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Home , Archaeocyon, Corsac fox, Hesperocyoninae, Hoary fox, Sechuran fox, Viverra

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A review of selected features of the family with reference to its fundamental taxonomic status Barnabas Pendragon

Dogs comprise 35 extant in 14 genera. They belong to the order , which has common morphological and karyotypic features. Within the order, member species can be grouped based on heterologous DNA melting temperatures. The family Canidae forms such a group. Selected features of the Canidae are reviewed here in order to examine the fundamental taxonomic status of this family. Hybrid relationships demonstrate that the family Canidae is a single, reproductively compatible group having the taxonomic status of basic type. As opposed to the various species in the family whose formation was accompanied by genetic change, establishment of the domestic was accompanied by almost no genetic change; genetically all domestic are grey . The remarkable variation observed among the various breeds of domestic dog reflects the potential for morphological change hard-wired into the canid genome. The basic type appears to be divided into two subfamilies in the Cenozoic strata; the extant and the extinct Borophaginae. The ‘oldest’ known canid species is Prohesperocyon, which is found in upper fossil deposits.

Q*HRUJH9HVWD0LVVRXULODZ\HUJDYHXVWKHDGDJH for slicing muscle tissue. However, in the omnivorous I“A dog is a man’s best friend”. More so than any other carnivores such as the , true carnassial teeth do not , dogs represent friendship and companionship. develop. Nevertheless, dogs, the Canidae, are beasts of prey Interestingly, the carnivore order has a largely belonging to the order Carnivora. They have long slender conservative karyotype. The chromosome morphologies heads with a prominent snout containing an extensive nasal DQG*EDQGLQJSDWWHUQVRIVHYHUDORIWKHIDPLOLHV FDYLW\ GRJVKDYHDZHOOGHYHORSHGVHQVHRIVPHOO 7KH are highly conserved. The is the prototype ears are usually held erect and are quite large (they can be family. The domestic has 19 chromosomes, 16 used to regulate body temperature). The legs are long and RIZKLFKDUHLQYDULDQWLQDOOVSHFLHVRIIHOLGV2I slender, since dogs tend to hunt their prey by chasing them these 16 chromosomes, 15 are present in several other DQGUXQQLQJWKHPGRZQ7KHIURQWIHHWKDYH¿YHGLJLWVWKH carnivore families (, , , hind feet, four. The is an exception, with Hyaenidae). In two families, however, the Canidae and four digits on all its feet, and some breeds of domestic dog Ursidae, there is a dramatic reorganization of this basic KDYH¿YHGLJLWVRQHDFKIRRW7KHWDLORIPRVWGRJVLVZHOO carnivore karyotype. Still, the overall picture is of a developed, characteristically so in the , where it is comparable group of with various features in referred to as the brush. common. Bennetzen and Freeling suggest the order Carnivora may represent a common ‘genetic system’ The order Carnivora because of these karyotypic similarities.3 Canidae belong to the order Carnivora, which +RPRORJLHV EHWZHHQ WKH VLQJOHFRS\ JHQHV comprises nine families (or ten if the are recognized by evaluating the thermal stability of DNA considered a separate family; Herpestidae), grouped into duplexes, can be used to distinguish many of the families two superfamilies, the and the . within the order.4 The technique estimates the difference in 7KHDTXDWLFFDUQLYRUHV2WDULLGDH VHDOLRQV DQG3KRFLGDH melting temperatures between homologous DNA duplexes (seals), are sometimes placed in a separate order, the (both DNA strands from one species) and heterologous Pinnipedia; however, the inclusion of these families within DNA duplexes (one strand from each of two species). the Carnivora is usual (see table 1). Species within the Canidae vary by less than 4°C from The main role of carnivores in nature is to keep in each other, but by more than 18°C from species in other FKHFNWKHQXPEHUVRIKHUELYRUHV7KH\DUHSULPDULO\ÀHVK carnivore families. Similarly, species within the Felidae eaters, and most are capable of running quickly. They have vary by less than 4°C from each other but by more than conspicuous long and sharp canine teeth for catching and 14°C from other carnivores; and this is also true of the killing prey. Most of them have the last upper premolar Hyaenidae.5 All three families, Canidae, Felidae and DQGWKH¿UVWORZHUPRODUWUDQVIRUPHGLQWRWKHVRFDOOHG Hyaenidae, may represent fundamental taxonomic units FDUQDVVLDOWHHWKZKLFKKDYHDÀDWWHQHGUD]RUOLNHFURZQ equivalent to basic types.

