revealed that the seven « -1 > U.clner eo arg ent nus - (Mainland) misclassified by the discriminant function. For island samples were divergent in size (CV1) but ...J « c -, both sexes there were no misclassifications not in shape (CV2) from the remaining 20 0 - from either the island fox, kit fox or Tiburon mainland samples (Figs. 5, 6). The island z a Island gray fox samples. Mainland gray foxes samples appear to have shifted away from the z « overlapped slightly with Tiburon Island gray north-south size cline exhibited by mainland U. 0 foxes (2 % of tlle males and 0.8% of the females cinc1'coa1'gcntcus samples (see Collins 1982: Fig. misclassified to the Tiburon Island sample) and 8). For both sexes the 27 samples were with island foxes (1. 7% of the male gray foxes arranged by size on the first canonical variate from Central America misclassified to the axis, with the U. littoTfllis samples situated to island fox sample). Pair-wise F-tests among tlle tlle extreme right of both plots (Figs. 5, 6). The four male and female groups were significant (P Tiburon Island population (TIBURON) :s; 0.001) for all samples except the male occupied an intermediate position between the Tiburon Island sample. This result was not U. littoralis and U. cinC1'COa1'gcntcus samples. For unexpected since the Tiburon Island male both sexes the U. littoTfllis samples were closest sample consisted of only one individual. to U. cinC1'COa1'gcntcus samples from mainland Figure 4. Three-dimensional projection of one Vulpes and th:ee UroCYOl1 samples onto th~ first. three can~nical axes based on discriminant function analyses of 28 cranial characters. POl11ts represent sample centrOIds wIth open cIrcles for females B.Pbcnctic Rclationsbips oftbc U1'o0'on OTUs.: California (Fig. 5, 6). Only the Tuburon Island and closed circles for males. Vllipes velox 7Ilacrotis from the San Joaquin Valley, California, were included in this a~alysis for A second set of canonical variates analyses were sample was divergent along the third canonical comparison with Urocyoll cil1el'eom'genteus and U. littoralis samples. Sample sizes for each sample ~vere: Inamland U. performed on 27 male and 27 female U1'ocyon axis in both the male and females analyses cil1ereomgentells (l11ales;542, females;476); Tiburon Island U. cil1ereomgentells (male;1, fel11ales;3); U. litton/lis (males;200, OTUs. All 28 of tlle cranial variables tested by (Figs. 5, 6). No other major pattern of fel11ales;202) and VlIlpes velox (l11ales;14, fel11ales;18). two-way ANOVA exhibited highly significant discrimination among tlle U1'o0'on samples was (P :s; 0.0001) interpopulation heterogeneity. evident on canonical variate axis 3 which centroids on the first three canonical axes. The a1'gcntcus OTU centroids, confirms that island The null hypothesis of no statistically accounted for only 4.9% and 5.7% of the first three axes account collectively for all fox more closely resemble, and thus are more significant geographic variation in cranial and between sample variation (Table 4). (100%) of the between-group variation for closely related to gray fox than kit fox. mandibular morphology was rejected for all The 2a mainland U1'ocyon cinc1'com-gcntcus both males and females. Thus, this plot is a For both sexes, the first canonical axis test criteria by significant F-values (F> 1.1, P < populations for both sexes generally were reasonably accurate depiction of the appeared to separate all four groups by size 0.0001) generated by the MANOVA. arranged by size on the first canonical variates morphologic relationships among the four a while the second axis separated Vitlpcs from the Mean centroids for each of 27 male and axis, with populations from northern California p1'im"i designated OTUs within multivariate three U1'o0'on OTUs by shape (Fig. 4). There female U1'o0'on samples are plotted on the first (NCOR, SFBA, MOSL) located to the left character space. The Vulpcs OTU is situated to was only slight separation ofthe U1'o0'on OTUs three canonical variate axes (Figs. 5 and 6 (largest size) of the plot (Figs. 5, 6). the extreme front left corner of the plot and is along the second CV axis. The third CV axis respectively). For both males and females, the Populations from Mexico (SONORA, MAD, divergent from the more closely packed separated the Tiburon Island gray fox from all variance-covariance matrices yielded a total of NIGR, NBCA, SBCA) occupied intermediate U1'ocyon OTUs in the center (Fig. 4). The other OTUs (Fig. 4). The large differences 17 canonical variates which exhibited positions at the center of the plot and location of both male and female island fox observed on the third axis between the sexes of statistically significant (P:S; 0.0 1) morphological populations from Central America (ORIN, OTU centroids, nearer to the U. cinc1'CO- the Tiburon Island OTU and between the variation (Table 4). The first three CV axes GUAT, COST, and FRAT) plotted to the

362 363 I I I I I I I T I I • TIBURON

3 I- MALE (87.9%) -

,...., SRle SSINV. °CHIHUA 2 - 0 - sac A .0 ORIN - If) ..J SFBA • (\. MOSL NBCA • '-" <{ SINV SDle NIGRo 8SCI 0 • QUAT SCLE. (f) Z NCOR. cOST. • FRAT MADe FRAT· W f- MOHAVE. 0 - oCHIHUA I - I- SONORA. Z <{ .SBCA <{ oSCAT NAVAJO. cr NBCAO 0 <{ save ••o sOle • SRI SFBA • SCAT SNI • > 0 - 2 - - • LADe ..J SSINV. ORIN· <{ . o GUAT 8MI. MaBLe NCOR 0 oSINV oNIGA Z - - 0 I - .COST 3 - Z • SFBA <{ 0 SClE· • SNI I II I I II I I I 2 - - I I I IIII T I I

I I I 1 I I I I I I I 2 - \ I I I I I I I I I I SRI. • SCAT SCI. oSFBA MaBLe SFBA. 8MI. o SCLE save • LADe SRI • - MOSL • SCATo - - • NCOR SNI· - SSINV .. • NCOR ,...., SINV •• SSINV ,...., SINV. SCLE· <{ - • ORIN 2 f- ..J -2 l- - > <{ ..J ORIN. 0 <{ .OUAT Z • COST 0 eCOST 0 Z 3 f- - Z -3 I- - 0 • GUAT <{ Z 0 <{ INCREASING SIZE 0 4 I- INCREASING SIZE - 4 l- - e FRAT

jFRAT I I I I I I I I I I I I I 1 I I I I I I 5 4 3 2 1 0 2 3 4 5 4 3 2 I 0 1 2 3 4 5 CANONICAL VARIATE 1 (70.4%) CANONICAL VARIATE 1 (70.3%)

Figure 5. Projection of 27 male Ul'OCYOll sample centroids onto the first three canonical axes based on discriminant function Figure 6. Projection of 27 female Ul'ocyon sample centroids onto the first three canonical axes based on discriminant function analysis of 28 cranial characters. Points represent sample centroids. Acronyms refer to population samples (OTUs) as analysis of 28 cranial characters. Points represent sample centroids. Acronyms refer to population samples (OTUs) as shown shown in Figure 1 and described in Table 1. in Figure 1 and described in Table 1.

