中国鲴亚科鱼类同工酶和骨骼特征及系统演化的探讨：鲤形目：鲤科

本文对鲴亚科Xenocyprinae共4属6种鱼和鲢亚科Hypophthal michthyinae的鲢、鳙Aristichihys nobilis进行了骨骼系统的研究,并对鲴亚科的6种鱼同工酶谱型,进行了分析比较。鲢亚科虽然具有鲴亚科的共同祖征和全部离征,但因其有较多的特化性状,仍将其列为和鲴亚科并列的一个亚科。应用分支系统学原理推导出鲴亚科的系统发育图。鲴亚科6种鱼的肝、肾、心、眼的晶状体、鳍、脑,肌肉等7种组织5种同工酶(LDH,MDH,ES,ADH,G6PDH)的电泳分析表明,生化分类和经典分类结果完全一致。     

鲴类寄生六鞭毛虫系统发育的研究

利用分支系统学（Ｃｌａｄｉｓｔｉｃｓ）的原理和方法,选取光镜下的２４个性状,对鲴亚科１７种寄生六鞭毛虫进行了系统发育分析,初步阐明了这１７种六鞭毛虫相互间的亲缘关系。结果还表明,鲴亚科寄生六鞭毛虫的分化较晚;一些明显特征：如杆状条纹,是进化适应的结果,具有系统学意义。还通过对寄生六鞭毛虫在鲴亚科鱼类中的区系分布特点分析,探讨了宿主相互间的亲缘关系。结果表明：寄生六鞭毛虫的区系分布能够反映宿主相互间     

Complete mitochondrial genomes of three sea basses Lateolabrax (Perciformes,Lateolabracidae) species: Genome description and phylogenetic considerations

Genus Lateolabrax consists of three species, Japanese sea bass Lateolabrax japonicus, spotted sea bass Lateolabrax maculatus and blackfin sea bass Lateolabrax latus. The complete mitochondrial DNA (mtDNA) of the three sea basses were amplified and sequenced to characterize and discuss their phylogenetic relationships. The length of mitogenomes was 16,593 bp, 16,479 bp and 16,600 bp, respectively, and all of them consisted of 13 protein-coding genes, 2 ribosomal RNA (rRNA), 22 transfer RNA (tRNA) and a control region, which are typical for mtDNA of vertebrate. Most genes were encoded on the H-strand, except for the ND6 and eight tRNA genes encoding on the L-strand. A significant variation among the three species was detected in length of the control region. Phylogenetic relationship among the three species was constructed based on the datasets, including the 12 protein-coding genes (except ND6 gene), 22 tRNA and 2 rRNA sequences. The results supported the sister taxon between L. japonicus and L. maculatus. The genetic resources reported here are useful for further studies in taxonomy and phylogeny of the three sea basses and related species.     

Phylogenetic structure of Zacco platypus (Teleostei, Cyprinidae) populations on the upper and middle Chang Jiang (=Yangtze) drainage inferred from cytochrome b sequences

We examined the genetic structure and phylogenetic relationships of some Chinese populations from the Chang Jiang (=Yangtze) drainage of the cyprinid Zacco platypus. We sequenced the complete mitochondrial cytochrome b gene of 64 individuals from 6 upper and middle tributaries of the Sichuan and Hunan Provinces to assess their population structure and systematics. The combined analyses of the phylogenetic information and the population structure suggested that Chinese Z. platypus consist of four distinct mtDNA lineages which exhibit high genetic variation and haplotypic diversity (Zacco A-D). The high molecular divergence observed among Zacco A-D mtDNA lineages (TrN+I (0.76) distance, mean 8.9%+/-1.7%) and their phylogeographic structure indicate that all four lineages have evolved independently. Analysis of molecular variance (AMOVA) indicates that most of the genetic variation observed is found among the four Zacco mtDNA lineages (thetaCT = 0.94) suggesting restricted gene flow among the Chang Jiang populations. Long-term interruption of gene flow was also evidenced by thetaST values higher than 0.9 that could be favoured by the discontinuous distributions of the lineages inhabiting upper (Sichuan Province) and middle (Hunan Province) Chang Jiang tributaries. The significant correlation between the geographic and genetic distances provide support for the importance of geographic discontinuity in shaping the Zacco genetic structure. Nested clade analysis (NCA) results were congruent with phylogenetic relationships recovered and confirm the genetic distinctiveness of four independent Zacco groups. These four groups correspond to the four Zacco A-D mtDNA lineages recovered in the phylogeny and were defined by nucleotide synapomorphies permitting bootstrapped and Bayesian confidence of 95% or greater. The high level of mitochondrial sequence divergence separating all Zacco mtDNA lineages suggested that the Z. platypus populations from the Chang Jiang drainage probably correspond to four different species.     