JOURNAL OF CREATION 25(3) 2011 79 Papers

The family Canidae canids sometimes exhibit the peculiar behavior of remaining perfectly motionless on being approached by humans.10 Subdivision of the canids has been a field rich in Darwin actually killed one by simply walking up to it and FRQÀLFWLQJK\SRWKHVHV/DQJJXWK2 described a reasonable hitting it on the head with his geological hammer.11 The three partition subgrouping, which, with subsequent VSHFLPHQDFFRPSDQLHGKLPEDFNWR(QJODQG,WEHORQJVWR isolation of the grey foxes, now includes four lineages (see a unique species of canid, the most recently recognized, and table 1). is named Darwin’s (Pseudalopex fulvipes) in his honor. A complete listing of recent canids is given in the Sadly, it is in grave danger of , listed as critically DSSHQGL[7KHDQDO\VLVRI:D\QHDQG2¶EULHQ6, based on endangered by the World Conservation Union. During that allozyme genetic distance and chromosome morphology, same voyage, Darwin reported that another South American indicated that the genera , Otocyon and canid, the Falkland Island ( australis), was the IRUPVHSDUDWHPRQRW\SLFOLQHDJHV VHH¿JXUH 3UHYLRXVO\ only indigenous on the Falkland Islands. By the placement of Otocyon within the OLNHFDQLGV VHH end of the 1800s the species had been exterminated by fur table 1) followed the recommendation of Berta. The only traders.10,11 These are stark reminders of how fragile many FDQLGZKLFKGLGQRWUHDGLO\¿WLQWRWKHHDUOLHUVFKHPHV species of wild canid have become.12 was Nyctereutes procyonoides ( dog). As the name suggests, due to its face mask, it remotely Hybrid relationships resembles a raccoon. It is the only canid which hibernates. /LPEPRUSKRORJ\VXJJHVWHGDZROIOLNHUHODWLRQVKLS8 An important question to clarify concerning the canids Based on masticatory characteristics, Berta had proposed is whether they belong to a single, fundamental taxonomic that Cerdocyon FUDEHDWLQJIR[ DQGNyctereutes might unit.13 'RIR[HV]RUURVDQGZROIOLNHFDQLGVDOOEHORQJWRD share a common ancestor, which would have placed common genetic ? In this respect, the concept of the Nyctereutes among the South American canids, despite it basic type as a group of interfertile species is very useful.14 EHLQJLQGLJHQRXVWRWKH)DU(DVW+RZHYHUWKHUPDOVWDELOLW\ (UQVW0D\U¶VLQÀXHQWLDOGH¿QLWLRQRIWKHWHUPµVSHFLHV¶ of 1\FWHUHXWHVSURF\RQRLGHV¶ unique sequence DNA varies emphasized ‘ability to hybridize’.15 2QO\ WKRVH DQLPDOV E\MXVWƒ&IURPVulpes vulpes (), clearly placing it capable of hybridization belong to the same species. DPRQJWKHIR[OLNHFDQLGV4 and more recent sequencing data However, many examples of hybridization between species KDVFRQ¿UPHGSODFHPHQWRIERWKNyctereutes and Otocyon are now known. Clearly, it is more appropriate to use ‘ability in the VulpesOLNHFODGH9 WRK\EULGL]H¶WRGH¿QHDKLJKHUWD[RQ%HFDXVHK\EULGL]DWLRQV South America canids form their own lineage; occur even between species from separate genera, ‘ability to geographically, morphologically and genetically. Many K\EULGL]H¶VHHPVWRGH¿QHJURXSVRIRUJDQLVPVDWDQHYHQ are locally referred to as zorros, and sometimes the whole higher taxon; tending towards the taxonomic level of family. lineage is referred to by this name. They live on the 8QWLOVXFKGH¿QLWLRQVFDQEHFODUL¿HGWKHXVHIXOWHUPµEDVLF mainland of South America and its neighboring islands. type’ is employed. It should be born in mind, however, that Various species were studied by Charles Darwin during µDELOLW\WRK\EULGL]H¶FDQEHDFDSULFLRXVGH¿QLWLRQ$VD his famous voyage on the HMS Beagle. South American group of organisms changes via recombination and natural selection, its karyotype does not always Table 1. of the order Carnivora. Families after Wozencraft 1, canid subgroups remain static. Karyotype incompatibility () after Langguth 2. can lead to prenatal mortality, or at best hybrid sterility, and prevent the Feliformia ( and cat allies) production of fertile offspring. Various Herpestidae (mongooses, sometimes included in the Viverridae) other mechanisms of reproductive Viverridae () incompatibility also exist. This should Felidae (cats) not detract from the fundamental genetic Hyaenidae () and phenotypic commonalities shared by VSHFLHVZLWKLQDEDVLFW\SH2UJDQLVPV Caniformia (Dogs and dog allies) are still considered to belong to the Ursidae (bears) same basic type if inability to hybridize Otariidae (sea , and sometimes the ) results from secondary causes. With these Procyonidae () OLPLWDWLRQVLQPLQGLWLVIHOWVXI¿FLHQWWR Mustelidae () demonstrate that hybridization between Phocidae (seals) WKHPDMRUGRJOLQHDJHVRFFXUVDQGWKDW Canidae (dogs) at least some hybridization also occurs Wolf-like canids: , Cuon, Lycaon within these lineages. If this can be done, South American canids: Atelocynus, Cerdocyon, Chrysocyon, Pseudalopex, then the hypothesis ‘all extant canids Red fox-like canids: Alopex, Otocyon, Nyctereutes, Vulpes Grey fox-like canids: Urocyon belong to a single basic type’, has been reasonably proven.

80 JOURNAL OF CREATION 25(3) 2011 Papers

Geological strata a reproductively compatible or single genetic family based on Pliocene their ability to form hybrids, and as such the extant members of black the Canidae represent a single

domestic dog Wolf-like basic type. grey wolf canids Cape hunting dog acrocentric autosomes Karyotype relationships black-backed jackal High diploid number

South American Although some trends

canids are observed with respect to chromosome number and type, and the development of the canid crab-eating fox NDU\RW\SHVLVDIDVFLQDWLQJ¿HOG of study, karyotypes per se are grey fox poorly indicative of fundamental bat eared fox FDQLGWD[RPRQ\([FHOOHQWVWXGLHV

metacentric autosomes RIWKHFDQLG*EDQGHGNDU\RW\SH raccoon dog Low diploid number  Vulpes have been published. All red fox RIWKHZROIOLNHFDQLGVKDYH -like canids chromosomes, the autosomes of which are usually acrocentric.

artic fox The chromosome morphology of these species is always similar. 0.67 0.32 0.24 0.16 0.08 0.00 The karyotype of Canis lupus and Canis lupus familiaris appear Genetic distance completely homoeologous (i.e. Figure 1. Consensus relationship tree of the canids based on allozyme genetic distance and genetically essentially identical). chromosome morphology (after WAYNE and O’brien6). The South American canids studied also have high numbers Gray’s checklist of mammalian hybrids16 provides an of acrocentric chromosomes. Chrysocyon brachyurus excellent starting point. Many crosses have been attempted PDQHGZROI  ¿JXUH KDVDGLSORLGFRPSOHPHQWRI or observed between the domestic dog (Canis lupus having lost chromosome 28. Speothos venaticus (bush familiaris) and wild dogs, including animals from all four dog) and Cerdocyon thous FUDEHDWLQJGRJ KDYHDGLSORLG PDMRUGRJFODGHV VHHWDEOH  FRPSOHPHQWRIKDYLQJORVWFKURPRVRPHVDQG As Canis lupus familiaris is descended from Canis The closely related Pseudalopex vetulus (hoary fox) also lupus, it is perhaps not surprising that hybrids have been KDVFKURPRVRPHVCerdocyonthous has a high number RIPHWDFHQWULFVRXWRI UHSRUWHGEHWZHHQWKHVHDQLPDOV2IPRUHVSHFL¿FLQWHUHVW 7KHIR[OLNHFDQLGVDQGNyctereutes procyonoides are its ability to hybridize with Cerdocyon thous and UDFFRRQGRJ KDYHFKURPRVRPHQXPEHUVUDQJLQJIURP Pseudalopex gymnocercus, both of which belong to the in Otocyon megalotis EDWHDUHGIR[ WRLQVulpes vulpes South American canids, and its ability to hybridize with (red fox). The primary changes include chromosome loss two Vulpes (fox) species. Vulpes vulpes also hybridizes with and chromosome fusion. Interestingly, seven fox species Urocyon cinereoargenteusOLQNLQJWKHUHGIR[OLNHFDQLGV SRVVHVVFKURPRVRPHZKLFKLVDEVHQWLQDOOWKHZROI DQGWKHJUH\IR[OLNHFDQLGV7KHVHFURVVHVGHPRQVWUDWHWKDW like and South American canids tested. Alopex lagopus K\EULGL]DWLRQVDPRQJDOOIRXUPDMRUGRJFODGHVDUHSRVVLEOH () and Vulpes macrotis (kit fox) both have 50 +\EULGVZLWKLQWKHZROIOLNHFDQLGVDUHH[SHFWHGWREHIHUWLOH chromosomes identical in morphology and banding pattern, WKH\DOOKDYHFKURPRVRPHV1HYHUWKHOHVVDWWHPSWVWR and all 48 autosomes are metacentric. Vulpes vulpes has 36 cross Canis lupus familiaris with Cuon alpinus have so chromosomes (32 metacentrics, 2 acrocentrics, and the 2 sex IDUEHHQXQVXFFHVVIXO6XFFHVVIXOLQWUDCanis crosses have chromosomes). None of these are entirely homoeologous to EHHQUHSRUWHG$PRQJWKHIR[OLNHFDQLGVWZRLQWHUJHQHULF Alopex lagopus chromosomes, although extensive regions crosses have been reported (see table 2). of homoeology do exist. Octocyon megalotis, Urocyon 1RK\EULGVZLWKµQRQFDQLG¶FDUQLYRUHVKDYHEHHQ cinereoargenteus (grey fox) and Vulpes zerda (fennec) have reported, at least none which can be taken seriously.16 The DQGPRVWO\DFURFHQWULFFKURPRVRPHVUHVSHFWLYHO\ hybrid list presented here is based primarily on Gray’s work. All three lack chromosome 34 as does Nyctereutes It is not meant to be an exhaustive listing. It is, however, procyonoides. Nyctereutes has a range of diploid numbers VXI¿FLHQWWRGHPRQVWUDWHWKDWDOOH[WDQWFDQLGVEHORQJWR due to the presence of varying numbers of B chromosomes.