364 365 Table 4. Logarithmized variables which were significant (P S 0.01) in distinguishing among the 27 male and Female Table 5. Matrix of probability values From F-tests which tested For significant diFFerences among Uroc)'o71 OTUs in Uroc)'o71 samples. Character acronyms are the same as in Figure 2. discriminant [,mction analysis. These tests are based on 28 cranial characters and the sexes were analyzed separately. Step \Vilk's lambda Approx. % ofInter OTU Probability values of F-tests for the males are on the upper diagonal, females on the lower diagonal. Degrees of freedom For these tests were 17 and 698 For males and 17 and 637 For Females. See Table I fDr an explanation of sample numbers. Some Number Variable U-Statistic F-Value dF Variance' probability values are specified (i.e., P < 0.05, P < 0.01), while all other values are noted with U1e Following abbreviations: S ~ MALE significant (P S 0.001) difference between two OTUs; and NS ~ not signiflcant (P> 0.(5) difFerence between two OTUs. 1 TOLiVI 0.1144 212.65 26,714 70.36 OTU 2 \VBTYP 0.0683 77.49 56,1426 12.60 No. 3 MRTL 0.0434 50.68 78,2130 4.86 Sample Male/Female I 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 4 ROSWC 0.0320 37.51 104,2823 3.46 I SlvH 17/20 S SS SS SSSSSSSSSSSSSS .05 SSSSSS 5 CHAD 0.0233 30.84 130,3503 2.46 2 SRI 31128.01 SS SS SSSSSSSSSSSSSS NS SSSSSS 6 MASW 0.0178 26.38 156,4167 1.62 7 TYNIL 0.0135 23.42 182,4814 1.15 3 SCI 64/6+ S S S SS SSSSSSSSSSSSSS NS SSSSSS 8 SORW 0.0109 20.99 208,5440 0.91 4 SNI 59/45 S SS SS SSSSSSSSSSSSSS .05 SSSSSS 9 DAPMN 0.0087 19.21 234,6045 0.76 5 SCAT 16/21 S S SS S SSSSSSSSSSSSSS .05 SSSSSS 10 PALL 0.0071 17.77 260,6627 0.53 11 PALW 0.0058 16.59 286,7185 0.43 6 SCLE 15/22 S SS S S SSSSSSSSSSSSSS .05 SSSSSS 12 IvlA}CL 0.0048 15.60 312,7719 0.33 7 NCOR 25/24 S SS S SS .05 .05 .05 NS .01 S .01 SSS .01 SSS .01 SSSSS 13 ROS\VO 0.0040 14.75 338,8229 0.23 8 SFBA 32/35 S S SS SS .05 S NS NS .05 .05 .0 ISS S.OISS .01 SSSSSS 14 BASL 0.0033 14.03 364,8713 0.16 15 TRLLM 0.0028 13.38 390,9174 0.13 9 SINV 27/49 S S SS SS NS .01 NS NS SS .01 SSS .01 SS .01 SSSSSS 16 NIANI-I 0.0024 12.80 416,9610 0.0006 IONIOSL 23/23 S S SS SS .05 SS NS .05 .05 .0 ISS SSS S.OI Jll SSSSS 17 ZYG\V 0.0021 12.26 442,10023 0.0004 II SSINV 8/11 S S SS SS NS .05 NS NS NS NS NS SS .01 NS NS NS .01 .05.01 SSSS FEMALE 12 SBVC 28/29 S SSS SS SS S S .05 NS NS S S.OI NS .05 .05.0I .05 SSSSS 1 TOLM 0.1292 169.26 26,653 70.31 13 LAOC 19/30 S SSS SS .05 .01 .01 .05 NS NS .05 SS .01 NS .05 .01 .01 .01 SSSSS 2 W13TYP 0.0710 69.04 52,1304 10.69 14 SDIC 28/25 S SSS SS .01 S .01 .01 NS .05 .05 SS .01 NS .05 NS .01 .01 SSSSS 3 DAPCC 0.0453 45.30 78,1947 5.70 4 NIASW 0.0324 34.11 104,2581 4.92 15 NBCA 15/19 S SSS SS SSSSSS S .05 S NS SSS .05 .05 SSSSS 5 ROSVlC 0.0226 28.53 130,3203 2.26 16SBCA 17/21 S SSS SS SSSSSS SS NS NS SSS .05 .0 ISS SSS 6 CRAD 0.0168 24.60 156,3810 1.54 17 SONORA 23/14 S SSS SS SSSS .05 S S .05 NS S NS NS .05 .05 .05 SSSSS 7 PALL 0.0126 21.90 182,4400 1.29 8 BASL 0.0100 19.65 208,4972 0.85 18 NI0HAVE 15/16 S SSS SS SSSS NS S S NS S S NS NS NS S .05 SSSSS 9 ZYGW 0.0080 17.99 234,5524 0.70 19 NAV1\JO 32/40 S SSS SS SSSS NS S S NS NS S NS S NS S .05 SSSSS SORW 0.0063 16.73 260,6056 0.57 10 20 CHIHUA 58/53 S SSS SS SSSSSS SSSS NS NS S S .05 SSSSS 11 DAPMN 0.0051 15.63 286,6565 0.38 12 TRLLM 0.0041 14.77 312,7052 0.36 21 TIBURON 3/1 S SSS SS SSSSSS SSSSSS S .05 .05 SSSSS 13 ANAW 0.0033 14.02 338,7517 0.24 22 MAD 417 S SSS S S .01 S .01 .01 NS .01 .05 .05 .05 .05 NS NS .05 NS .01 NS .05 SS .05 14 ROSWO 0.0027 13.37 364,7959 0.17 23 NIGR 52/51 S SSS SS SSSS SS SSSS SS S S S .01 SSSS 15 ALPM 0.0023 12.77 390,8379 0.13 16 MAXL 0.0020 12.19 416,8776 0.05 24 ORIN 18/18 S SSS SS SSSS SS SSSS SS S S SSS SS .05 17 TYML 0.0017 11.70 442,9152 0.04 25 FRAT 29/29 S S SS SS SSSS SS SSSS SS S S SSSS SS , Percent of between sample morphological variance explained For each canonical vector of interlocality phenetic variation 26 GUAT 25/41 S SSS SS SSSS SS SSSS SS S S SSS .05 S NS in Ul'01YOll samples. 27COST ~ S SSS SS SSSS SS SSS .01 SS S S SSSNSSS 6801741 right (smallest size) of the plot (Figs. 5, 6). F-tests among UroL)'oll samples for both sexes Gray foxes from northern California and indicated that the six U. littomlis populations tests and to tlle higher P-values recorded for a This is especially evident in comparisons Central America plotted at opposite ends of the were significantly different (P ~ 0.001) from number of other pair-wise comparisons made between the t07vmeudi samples (NCOR, SFBA, size spectrum on canonical variate I (Figs. 5, 6). one another as well as from all other UroiYou with this sample (Table 5). The majority of SINV, MOSL), the caliJonzicus samples Of particular interest in CVA analyses for both samples (Table 5). The only exception non-significant comparisons and higher P­ (SSINV, SBVC, LAOC) and the scottii samples sexes was the fact that the four Central occurred in the male pair-wise comparisons values obtained for F-tests between the samples (SONORA, MOl-lAVE, NAVAJO, CHIHUA) American taxa (FRAT, ORIN, COST and between Tiburon Island and the Santa Cruz occurred in comparisons between samples with (Table 5). Low sample sizes in the TIBURON, GUAT) were closest to U. littomlis samples in and Santa Rosa Island samples. The low sample low sample sizes and in comparisons between SSINV, MAD and COST samples probably size (CVl) but were most divergent when size of the TIBURON sample (u=1) probably samples from the same taxon or from helped contribute to the higher P-values and shape (CV2) was considered (Figs. 5, 6). helped to contribute to these insignificant F- geographically contiguous samples (Table 5). inCl'eased number of non-significant pairwise

366 367 Table 6. Discriminant jacknifed classification ofindividual male Ul'O')'011 from western North America, Mexico and Central Table 7. Discriminant jaclmifed classification of individual female Ul'ocyol1 from western North America, Mexico and America. Rows are actual groups and columns are predicted groups. See Table 1 for an explanation of sample acronyms and Central America. Rows are actual groups and columns are predicted groups. See Table 1 for an explanation of sample numbers. acronyms and numbers. (x) % Predicted Locality Predicted Locality Actual Classified Act1IaI C1assificd Locality IJ Correctly I 2 3 'I' 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Locality 11 Correctly 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 1 SNII 17 94.1 16 1 1 SNII 20 90.0 18 2 2 SIU 30 83.3 2 25 2 SRI 28 92.9 2 26 2 3 SCI 6'f 96.9 2 62 3 SCI 64 92.2 2 59 2 1 4SNI 59 100 4SNI 45 95.6 1 43 1 59 5 SCAT 16 93.8 1 15 5 SCAT 21 71.'1 1 4 15 1 6SCLE 16 87.5 6SCLE 21 86.4 1 1 19 2 14 7 NCOR 25 16.0 4 4 8 2 1 4 7 NCOR 24 33.3 8 4 3 3 2 2 8 SFBA 32 53.1 4 17 3 3 1 8 SFBA 35 11.4 4 4 4 8 5 2 2 9SINV 27 37.0 2 3 10 4 2 9SINV 49 32.7 6 4 16 6 4 1 1 1 IONIOSL 23 30.4 3 1 2 7 4 IONIOSL 23 13.0 3 4 5 3 4 2 11 SSINV 8 12.5 2 1 1 11 SSINV 11 18.2 2 1 2 1 1 1 12 SEVC 28 28.6 4 8 4 2 1 12 SEVC 29 17.2 2 1 5 6 1 5 1 13LAOC 19 21.1 1 1 4 2 1 13 LAOC 30 16.7 1 6 5 1 1 4 14SDIC 28 3.60 1 3 3 1 1 2 14SDIC 25 12.0 2 4 3 1 1 2 1 1 15NECA 15 20.0 1 3 3 1 15 NECA 19 63.2 12 2 1 1 16 SECA 17 58.8 3 10 1 16 SBCA 21 52.4 3 11 1 1 1 2 17 SONORA 23 30.4 1 2 7 2 5 17 SONORA 14 21.4 3 1 3 3 1 18MOHAVE 15 26.7 2 1 4 2 18 MOl-lAVE 16 6.3 4 2 1 1 1 3 1 19 NAVAJO 32 18.8 1 3 4 5 6 2 19 NAVAJO 40 12.5 3 1 2 4 4 6 5 3 1 20CHIHUA 58 5.2 6 5 8 6 4 3 11 20 CHIHUA 53 7.5 4 2 4 1 4 5 2 4 3 4 5 4 21 TIBURON 1 100 21 TIBURON 3 100 22 MAD 4 25.0 1 22 MAD 7 0 3 3 23 NIGR 52 44.2 1 2 1 5 2 23 4 3 23 NIGR 51 39.2 4 3 7 20 4 24 ORIN 18 16.7 1 2 3 2 3 24 ORIN 18 33.3 1 2 2 6 3 25 FRAT 21 90.5 19 2 25 FRAT 29 96.6 28 1 26 GUAT 25 60.0 6 1 15 2 26 GUAT 41 61.0 1 4 1 26 27 COST 5 20.0 3 1 27 COST ---.i 20.0 3 TOTAL 680 TOTAL 741 comparisons obtained for these samples (Table Island misclassified (Tables 6, 7). The most (TIBURON) and from the Yucatan Peninsula day samples from the six U. littomlis popula­ 5). The F-test results confirmed that for both distinctive localities for both males and females of Mexico (FRAT) were the only U. tions were used as targets for classification of sexes there was significant interpopulation were the six U. littoralis samples, and the cine1'eoargenteus samples to approach a similar the archaeologically recovered material. heterogeneity among the 27 Urocyon samples TIBURON and FRAT U. cinereoa1'genteus level of phenetic distinction with 100% Because a multivariate analysis of variance tested. samples (Tables 6, 7). For U. littoralis, the (TIBURON) and 90.5-96.6% (FRAT) being based on the 28 cranial characters revealed that The degree of phenetic overlap among the classification procedure produced by the correctly classified (Tables 6, 7). The low statistically significant differences (F 27 Urocyon samples is indicated by the discriminant function analysis correctly proportion of correct classifications in transformation of Wilk's lambda statistic = percentage of misclassified individuals. For classified 90.5 % (n= 180) of the males and mainland gray fox samples (Tables 6, 7) 27.87; df = 145 and 1,793; P < 0.0001) exist mainland U. cinereoargenteus samples, 94.6% (n=191) of the females to their suggests that the degree of phenetic overlap among the six present-day samples, the misclassified males averaged 71.6% and ranged respective a priori designated localities. between these samples was great and that only phenetic relationships among U. littoralis from 100% (MAD) to 3.4% (FRAT) and The higher percentage of correctly classified small-scale changes were occurring between samples were investigated by canonical variates misclassified females averaged 69.1 % and individuals in the island populations, coupled locality samples. analysis using only the 22 cranial characters ranged from 96.4% (SDIC) to 9.5% (FRAT) with the lack of any island-to-mainland C. Pbenetic Relationsbips oftbe Urocyon littomlis (Fig. 2). (Tables 6, 7). For U. littoralis samples, misclassifications, suggests a high degree of Samples: A third set of canonical variates F-tests among both male and female Urocyon misclassified males averaged 11.9% and ranged phenetic distinction between Urocyon littomlis analyses were performed using the six Urocyon littoralis samples detected statistically from 28.6% (SCAT) to 4.4% (SNI) while and U. cinereoargenteus samples. These littoralis samples. Island fox specimens significant (P < 0.05) differences among the six misclassified females averaged 7.4% and ranged classification results suggest that the island fox recovered from island archaeological sites were present-day and four archaeological samples from 16.7% (SRI) to 0% (SNI) (Tables 6, 7). is a distinct species that is closely allied with the entered as unknowns in these CVAs to (Table 8), tlms invalidating the null hypothesis For both sexes none of the foxes from Tiburon gray fox. Gray foxes on Tiburon Island investigate their population affinities. Present of no statistically significant geographic