Phylogeography of Bufo marinus from its natural and introduced ranges.

The marine toad, Bufo marinus, has a broad natural distribution extending from the south-west of the USA to southern Peru and the central Amazon. It was introduced to several localities in the Caribbean and Pacific Oceans to control sugar cane pests. We sequenced 468 bp of mitochondrial DNA (mtDNA) containing the ND3 gene, and flanking tRNA genes from toads spanning the broad natural and introduced ranges. Consistent with the known history of introductions and expected effects of serial bottlenecks, mtDNA within introduced populations in Hawaii and Australia was uniform and most closely related to samples from eastern Venezuela and French Guiana. However, mtDNA nucleotide diversity in the geographic region spanning the source areas is also relative low (0.18-0.46%) and the absence of variation in the introduced populations precludes quantitative assessment of the reduction in genetic diversity. Unexpectedly, there was a large phylogeographic break (5.4% sequence divergence) within the natural range separating populations east and west of the Venezuelan Andes. We hypothesize that the two major lineages of B. marinus were isolated by the uplift of the eastern Andean cordillera which was completed approximately 2.7 Ma. Another species of the marinus group, B. paracnemis, had mtDNA paraphyletic, with marinus, being nested within the eastern lineage. Thus, at least one speciation event within the marinus group postdates the split within marinus. These findings suggest that the taxonomy of B. marinus should be re-evaluated and that the search for pathogens to control Australian populations should be conducted in populations from both lineages in the natural range.     

Evidence for gene flow in parasitic nematodes between two host species of shrews

We describe the genetic structure of populations of the intestinal nematode Longistriata caudabullata (Trichostrongyloidea: Heligmosomidae), a common parasite of short-tailed shrews (genus Blarina, Insectivora: Soricidae). Parasites and hosts were collected from a transect across a contact zone between two species of hosts, Blarina brevicauda and B. hylophaga, in central North America. An 800-base pairs (bp) fragment of the ND4 mitochondrial DNA (mtDNA) gene was sequenced for 28 worms and a 783-bp fragment of the mtDNA control region was analysed for 16 shrews. Phylogenetic analyses of mtDNA sequences revealed reciprocal monophyly for the shrew species, concordant with morphological diagnosis, and supported the idea that the transect cuts through a secondary contact zone between well-differentiated B. brevicauda and B. hylophaga. In contrast to this pattern, the parasitic nematode mtDNA phylogeny was not subdivided according to host affiliation. Genealogical discordance between parasite and host phylogenies suggests extensive gene flow among parasites across the host species boundary.     

Molecular systematics of short-horned lizards: biogeography and taxonomy of a widespread species complex

We surveyed mitochondrial DNA (mtDNA) sequence variation in short-horned lizards (Phrynosoma douglasi) from throughout western North America and used these data to estimate an intraspecific phylogeny and to assess biogeographic scenarios underlying the geographic structure of lineages in this species. We sequenced 783 base pairs from 38 populations of P. douglasi and three putative outgroups (P. ditmarsi, P. orbiculare, P. platyrhinos). We detected high levels of nucleotide variation among populations and a spatial distribution of mtDNA lineages compatible with major geographic regions. The phylogenetic hypotheses best supported by the data suggest that P. douglasi, as currently described, is paraphyletic with respect to P. ditmarsi. Populations of P. douglasi from the Pacific Northwest (ID, CA, OR, WA) form a monophyletic group that is sister to the subsequent radiation of P. ditmarsi and other P. douglasi clades. These results suggest that divergences within this widespread species are fairly old. We focused on the genetic structure of populations of P. douglasi from a geographic perspective and interpreted the intraspecific phylogeny in light of geologic and climatic changes in western North America during the last 20 million years. The generally high levels of genetic variation found in these population comparisons are in accord with high levels of morphological variation in this species group; however, only in the Pacific Northwest region is there spatial congruence between these phylogenetic results and subspecific ranges based on previous morphological studies. We compared the evolutionary units delineated in this study with previously described subspecies of P. douglasi and evaluated the support (from morphology and mtDNA) for each population lineage in the phylogeny and the implications for the taxonomy of this group.     