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Table 2. Interspecific hybrids within the family Canidae, according procyonoidesIURPWKHSKHQRW\SLFDOO\VLPLODU-DSDQHVH to Gray16 and Alderton11.2 subspecies, N. p. viverrinus.19 Can underlying genetic causes of speciation be brought to light using such model karyotype Intrageneric hybrids: V\VWHPV"6WXGLHVRIGLIIHUHQWVSHFLHVRISLFWXUHZLQJ Canis lupus familiaris x Canis lupus dingo (dingo) Drosophila in Hawaii showed the speciation events were Canis lupus familiaris x Canis lupus (grey wolf) accompanied by 214 chromosomal inversion events. The Canis lupus familiaris x Canis latrans (coyote) associated karyotypic changes permitted tracking of the Canis lupus familiaris x Canis aureus () species phylogeny. However, there was little to suggest the Canis lupus x Canis latrans (fertile) inversion events were in any way causative of the phenotypic Canis rufus x Canis latrans changes.20 Nevertheless, an attempt is currently underway Canis aureus x Canis latrans (fertile) to map and eventually sequence the actual sites of canid chromosome rearrangements.21 The hope is that some Intergeneric hybrids: genetic causes of speciation will be revealed. Canis lupus familiaris x Cerdocyon thous (crab-eating fox) Canis lupus familiaris x Pseudalopex gymnocercus () Fossil dogs Canis lupus familiaris x Vulpes bengalensis () *Canis lupus familiaris x Vulpes vulpes (red fox) Basic type taxonomy is based upon hybridization criteria Vulpes vulpes x Alopex lagopus (arctic fox) between extant species of organisms. This approach does Vulpes vulpes x Urocyon cinereoargenteus (grey fox) PRUHWKDQGH¿QHVLPSOHOLQHDUUHODWLRQVKLSVEHWZHHQFORVHO\ related species. The approach tacitly assumes natural limits * A dog x fox hybrid is on display at ‘Haus der Natur’, Salzburg, Austria. exist to the morphogenetic (phenotypic) potential of a basic type. Therefore, organisms are placed within polyphyletic The chromosomes of Nyctereutes share arm homoeology to RUV\OYDQUHODWLRQVKLSVUDWKHUWKDQDVLQJOHDOOHPEUDFLQJ FKURPRVRPHVRIFDQLGVLQHDFKRIWKHPDMRUEUDQFKHVRIWKH monophyletic tree of life. Choice between these two models Canidae. The karyotype is homoeologous to approximately 85% of the Canis lupus karyotype. would be easy if intermediate forms were abundantly present While the karyotypes of felids, mustelids, ursids and in the ‘fossil record’. This is not the case, and is a primary reason why punctuated equilibrium models of evolution have remained relatively stable as these families 22,23 underwent speciation and adaptive radiations, the karyotypes become more and more popular in mainstream biology. of canids displayed extensive genome rearrangement.19 The unmistakable paucity of intermediate forms is clearly Graphodatsky and his colleagues19 noted that chromosome predicted in polyphyletic models of the ‘fossil record’. variation in carnivores is an excellent example of species, $ VHFRQGEHVW OHDVWZRUVW PRQRSK\OHWLFGHIDXOW and families, belonging to the same mammalian order interpretation is what remains. With few, only questionable but with contrasting genomic organizations, i.e. highly intermediates to work from, ‘default’ evolutionary scenarios 15 conserved versus highly rearranged. These studies highlight PXVWVXI¿FH families are designated by default. the fact that within an order some families can share very Within an order, the family (or basic type) represented by the similar karyotypes (even though they may be separate ‘oldest’ fossils must be the most primitive. The designation is EDVLFW\SHV ZKHUHDVRWKHUIDPLOLHVFDQGLVSOD\VLJQL¿FDQW not by proof but by default. It must change if ‘older’ fossils karyotypic variation. Nevertheless, despite numerous from another family are subsequently discovered. Always phenotypic traits shared with members of other carnivore the ‘oldest’ family must necessarily be designated most families, the postulated canine ancestral karyotype differs SULPLWLYH/LNHZLVHOLQNIRVVLOVDUHGHVLJQDWHGE\GHIDXOW E\DWOHDVW¿VVLRQHYHQWVDQGIXVLRQHYHQWVIURPWKH Among the various species in a ‘most primitive’ family, postulated ancestral carnivore karyotype.19 WKDWVSHFLHVZLWKWKHµOHDVWIHZHVW¶FKDUDFWHUVLQFRPPRQ Using chromosome painting methods, it has been with the ‘most primitive’ (i.e. ‘oldest’) species from a sister possible to track the karyotype changes that have occurred family is necessarily the intermediate or link to that other within the canids, and to determine a consensus canid IDPLO\2QFHDJDLQGHVLJQDWLRQLVQRWE\SURRIEXWE\GHIDXOW phylogeny.19 This phylogeny corroborates the one previously 6XFKPRGHOGULYHQLQWHUSUHWDWLRQOHDGVWRGHVLJQDWLRQRI SXEOLVKHGE\/LQGEODG7RKDQGFROOHDJXHVEDVHGRQ OLQNIRVVLOVEXWXVXDOO\LQVSLWHRIXQZLHOG\¿W7KHUHIRUH kb of exon and intron sequencing data.9 These studies FLYHWOLNH Proailurus RUPXVWHOLGOLNH +HVSHURF\RQLQDH  demonstrate that extensive phenotypic variation, even VSHFLHVDUHUHTXLUHGWRJLYHULVHWRFDWVDQGGRJVHDUO\WDSLU associated with speciation, does not require karyotypic like species (Hyracotheriinae) are required to give rise to change; for example, as evidenced by the and KRUVHVXQJXODWHOLNHVSHFLHV 0HVRQ\FKLGV DUHUHTXLUHG domestic dogs. The studies also demonstrate the converse, WRJLYHULVHWRZKDOHVDQGVRRQ7KHGHIDXOWLQWHUSUHWDWLRQ that phenotypic variation is not necessarily caused by DSSURDFKLVWKHOHDVWZRUVWRSWLRQDYDLODEOHIRULQWHUSUHWLQJ extensive karyotypic change; for example, as evidenced in a polyphyletic ‘fossil record’ within a monophyletic model. the raccoon dog, where eight centric fusions distinguish the 2QHLVOHIWZLWKTXHVWLRQDEOHOLQNIRVVLOVLQVHUWHGLQWR nominate (Chinese) subspecies’ Nyctereutes procyonoides RWKHUZLVHZHOOVHSDUDWHGIDPLOLHV EDVLFW\SHV RIRUJDQLVPV

