EVOLUTIOKARY GENETICS OF IKSULAR ADRIATIC LIZARDS GEORGEC. GORMAN Department of Biology, University of California, Los Angeles, Los Angeles, California 90024 MICHAELSOUL^ AND SUHYUNGYANG' Department of Biology, University of California, Sun Diego, La Jolla, California 92037 AND EVIATARNEVO Biology Department, University of Haifa, Haifa, Israel Received March 16, 1974 The use of electrophoresis to study sicula is found on virtually every island in allozyme variation allows the evolutionary the Adriatic. The pattern of distribution in biologist to compare various genetic param- places is completely interdigitating, but eters of populations. In this paper we sympatry is completely absent on islands employ this technique in an analysis of the smaller than several sauare kilometers. On ev61utionary genetics of the genus Lacerta some large islands both species can be in the Adriatic region. We compare genetic found, but there is usually parapatry or similarity among populations and species only marginal sympatry. Second, both L. to obtain a quantitative estimate of related- melisellensis and L. sicula have undergoneu ness. We compare genetic variability on considerable evolution in size, color, and islands and on the mainland to examine pattern. Thus Mertens and \Yermuth genetic consequences of insularity. \Ye (1960) list 18 subspecies for Lacerta examine the relative contributions of island melisellensis. and no fewer than 39 for L. size, habitat complexity, and various sicula. The subspecies controversy aside, measures of isolation to the determination there is no doubt that some of the insular of the observed levels of heterozygosity. isolates are very distinctive. For example, Finally, we attempt to estimate the relative there are populations of L. 7nelisellensis importance of selection and genetic drift, comprised of large (adult males > 10 and apply our findings to the question of grams) jet-black lizards, others of small allelic neutrality. brown lizards (adult males -- 5 grams) with The Adriatic waters of Yugoslavia are a solid green middorsal area, and still others dotted with more than 1000 islands of that are highly patterned. In addition to diverse size and habitat complexity, ranging being polytypic, many populations are from rocks barely emergent from the sea to highly polymorphic for dorsal pattern and substantial islands measuring hundreds of for ventral coloration (salmon, cream, yel- square kilometers. Lacertid lizards are low, and pale blue may exist in a single abundant on most of these islands and the population). adjacent coastal strip. They have interested Lacerta melisellensis and L. sicula appear evolutionists for two reasons: First, there to be of broad ecological tolerance occur- is a classic case of competitive exclusion ring in a variety of terrestrial situations. (RadovanoviC, 1956, 1959 cited in hlayr, They are most often collected in shrub and 1963). Either Lacerta melisellensis or L. grassy areas, and also around small stones. A third species enters marginally- into the Present address: Museum of Vertebrate Zoology, University of California, Berkeley, Calif. present study. L. oxycephala is restricted to 94720. large boulders and rock faces on the main- EVOLUTION29: 52-71. March 1975 52 E\'OLUTIONARY GENETICS 53 land and on the islands. Unlike the other Populations Sampled two species, it does not show inter-island 1) Lacerta sicula. variation, nor is it polymorphic within a) L. s. campestris.-This is one of the populations. Xo subspecies have been more widely distributed races of L. sicula. designated (Mertens and n'ermuth, 1960). Population samples were collected at Zadar L. oxycephala is broadly sympatric with L. (n =30) and Trogir (n = 30), Yugo- melisellensis in the southern portion of the slavia; and Pescara (n= 30)) Italy (all latter's range, and has been found on at mainland). All collections were made within least one island in sympatry with L. sicula an area < 1 km sq. (Xevo et al., 1972). What we now call L. b) L. s. pe1agosae.-This form is endemic melisellensis and L. sicula have historically to Palagruia (n = 16). been considered closely related in con- c) L. s. cazzae.-Three island popula- ventional taxonomic terms (even con- tions were sampled: SuSac (n = 34), specific), and L, oxycephala is considered KopiSte (n = 19)) and Pod KopiSte (n = distant from them (Boulenger, 1920). 30). Recently, Arnold (1973) split the genus Lacerta into several genera, leaving oxy- 2) Lacerta melisel1ensis.-(islands only, cephala in Lacerta and placing melisellensis we were unable to collect a mainland and sicula in Podarcis. For convenience series). only, we retain the older nomenclature. a) L. m. curzo1ensis.-Collected at grnovo, island of KorEula (n = 14) ; within an area < 1 km sq. b) L. m. 1issana.-Collected at Pasadur, Species Studied island of Lastovo (n = 24) and Pod AlrEaru 1) Lacerta sicu1a.