368 369 Table 8. Matrix of probability values l from F-tests which tested for signiflcant differences among island fox samples in the discriminant function analyses. These tests are based on 22 cranial characters and the sexes were analyzed separately. Probability values ofF-tests for the males are on the upper diagonal, females on the lower diagonal. Degrees of freedom for these tests were 13 and 194 for males and 17 and 190 for females. A. MALE ~ ?f!. 3.75 (78.1 %) Locality2 SMI SRl SCI SNI SCAT SCIE SRlI scn SNII CO':! I[) C') SMI 20 25 SSSS S .01 SS ~ 2.50 SRI 32 30 S SSS S .05 S S (\J SCI 67 68 SS SS S S .05 S W I- 1.25 SNI 61 46 SSS S S S .01 .01 ::.':: 0: SCAT 16 21 S S SS S S .01 S « SCIE 17 22 S S SS S SSS > 0 ..J SRn 5 8 .05 NS SS S S .05 .01 « 2 scn I 6 .05 .05 .05 .01 .01 .05 .05 .01 z S S 0 -1.25 SNII 12 10 S SS S S .05 z SCIEI I 0 .05 .05 .05 .05 .05 NS .05 .05 .05 « TOTALS 232 236 u -2.50

I Probability notations used in this table are: S ; signiflcant (P < 0.001); NS ; not signiflcant (P > 0.05); and intermediate P -3.75 values (i.e., P < 0.05 ; .05). 2 Locality acronyms are as follows: PRESENT-DAY SAMPLES: (SMI ; San Miguel Island; SRl ; Santa Rosa Island; SCI -4.5 -3.0 -1.5 ; Santa Cruz Island; SNI ; San Nicolas Island; SCAT; Santa Catalina Island; SCIE ; San Clemente Island); ARCHAE- CANONICAL VARIATE OLOGICAL SAMPLES: (Scn ; Santa Cruz Island; SRlI ; Santa Rosa Island; SNII ; San Nicolas Island; SCIEI ; San Clemente Island). variation among samples. F-tests for females (Table 9). Although canonical variates comparisons between present-day samples all 3-13 and 17 respectively were significant (P ~ 6.0 B. FEMALE SCLEI were highly significant (P < 0.001) while 0.01), each provides only a small amount of (75.7%) comparisons between the archaeological additional discrimination between samples. CV 4.5 samples were generally significant but at axes 3-5 account for the remaining 21.9% and C\j *v ~ slightly higher probability values (Table 8). 24.3 % of the between-sample variation (Table 3.0 (\J The small sample sizes for the archaeological 9). Therefore, there is relatively little distortion W SRI I- samples probably helped to contribute to the of phenetic distances observed between samples « a: 1.5 higher P-values obtained for F-tests using these when the character space is reduced from 22 « > samples. Based upon the results of the F-tests dimensions to only two. «..J 0 and the MANOV, I concluded that it was For both sexes a considerable amount of u z appropriate to investigate dispersion of these overlap between samples is evident in the plots 0 z -1.5 samples within discriminant space. of the first two canonical variates (Fig. 7). « u Results of canonical variates analyses for both There are tl1ree basic clusters in the male CVA -3.0 male and female U. littoralis sampIes are (Fig. 7): San Miguel-Santa Rosa; Santa Cruz­ presented in Figure 7. The mean centroids for Santa Catalina-San Nicolas and San Clemente. each of the 6 present-day and 3-4 In the female CVA, four of the samples -4.5 archaeological samples are plotted on the first overlaped broadly to form two basic clusters. -5.4 two canonical variates axes (Fig. 7). The The first cluster is composed of the San Miguel variance-covariance matrices yielded a total of and Santa Rosa Island samples while the second Figure 7. Projection of populations onto the first two canonical ~L"{es based on discriminant function analys!s of cranial 13 canonical variates for males and 17 variates 2: cluster consists of Santa Cruz and Santa characters for (A) male and (B) female U1'OeyOll littomlis. Solid squares denote present-day sample centrOIds wlule. open for females that exhibited statistically significant Catalina Island samples (Fig. 7). For both sexes, squares denote archaeological samples. A star is used to denote the location of fossil island fox specimeI~s. ~mIInum (P ~ 0.01) morphological variation (Table 9). there is general correspondence between the polygons (solid lines; present-day samples; dashed lines; archaeologically recovered samples) enclose all mdl\'1duals of ~able The first two axes depicted accounted for position of present day samples in multivariate each island sample. Acronyms identify population samples as shown in Figure 1 and described in 1. Acronyms for the archaeological specimens are: SRlI ; Santa Rosa Island; scn ; Santa Cruz Island; SNII ; San NIcolas Island and SCLn ; 78.1 % 75.5% of the variance in males and in character space and their actual geographic San Clemente Island.

370 371 locations. For males, the samples are arrayed The archaeological samples generally Table 9. Logarithmized variables which were significant (P < 0.01) in distin/o'Uishing among the Urocyon littoralis samples. counter-clockwise from north to south starting overlap extensively with the present-day sample Character acronyms are the same as in Figure 2. with San Miguel in the upper right and ending from the island on which they were excavated Step 'Ville's lambda Approx. % InterOTU with San Clemente in the lower right (Fig. 7). (Fig. 7). This can best be seen by the degree to Number Variable U-Statistic F-Value df Variance l For females, the samples are distributed north which present-day and archaeological samples MALE to south in a clockwise pattern (Fig. 7). For from San Nicolas Island overlap (Fig. 7). Also, 1 WBTYP 0.5230 37.58 5,206 42.9 10,410 35.3 both sexes, there does not appear to be a direct the group centroids for the archaeological 2 MASW 0.2961 34.35 3 SORW 0.1666 34.34 15,564 11.7 association between the location of samples in samples are situated more closely to one 4 NAiVnV 0.1035 33.09 20,674 6.4 multivariate character space and the actual another in both plots than are the centroids for 5 NIA,'(L 0.0705 31.35 25,752 3.8 geographic distances between islands. For the present-day samples (Fig. 7). This, coupled 6 NASL 0.0448 31.54 30,806 example, the Santa Catalina Island sample is with the broad overlap observed between 7 PAL'V 0.0341 29.70 35,844 CRA\V 0.0266 28.26 40,870 morphologically closer to Santa Cruz Island present day samples from Santa Cruz, Santa 8 9 BASL 0.0213 26.94 45,889 than to its geographically closest neighbors San Catalina and San Nicolas Islands and the slight 10 CRAD 0.0179 25.55 50,902 Clemente and San Nicolas Islands (Fig. 7). In overlap between San l'.1iguel and San Clemente 11 ROSWC 0.0150 24.47 55,911 both CVAs, the degree of divergence observed Island samples (Fig. 7), suggests that island 12 TYML 0.0132 23.21 60,917 22.09 65,921 among the northern Channel Island samples foxes were probably being moved between 13 ZYGW 0.0118 (SMI, SRI, SCI) roughly corresponds to the islands during Indian occupation. FEMALE length of time that these islands have been Of particular interest in the female CVA is 1 WBTYP 0.3814 67.16 5,207 51.6 isolated from one another. Following the last the location of a fossil island fox specimen 2 IvIAS'V 0.1953 52.03 10,412 24.2 glacial epoc, Santa Cruz Island last separated which had been recovered from a geological 3 SORW 0.0925 51.66 15,566 11.8 4 MAXL 0.0527 48.39 20,678 8.9 from Santa Rosa and San Miguel Islands about formation on Santa Rosa that dates between 5 NAIvIW 0.0349 44.37 25,756 3.6 2,000 years before the latter two islands 10,400-16,000 years of age (Orr 1968). This 6 BASL 0.0262 40.13 30,810 separated fTom each other aohnson 1983). specimen, noted by the star, is situated between 7 CRAD 0.0200 37.15 35,848 The present-day sample from San Clemente the group centroids for present-day samples 8 ANAW 0.0161 34.55 40,875 32.60 45,893 Island is divergent from the other samples for from San l'.1iguel and Santa Rosa Islands (Fig. 9 NASL 0.0130 10 CRAW 0.0107 30.92 50,906 both the male and female analyses (Fig. 7). 7). At the time that this specimen was 11 ROSWO 0.0088 29.62 55,915 Although the San Clemente Island sample is deposited, the northern Channel Islands were 12 IvIRTL 0.0075 28.36 60,922 divergent on the size axis (CV-1), it is virtually all interconnected as one super island known as 13 PALL 0.0065 27.16 65,925 indistinguishable from the other present-day Santarosae. This specimen proves that small­ 14 ROSWC 0.0056 26.12 70,928 15 PALW 0.0049 25.15 75,929 samples on the shape axis (CV-2) (Fig. 7). Tlus sized island foxes were present on Santa Rosa 16 ZYGW 0,0043 24.47 80,929 suggests that foxes on San Clemente Island Island prior to currently accepted dates (9,000­ 17 PORW 0.0038 23.68 85,928 only have been isolated for a relatively short 10,000 years B.P.) for the arrival of Native I Percent of between sample morphological variance explained for each canonical vector of interlocality phenetic variation period of time, and as such, have not had a Americans to the northern Channel Islands in U. littomlis. sufficient length of isolation to evolve (Erlandson 1988). It also indicates that foxes on substantive shape differences. the northern Channel Islands have changed the percentage of correctly classified had a sufficient length of time to evolve In the female CVA, the San Nicolas Island very little, at least in overall size and shape, individuals, the most distinctive localities for substantive morphological traits different from sample was divergent in size (CV-1) but not in during tlle last 16,000 years. males were San Nicolas (95.7%) and San those possessed by the original founders. As a shape (CV-2) from the other island samples The degree of phenetic overlap among the Clemente Islands (95.5%), and for females result, foxes present on the soutllern Channel (Fig. 7). Also, the archaeological sample from present day Urocyon littoralis samples was were San Nicolas and Santa Catalina Islands Islands may resemble one another more closely San Nicolas Island overlapped with present-day further assessed by comparing the proportion (100% for both samples) (Table 10). The high than do foxes on tlle nortllern Channel Islands samples from San Nicolas and San Clemente of individuals from each sample that were proportion of correctly classified individuals because of the short lengtll of time (800-3,400 Islands (Fig. 7). Overlap observed in the female misclassified by the discriminant function. The among the southern Channel Island years) that they have been isolated from one CVA among present-day samples and between classification procedure of the discriminant populations (Table 10) could be due to the another and because of the small size of the present day and archaeological samples (Fig. 7) function analysis correctly classified 89% influence of a morphologic and/or genetic original founding populations. suggests that gene interchange may have been (n=189 of212) ofthe males and 93% (77=199 of bottleneck. If these populations were Given the high proportion of correct occurring between island fox populations 213) of tlle females to tlleir respective a p1'i01'i introduced by Native American as documented classifications in both the male and female during Indian occupation of these islands. designated localities (Table 10). As indicated by by Collins (1991a, b), tllen they may not have analyses (Table 10), it should be possible to