82 JOURNAL OF CREATION 25(3) 2011 Papers

2EYLRXVO\WKHSRO\SK\OHWLFPRGHOGRHVQRWUHTXLUHWKHVH primarily those characters vital to ontogenetic success that unwieldy insertions. GH¿QHVSHFLHVLQFOXVLRQ Hybridizations observed within basic types provide The occurrence of hybridization in extinct species a theoretical scaffold, which delimits and predicts is almost impossible to assess. Therefore, basic type morphogenetic potential of these groups. The hybridization categorization of fossils must employ alternative approaches. criterion relates species not by a single or even a few Three versatile principles are listed below. If such principles characters but by the theoretical maximum available. It FDQQRWEHDSSOLHGµXQVSHFL¿HGEDVLFW\SH¶VWDWXVLVUHWDLQHG is a holistic rather than a simplistic approach. Biologists HYHQWKRXJKFODVVL¿FDWLRQLQWRKLJKHUWD[DPD\VWLOOEH often use various cranial and dental characters to identify undertaken using various contemporary techniques. canids,24 which have proven to be symptomatic, but are ,IWKHSKHQRW\SHRIWKHIRVVLOIDOOV not considered causative, of the canid state. For example, 1. Within the holistic morphogenetic space of a basic type, if morphogenetic potential within the canids permitted as delineated by the documented hybridizations between WKHDW\SLFDOGHYHORSPHQWRIWKHµIHOLIRUPFKDUDFWHULVWLF¶ species, inclusion within the basic type is considered appropriate. bilaminate septum in the auditory bulla of the of a  2XWVLGHWKLVKROLVWLFPRUSKRJHQHWLFVSDFHEXWZLWKLQ particular animal, it would not cease to be a canid. Should its reasonable morphogenetic potential, inclusion within more and more characters be found to be of a feliform the basic type is indicated. type, at some stage placement of the animal within the 3. Within the holistic morphogenetic potential of a basic Canidae would be questioned. In practice, characters are type, but displaying a limited number of characters used chosen which do not lead to inclusion or exclusion errors. If WRGH¿QHRUJDQLVPVRXWVLGHWKHEDVLFW\SHLQFOXVLRQ exceptions are found, the characters are replaced, or suites of within the basic type is indicated, and the reliability of FKDUDFWHUVDUHXVHGWRGH¿QHWHQGHQFLHV7KHKROLVWLFQDWXUH WKHGH¿QLQJFKDUDFWHUVLVTXHVWLRQHG of hybridization is, in effect, a maximum character indicator The holistic approach to phylogenetic categorization for species inclusion. Furthermore, the reproductive nature of fossils, based on the concept of basic types and ability of hybridization resolves at least two acknowledged to hybridize, avoids unnecessary multiplication of ZHDNQHVVHVRIFKDUDFWHUGHSHQGHQW SKHQHWLF LQFOXVLRQ anachronistic or ‘chimeric’ forms at basal locations in methods. First, degree of trait variability can be highly RWKHUZLVHPRQRSK\OHWLFFODGHV,WOHDGVWRFODUL¿FDWLRQRI irregular, which can lead to ambiguous inclusion criteria a number of fossil relationships, and it indicates limits to LQDQXQNQRZQQXPEHURIFKDUDFWHUV (UQVW0D\U¶V morphogenetic potential which can be tested empirically. ‘high variability’ characters15). Second, trait variability in Canids are typically recognized by three aspects of cranial GLIIHUHQWFKDUDFWHUVLVLQWHUFRQQHFWHGE\LOOGH¿QHGJHQHWLF DQDWRP\WKHW\SHRIDXGLWRU\EXOODWKHORFDWLRQRIWKHLQWHUQDO mechanisms, which leads to unknown bias in the importance FDURWLGDUWHU\DQGVSHFL¿FIHDWXUHVRIGHQWLWLRQ7KHIDPLO\ RIGLIIHUHQWWUDLWV (UQVW0D\U¶VµUHGXQGDQW¶FKDUDFWHUV15). Canidae, both extant and extinct, is currently recognized as Hybridization naturally ensures it is all the characters, and FRPSULVLQJWKUHHPDMRUVXEIDPLOLHVWKH&DQLQDHDQGWZR others known only from fossil specimens.25,26 The Caninae and the Borophaginae are considered sister groups. The third subfamily, , appears to include a different kind, or type, of animal. Many Hesperocyoninae species are known only from cranial remains. Theyare placed within the Canidae based on the three characteristic aspects of FUDQLDODQDWRP\+RZHYHUWKHSRVWFUDQLDOVNHOHWRQ ZKHQ available) emphasizes the separate nature of these animals. The skeleton displays a short muzzle (rather than an elongate snout), a long tail and a long, slender body shape. The features are far more reminiscent of various Mustelidae, whose auditory bulla can be very similar to those of the Canidae.29,30 From a holistic perspective, which takes into 6DJH5RVV f DFFRXQWERWKFUDQLDODQGSRVWFUDQLDOFKDUDFWHULVWLFVWKH Hesperocyoninae appear to belong to a basic type separate IURPWKHRWKHUWZRFDQLGVXEIDPLOLHVSRVVLEO\DPXVWHOLG like animal.24 Photo courtesy o The Hespercyoninae are considered forerunners of Figure 2. Chrysocyon brachyurus, the maned wolf. Sometimes both the Borophaginae and the Caninae. An excellent and referred to as a fox on stilts, its long legs help it to see over the tall pampas grass. Its karyotype is very similar to that of the grey comprehensive review of the Hespercyoninae, with many 28 wolf but has 76 chromosomes instead of 78, having lost a single photographs of fossil , is available from Wang. chromosome pair. Their dental pattern is I3/3, C1/1, P4/4, M2/2. This is