-This species occurs (n = 34)) a tiny island near Lastovo; the in Italy and along the Adriatic coast of town of Komiia, island of Vis (n = 17), Yugoslavia. Its present distribution in and Greben (n = 30), a small island adja- northern Yugoslavia suggests that it has cent to Vis; and BiSevo (n = 28), a mod- been a relatively recent invader, having erately large island west of Vis. come from north-eastern Italy around the c) L. m. gigas.-This subspecies is Adriatic. Its occurrence on some south- endemic to the tiny island of Mali Parianj, central Adriatic islands, and its absence adjacent to the east coast of Vis (n = 11). from the Yugoslav mainland at these lati- d) L. m. kammereri.-This subspecies is L2 tudes suggests direct over-water coloniza- endemic to the tiny island of Mali Barjak, tion of these islands (Palagruia, SuSac, adjacent to the west coast of Vis (n = 7). KopiSte, Pod KopiSte) from Italy. L. sicula e) L. m. digenea.-This form is endemic is also present in southern Yugoslavia, its to Svetac, west of Vis and BiSevo (n =32). presence there is presumably the result of f) L. m. melisel1ensis.-The nominate another over-water colonization. About race is endemic to Brusnik near Svetac one-third of the described subspecies are (n = 28). on islands in the eastern Adriatic. g) L. m. ga1vagnii.-A race endemic to Kamik near Svetac (n = 20). 2) Lacerta melisel1ensis.-This is an h) L. m. pornoensis.-Endemic to the autochthonous species to the coastal regions tiny isolated island of Jabuka west of of Yugoslavia. Of the 18 named subspecies, Svetac (n = 18). one is on mainland Yugoslavia, the remain- der are all insular isolates. 3) Lacerta oxycepha1a.-Only 7 indi- viduals were studied, three from Lastovo 3) Lacerta oxycepha1a.-This species is and two each from Greben and Vis. also restricted to Yugoslavia, occurring on As we are not concerned with nomen- the Dalmatian coast and islands. clature at the subspecific level, the popu- 54 G. C. GORMAN ET AL. lations hereinafter are primarily referred to scorable for all populations of all species by locality only. Figures 14show collect- and Sn calculations are based only on these ing sites, and Table 1 presents data on the 19 loci. localities. Electrophoresis Allele frequency data for 20 populations Specimens were collected and transported (oxycephala treated as one population) are alive to the laboratory where they were presented in Table 2, and levels of poly- placed in a -68C freezer. Before processing morphism and heterozygosity are presented for electrophoresis, the head, feet, and skin in Table 1. Data on genetic similarity (SR) were removed for morphological studies. appear in Table 3. After removal of the gut, the body was homogenized in two volumes of grinding 1) Taxonomic Comparisons buffer (0.1 M Tris, 0.001 M EDTA, and 5 X M NADP, pH adjusted to 7.0 with The similarity coefficients in Table 3 con- concentrated HCl) and centrifuged with firm the morphologically based taxonomy 0.5 ml of toluene at 18,000 r.p.m. for 30 for the species level. Within-species simi- minutes. The supernatant was removed and larities range from .84-1.0 among L. frozen at -68C. melisellensis populations and .88-.99 for L. Starch gel electrophoresis was carried out sicula. Between species similarities for this with the same proteins and procedures pair show no overlap with the above, rang- described by AlcKinney et al. (1972) for ing from .61-.74. L. oxycephala is less 22 loci with the following exceptions: closely related to L. melisellensis and L. Albumin was not electrophoresed; 6-phos- sicula than the latter are to each other. The phogluconate dehydrogenase (6 Pgd) was mean similarity value is .42 with sicula and demonstrated with a Tris maleate EDTA .44 with melisellensis. This confirms the buffer, pH 7.4, and isocitrate dehydrogenase results of a preliminary study (Gorman, (Idh) with a Tris citrate buffer, pH 8.0. 1972). Fumarase (Fum) was demonstrated with These data are relevant to the general a Poulik buffer system, pH 8.1, for the problem of how similar congeners can be tray buffer, and pH 8.6 for the gel buffer. genetically, and are relevant to the question Heterozygosity estimates are based on of whether there need be a "genetic revolu- actual counts of presumed heterozygotic tion" following speciation. Two races of genotypes. Mean heterozygosity (H) is Danish house mice (Mus ~nusculus) have defined as the number of presumed hetero- average SE values between them of about zygotic genotypes recorded in a sample 0.50 (Rogers, 1972) and disjunct popula- divided by the product of the number of tions of the lizard Anolis carolinensis from individuals and the number of loci sur- Texas and the Bahamas have a value of veyed. Polymorphism estimates are based 0.68 (Webster et al., 1972). Within the on the number of loci with more than a relatively tightly-knit roquet species group single allele divided by the total number of of Anolis, between species SR values are as loci.