372 373 Table 10. Discriminant jackknifcd classification of individual island fox, based on 22 skull characters. Rows :lre actual reveals that, aside from resembling gray foxes Spermopbillls sp. and Neot07Jlfl sp.) has kept gray groups and columns are predicted groups. The archaeological material is classified in relation to the discriminant equation from Central America in overall size, island established from the six present-day island samples. Sample acronyms are the same as those in Table 8. foxes on Tiburon Island from evolving to a foxes are furthest from Central American gray Predicted Locality smaller body size. Finally, Tiburon Island has Actual % Classified foxes when other non-size related characters two other carnivores (Cflnis lfltrflns and SRI SCI SNI SCAT SClE Locality 11 Correctly SMI are considered (i.e., shape). Insular populations BflSSflrisCllS flstUtltS) that compete with the gray MALE of UroL)'on have shifted to the right (i.e. smaller fox (Lawlor 1983). Competition from these SMI 25 92.0 23 2 size) of the north-south size cline exhibited by SRI 30 90.0 2 27 I carnivores for available food resources may SCI 68 86.8 2 59 5 2 mainland Urocyon samples (Figs. 5, 6). Results have had the effect of restricting gray foxes to SNI 46 95.7 I I 44 from the present study refute Stock (1943) and utilizing moderate sized food resources. As a SCAT 21 71.4 2 3 IS von Bloeker (1967) who hypothesized that result, it has not been adaptive for Tiburon 95.5 21 SClE 22 island foxes evolved from Central American Island gray foxes to evolve a body size as small 8 5 SRII gray foxes. Once size is removed as a con­ SCll 6 I 2 I as that seen in island fox populations. Thus, tlle SNII J.Q 9 trolling factor in tlle canonical variates analysis, intermediate nature of the body size of gray TOTAL 236 island foxes are phenetically closer to gray foxes foxes on Tiburon Island (Figs. 5, 6) is probably presently found in central and northern a combined result ofshorter length ofisolation, FEMALE California (Figs. 5, 6). This result confirms tl1at SMI 20 80.0 16 3 I larger available prey size and competition Witll SRI 32 84.4 3 27 I I island foxes originated from gray foxes found in other carnivores. Of particular interest is the SCI 67 94.0 2 63 I California and not from gray foxes found in fact that foxes on Tiburon Island have declined SNI 61 100.0 61 southern Mexico or Central America. an average of 10% in body size after being SCAT 16 100.0 16 All seven of the insular populations show a SClE 17 94.1 16 isolated for only 15,000 years. This rapid rate SRll 5 2 reduction in overall body size when compared of evolution has been documented for other scn 1 Witll adjacent mainland populations (Figs. 5, 6). island mammal populations (Sondaar 1977; SNII 12 7 2 Island foxes exhibit a size reduction of 14-18% Marshall & Corruccini 1978; Lister 1989). SCIEI _1 in males and 12-17% in females (Collins 1982). TOTAL 232 Canonical variates analysis of the Foxes on Santa Catalina Island were tl1e largest morphologic data revealed that the only major sized foxes while Santa Cruz Island foxes were phenetic discontinuities between Urocyon classify tl1e archaeological samples witl1 a high Islands, while one each were classified to the the smallest. Case (1978) suggests that the samples coincided with significant natural degree of precision. For the male analysis Santa Rosa and San Clemente Island samples availability of larger sized prey on Santa barriers to gene flow such as water gaps or 66.7% (n=16 of 24) of the archaeological (Table 10). The fossil specimen from Santa Catalina Island is the principal factor isolation by distance on peninsulas. specimens classified to the island from which Rosa Island was correctly classified to its island responsible for the larger size of the Santa Morphometric data presented herein reveals tlley were excavated while 63% (n=12 of 19) of of origin as was the single archaeological fox Catalina island fox. Smaller body size has that, aside from the seven island populations, the females were classified to their island of specimen from San Clemente Island. The probably been selected for in island foxes due all of the remaining U1wyon populations are origin (Table 10). Of particular interest classification results of the archaeological to the high predominance of smaller sized arrayed on a north to south size cline (Figs. 5, regarding the possible role which Native samples further suggests tl1at Native Americans foods (e.g., insects, seeds, fruits, berries and 6). The largest sized foxes are found in American may have played in establishing some played an active role in helping to establish deer mice) in tlleir diet. northern California and Oregon while of the island fox populations, is the pattern of island foxes on some ofthe California Islands. Gray foxes from Tiburon Island have intermediate sized foxes occur in central misclassifications exhibited by the declined an average of 10.3-10.8% (Collins Mexico and small sized foxes occur in southern archaeological samples. Of the Santa Rosa Discussion 1982). This smaller size reduction compared to Mexico and Central America (Figs. 5, 6). This Island archaeological specimens to misclassify, iliat exhibited by island foxes could be a result result is similar to the size cline which Koch Morphologic Variation: Similarities in size all (n=5) misclassified to the adjacent San of several factors. First, foxes on Tiburon (1986) reported for the length of M 1 in gray Miguel Island sample. Of the 4 Santa Cruz and color between island foxes and gray foxes Island may not have had a sufficient length of foxes from North Dakota to Guatemala. Island archaeological specimens that were found in Central America led several autllOrs to time to evolve an optimum body size because There is extensive geographic variation, at misclassified, one was misclassified to each of suggest the hypothesis that island foxes had they occur on a nearshore landbridge island least in overall size, among western North the islands except San Clemente Island (Table descended from gray foxes presently found in which has been isolated from the adjacent American populations of Urocyon cinereo­ 10). Of the 6 archaeological specimens from southern Mexico and Central America (Stock Sonoran mainland for only 15,000 years fl1-genteus. Except for foxes on the Yucatan San Nicolas Island to misclassify, 2 each were 1943; von Bloeker 1967; Remington 1971). (Lawlor 1971). Second, the presence of large peninsula (FRAT), there is a fairly high degree classified to San Miguel and Santa Catalina The morphometric data presented herein available prey species (e.g., Lepus sp., of phenetic overlap among the 20 mainland