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typical of canids and viverrids, and close to and A dental patterns (both mustelids). The relatively prominent carnassials and the inflated auditory bullae are more indicative of canid and mustelid types than the viverrid type. Distinguishing between extant species of canid and mustelid is readily accomplished by examining WKHURVWUDOSDUWRIWKHVNXOO VHH¿JXUH 7KLVLVGUDZQRXW into a prominent snout in canids, often accompanied by an excellent sense of smell. In mustelids the muzzle does not display this rostral extension; the infraorbital foramen (a KROHWKURXJKWKHVNXOOMXVWLQIURQWRIRUEHORZWKHRUELW  is not stretched and remains a prominent and characteristic hole. Viverrids display a somewhat intermediary state, very like the Hesperocyoninae; an abbreviated snout but with a prominent infraorbital foramen. Specimens from the fossil record paint an intriguing picture. The basal canid species, Prohesperocyon wilsoni, has many cranial features typical of canids, including the B extended snout. However, it is placed as Canidae incertis cedis ‘canid of uncertain status’.28 This is because it is FRQVLGHUHGDQFHVWUDOWRWKHIDUOHVVGRJOLNH+HVSHURF\RQLQDH Therefore, Prohesperocyon LVSUHPDWXUHO\GRJOLNHDQGVR cannot be a dog. The subsequent canid fossils include VNXOOVRIWKH+HVSHURF\RQLQDH:KHQDYDLODEOHWKHSRVW cranial skeletons of the Hesperocyoninae are slender and ORQJWDLOHGVLPLODUWRWKDWRIYLYHUULGVRUPXVWHOLGV and they possess a prominent baculum, typical of mustelids and occasional viverrids, but not like canids. In addition, the musteloid species Mustelavus, which is found in the same stratum as Hesperocyon, had an identical dental formula and similar skull and dental proportions; it was simply 25% smaller.28 These many features strongly support placement of the Hersperocyoninae among mustelid (or perhaps viverrid) carnivores rather than among the canids. The fossils at least, if not the monophyletic interpretation, place Prohesperocyon as the ancestral dog. Figure 3. Crania of Urocyon cinereoargentus, the grey fox (top), 2IWKHYDULRXVFODGHVRI%RURSKDJLQDHPHPEHUV and Martes pennanti, the (bottom). A) view from above; B) view from below. The rostrum of the grey fox (and all dogs) of the basal clade thought to link the Borophaginae to forms an extended snout, which results in the eyes being located the Herpercyonidae include , Oxetocyon, approximately half-way along the skull, creating room for an extra and Otarocyon. They share much in common with set of molar teeth and the typically longer face of canids. The rostrum of the fisher is shorter, which results in the eyes being located Hesperocyon, and it has been acknowledged that cladistic less than 40% of the way along the skull, creating the typically analysis might fail to place these basal species in the shorter face of mustelids. Despite the similarity of the two crania, monophyletic Borophaginae subfamily.31 It is submitted the two animals belong to separate families of carnivores. The grey that the Hesperocyoninae and these closely similar basal fox is a small-sized species of canid. The fisher is a medium-sized species of mustelid. The cranium of the fisher is similar to that of the %RURSKDJLQDHEHORQJWRDVHSDUDWHPXVWHOLGOLNH RUYLYHUULG Hesperocyonidae. The dental formula of the fisher is: I3/3, C1/1, like) basic type. The more recent Borophaginae appear to be P4/4, M1/2; of the Hesperocyonidae is: I3/3, C1/1, P4/4, M2/2, a sister clade of the Caninae. The enhanced dental features of and of the grey fox is: I3/3, C1/1, P4/4, M2/3. the Borophaginae, in some cases for crushing bone, appear to lie reasonably within the morphogenetic potential of the The domestic dog: Canislupus familiaris FDQLGEDVLFW\SH,IVRQRQEDVDO%RURSKDJLQDHDQG&DQLQDH The domestic dog, Canislupus familiaris, is a grey may have arisen from a common basic type. To summarize, wolf.5,33 Karyotypic and mitochondrial DNA sequence evaluation of extant and extinct Canidae suggests that evidence clearly demonstrates this. Mitochondrial DNA current interpretation of the family actually encompasses sequences between the domestic dog and the grey wolf DELSK\OHWLFFODGHWKH&DQLGDHDQGWKH+HVSHURF\RQLQDH differ by at most 0.2%. This is to be compared with a 4%

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difference between the grey wolf and the coyote (C. latrans) the large domestic dog breeds are very similar to the grey and a 4% difference even between some populations of grey ZROIDOOWKHVPDOOEUHHGVDUHWRVRPHH[WHQWMXYHQLOL]HGRU wolf.5 Morphologically, however, the domestic dog displays paedomorphic.8 Despite phenotypic change not requiring DQXQVXUSDVVHGGHJUHHRIYDULDWLRQ2QHFOHDUH[DPSOHLV genetic change, the latter is an ongoing process, and in the size variation, which in the domestic dog surpasses that case of length variations in tandemly repeated sequences, of all other living and extinct species of dog.34 In many these have been shown to be a significant source of cases differences observed in the domestic dog are at morphological variation within breeds. least as great as differences observed between genera of Despite the large spectrum of diversity displayed among wild canids. Before cytogenetic and DNA analyses were GRPHVWLFDWHGEUHHGVQRIR[OLNHGRJVKDYHEHHQREVHUYHG available, the morphological differences led to the erroneous It would appear that wolves no longer have the genetic assumption that dogs arose from a number of wild canids. SRWHQWLDOWRIRUPDIR[OLNHFDQLG:D\QHVWXGLHGFUDQLDO Based on the diversity of breeds, on geographical and on morphology.46 Foxes have small, narrow skulls. Domestic other considerations Darwin thought it “highly probable breeds include those with small skulls (toy breeds) or with that our domestic dogs have descended from several wild narrow skulls (Russian wolfhounds and Salukis) but of the species”.35,36 This is not the case. The domestic dog is breeds sampled, none displayed both features. If skull length descended from the grey wolf only. was increased but overall growth rate reduced, small dogs A number of recent genetic studies have pieced with long, narrow skulls, not unlike foxes, would result. together the following history of domestication. During Similarly, the domestic dog displays an impressive diversity the Pleistocene, domesticated dogs began to appear in of limb sizes and proportions. Here, too, allometric analysis and migrated with nomadic human groups both RIWKHOLPEGHPRQVWUDWHVFORVHNLQVKLSZLWKWKHZROIOLNH south to Africa and north to the Arctic, with subsequent canids, but not with other wild canids such as the fox.8 The migrations throughout Asia and via the Bering Strait into wolf/fox transition involves complex phenotypic changes. the Americas. There are fascinating parallels between Modulation or activation of suites of genes is required for these hypothesized dog migrations and our contemporary WKLVSURFHVVQRVLPSOHPXWDWLRQHYHQWDSSHDUVWRVXI¿FH understanding of human migrations, especially as evidenced The selective breeding of the domestic dog does not appear by studies of human genetic haplotypes and the development to be able to mimic this process and to produce a fox.46 of languages.42 ([SHULPHQWDOHYLGHQFHVXJJHVWVWKDWGRJ Mechanisms involving simply mutation and selection are domestication may have been rapid. Recently, Trut and unable to produce a fox. An alternative model, requiring colleagues reported on extensive domestication studies in creation of no new genetic information, is one where early the silver fox.437HQJHQHUDWLRQVZHUHVXI¿FLHQWWRVHOHFWIRU dogs possessed combinations of alleles able to produce domestication. The study demonstrated both the rapidity of both wolf and fox phenotypes. In subsequent generations, the process, under guided selection, and the simultaneous due to loss of heterozygosity and reproductive isolation, drop in glucocorticoid blood levels in the animals, which ZROIOLNHGHVFHQGDQWVORVWWKHDOOHOHVFULWLFDOIRUWKHIR[ appears to provide a biochemical explanation for the phenotype. Because domestic dogs are descended from the alteration in behavior. A number of unique phenotype JUH\ZROIWKH\DOVRODFNWKHVHIR[DOOHOHVZKLFKLVZK\ changes accompanied domestication in the foxes. The same selective breeding in dogs has been unable to give rise to changes are thought to have accompanied domestication of foxes. However, dogs and foxes belong to the same basic the dog.43,44 It is still unclear whether the unique form of type, and dogs are able to hybridize with foxes. Under these dominant melanism observed in dogs, which is exceptional FLUFXPVWDQFHVIR[DOOHOHVFDQEHUHLQWURGXFHGLQWRWKHGRJ among , arose before or after domestication genome. The presence of chromosome 40 in many fox occurred.45 VSHFLHVDQGLWVDEVHQFHLQZROIOLNHDQG6RXWK$PHULFDQ Since domestication, dog breeding has been characterized canids make it a candidate repository for at least some of E\VLJQL¿FDQWSKHQRW\SLFGLYHUVLW\EXWOLWWOHJHQHWLFGLYHUVLW\ WKHPLVVLQJIR[DOOHOHV :D\QHSURYLGHGLQWHUHVWLQJLQVLJKWVLQWRGRJGLYHUVL¿FDWLRQ The behavioral studies of Trut and colleagues in ZKHQKHDVNHGWKHTXHVWLRQ³,QZKDWZD\VFDQPRUSKRORJ\ Novosibirsk indicated that tameness (domestication) is change in the absence of appreciable genetic change?”46 GRUPDQWLQIR[HV2QFHVHOHFWHGIRUDQGLWUHTXLUHGRQO\ 8VLQJWKHWKUHHSURQJHGDSSURDFKRIELYDULDWHDOORPHWU\ 10 generations, the behavior greatly resembled tameness in discriminate analysis, and allometric scaling to compare wolves, i.e. domestic dogs, even though foxes and wolves 21 dental and cranial measurements, Wayne concluded are genetically well separated.48,49 Selection for tameness was that most small breeds of domestic dog are paedomorphic DFFRPSDQLHGE\FRVHJUHJDWLRQRIDGGLWLRQDOPRUSKRORJLFDO with respect to certain morphologic characters, and that WUDLWVLQFOXGLQJÀRSS\HDUVUROOHGWDLOVDQGFKDQJHVLQ potential morphologic diversity depends on the spectrum skull shape.48 Such studies indicate that although in some of diversity expressed during development. In a second instances traits may be lost from populations, for instance by study of canid limbs identical conclusions were reached.46 JHQH¿[DWLRQDQGFDQQRORQJHUEHVHOHFWHGIRULHWKHIR[ /LPESURSRUWLRQVRIDGXOWVRIVPDOOGRJEUHHGVFRUUHVSRQG phenotype in wolves; in other instances traits can lie dormant WRWKRVHRIWKHMXYHQLOHVRIODUJHUGRJEUHHGV$OWKRXJK in genomes, perhaps suppressed by regulatory genes, and