Speciation in an avian complex endemic to the mountains of Middle America (Ergaticus, Aves: Parulidae)

The implementation of the phylogeographic approach for the study of biodiversity is critical in poorly sampled regions like the montane systems of Middle America, as complex evolutionary histories often result in the presence of independent lineages not properly considered by traditional taxonomy. Herein we sequenced 2370 bp of mtDNA (ND2, cyt b and ATPase) from 81 individuals of Ergaticus, a complex of birds endemic to the montane forests of Middle America. Although current taxonomy recognizes two species, the results reveal considerable genetic structure with the presence of four mtDNA lineages. Two of these lineages within Ergaticus ruber evidence the need of a revaluation of the species limits for this taxon. The general phylogeographic pattern can be explained as a consequence of relative isolation of the populations in different mountain ranges separated by low elevation barriers. Most population groups did not show signals of demographic expansion with the exception of the one corresponding to clade 1. The divergence time estimates point to the Pleistocene as an important time period for the diversification of this complex.     

Mitochondrial DNA Variation and the Evolution of Robertsonian Chromosomal Races of House Mice, Mus Domesticus

The house mouse, Mus domesticus, includes many distinct Robertsonian (Rb) chromosomal races with diploid numbers from 2n = 22 to 2n = 38. Although these races are highly differentiated karyotypically, they are otherwise indistinguishable from standard karyotype (i.e., 2n = 40) mice, and consequently their evolutionary histories are not well understood. We have examined mitochondrial DNA (mtDNA) sequence variation from the control region and the ND3 gene region among 56 M. domesticus from Western Europe, including 15 Rb populations and 13 standard karyotype populations, and two individuals of the sister species, Mus musculus. mtDNA exhibited an average sequence divergence of 0.84% within M. domesticus and 3.4% between M. domesticus and M. musculus. The transition/transversion bias for the regions sequenced is 5.7:1, and the overall rate of sequence evolution is approximately 10% divergence per million years. The amount of mtDNA variation was as great among different Rb races as among different populations of standard karyotype mice, suggesting that different Rb races do not derive from a single recent maternal lineage. Phylogenetic analysis of the mtDNA sequences resulted in a parsimony tree which contained six major clades. Each of these clades contained both Rb and standard karyotype mice, consistent with the hypothesis that Rb races have arisen independently multiple times. Discordance between phylogeny and geography was attributable to ancestral polymorphism as a consequence of the recent colonization of Western Europe by mice. Two major mtDNA lineages were geographically localized and contained both Rb and standard karyotype mice. The age of these lineages suggests that mice have moved into Europe only within the last 10,000 years and that Rb populations in different geographic regions arose during this time.     

Comparative phylogeography in a genus of coral reef fishes: biogeographic and genetic concordance in the Caribbean

Geographic barriers that limit the movement of individuals between populations may create or maintain phylogenetically discrete lineages. Such barriers are often inferred from geographic surveys of a single mitochondrial marker to identify phylogenetic splits. Mitochondrial DNA, however, has an effective population size one-fourth that of nuclear DNA, which can facilitate the rapid evolution of monophyletic mtDNA lineages in the absence of geographic barriers. The identification of geographic barriers will thus be more robust if barriers are proposed a priori, and tested with multiple independent genetic markers in multiple species. Here, we tested two proposed marine biogeographic breaks located at the Mona Passage in the Caribbean Sea and at the southern end of Exuma Sound in the Bahamas. We sequenced mitochondrial cytochrome b (400 bp) and nuclear rag1 (573 bp) for nine species and colour forms (183 individuals total) within the teleost genus Elacatinus (Gobiidae) that span the proposed breaks. Our results showed that Mona Passage separated mtcyb and rag1 lineages, with no genetic exchange between populations separated by just 23 km. However, the Central Bahamas barrier was only weakly supported by our data. Importantly, neither barrier coincided with deep genetic splits. This suggests that these two barriers did not initially isolate regional populations, but instead disrupt ongoing gene flow between regions. Our inferred relationships further suggested a division of the Caribbean region into northwestern and southeastern regions, a pattern reflected by some freshwater and terrestrial vertebrates. Our results, coupled with genetic and demographic data from other reef fishes and corals, provide robust support for the Mona Passage as a long-term biogeographic barrier for Caribbean animals.     