374 375 Table 11. Estimates of morphological variability for island and mainland Ul'OC)'Oll populations. samples as evidenced by the low proportions Geographic Patterns of Population (0-63 %) of correctly classified individuals in Variability: vVith the exception of LYRW, Males Females WBTYP and NANlvV all of the remaining Sample Sample both the male and female discriminant [-unction Sample! Size CV2 SD Size CV2 SD analyses (Tables 6, 7). These data suggest that cranial characters used in this study had ISLAND POPULATIONS coefficients of variation (CVs) less than 10% only gradual small-scale phenetic changes have 1 SNII 20 3.26 1.81 17 2.69 1.02 occurred between adjacent gray fox (Collins 1982). The higher CVs obtained for 2 SRI 28 3.85 1.96 31 3.45 0.98 populations. This pattern of morphometric these three characters could be the result of 3 SCI 64 3,36 1.83 64 3.05 1.18 variation is attributable, at least in part, to the greater inherent variation in these characters or 4 SNI 45 3,30 1.17 59 2.91 0.98 5 SCAT 21 4.41 1.92 16 3.94 1.48 absence of any significant geographic barriers higher than average measurement error. Other 6 SCLE 23 3.88 1.45 16 3.79 1.44 adequate to result in the level of morphologic cranial characters that showed fairly high levels 21 TIBURON 1 3 Lll 1.80 divergence observed in Urocyon populations of variability (6-9%) included tympanic length Island .1' 3.68 0.41 3.61 0.55 that are restricted to islands. (TYML), several characters of the rostrum Gray foxes on the Yucatan Peninsula (NAMW, ANAW, ROSW, NASL, ROSWO) MAINLAND POPULATIONS 7 NCOR 24 4.57 2.06 25 4.78 1.84 and several mandibular characters (DAPCC, (FRAT) are the only mainland gray fox 8 SFBA 35 4.50 2.41 32 4.71 2,36 population to exhibit a moderate amount of RAMW, DAPMN). The remaining cranial 9 SINV 49 5.38 2.43 27 4.60 2.28 morphologic divergence. This is best exempli­ characters showed lower levels ofvariability (I­ 10 MOSL 23 4.17 1.95 23 4.62 2.07 fied by the high proportion (90.5-96.6%) of 5%) that were relatively uniform across 11 SSINV 11 4.87 3.56 9 4.54 2,31 12 SBVC 29 4.58 2.07 28 5.25 2.08 correctly classified individuals in the localities. 13 LAOC 30 4.45 2.03 19 4.69 2.23 discriminant function analysis and in tlle extent Morphological variability between island and 14 SDIC 25 4.95 2.69 28 4.98 1.93 to which this population has diverged from mainland populations was evaluated by 15 NBCA 19 4.69 2.24 15 5.06 1.88 other gray fox populations in southern Mexico calculating a mean coefficient ofvariation (CV) 16 SBCA 21 4.96 2.53 17 5.43 2.40 and Central America (Figs. 5, 6). The for each population based on coefficients of 17 SONORA 22 5.29 2.50 51 4.48 1.95 18 MOHAVE 25 4.64 2.49 25 4.96 2.45 geographic barrier which has isolated gray variation calculated on untransformed data for 19 NAVAJO 42 4.92 2.69 23 4.67 1.85 foxes on the Yucatan Peninsula [rom adjacent the 29 cranial and mandibular characters 20 CHIT-IDA 53 5.08 2.56 29 5.10 2.25 gray fox populations has apparently been of (Table 11). For both the male and female 22 MAD 7 4.14 2.47 4 5.01 2.63 sufficient magnitude to result in a moderate samples, island populations showed lower mean 23 NIGR 51 5.47 2.18 52 5.49 1.93 2.36 coefficients of variation (3.61-3.68) than did 24 ORIN 18 6.52 2.14 18 5.32 level ofmorphologic divergence. 25 FRAT 29 4.54 1.83 21 5.57 1.78 Latitudinal variation in body size exhibited mainland populations (4.93-4.95). In general 26 GUAT 41 5.99 2.50 25 5.18 2.49 by mainland Urocyon populations is consistent the two smallest islands (SMI, SNI) had the 27 COST 5 4.85 .ul 5 4.60 2.89 with size trends predicted by Bergmann's rule lowest levels of variability while Santa Catalina Mainland.i' 4.93 0.57 4.95 0,33 (i.e. races of warm blooded animals in colder Island had the highest variability (3.94-4.41) 1 Sample acronyms are the same as in Table 1. climates tend to be larger than races of the recorded for any island sample. The low level 2 CV equals the mean coefficient of variation based on coefficients of variation calculated 011 untransfonned data for 29 cranial and mandibular (mensural) characters for each population sample. same species living in warmer climates; Mayr of morphologic variability (2.31) recorded for 1963). The observed clinal pattern of size female foxes on Tiburon Island is probably a and COST samples. When mainland samples California and Oregon. There were no other variation in U1'ocyon is probably best explained result of the low sample size (n=3) for this with low sample sizes (COST and MAD) and consistent patterns of variation in mean CVs by phenotypic expression of physiological population. samples from the Yucatan Peninsula (FRAT) for cranial characters that might correspond to adaptations of populations to gradual change in Mainland male samples showed an overall were left out of least squares regression ecological, environmental or geographic climatic variables such as temperature, rainfall, mean coefficient of variation of 4.93 with a humidity and annual actual evapotranspiration. range of 4.14-6.52. The majority of male analyses, then mean coefficients of variation parameters. Thus, the observed size variation may repre­ samples had mean CVs in the 4-5% range exhibited significant negative correlations with A number of studies have reported that sent an ecophenotypic response rather than (Table 11). For females, mean CVs were latitude for both males (1'= -0.762, P < 0.025) island populations tend to have lower levels of evolutionary divergence. Similar patterns of slightly higher averaging 4.95 and ranging and females (1'= -0.972, P < 0.005). Thus, morphological and genetic variability than clinal size variation have been documented for from 4.48-5.57. A greater proportion of female mainland U1'ocyon populations exhibit clinal their mainland counterparts (Van Valen 1962; a number of other North American carnivores, samples exhibited mean CVs in the 5% or variation in morphological variability with the Soule et al. 1973; Patton et al. 1975; Berty & namely: Procyon (Goldman 1950; Ritke & above range. Low sample size probably most variable populations occurring in Peters 1976; Gill 1980; Aquadro & Kilpatrick Kennedy 1988); Canis (Young & Goldman contributed to the lower levels of southern Mexico and Central America and the 1981; Ashley & Wills 1987, 1989; Baker et al. 1944) and Spilogale (van Gelder 1959). morphological variability recorded in the MAD least variable populations occurring in northern 1990; Dennison & Baker 1991). Drift, gene

376 377 flow, mutation and microevolutionary competition and limited gene flow. However, resulted in higher morphological variability in Tiburon Island have declined an average of processes are factors believed to be responsible all of these factors are known to select for a the Santa Catalina Island population. The fox 10.3-10.8% (Collins 1982). for the origin and maintenance of variability reduction in morphologic and genetic population on Santa Cruz Island may have Various hypotheses have been offered to within populations (Dennison & Baker 1991). variability. gone through more population bottlenecks account for insular body size trends (Case Founder effect is the principal factor believed Size of island and thus the effective size of a during its longer period of isolation than has 1978; I-Ieaney 1978; Wassersug et fli. 1979; to be responsible for the initial decline in population coupled with historical effects are the fox population on Santa Catalina Island. Lawlor 1982, 1983). The consistent trend morphological variability in island populations. two factors which have apparently influenced The observed patterns of morphological toward smaller body size in insular Urocyon This is because most island populations tend to morphological variability in Ur0i)'0n littoralis variability in island fox populations are populations suggests that changes in the size of be founded by only a few colonizers who bring populations. Fox populations on the two probably a combined result of colonization faxes on islands has not been due to random with them limited genetic and morphological smallest islands (SMI, SNl) have lower levels of events, reduced gene flow (variable rates of events (vVassersug et fli. 1979). Nor can variability. Founder effect is the factor which morphological variability than fox populations genetic interchange), genetic drift in small stochastic effects be used to explain the best explains the initial development of reduced on the larger islands. Small population size populations and past island specific bottlenecks. widespread occurrence of dwarfism among levels of morphological variability in island coupled WitIl strong directional selection could Variation in Body Size: Previous studies of insular populations of canids or for tlle initial U1'OCyon populations. In addition to having only have led to a reduction in phenotypic size variation in insular mammals have shown occurrence of dwarfed individuals in an island been founded by a few individuals, most of the variability. However, morphological variability that carnivores, artiodactyles and Perognatbus population (Wassersug et fli. 1979; Lawlor island populations have probably also suffered in insular populations of UroiJ'on does not tend to decrease in body size on islands while 1982, 1983). periodic population crashes. These bottlenecks correspond directly with degree of isolation lagomorphs andmurid rodents tend to increase The initial appearance of dwarfism within a would further tend to reduce morphological (i.e., distance from available colonizers), habitat in body size (Foster 1963,1964,1965; Heaney population is probably the result of a mutation variability. Continued isolation of island diversity, size of island or with effective 1978; Case 1978; Lawlor 1982,1983). expressed due to inbreeding which occurs in populations from mainland gene pools, coupled population size at least for the larger islands Dwarfing of large mammals on islands is small isolated populations. Selective inbreeding with strong directional selection, are two (Table 11). Faxes on Santa Catalina Island particularly evident in t~'{a like deer, elephants, has been used to produce dwarf breeds of dogs, factors that would tend to maintain reduced exhibit greater morphological variability than hippopotamuses and carnivores (Kurten 1959; horses, sheep, cattle and goats. Dwarfism in levels of morphological variability in insular fox do faxes on Santa Cruz Island despite Santa Sondaar 1977). Dwarfism of large mammals inbred populations could be related to a point populations. Catalina Island being smaller in overall size isolated on small islands is one of tlle "island mutation that results in a hypopituitary As a result of colonization events, bottle­ (194 km2) than Santa Cruz Island (249 km2) rules" which seems to have few exceptions. condition that leads to a deficiency of the necks and novel ecological situations, and in having fewer resources and a narrower Among carnivores Foster (1963,1964) growth hormone. In humans, ateliotic and peripherally isolated island populations range of habitats than Santa Cruz Island. The reported that bears tend to increase in size on achondroplastic dwarfs are known to occur generally experience new selective pressures morphological variability differences observed islands while faxes and raccoons tend to more frequently in inbreed populations which result in dramatic shifts in morphology between these two island could be related to decrease in size. Other carnivore genera such as (Capapin 1937; McKusick 1955). The gene or and variances. Morphological variability in the fact that the largest island faxes occur on lVlartes and lVlustela show no consistent size gene complex believed to be responsible for populations have been correlated: 1) with niche Santa Catalina Island and the smallest faxes trends while Spilogale and Lynx are dwarfism in humans is an autosomal recessive breadth (i.e., habitat complexity, resource occur on Santa Cruz Island. It could also be a indistinguishable from their mainland relatives gene. Thus, high rates of inbreeding within a partitioning and availability; Van Valen 1965; result of historical colonization events. Island (Case 1978). Among canids 25 of 33 insular population can result in this gene or gene Rothstein 1973; Grant 1979a; Power 1983); 2) faxes have been present of Santa Cruz Island populations have declined in body size, one complex showing up in relatively high with changes in interspecific competition for more than 16,000 years, while the remained tlle same and seven increased in size frequency within a population in a relatively (Schoener 1970); 3) with a reduction in gene archaeological record suggests that island faxes (Collins 1982). Six of the seven populations short period of time. If there is a selective flow (Grant 1979b); 4) with effective from one of the nortllern Channel Islands were tIlat inCl'eased in size OCCUlTed on islands above advantage to becoming a dwarf then inbreeding population size (i.e., genetic bottlenecks and used by Indians to establish an island fox 48° latitude. The only mid-latitude canid could result in dwarfs becoming dominant founder effects; Lawlor 1983; Wayne et al. population on Santa Catalina Island sometime population to increase in size occurs on Sri fairly rapidly in a population. 1991 a); or 5) with some combination of these between 800 and 3,800 years B.P. (Collins Lanka where an abundance of large sized prey A number of models have been proposed for factors. Determining which of the above 1991 a). Since Santa Catalina Island was a species occur and a reduction in interspecific factors that would tend to select for insular factors is responsible for the variability trends center for trade between the northern and competition with other carnivores may have dwarfism. Wassersug & co-authors (1979) used observed in U1'oiyon populations is difficult to southern Channel Islands (Collins 1991 b), it is selected for larger body size (Collins 1982). In a computer simulation model to show that assess because it is hard to test each factor possible that faxes from several of the islands the genus Urocyon, all seven of the island dwarfism would develop in populations where separately. Islands tend to have a narrower were introduced to Santa Catalina Island a populations have declined in body size (Figs. 5, there was strict resource limitations. range of habitats, fewer available resources, number of times. Increased gene flow along 6). Size reductions in U. littoralis populations Populations composed of smaller sized smaller effective population sizes, less with a shorter period of isolation could have have ranged from 12 -18 % while foxes on individuals could better track environments