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WKHVHFDQEHµUHDFWLYDWHG¶XSRQDUWL¿FLDOVHOHFWLRQ5DFFRRQ GRJVIURP¿YHWRIRXURQWKHIURQWOLPEVRILycaon pictus dog skulls greatly resemble those of South American foxes, $IULFDQZLOGGRJ DQGIURPIRXUWR¿YHRQWKHKLQGOLPEV SDUWLFXODUO\WKHFUDEHDWLQJIR[ Cerdocyonthous), even of some breeds of Canis lupus familiaris (domestic dog). though these two species are genetically well separated.50 Not only dentition but also coat color schemes are 6NXOOVKDSHYDULDWLRQPD\EHµKDUGZLUHG¶LQWRWKHFDQLG shared among carnivores, and mammals in general.51,52 genome. Alopex lagopus (arctic fox) displays two coat colors, the winter pelage being snow white. This trait is shared by the Activation of common, inherent genetic (Vulpes corsac), though it is less pronounced. potential by carnivore species The unrelated mustelid, Mustela ermina (/ermine), An exception to the rule, ‘large domestic dogs are similarly shares this trait. Although white coat color may morphologically equivalent to grey wolves’, is seen in their have arisen independently in foxes and , the trait dentition. Grey wolves usually have longer teeth than equally probably results from simple activation of common genetic VL]HGGRPHVWLFEUHHGV,QIDFWWRRWKGZDU¿VPIUHTXHQWO\ potential within at least the order Carnivora; certainly a accompanies animal domestication.46 This observation QXPEHURIRWKHUVSHFLHVGLVSOD\ZKLWHFRDWFRORUYDULDQWV probably reflects a general feature of the carnivore $QRWKHUH[DPSOHRIDVKDUHGWUDLWLVWKHIDFHPDVN RI phenotype. The heart of the wolf is the breeding Nyctereutes,QLWVEXVK\VXPPHUFRDWZLWKLWVEODFNH\H couple. It is invariably the only couple who mate. These cheek patches, white snout, and white forehead, it looks LQGLYLGXDOVDUHWKH¿WWHVWPRVWDJJUHVVLYHDQLPDOV$Q\WUDLW OLNHDUDFFRRQDWOHDVWDW¿UVWJODQFH7KLVIDFHPDVNLVDOVR in their phenotype which promotes this type of dominance shared with Otocyon megalotis EDWHDUHGIR[ DPRQJWKH such as tooth length, body size, or assertive behavior, will dogs, with (the raccoons), Ailurus fulgens (lesser be positively selected for. Domestication, however, will be panda), melanoleuca (), Tremarctos accompanied by a relaxation of this strict selection pressure ornatus (), Mustela putorius FRPPRQSROH XQOHVVWKHIHDWXUHVDUHDUWL¿FLDOO\VHOHFWHGIRU 7KXVWKH cat), Mustela eversmanni ( polecat), civetta natural state of an animal biases selection towards particular (African ) and hermaphroditus (palm extremes of its potential phenotypic diversity. This accounts FLYHW ,WDSSHDUVXQOLNHO\WKDWWKHIDFHPDVNLVXQGHUVXFK for the phylogenetic inconsistency reported by Wayne46 strong selective pressure that it would develop independently in the pattern of morphological similarity between breeds in all these species. It is more likely that the trait is caused of domestic dog and the grey wolf. The placing of the by activation of common genetic potential within the order. grey wolf, although clearly the progenitor of the domestic A further example of common genetic potential involves the breeds, is not intermediate within the range of the breeds ORQJOHJJHGQDUURZERGLHGODUJHHDUHGSKHQRW\SHW\SLFDO but peripheral. The traits responsible for this inconsistency of the grassland carnivore ecomorph, which both the maned were the generally greater size and the longer teeth of the wolf (Chrysocyon brachyurus) among the canids, and the grey wolf, which are precisely those traits predicted to be at ( serval) among the felids, so clearly exemplify. their extremes due to natural selection pressure. Therefore, although the canid basic type is unique, it appears Another interesting aspect of canine dental adaptation to use genetic potential common to various basic types of is the development of a trenchant heel on the carnassial carnivore. WHHWKRIWKUHHFDQLGVSHFLHVCuon alpinus (Dhole), Lycaon Conclusion pictus (African wild dog), and Speothos venaticus (bush dog). The carnassials are composed of an anterior cutting The primary requirement of belonging to a single blade (trigonid) and a posterior grinding basin (talonid). In EDVLFW\SHDELOLW\WRK\EULGL]HLVIXO¿OOHGE\WKHFDQLGV,Q canids with a trenchant heel, the talonid basin is reduced addition to this, on the basis of their single gene sequence DQGDOWHUHGWRIRUPDVHFRQGEODGH$UHGXFWLRQRIWKHSRVW homologies and the thermal stability of DNA duplexes, carnassial molars occurs parallel with this. It is similar to the canids clearly belong to a unique group, and karyotype the carnivorous dentition observed in felids. Because there data also supports this. Canid karyotypes have far more in is a wide biological distance between Speothos and the other common with each other than with other members of the two canid species, it has been proposed that the trenchant Carnivora. Therefore, the extant canids form a recognizable heel developed independently at least twice.6 However, this and fundamental taxonomic unit with the status of basic dental pattern is observed in a number of carnivore families. type. Currently recognized extinct canids, however, appear ,WVHHPVPRUHOLNHO\WKDWLWUHÀHFWVDFWLYDWLRQRIFRPPRQ to include animals from at least one other basic type. genetic potential among the carnivores, rather than the The Canidae are a part of the order Carnivora, and have repeated development of new genetic information and novel various traits in common with members of other carnivore phenotypic traits. Activation of common genetic potential families. These include features of karyotype, morphology, could also be responsible for the presence of additional teeth dentition, and coat colour. This suggests that the various in Otocyon megalotis EDWHDUHGIR[ UHÀHFWLQJLWVPRUH carnivore families have much genetics in common. The term omnivorous diet. Similarly, activation of common genetic ‘common genetic system’ could be applied here.3 The canid potential could also cause change in toe number in various pattern adopts the common carnivore ‘phenotype’ as a base

