Geographic Variation in Allozymes in a "Ring Species," the Plethodontid Salamander Ensatina eschscholtzii of Western North America

Wake, David B.; Yanev, Kay P.

doi:10.2307/2408457

Cited by 47 publications

(38 citation statements)

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“…The total number of presumptive alleles in the northern populations is also high (e.g., in one population, 59 alleles for 28 allozymes, n ϭ 10), as expected for old, large populations relative to newer, smaller ones. Genetic distance generally increases between paired comparative populations on either side of the valley from north to south, also as expected (12).…”

supporting

confidence: 77%

“…A survey of protein variation in 19 populations throughout the complex disclosed great differentiation and showed that gene flow cannot be holding this far-flung complex together (11,12). The analysis revealed values of F st Ͼ 0.7, thus refuting the hypothesis of continuous gene flow.…”

mentioning

confidence: 98%

“…Polymorphism and heterozygosity, estimated from allozymes, are extraordinarily high in northwestern California, among the highest recorded for any vertebrate, whereas more southern populations have less variation (the least occurs in the postulated colonists, the Sierran xanthoptica) (11,12). The total number of presumptive alleles in the northern populations is also high (e.g., in one population, 59 alleles for 28 allozymes, n ϭ 10), as expected for old, large populations relative to newer, smaller ones.…”

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confidence: 99%

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Incipient species formation in salamanders of the Ensatina complex

Wake

1997

Proc. Natl. Acad. Sci. U.S.A.

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The Ensatina eschscholtzii complex of plethodontid salamanders, a well-known ''ring species,'' is thought to illustrate stages in the speciation process. Early research, based on morphology and coloration, has been extended by the incorporation of studies of protein variation and mitochondrial DNA sequences. The new data show that the complex includes a number of geographically and genetically distinct components that are at or near the species level. The complex is old and apparently has undergone instances of range contraction, isolation, differentiation, and then expansion and secondary contact. While the hypothesis that speciation is retarded by gene f low around the ring is not supported by molecular data, the general biogeographical hypothesis is supported. There is evidence of a north to south range expansion along two axes, with secondary contact and completion of the ring in southern California. Current research targets regions once thought to show primary intergradation, but which molecular markers reveal to be zones of secondary contact. Here emphasis is on the subspecies E. e. xanthoptica, which is involved in four distinct secondary contacts in central California. There is evidence of renewed genetic interactions upon recontact, with greater genetic differentiation within xanthoptica than between it and some of the interacting populations. The complex presents a full array of intermediate conditions between well-marked species and geographically variable populations. Geographically differentiated segments represent a diversity of depths of time of isolation and admixture, ref lecting the complicated geomorphological history of California. Ensatina illustrates the continuing difficulty in making taxonomic assignments in complexes studied during species formation.

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confidence: 77%

mentioning

confidence: 98%

mentioning

confidence: 99%

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Incipient species formation in salamanders of the Ensatina complex

Wake

1997

Proc. Natl. Acad. Sci. U.S.A.

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156

150

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“…Moritz et al 1992;Crochet et al 2002;Liebers et al 2004). Fewer have been addressed with complementary phylogenetic and population genetic perspectives from both mitochondrial and nuclear DNA (nDNA; Wake & Yanev 1986;Moritz et al 1992;Irwin et al 2001bIrwin et al , 2005Alexandrino et al 2005). Prior studies have largely focused on using mitochondrial DNA (mtDNA) diversity to test whether members of a ring species are monophyletic, and on estimating where gene flow occurs in a ring (Irwin et al 2001b;Martens & Päckert 2007).…”

Section: Introductionmentioning

confidence: 99%

Where and when does a ring start and end? Testing the ring-species hypothesis in a species complex of Australian parrots

et al. 2008

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Speciation, despite ongoing gene flow can be studied directly in nature in ring species that comprise two reproductively isolated populations connected by a chain or ring of intergrading populations. We applied three tiers of spatio-temporal analysis (phylogeny/historical biogeography, phylogeography and landscape/population genetics) to the data from mitochondrial and nuclear genomes of eastern Australian parrots of the Crimson Rosella Platycercus elegans complex to understand the history and present genetic structure of the ring they have long been considered to form. A ring speciation hypothesis does not explain the patterns we have observed in our data (e.g. multiple genetic discontinuities, discordance in genotypic and phenotypic assignments where terminal differentiates meet). However, we cannot reject that a continuous circular distribution has been involved in the group's history or indeed that one was formed through secondary contact at the 'ring's' east and west; however, we reject a simple ring-species hypothesis as traditionally applied, with secondary contact only at its east. We discuss alternative models involving historical allopatry of populations. We suggest that population expansion shown by population genetics parameters in one of these isolates was accompanied by geographical range expansion, secondary contact and hybridization on the eastern and western sides of the ring. Pleistocene landscape and sea-level and habitat changes then established the birds' current distributions and range disjunctions. Populations now show idiosyncratic patterns of selection and drift. We suggest that selection and drift now drive evolution in different populations within what has been considered the ring.

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“…They may be difficult to find during the day, but may be abundant on the surface at night during warm wet weather and are sometimes observed on paved roads when conditions are favourable. This species has not been studied in British Columbia, but its ecology and genetics has been intensively studied in California (Stebbins 1954;Wake and Yanev 1986).…”

Section: Ensatina (Ensatina Eschscholtzii)mentioning

confidence: 99%