Phylogeographic structure and historical demography of the western diamondback rattlesnake (Crotalus atrox): A perspective on North American desert biogeography

    Authors

    T. A. Castoe; C. L. Spencer;C. L. Parkinson

    Comments

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    Abbreviated Journal Title

    Mol. Phylogenet. Evol.

    Keywords

    Crotalus atrox; Crotalus tortugensis; desert biogeography; mtDNA; phylogeography; pleistocene refugia; Western diamondback rattlesnake; MITOCHONDRIAL-DNA SEQUENCES; CALIFORNIA PENINSULAR DESERT; EREMICUS; SPECIES GROUP; PHYLOGENETIC-RELATIONSHIPS; MOLECULAR SYSTEMATICS; MAXIMUM-LIKELIHOOD; HORNED LIZARDS; EVOLUTIONARY RELATIONSHIPS; GEOGRAPHICAL-DISTRIBUTION; CRYPTIC VICARIANCE; Biochemistry & Molecular Biology; Evolutionary Biology; Genetics &; Heredity

    Abstract

    The western diamondback rattlesnake (Crotalus atrox) is a prominent member of North American desert and semi-arid ecosystems, and its importance extends from its impact on the region's ecology and imagery, to its medical relevance as a large deadly venomous snake. We used mtDNA sequences to identify population genetic structure and historical demographic patterns across the range of this species, and relate these to broader patterns of historical biogeography of desert and semi-arid regions of the southwestern USA and adjacent Mexico. We inferred a Late Pliocene divergence between peninsular and continental lineages of Crotalus, followed by an Early Mid Pleistocene divergence across the continental divide within C atrox. Within desert regions (Sonoran and Chihuahuan Deserts, Southern Plains, and Tamaulipan Plain) we observed population structure indicating isolation of populations in multiple Pleistocene refugia on either side of the continental divide, which we attempt to identify. Evidence of post-glacial population growth and range expansion was inferred, particularly in populations east of the continental divide. We observed clear evidence of (probably recent) gene flow across the continental divide and secondary contact of haplotype lineages. This recent gene flow appears to be particularly strong ill the West-to-East direction. Our results also suggest that Crotalus tortugensis (Tortuga Island rattlesnake) and a population of 'C atrox' inhabiting Santa Cruz Island (in the Gulf of California) previously suggested to be an unnamed species, are in fact deeply phylogenetically nested within continental lineages of C atrox. Accordingly, we suggest C tortugensis and 'C. atrox' from Santa Cruz Island be placed in the synonymy of C. atrox. (c) 2006 Elsevier Inc. All rights reserved.

    Journal Title

    Molecular Phylogenetics and Evolution

    Volume

    42

    Issue/Number

    1

    Publication Date

    1-1-2007

    Document Type

    Review

    Language

    English

    First Page

    193

    Last Page

    212

    WOS Identifier

    WOS:000243644600014

    ISSN

    1055-7903

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