86 JOURNAL OF CREATION 25(3) 2011 Papers

from which to express its unique set of characters. However, References ERXQGDULHVGH¿QHGE\QDWXUDOK\EULGL]DWLRQSRWHQWLDOHQVXUH 1. :R]HQFUDIW:&&ODVVLILFDWLRQRIWKHUHFHQW&DUQLYRUDLQ that, although the Canidae are a part of the order Carnivora, *LWWOHPDQ-/ (G Carnivore Behaviour, Ecology and Evolution, they represent a unique basic type with a recognizable and Cornell University Press, Ithaca, NY, pp. 569–593, 1989. VHSDUDWHLGHQWLW\'H¿QLQJWKHH[WHQWDQGQDWXUHRIVXFK 2. /DQJJXWK$(FRORJ\DQGHYROXWLRQLQWKH6RXWK$PHULFDQFDQLGV ERXQGDULHVLVDVLJQL¿FDQWJRDORIIXWXUHVWXGLHVLQEDVLF LQ)R[0: (G The Wild Canids: Their Systematics, Behavioural type research. Ecology, and Evolution, Van Nostrand Reinhold Company, New York, SS± Appendix 3. %HQQHW]HQ-/DQG)UHHOLQJ0*UDVVHVDVDVLQJOHJHQHWLFV\VWHP genome composition, collinearity and compatibility, Trends . 7KHUHFHQW&DQLGDHDIWHU6LOOHUR=XELULet al.53 and 9± 9 /LQGEODG7RKet al. 4. :D\QH5.%HQYHQLVWH5(-DQF]HZVNL'1DQG2¶%ULHQ6- 0ROHFXODUDQGELRFKHPLFDOHYROXWLRQRIWKHFDUQLYRUHLQ*LWWOHPDQ -/ (G Carnivore Behavior, Ecology and Evolution, Cornell Wolf-like canids (9) University Press, Ithaca, NY, pp. 465–494, 1989. Canis lupus grey wolf (incl. dog & dingo) 5. Wayne, R.K., Molecular evolution of the dog family, Trends Genet. Canis rufus 9± Canis latrans coyote 6. :D\QH5.DQG2¶%ULHQ6-$OOR]\PHGLYHUJHQFHZLWKLQWKH Canis aureus golden jackal Canidae, Syst. Zool. 36± Canis simensis  %HUWD$2ULJLQGLYHUVL¿FDWLRQDQG]RRJHRJUDSK\RIWKH6RXWK Cuon alpinus dhole $PHULFDQ&DQLGDHLQ3DWWHUVRQ%'DQG7LPP56 (GV 6WXGLHV Lycaon pictus African wild dog LQ1HRWURSLFDO0DPPDORJ\(VVD\VLQKRQRXURI3KLOLS+HUVKNRYLW] Canis adustus side-striped jackal Fieldiana Zoology9 (New Series) 39± Canis mesomelas black-backed jackal 8. :D\QH5./LPEPRUSKRORJ\RIGRPHVWLFDQGZLOGFDQLGV7KH influence of development on morphological change, J. Morph. 187± South American canids/ Zorros (11) Chrysocyon brachyurus maned wolf 9. /LQGEODG7RK.:DGH&00LNNHOVHQ7 et al., Genome sequence, comparative analysis and haplotype structure of the Speothos venaticus bush dog domestic dog, Nature 438± Atelocynus microtis short-eared dog 10. 6KHOGRQ-:Wild Dogs: the Natural History of the Nondomestic Cerdocyon thous crab-eating fox Canidae, Academic Press, San Diego, CA, 1992. Pseudalopex culpaeus Pseudalopex fulvipes Darwin’s fox 11. Alderton, D., Foxes, Wolves and Wild Dogs of the World, Blandford 3UHVV/RQGRQ Pseudalopex griseus chilla Pseudalopex gymnocercus pampas fox 12. 0DFGRQDOG':DQG6LOOHUR=XELUL&The Biology and Conservation of Wild Canids.2[IRUG8QLYHUVLW\3UHVV2[IRUG Pseudalopex sechurae Pseudalopex vetulus hoary fox 13. /LJKWQHU-..DU\RW\SLFDQGDOOHOLFGLYHUVLW\ZLWKLQWKHFDQLG baramin (Canidae), J. Creation 23± Dusicyon australis Falkland Island wolf (†) 14. Scherer, S., Basic types of lifeLQ6FKHUHU6 (G  Typens des Lebens, Pascal Verl., Berlin, pp. 11–30, 1993. Red fox-like canids (14) Nyctereutes procyonoides racoon dog 15. 0D\U(Principles of Systematic Zoology, 0FJUDZ+LOO %RRN Company, New York, 1969. Otocyon megalotis bat-eared fox Vulpes bengalensis Indian fox 16. Gray, A.P., Mammalian Hybrids, Commonwealth Agricultural %XUHDX[6ORXJK(QJODQG Vulpes cana Blanford’s fox Vulpes chama Cape fox  :D\QH5.1DVK:*DQG2¶%ULHQ6-&KURPRVRPDOHYROXWLRQ Vulpes corsac corsac fox of the Canidae I, Cytogenet, Cell Genet. 44± Vulpes ferrilata 18. :D\QH5.1DVK:*DQG2¶%ULHQ6-&KURPRVRPDOHYROXWLRQ Vulpes macrostis kit fox of the Canidea II, Cytogenet, Cell Genet. 44± Vulpes pallida pale/pallid fox 19. *UDSKRGDWVN\$63HUHOPDQ3/6RNRORYVND\D19 Vulpes rueppelli Rueppell’s fox %HNOHPLVKHYD956HUGXNRYD1$'RELJQ\*2¶%ULHQ6- )HUJXVRQ6PLWK0$DQG

