Evolution, phylogeography and species boundaries of the ringneck snake genus Diadophis
Item
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Title
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Evolution, phylogeography and species boundaries of the ringneck snake genus Diadophis
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Identifier
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d_2009_2013:873c8367c411:10095
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identifier
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10259
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Creator
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Fontanella, Frank Matthew,
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Contributor
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Mark E. Siddall
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Date
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2009
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Language
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English
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Publisher
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City University of New York.
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Subject
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Zoology | microsatellite | mtDNA | phylogeography | Pliestocene
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Abstract
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The monotypic snake genus Diadophis Baird and Girard, 1853 is one of the most widely distributed and morphologically variable snakes throughout North America. This snake (Diadophis punctatus) exploits a variety of habitats and ecological niches ranging from the mixed hardwood forests of southern Canada to the desert of the Southwestern US and Central Mexico (excluding the northern Great Plains states. Ringneck snakes have traditionally been divided into 13 subspecies based on a combination of morphology and geography. This study has provided the first range-wide molecular study and provides a framework for the origin, evolution and biodiversity in the genus Diadophis. Analysis of mtDNA sequence data inferred 16 mtDNA lineages that replace each other geographically across the United States and into central Mexico. In contrast to previous hypothesis, ancestral area reconstructions inferred an origin for D. punctatus in the southeastern United States during the Miocene, followed by a southeast to northeast then westward directionality of historical migration. Demographic analyses indicate that independent lineages currently occupying previously glaciated or unsuitable areas in eastern, central and western U.S. underwent post-glacial population expansion likely from southern refugia during the late Pleistocene/early Holocene. Conversely, southern lineages display patterns consistent with long-term population stability. For the purposes of species delineation, ecological niche modeling does not show isolation due to unsuitable habitat. Ten novel microsatellite loci developed for this study suggest that most species boundaries are maintained through a balance of selection and dispersal in hybrid zones. Based on the geographic distribution of the mtDNA lineages and the microsatellite frequency data, we hypothesize that there are eight species within the genus Diadophis throughout the Eastern United States. This body of work provides a rich framework for further study including, examining species boundaries in the western lineages, determining population structure within species, and detailed examination of hybrid zones.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Biology