Phylogenetic discordance at the species boundary: comparative gene genealogies among rapidly radiating Heliconius butterflies

Recent adaptive radiations provide excellent model systems for understanding speciation, but rapid diversification can cause problems for phylogenetic inference. Here we use gene genealogies to investigate the phylogeny of recent speciation in the heliconiine butterflies. We sequenced three gene regions, intron 3 ( approximately 550 bp) of sex-linked triose-phosphate isomerase (Tpi), intron 3 ( approximately 450 bp) of autosomal mannose-phosphate isomerase (Mpi), and 1,603 bp of mitochondrial cytochrome oxidase subunits I and II (COI and COII), for 37 individuals from 25 species of Heliconius and related genera. The nuclear intron sequences evolved at rates similar to those of mitochondrial coding sequences, but the phylogenetic utility of introns was restricted to closely related geographic populations and species due to high levels of indel variation. For two sister species pairs, Heliconius erato-Heliconius himera and Heliconius melpomene-Heliconius cydno, there was highly significant discordance between the three genes. At mtDNA and Tpi, the hypotheses of reciprocal monophyly and paraphyly of at least one species with respect to its sister could not be distinguished. In contrast alleles sampled from the third locus, Mpi, showed polyphyletic relationships between both species pairs. In all cases, recent coalescence of mtDNA lineages within species suggests that polyphyly of nuclear genes is not unexpected. In addition, very similar alleles were shared between melpomene and cydno, implying recent gene flow. Our finding of discordant genealogies between genes is consistent with models of adaptive speciation with ongoing gene flow and highlights the need for multiple locus comparisons to resolve phylogeny among closely related species.     

Phylogenetic relationships of north American field crickets inferred from mitochondrial DNA data

A well-supported molecular phylogeny for North American Gryllus species based on a combined data set of mitochondrial (mt) DNA is presented. A total of 26 individuals representing 13 populations of 11 species of the genus Gryllus and 4 individuals of two outgroup species, Teleogryllus oceanicus and Acheta domestica, were sampled in this study. The complete cytochrome b gene (1036 bp) and a 500-bp fragment of the 16S rRNA gene were sequenced for each individual. Since results from separate analyses of the cytochrome b and 16S data sets, as well as a previously published mtDNA restriction-site data set, were not conflicting, all data were combined for phylogenetic analyses. The clade of European Gryllus was clearly separated from the North American clade. The amount of sequence divergence between these clades was significantly greater than within the clades, suggesting a basal drift-vicariant event in the genus. This is the first phylogenetic analysis of North American Gryllus that includes western species. Four well-supported groups were identified but their relationships showed no clear east-west structure. Our phylogeny supports the recent reassignment of G. integer Scudder 1901 from Texas to G. texensis Cade and Otte 2000. The evolution of cricket song and life cycle is discussed using the new phylogenetic framework.     

Phylogenetic relationships among the Ibero-African cobitids (Cobitis, cobitidae) based on cytochrome b sequence data

We estimated the phylogenetic relationships of all Ibero-African spined loaches of the genus Cobitis using the complete mitochondrial cytochrome b gene (1140bp). We analysed 93 individuals of seven cobitid species found in all the principal drainages of the Iberian Peninsula and North Africa. A molecular phylogeny was used to revise current systematics of the Ibero-African Cobitis species and to infer a biogeographical model for Cobitis in the Western Mediterranean area during the Cenozoic period. Phylogenetic analysis provided support for the monophyly of two mtDNA clades: Clade A or Italian Clade with the Italian species (C. bilineata, C. zanandreai), and Clade B or the Ibero-African Clade. The Ibero-African Clade included all species endemic for the Iberian Peninsula (C. vettonica, C. calderoni, and C. paludica) and North Africa (C. maroccana). The species C. paludica does not constitute a natural group, and could be divided into at least four monophyletic mtDNA lineages with moderate to high bootstrap values and posterior probability support. Phylogenetic relationships of the Ibero-African species were not resolved satisfactorily, but in all analyses C. calderoni from Northern Iberian Peninsula was basal. We have re-calibrated a molecular clock for the genus Cobitis (0.68% per million year by pairwise) using populations inhabiting both sides of the Gibraltar Strait. Application of this Cobitis mtDNA clock provides evidence that the Messinian salinity crisis played a primary role in the diversification of some Ibero-African cobitid species. The basal polytomies of the Ibero-African Clade might suggest that all mtDNA lineages diversified rapidly.     