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22. (OGUHGJH1DQG*RXOG6-Punctuated equilibria: an alternative to 44. +DUH%3O\XVQLQD,=,JQDFLR16FKHSLQD26WHSLND$ phyletic gradualismLQ6FKRSI7-0 (G Models in Paleobiology, :UDQJKDP5DQG7UXW/6RFLDOFRJQLWLYHHYROXWLRQLQFDSWLYH Freeman, Cooper & Co., San Francisco, CA, 1969. foxes is a correlated by product of experimental domestication, Curr. Biol. 15± 23. 'HXWVFK-6DQG0RXFKHO9LHOK(+R[JHQHVDQGWKHFUXVWDFHDQ body plan, Bioassays 25± 45. Anderson, T.M., Vonholdt, B.M., Candille, S.I. et al., Molecular and evolutionary history of melanism in North American gray wolves, 24. Munthe, K., CanidaeLQ-DQLV&0 (G Evolution of Tertiary Science 323± Mammals of , Cambridge University Press, Cambridge, pp. 124–143, 1998. 46. :D\QH5.&UDQLDOPRUSKRORJ\RIGRPHVWLFDQGZLOGFDQLGV WKHLQÀXHQFHRIGHYHORSPHQWRQPRUSKRORJLFDOFKDQJHEvolution 25. 9DQ9DONHQEXUJK%:DQG;DQG'DPXWK-&RSH¶VUXOH 40± hypercarnivory, and extinction in North American canids, Science 306±  )RQGRQ-:DQG*DUQHU+50ROHFXODURULJLQVRIUDSLGDQG continuous morphological evolution, Proc. Natl. Acad. Sci. USA. 26. Wang, X., Tedford, R.H., Van Valkenburgh, B. and Wayne, R.K., 101± $QFHVWRU\HYROXWLRQDU\KLVWRU\PROHFXODUV\VWHPDWLFDQG HYROXWLRQDU\HFRORJ\RI&DQLGDHLQ0DFGRQDOG':DQG6LOOHUR 48. 7UXW/1.KDUODPRYD$9.XNHNRYD$9$FODQG*0&DUULHU =XELUL& (GV  The Biology and Conservation of Wild Canids, '5&KDVH.DQG/DUN.*0RUSKRORJ\DQGEHKDYLRUDUHWKH\ 2[IRUG8QLYHUVLW\3UHVV2[IRUG FRXSOHGDWWKHJHQRPLFOHYHO"LQ2VWUDQGHU($*LJHU8DQG /,LQGEODG7RK . (GV  The Dog and its Genome, Cold Spring rd  Romer, A.S., Vertebrate Paleontology, 3 ed., University of Chicago +DUERU/DERUDWRU\3UHVV:RRGEXU\1<SS± Press, Chicago, 1966. 49. .XNHNRYD$9$FODQG*02VNLQD,1.KDUODPRYD$9 28. Wang, X., Phylogenetic Systematic of the Hesperocyoninae 7UXW/1&KDVH./DUN.*(UE+1DQG$JXLUUH*'The &DUQLYRUD&DQLGDH Bulletin of the American Museum of Natural genetics of domesticated behavior in canids: what can dogs and History 221± silver foxes tell us about each other? LQ2VWUDQGHU($*LJHU8 29. +XQW507KHDXGLWRU\EXOODLQ&DUQLYRUDDQDQDWRPLFDOEDVLV DQG/,LQGEODG7RK. (GV The Dog and its Genome, Cold Spring for reappraisal of Carnivore evolution, J. Morph. 143± +DUERU/DERUDWRU\3UHVV:RRGEXU\1<SS± 30. 0RRUH:-The Mammalian Skull, Cambridge University Press, 50. :D\QH5.*HIIHQ(*LUPDQ'-.RHSOL.3/DX/0DQG Cambridge, 1981. Marshall, C.R., Molecular systematics of the Canidae, Syst. Biol. 46± 31. :DQJ;7HGIRUG5+DQG7D\ORU%(3K\ORJHQHWLF6\VWHPDWLF RIWKH%RURSKDJLQDH &DUQLYRUD&DQLGDH Bulletin of the American 51. .HUQV-$&DUJLOO(-&ODUN/$&DQGLOOH6,%HUU\HUH7* Museum of Natural History 243± 2OLYLHU0/XVW*7RGKXQWHU5-6FKPXW]600XUSK\.( DQG%DUVK*6/LQNDJHDQGVHJUHJDWLRQDQDO\VLVRIEODFNDQG 32. Wang, X. and Tedford, R.H., Dogs: Their Fossil Relatives and brindle coat color in domestic dogs, Genetics 176± Evolutionary History, Columbia University Press, New York, 2008. 52. Candille, S.I., Kaelin, C.B., Cattanach, B.M., Yu, B., Thompson, D.A., 33. 9LOD&6DYRODLQHQ30DOGRQDGR-($PRULP,55LFH 1L[0$.HUQV-$6FKPXW]600LOOKDXVHU*/DQG%DUVK -(+RQH\FXWW5/&UDQGDOO.$/XQGHEHUJ-DQG:D\QH G.S., A EGHIHQVLQPXWDWLRQFDXVHVEODFNFRDWFRORULQGRPHVWLFGRJV R.K., Multiple and ancient origins of the domestic dog, Science Science 318± 276± 53. 6LOOHUR=XELUL&6+RIIPDQ00DF'RQDOG':&DQLGV)R[HV 34. Sutter, N.B., Bustamante, C.D., Chase, K. et al., A single IGF1 allele :ROYHV-DFNDOVDQG'RJV,8&166&&DQLG6SHFLDOLVW*URXS,8&1 LVDPDMRUGHWHUPLQDQWRIVPDOOVL]HLQGRJVScience 316± the world Conservation Union, 2004.  35. Darwin, C., On the Origin of Species by Means of Natural Selection, -RKQ0XUUD\/RQGRQ Barnabas Pendragon holds a B.Sc. (hons.) (1980) and 36. 6XWWHU1%DQG2VWUDQGHU($'RJVWDUULVLQJWKHFDQLQHJHQHWLF an M.Sc. (1982) from the faculty of science at Manchester system, Nature Rev. Genet. 5± University, England, a Ph.D. (1987) from the faculty of science  3HQQLVL($VKDJJ\GRJKLVWRU\Science 298± at the Justus Liebig University, Giessen, Germany, and a 38. 6DYROHLQHQ3=KDQJ<3/XR-/XQGHEHUJ-DQG/HLWQHU7 D.Sc. (1998) from the faculty of medicine at Zurich University, *HQHWLFHYLGHQFHIRUDQ(DVW$VLDQRULJLQRIGRPHVWLFGRJVScience Switzerland. He has published almost 100 scientific papers 298± and is a referee for ten international science journals. He has 39. /HRQDUG-$:D\QH5.:KHHOHU-9DODGH]5*XLOOHQ6DQG taught and held consultancy positions throughout Europe, Vila, C., Ancient DNA evidence for old world origin of new world USA and Asia. dogs, Science 298± 40. 3DUNHU+*.LP/96XWWHU1%et al., Genetic structure of the purebred domestic dog, Science 304± 41. :D\QH5.DQG2VWUDQGHU($/HVVRQVOHDUQHGIURPWKHGRJ genome, Trends Genet. 23± 42. 2OVRQ6Mapping Human History,+RXJKWRQ0LIÀLQ&RPSDQ\ New York, 2002. 43. 7UXW/13O\XVQLQD,=DQG2VNLQD,1$QH[SHULPHQWRQIR[ domestication and debatable issues of evolution of the dog, Russian J. Genet. 40±

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