378 379 with limited carrying capacitIes. During yet defend mutually exclusive territories. Case such as seeds, berries, fruits and insects tend to on floating debris from the adjacent mainland. environmental perturbations a greater number (1978) proposed tllat body size in island foxes is be distributed in a more heterogeneous fashion Rafting previously has been documented off of small-bodied individuals would survive than probably controlled by either physical or biotic (i.e., log normally distributed). As such, search the coast of southern California when a Lepus would larger-bodied individuals thus assuring factors such as an animal's effectiveness in costs for particulate foods tend to be hig'her cal~Fmlicus was found alive on a raft of kelp 24 population survivorship. An insular population finding or handling preferred food items and than for nonparticulate foods (Lawlor 1982). Ian northwest of San Clemente Island and 63 would have a better chance of surviving for a increases in intraspecific competition. Annual production of particulate foods on km off the mainland coast (Prescott 1959). longer period of time if its population was On the mainland, carnivore communities are islands tend to be poor or capricious and the Thus, overwater dispersal via swimming, composed ofindividuals ofsmaller body size. apparently segregated by the mean size of their diversity and abundance of these food resources rafting or human assisted transport offer the Heaney (1978) and Van Valen (1973a, b) prey (Rosenzweig 1973; Schoener 1969). Case tend to be lower on islands compared with only plausible mechanisms for initially getting purported that body size of insular mammals is (1978) suggests that a reduction in the average mainland localities (Lawlor 1982). In the foxes to one of the California Islands (Wenner related to the extent and interaction of size of prey on the islands coupled with a lack absence or reduction of predation and & Johnson 1980). competition, predation, and food limitations on of competition from various sized sympatric interspecific competition, island foxes evolved a The fact that an already small-sized island islands. I-Ieaney (1978) suggested that dwarfism carnivores were two additional factors which smaller body size to balance their metabolic fox fossil was present on Santa Rosa Island at is favored in mammals that inhabit small have contributed to the selection for small demands with the energy required to locate and least 16,000 years B.P. (Orr 1968), coupled islands where resources are most limiting and body size in island foxes. Foxes dwarfed on the consume small-sized particulate food resources. with the presence of island fox bones on large islands where interspecific islands because they were not competing with Hypothesis on Island Colonization: throughout all levels of Indian occupation on competition is most intense. One of Heaney's sympatric carnivores along a body size gradient Although there have been a number of land Santa Rosa and Santa Cruz Islands (Collins predictions is that species with similar average and because there were few larger sized prey bridges proposed to explain the present 1991a), infers that Native Americans were not body size on the mainland should show body­ species (e.g., rabbits, squirrels, woodrats and distribution of plants and animals on the responsible for the initial transport of gray size changes in the same direction on islands gophers) available on the islands for foxes to California Islands (Chaney & Mason 1930; foxes fi'om the mainland to tlle islands. Ratller, where they CO-occur. Coyotes and gray foxes eat. As a result, island foxes utilize a greater Stock 1943; Clements 1955; Van Gelder 1965; gray foxes from the adjacent mainland probably on Tiburon Island and Nasua nelsoni and proportion of small prey items (e.g., berries, Valentine & Lipps 1967; Remington 1971), the first reached one of the northern Channel Proc),on p),gmaeus on Cozumel Island provide fruits, insects, small birds and deer mice) in recent geologic history of these islands Islands on their own accord by chance support for this prediction (Collins 1982). their diets than do mainland gray foxes confirms that there were no land bridges overwater dispersal prior to the arrival of However, Heaney's second prediction that (Laughrin 1977; Collins 1980). during tlle Pleistocene between the islands and Native Americans 9,000-10,000 years B.P. body size is negatively correlated with island Lawlor (1982) provides yet another the mainland, between the northern and Following an initial period of isolation on tlle area is not supported by data from insular hypothesis for the evolution of body size in southern Channel Islands, or between any of first island colonized, foxes rapidly evolved to Uroc)'on populations. This is probably due to insular mammals. He suggests that there is a the southern Channel Islands Gohnson 1978, their present small body size. species-specific responses to the availability of decline in tlle absolute abundance of resources 1983; Junger & Johnson 1980; Vedder & Small-sized island foxes would have different types of resources and different levels on islands and, as a result, the available food Howell 1980). Thus, alternative explanations dispersed to the remainder of the northern of competition on islands of similar sizes. supplies become more course-grained and thus are needed to explain the dispersal of foxes to Channel Islands during the late Quaternary Niche hypotheses for the development of tend to be more limiting to particulate the Channel Islands. when these islands were connected as one super dwarfism are difficult to test because resource specialists (i.e., seed eaters). Under these There is no evidence that gray foxes are island (Santarosae). The Santarosae landmass limitation and competition are not mutually conditions, energy and nutritional yields per good swimmers or that they would be capable developed several times during glacial episodes exclusive phenomena. animal decline thus resulting in severe of swimming a distance of 6 km (4 miles), in the Pleistocene aohnson 1978, 1983). Case (1978) predicted via optimal energy competitive constraints on large body size which was the shortest distance to occur during Santarosae reached its maximum size and consumption Lotka-Volterra equations of (Lawlor 1982). Since the metabolic demands the Pleistocene between the northern Channel coalesced for the last time about 24,000-18,000 consumer-resource relationships that the for mammals of small body size are less than Islands and the mainland Gohnson 1978). It is years B.P. when sea level was about 120 m optimum body size of an insular population those for a larger body size, small body size is reasonable to assume that foxes from the below its present-day level Gohnson 1983). As should be directly related to tlle availability of selected for among particulate specialists on adjacent mainland could have first reached one glaciers began receding following the end of resources. Case (1978) suggested that a islands. Lawlor (1982) suggests tllat carnivores of the Channel Islands on a raft of debris the last Wisconsin Glacial epoc, 16,000-17,000 population would increase in body size if the on islands fit this body size hypothesis because washed out to sea during a winter storm from years ago, sea level began to rise and the overall resource availability per individual were their diets tend to be limited to particulate one of southern California's rain-swollen rivers Santarosae landmass started to break up. greater and if a species prevented resource foods such as mice, insects, berries and fruits. (Wenner & Johnson 1980). Johnson (1983) Anacapa Island separated from Santarosae first depletion by defending feeding territories. The body size trends exhibited by insular provides a convincing argument that islands off around 12,000 years B.P., followed by Santa Island foxes are an apparent exception to Case's Uroc)'on populations ultimately are a function of the coast of southern California were probably Cruz Island at 11,500 years B.P., and finally by hypothesis since they decrease in size on islands metabolic considerations. Particulate foods colonized by terrestrial vertebrates that rafted San Miguel and Santa Rosa Islands at 9,500