Mitochondrial diversity of Opsariichthys bidens (Teleostei, Cyprinidae) in three Chinese drainages

We describe the phylogeographic structure of 28 Chinese populations of the cyprinid Opsariichthys bidens across three main Chinese river drainages. Our study is based on the phylogenetic analysis of the complete mitochondrial cytochrome b gene (1140 bp). We combined this analysis with population processes inferred from nested clade analysis (NCA) and mismatch distributions. Both analyses showed that Chinese O. bidens consists of five mtDNA lineages (Opsariichthys 1-5) with high genetic divergence among them. Molecular divergences (TrN+G) higher than 20% among the Opsariichthys 1-5 mtDNA lineages suggest a taxonomic underestimation at the species level. About 92% of the genetic variance among samples was explained by differences among Opsariichthys mtDNA lineages. Drainage-restricted haplotypes with high frequencies and moderate nucleotide diversity show that Opsariichthys populations have evolved independently. NCA results were congruent with the phylogeny, and unimodal mismatch distributions with negative Tajima's D values suggest population expansions in some Opsariichthys lineages. The phylogeographic structure of the Opsariichthys 1-5 mtDNA lineages appears to be related to their long-term interruption of gene flow (theta(ST)>0.97). Our results suggested that fragmentation of ancestral ranges might have caused Opsariichthys diversification in Chinese waters. However, current distribution of common haplotypes across the Yangtze and Pearl drainages suggests a recent river connection that could have favoured gene flow across drainages. Overall, the results indicated that the richness of current Asian widespread species might have been underestimated, and that the cyprinid populations of O. bidens in the Yangtze, Pearl and Hai He drainages may correspond to five species.     

Mitochondrial DNA differentiation between two forms of trout Salmo letnica, endemic to the Balkan Lake Ohrid, reflects their reproductive isolation

Mitochondrial haplotype diversity in sympatric populations of Ohrid trout, Salmo letnica was investigated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the mtDNA control region and ND1, ND3/4, ND5/6 segments. A 310 bp fragment at the 5' end, and a 340-572 bp fragment at the 3' end of the control region were sequenced from representatives of the populations studied. Based on pairwise comparison of the sequences, five new haplotypes were identified plus one identical with the brown trout Andalusian haplotype from the southern Iberian Peninsula. The combination of both RFLP and sequence data sets yielded a total of 10 composite haplotypes. A high degree of genetic subdivision between S. letnica typicus and S. letnica aestivalis populations was observed. The notion of a sympatric origin for the two morphs is discussed. Length variation of the mtDNA control region due to the presence of an 82 bp unit, tandemly repeated one to four times, in the region between the conserved sequence block-3 (CSB-3) and the gene for phenylalanine tRNA is reported. Further, we demonstrate that a single duplication of the approximately 82 bp repeat unit is a common element of the salmonid mitochondrial control region. The unique genetic structure of Ohrid trout represents a highly valuable genetic resource that deserves appropriate management and conservation.     

Phylogenetic relationships within Diadasia, a group of specialist bees

We estimated phylogenetic relationships among species of the bee genus Diadasia, a group of new world, specialist bees. We sequenced approximately 2 kb of the mitochondrial genes cytochrome oxidase subunit I and II and tRNA leucine and approximately 1 kb of the nuclear gene elongation factor 1-alpha for 24 North American Diadasia species, 4 South American species, and five outgroup genera. Parsimony analyses of the two data sets were highly congruent. A combined analysis produced a well-resolved phylogenetic hypothesis that supported the monophyly of Diadasia, but not that of traditional subgenera: Diadasia s. str. was paraphyletic in all analyses. With one exception, the North and South American species formed separate clades, supporting previous hypotheses that two lineages of Diadasia have dispersed from South to North America: a more recent dispersal of D. ochracea and an older dispersal of the ancestor to all other North American species. Different species of Diadasia specialize on pollen from at least five different plant families; the phylogeny presented here, along with known host affinities, indicates that host-switching has been rare.     

Cryptic diversity in European bats

Different species of bat can be morphologically very similar. In order to estimate the amount of cryptic diversity among European bats we screened the intra- and interspecific genetic variation in 26 European vespertilionid bat species. We sequenced the DNA of subunit 1 of the mitochondrial protein NADH dehydrogenase (ND1) from several individuals of a species, which were sampled in a variety of geographical regions. A phylogeny based on the mitochondrial (mt) DNA data is in good agreement with the current classification in the family. Highly divergent mitochondrial lineages were found in two taxa, which differed in at least 11% of their ND1 sequence. The two mtDNA lineages in Plecotus austriacus correlated with the two subspecies Plecotus austriacus austriacus and Plecotus austriacus kolombatovici. The two mtDNA lineages in Myotis mystacinus were partitioned among two morphotypes. The evidence for two new bat species within Europe is discussed. Convergent adaptive evolution might have contributed to the morphological similarity among distantly related species if they occupy similar ecological niches. Closely related species may differ in their ecology but not necessarily in their morphology. On the other hand, two morphologically clearly different species (Eptesicus serotinus and Eptesicus nilssonii) were found to be genetically very similar. Neither morphological nor mitochondrial DNA sequence analysis alone can be guaranteed to identify species.     