380 381 Absence of variability in fingerprint restriction years D.P. Gohnson 1978). Thus, island foxes than 2,000 yr, coupled with the lack of any San Clemente Island archaeological sites fragment profiles, in allozymes and in mtDNA have been isolated on Santa Cruz Island for a intermediate sized fossil foxes on the islands (Collins 1991). The recovelY of an island fox genotypes as well as reduced levels of longer period of time (about 2,000 yr) than provides evidence that island foxes are capabl~ bone from tlle Eel Point Site (SCII-43C) below morphologic variation in San Nicolas Island have the Santa Rosa and San Miguel Island fox of tlirly rapid rates of evolution. a level which has been radiocarbon dated at faxes (Wayne et al. 1991 a) supports a fairly populations. The degree of morphological In the absence of any island-to-mainland and 3,400 years B.P. suggests that island faxes were divergence observed in present-day fox between island land bridges, it is highly recent colonization of San Nicolas Island. If introduced to this island by Indians sometime faxes had been present on any of the southern populations on the northern Channel Islands improbable to assume that the southern after 4,300 B.P. but before 3,400 B.P., which is correlates with the recent geologic history as Channel Islands were independently colonized Channel Islands prior to the arrival of Native the length of time that this horizon of the evidenced by the slight divergence of the Santa by foxes from the mainland or the northern Americans, then I would have expected to find SCII-43C site is believed to have been occupied Cruz Island population and the broad overlap Channel Islands. If this were the case, then their remains in middens throughout all (Collins 1991a). of the San Miguel and Santa Rosa Island foxes would have to have made successful periods of Indian occupation as they are found It is unclear whether the fox population on populations (Fig. 7). Misclassification of overwater crossings on their own at least three in archaeological sites on the northern Channel San Clemente Island resulted from a single or present-day and archaeologically recovered different times. At 18,000 years B.P. the extent Islands (Collins 1991 a). This is not the case. I multiple colonizations from San Nicolas or foxes between these three islands (Table 10) of the water barriers to be crossed would have have reported in a previous paper (Collins Santa Catalina Islands, or from one of the suggests that foxes were probably being ranged from 35-105 km between the northern 1991 a) that foxes do not appear in northern Channel Islands. Based on genetic transported between the northern Channel and southern Channel Islands, 18-70 km archaeological sites until about 3,400 years B.P. data Wayne & co-authors (1991a) concluded Islands during Indian occupation. between the southern Channel Islands and the on San Clemente Island, 800-3,880 years B.P. that San Clemente Island was the first of tlle Establishing an exact time when gray foxes mainland, and 27-52 km between the southern on Santa Catalina Island, and 2,200 years B.P. southern Channel Islands colonized, probably first reached one of the northern Channel Channel Islands Gohnson 1983). These on San Nicolas Island. Thus, island faxes must with foxes transported from San Miguel Island. Islands is problematic given the meager fossil distances would have made it highly have reached the southern Channel Islands via The morphometric analyses indicate that while record of faxes on the islands. Morphologic improbable that faxes could have reached the transport in Indian watercraft well after Native foxes on San Clemente Island have diverged data leads me to conclude that gray faxes southern Channel Islands on their own accord Americans first colonized the southern slightly from the other island fox populations, probably first reached one of the northern by swimming or rafting. Channel Islands 9,000-10,000 years B.P. they are situated closest to tlle Santa Catalina Channel Islands during the later part of the The morphometric and archaeological Misclassification of archaeological specimens and San Nicolas populations in the male CV Pleistocene (25,000-40,000 years B.P.) just analyses support a fairly recent, post-Holocene from San Nicolas Island to four other island analysis and overlap slightly with the San prior to the maximum Wisconsin glaciation of introduction of island foxes from tlle nortllern samples (Table 10) suggests that faxes were Miguel Island population in the female CV 24,000-14,000 years B.P. Following a short Channel Islands to the southern Channel probably occasionally being transported by analysis (Fig 7). This, coupled with the high (i.e., 10,000 yr or less) initial_period of Islands by Native Americans (Collins 1991a). Indians between the islands tllroughout at least proportion of correctly classified individuals isolation, these foxes rapidly evolved to their Regular transport of supplies and materials the Late Period (800-120 years B.P). Indian (94-96%) in the Jackknifed classification present small body size as a result of unique between the northern and southern Channel assisted transport of island foxes provides tlle procedure of the discriminant function analyses selective factors such as lack of close Islands by ilie Chumash and Gabrielino Indians most plausible explanation for the presence of (Table 10), might be argued as evidence for a competitors, inbreeding, genetic drift and was extensive beginning more ilian 4,000 yr ago island faxes on the soutllern Channel Islands. longer period of isolation which led to resource limitations. If the shift to a smaller (Collins 1991b). Morphologic overlap between Determining tlle origin and setting an exact subsequent morphological differentiation, or it body size occurred rapidly, then fossil evidence present-day San Nicolas, Santa Catalina and time for the colonization of San Clemente could be used as support for the continued of intermediate forms between gray and island Santa Cruz island fox populations (Fig. 7), along Island by island foxes is more problematic. existence of a founder effect. The fact that faxes would be scarce. Evidence that changes witll ilie misclassification of specimens between Grinnell & co-authors (1937) reported that island faxes were introduced to San Clemente in body size can occur rapidly in small these three islands (Table 10), suggests that Salvador Ramirez introduced a pair of island Island by Indians as recently as 3,400 years D.P. allopatric populations of mammals on islands faxes from Santa Cruz Island may have been foxes from Santa Catalina Island to San (Collins 1991 a), suggests that the latter case has been found elsewhere in the world used to establish fox populations on Santa Clemente Island in 1875. However, VV.E. may be true; the population has not been (Sondaar 1977; Marshall & Corruccini 1978). Catalina and San Nicolas Islands. Greenwell observed foxes on San Clemente present on the island for a long enough period Red deer (eer-uus elapbus) on Jersey Island off According to Wayne & co-authors (1991a) Island in 1860 Gohnson 1975) and].G. Cooper of time to permit the development of a the coast of France showed a sixfold decline in higher than expected levels of mtDNA is reported to have collected a fox off San moderate amount of morphological variability. weight in less than 6,000 yr (Lister 1989). The genotypes in the Santa Catalina Island fox Clemente Island in July 1863 (Collins 1982). Rather, the population is still under the fact that there is a moderate amount of population may reflect the effect of past Thus, foxes were present on San Clemente constraints of a founder effect having low divergence in present-day fox populations on multiple colonization events on tllis population Island prior to Ramirez's introduction of the intrapopulation variability resulting in high the northern Channel Islands (fig. 7), which probably as a result of its position as a Native faxes from Santa Catalina Island. In addition, self-fidelity in the Jackknifed classification have been isolated from one another for less American trade center (Collins 1982, 1991 b). island fox bones have been recovered from five results. Small population size coupled with

382 383

i :ii b' inbreeding, past founding events, genetic drift particularly within the species U. litto1'fllis fox. The extent of morphologic divergence the allospecies described by Amadon (1966). and/or past population bottlenecks are all (Gilbert et al. 1990; "Wayne et al. 1991a,b. between island and mainland samples is readily Until additional specimens are available for factors that could have limited morphological Chromosomal analysis revealed that the apparent in the results of the canonical variates genetic and morphometric assessment, it is best variability and yet resulted in a slight karyotype of the island fox is identical analyses. The small size of foxes on the islands to consider foxes on Tiburon Island as a divergence in the fox population on San (diploid=66) to that of the gray fox (Wayne et is evident in the shift of these populations to semispecies or race of U. cinereom·genteus. Clemente Island. al. 1991a) "which is consistent with the close the far right on the first canonical variate axis Additional specimens are needed before a new Taxonomic Conclusions: Multivariate taxonomic and phylogenetic relationships of (Figs. 5, 6). The lack of any island-to-mainland infraspecific taxa can be described for the analyses of morphologic data presented in this these two taxa. Thus, chromosomal data misclassifications (Tables 6, 7) coupled with the Tiburon Island population. paper denotes a clear separation between kit provides little direct evidence useful for F-test results (Table 5) provide clear evidence Gray foxes that inhabit the Yucatan foxes of the genus Vulpes and gray foxes of the evaluating the systematic status of U. littomlis. that the island fox has differentiated from the Peninsula displayed the greatest morphological genus Urocyotl. This is in contrast to Clutton­ Recent studies by Wayne & co-authors (1991a, adjacent mainland gray fox. The degree of divergence for any of the mainland gray fox Brock & co-authors' (1976) and Van Gelder's 1991 b) examined genetic variability within differentiation is sufficient to warrant full samples (Figs. 5, 6). Foxes from the Yucatan (1978) conclusions that the genus U1'O()'on island fox and adjacent mainland gray fox species status recognition for foxes found on Peninsula are currently assigned to the should be relagated to synonomy with the populations using allozyme electrophoresis, the California Islands. subspecies U1'O()'on cinereoargenteus fmterculus genus Vulpes or with the genus Canis, mitochondrial DNA restriction site analysis Whether the taxa UrOL)'on cinereoargenteus (Hall 1981). These foxes are characterized as respectively. The degree of phenetic and genetic fingerprinting.\iVhile seven of 20 and U. littomlis are separate species or merely having inflated tympanic bullae and are smaller divergence observed in this study between genetic loci examined were polymorphic for subspecies of one broadly distributed and and darker than gray foxes from other localities Vulpes and Urocyon suggests that congeneracy island and mainland samples, four loci (IDH, geographically variable species is open to in southern Mexico and Central America between these two genera is unwarranted. The PEP-B, PEP-C and PEP-D) were found only interpretation. Given the degree of genetic and (Elliot 1896; Miller 1899). Although foxes from morphometric results are consistent with in mainland gray fox samples and one loci (A morphologic divergence observed between the Yucatan Peninsula are clearly divergent recent studies that have utilized chromosomal allele ofloci PEP-D) was unique to island foxes populations from these two purported taxa, it is from other mainland gray fox samples (Figs. 5, and biochemical data to uphold the generic (Wayne et al. 1991b). Nei's allozyme genetic best to regard all of the fox populations on the 6), there is no discrete geographic barrier to status of Uroeyon (Wayne et al. 1987a, b; Wayne distance between island and mainland Urocyon California Islands as a single polytypic species gene flow, like that seen with the island fox, & O'Brien 1987; Wayne et al. 1991 b). Based on samples averaged 0.115 (Wayne et al. 1991a) under the name U. littoralis, which has which could permit an opportunity for results derived from chromosomal, genic and which is equivalent to values obtained among nomenclatorial priority. I therefore conclude sustained evolutionalY divergence that might morphologic data, I recommend that the genus discrete canid species (Wayne & O'Brien that recognition of two species of Uroeyon, U. eventually lead to the evolution of a separate Uroeyon continue to be used for classification of 1987). Of the twelve mtDNA genotypes found cinereomgenteus and U. littomlis, is justified. species. However, the phenetic divergence gray foxes and island foxes. by restriction-site analysis of island and Questions persist as to the systematic status observed in tIlls study provides morphological Since information on reproductive isolation mainland Urocyon samples, five were unique to of fox populations on Tiburon Island off the attributes that are adequate to warrant is not available for the allopatric island fox island fox samples with each island genotype coast of Sonora, Mexico, and on the Yucatan subspecific recognition for gray foxes found on populations, the biological species concept of sharing a unique restriction site for HhaI Peninsula. Morphometric analyses indicate tllat the Yucatan Peninsula. Until genetic data is MayI' (1969) is not directly applicable for (Wayne et al. 1991 b). The average genetic these two gray fox populations exhibit a level of available to assess genetic relationships among determining the systematic status of U1wyon distance between island and mainland samples morphologic divergence equivalent to that gray fox populations in Mexico and Central littomlis. However, Sokal & Crovello's (1970) based on mtDNA analysis was 1.29 (Wayne et found in the island fox samples. Foxes on America, it is impossible to determine whether phenetic species concept, which emphasizes al. 1991 b). The average percent difference Tiburon Island have declined in overall body gray foxes from the Yucatan Peninsula deserve the analysis of known observable characters, (ADP) between island fox and mainland gray size as evidenced by their shift off the north-to­ full specific recognition. Based on the may be applicable for evaluating the specific fox populations based on hypervariable south size cline exhibited by Urocyon morphometric results I recommend that foxes status of U. littomlis. If results from separate minisatellite DNA analysis was 88.7% (Wayne cinereomgenteus samples (Figs. 5, 6). Whether from the Yucatan Peninsula continue to be analyses of genetic and morphometric et al. 1991 b). The extent of genetic divergence this morphologic divergence warrants full recognized as a unique subspecies U. c. variation detect discrete differences between observed between U. cine1'eoargenteus and U. specific recognition is unclear given the small fraterculus. island and mainland fox populations, then it littomlis samples is sufficient to support species sampIe size (n= 1 male, 3 females) used in the In studies of geographic variation, it is not should be possible to evaluate the specific level recognition for foxes found on islands off morphometric analyses and the lack of any the naming of subspecies which is as important status of U. littomlis. the coast ofsouthern California. corroborative data on genetic variability in the as deciphering the patterns of variation Until recently there was almost no informa­ The morphometric data presented in this Tiburon Island sample. The morphometric observed within a species in order to tion on genetic or karyotypic variability within study provides additional evidence that fox results suggest that foxes on Tiburon Island reconstruct its phylogenetic history. A the genus Urocyon as a whole (Wayne et al. populations on the California Islands have resemble the recently-formed sister species subspecies is the taxonomic category assigned 1987a, b; Wayne & O'Brien 1987) and differentiated £Tom the adjacent mainland gray found in Cyno7ll)'s by Pizzimenti (1975) and/or to distinct geographic variants of the same

384 385 species. This infraspecific category has been evolution to permit the development of discrete Aclmowledgments Chaney, R.YV. and 1-1.L. Mason. 1930. A Pleistocene used to identify populations that have discrete diagnostic morphologic and genetic attributes flora [TOm Santa Cruz Island, California. Carnegie geographic ranges and/or have diverged adequate to identify each of the island fox I thank T. Collins, S. Holbrook, the late T. lnst. ~Washington Publ. No. 415:1-24. genetically or morphologically, but which have populations (Collins 1982, 1991; 'Vayne et al. Hudson, C. D. Woodhouse, D. M. Power, P. Clements, T 1955. The Pleistocene history of the not yet developed isolating mechanisms 1991, 1991 b). The high percentage of correctly L. vValker and S. 1. Rothstein for their Channel Island region, southern California. Pp. sufficient to maintain reproductive isolation 311-323. In: Essays in the natural sciences in classified individuals in the canonical variates encouragement, guidance and advice (Ratti 1980). In recent years, taxonomists have honor of Capt. Alan Hancock. University of analyses (Table 10) for all island fox populations throughout the course of this study. S. George, begun to delineate infraspecific categories Southern California Press: Los Angeles, CA. 345 is indicative of the degree to which these F.G. Hochberg, L. Rotll, D. M. Power and C. based on genetic relationships as well as on pp. populations have diverged from one another. D. vVoodhouse offered valuable comments on Clutton-Brock, J., G.B. Corbet and M. I-rills. 1976. shared morphological attributes (Barrowclough Since migration among the islands is low earlier drafts of this manuscript. D. Schroeder, A review of the family Canidae, with a 1982; Patton & Smith 1991). By using both K. Rindlaub and D. M. Power provided classification by numerical methods. Bull. Brit. genetic and morphologic data it should be (\Vayne et al. 1991 b), and since opportunities assistance with statistical analyses. J. Schmitt Mus. Nat. I-list., Zool. 29(3): 117-199. possible to identify geographic units within a for gene flow between the island populations prepared the illustrations of the skull (Fig. 2) Collins, P.YV. 1980. Food habits of the island fox species that represent opportunities for have been eliminated, each of the populations and molar teeth (Fig. 3). (Uroc)'on littomlis littomlis) on San Miguel Island, sustained evolutionary divergence (Patton & have developed unique morphologic and California. Pp. 152-164. In: Proceedings of the genetic characteristics. Thus, the continued Smith 1991). These types of geographic units Literature Cited second conference on scientific research in the would equate to subspecies. recognition of separate subspecies for each National Parks. Volume 12: Terrestrial Biology: In allopatric populations, it is often island population is justified. Amadon, D. 1966. The superspecies concept. Syst. Zoology. National Park Service: Washington, impossible to determine whether they have Absence of variability in fingerprint Zool. 15:245-249. DC. NTIS:PB81-100133. Aquadro, C.F. and CWo Kilpatrick. 1981. Morpho­ ______. 1982. Origin and differentiation of the developed isolating mechanisms sufficient to restriction fragment profiles, in allozymes logical and biochemical variation and differen­ island fox: a study of evolution in insular maintain reproductive isolation should their and in mtDNA genotypes (Gilbert et al. 1990; tiation in insular and mainland deer mice populations. M.A. thesis, University of California, geographic ranges overlap in the future. Thus, Wayne et al. 1991a,b), as well as reduced (Pe'l'07IlY.l'ClIS 7llfmiculatlls). Pp. 214-230. In: M.H. Santa Barbara, CA. 303 pp. it is difficult to determine whether an allopatric levels of morphologic variation (Collins 1982, Smith and]. Joule (eds.), Mammalian population . 1991a. Interaction between island foxes population that exhibits discrete diagnostic 1991 a), and increased frequencies of cranial genetics. University of Georgia Press: Athens, GA. (U7wyon littomlis) and Indians on islands off the attributes warrants classification as a species or abnormalities (Collins 1982), are traits Ashley, M.V. and C. Wills. 1987. Analysis of coast of soutllern California: 1. morphologic and archaeological evidence of human assisted subspecies. As Stebbins (1971 :99) points out characteristic of the three southern Channel mitochondrial DNA polymorphisms among "these populations have never had a chance to Channel Island deer mice. Evolution 41: 854-863. dispersal.]. Ethnobiol. 11(1):51-81. Island samples. These results suggest that and . 1989. Mitochondrial-DNA and . 1991 b. Interaction between island foxes take the test of sympatry and so could be either founder effects, inbreeding among close species or subspecies." allozyme divergence patterns are correlated (U7'ocyon littoralis) and Native Americans on relatives and genetic drift are factors that among deer mice. Evolution 43:646-647. islands off the coast of southern California: II. In the case of the island fox, where there continue to influence recently established fox Baird, S.F. 1857. Reports of explorations and surveys ethnographic, archaeological and historical populations are all allopatric, it is difficult to populations on the southern Channel Islands to ascertain the most practicable and economical evidence.]' Ethnobiol. 11(2):205-229. determine if their populations are, in fact, a Cooley, W.\V. and P.R. Lohnes. 1971. Multivariate (Wayne et al. 1991 a). As a result of founder route for a railroad [Tom the Mississippi River to single polytypic subspecies or a series of the Pacific Ocean. 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388 389 Activity and Movelnent ofthe Island Fox, Urocyon littoralis, on Santa Cruz Island, California __ and R.M. Norris. 1963. Geology of S

Genet. 44: Philbrick (ed.), Proceedings of the symposium on 123-133. Santa Barbara, CA 93101 the biology of the California Islands. Santa __, and __. 1987b. Chromosomal evolu- Barbara Botanic Garden: Santa Barbara, CA. tion of the Canidae: II. species with low diploid vVassersug, RJ., H. Yang, ].]. Sepkoski and D.M. numbers. Cytogenet. & Cell Genet. 44: 134-141. Raup. 1979. The evolution of body size on ___ and SJ O'Brien. 1987. Allozyme divergence close proximity to Los Angeles, one of the islands: a computer simulation. Amer. Nat. within tlle Canidae. Syst. Zoo!' 36:339-355. Abstract - Island foxes (UTO[yon littora!J~) were major population centers in the U.S. and 3) 114:287-295. there is increasing pressure to exploit the 'Venner, A.M. and D.L. Johnson. 1980. Land studied using radio-telemetry and direct 'Vayne, R.K., S.B. George, D.Gilbert, P.V\!. Collins, vertebrates on the California Channel Islands: California Islands both for natural resources observation on Santa Cruz Island, California, to S.D. Kovach, D. Girman and N. Lehman. 1991a sweepstakes or bridges? Pp. 497-530. In: D.M. and recreation. For these reasons I began a quantify their activity and movement behavior. A morphologic and genetic study of the island fox, Power (ed.), The California Islands: proceedings study to quantify aspects of the behavior of There were seasonal variations in: 1) time of UroiJon littoralis. Evolution 45: 1849-1868. of a multidisciplinary symposium. Santa Barbara island foxes, emphasizing their activity and __, __, __ and __. 1991b. The Chan­ J\lIuseum ofNatural History: Santa Barbara, CA. day for activity (diurnal in winter but movement. nel Island fox (Uro(J!0n littoraliJ) as a model of Viood,].E. 1958. Age structure and productivity of a crepuscular/nocturnal in summer) and 2) genetic change in small populations. Pp. 639-649. gray fox population. J. Mamm. 39:74-86. percentage of time active (summer low of 30% Methods In: E.c. Dudley (ed.), The unity of evolutionary Young, S.P. and E.A. Goldman. 1944. The wolves of to winter high of 46%). The size and type of biology: proceedings of the fourth international North America. Part 2. Dover Publications, Inc.: area covered varied with age, sex and season. The study was conducted on Santa Cruz congTess of systematics and evolutionary biology. New York, NY. 636 pp. Adult males covered 40 ha in winter. In Island, California (HON, 119°45 'Wi Fig. 1). summer, males remained within a 20 ha range From the standpoint of access and logistics as did females in both winter and summer. Santa Cruz Island was the easiest place to work because the University of California operates a field station on the island. Santa Cruz Island Introduction also has the widest variety of habitats and the largest population of foxes of any of the The island fox (UTO[yon littoTalis Baird, 1857), California Islands therefore more variables a small fox found exclusively on the six largest could be included in the study. The population California Islands, historically has been of foxes was categorized by sex, age and discussed in one of two ways: 1) descriptive/ reproductive state. The number of animals taxonomic (Grey 1858; Merriam 1903; Grinnell tracked by category and season is shown in & Linsdale 1930; Clutton-Brock et al. 1976; Table 1. Van Gelder 1978) or 2) short natural history Island foxes repeatedly can be captured in expositions (Stephens 1906; Grinnell et al. wire mesh live traps. Folding single-door traps 1937; Von Bloeker 1967). Laughrin (1977, were set under cover of brush to protect 1980) recently described their population captured animals from being overheated by dynamics, food habits and qualitative direct solar radiation during the day and from observations of their behavior. being chilled at night by reradiation to sky It generally is accepted that information on temperature and exposure to wind. Traps were an animals activity is a key to understanding the placed near obvious animal trails, or in areas role it has in it's habitat and it's adaptations to where foxes had been seen or trapped changing conditions (e.g., Kavanau & Rischer previously. 1968). It is also essential to know as much as While an animal was in hand standard possible about activity and movement of a given mammalian measurements were taken to species if the impact of humans on the species is increase our knowledge of the physical to be understood. This is particularly important characteristics of these seldom studied animals. in the case of the island fox because: 1) it is Results are reported in Fausett (1982). Age was listed as threatened in California; 2) it lives in determined by checking wear on the first upper

390 Third California Islands Symposium 391