POPU金钱豹mtDNA ND5基因序列及其遗传变异

测定山西7个不同地域金钱豹9个体mtDNA ND5基因部分序列,结合GenBank下载的37条序列,进行遗传多样性分析,用豹属的狮Panthera leo和虎Panthera tigris作外群,构建其不同单倍型的NJ分子聚类关系。46条序列共产生18个单倍型,单倍型多样度和核苷酸多样度指数表明金钱豹的遗传多样性比较丰富,AMOVA分析显示其种群间出现显著的遗传分化。单倍型聚类分析表明,亚洲和非洲种群尽管有一定的分化,但其置信度很低,不足以形成各自独立的分支。     

Phylogeny and evolution of dorsal pattern in the Mexican endemic lizard genus Barisia (Anguidae: Gerrhonotinae)

The phylogeny of the Mexican lizard genus Barisia was assessed using an 878 bp fragment of the mtDNA ND4 gene and a section of associated tRNA genes, as well as 16 external morphological characters. The terminal taxa comprised the currently recognized members of Barisia, including the four subspecies of the polytypic Barisia imbricata and individuals from different populations of the widespread B. i. imbricata and Barisia i. ciliaris, although for Barisia levicollis only morphology could be examined. The ‘step‐matrix frequency’ and the ‘step‐matrix gap‐weighting’ coding approaches were employed simultaneously for the morphological data set, and three different scaling methods were evaluated for the last approach. Maximum parsimony (MP) analyses were performed for the separate and combined data sets and Bayesian analysis was also performed for the mtDNA sequence data. The hypothesis obtained from the simultaneous MP analysis strongly supports the monophyly of Barisia, but the ‘exclusivity’ of B. imbricata as well as of B. i. imbricata and B. i. ciliaris were not recovered. Moreover, inclusion of the morphological data showed B. levicollis nested within a clade together with the taxa assigned to B. i. ciliaris. This, together with the genetic distances and geographic concordance among the haplotypes examined, confirms that B. imbricata represents several species, although the actual species limits in this composite taxon are still unclear. Applying previously published rates of molecular evolution to the mtDNA data gives ages of divergence similar to the times proposed for some Pleistocene–Miocene geological and climatic phenomena that occurred in the Mexican territory. Variation of the dorsal pattern within Barisia was mapped onto the simultaneous morphological and molecular phylogeny, indicating that the two main states present in the taxa assigned to B. imbricata, an adult dorsal pattern present in females and absent in males and the absence of any pattern in both sexes, occur each in separate lineages. This suggests a possible scenario, where sexual dichromatism within Barisia has been repeatedly lost in different lineages.     

MOLECULAR PHYLOGENETICS AND EVOLUTION OF SEXUAL DICHROMATISM AMONG POPULATIONS OF THE YARROW'S SPINY LIZARD (SCELOPORUS JARROVII)

Understanding evolution of geographic variation in sexually dimorphic traits is critical for understanding the role that sexual selection may play in speciation. We performed a phylogenetic analysis of geographic variation in sexual dichromatism in the Yarrow's spiny lizard (Sceloporus jarrovii), a taxon that exhibits remarkable diversity in male coloration among populations (e.g., black, red, green, yellow, blue, brown). An mtDNA phylogeny based on approximately 880 bp from the 12S ribosomal RNA gene and 890 bp from the ND4 gene was reconstructed for 30 populations of S. jarrovii and eight other species of the torquatus species group using maximum-likelihood and parsimony methods. The phylogeny suggests that S. jarrovii consists of at least five evolutionary species, none of which are sister taxa. Although intraspecific diversity in male coloration is less than indicated by previous taxonomy, two species formerly referred to as S. jarrovii exhibit impressive geographic variation in sexual dichromatism. In one of these species, the phylogeny shows the independent evolution of a distinctive blue color morph in different parts of the species range. This pattern suggests that sexual selection may lead to striking phenotypic divergence among conspecific populations and striking convergence. Results also demonstrate the importance of a phylogenetic perspective in studies of evolutionary processes within nominal species and the problematic nature of “polytypic” species recognized under the biological species concept.