Influence of drainage divides versus arid corridors on genetic structure and demography of a widespread freshwater turtle, Emydura macquarii krefftii, from Australia

Todd, Erica V., Blair, David, and Jerry, Dean R. (2014) Influence of drainage divides versus arid corridors on genetic structure and demography of a widespread freshwater turtle, Emydura macquarii krefftii, from Australia. Ecology and Evolution, 4 (5). pp. 606-622.

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The influence of Pleistocene climatic cycles on Southern Hemisphere biotas is not yet well understood. Australia's eastern coastal margin provides an ideal setting for examining the relative influence of landscape development, sea level fluctuation, and cyclic climatic aridity on the evolution of freshwater biodiversity. We examined the impact of climatic oscillations and physical biogeographic barriers on the evolutionary history of the wide-ranging Krefft's river turtle (Emydura macquarii krefftii), using range-wide sampling (649 individuals representing 18 locations across 11 drainages) and analysis of mitochondrial sequences (similar to 1.3-kb control region and ND4) and nuclear microsatellites (12 polymorphic loci). A range of phylogeographic (haplotype networks, molecular dating), demographic (neutrality tests, mismatch distributions), and population genetic analyses (pairwise F-ST, analysis of molecular variance, Bayesian clustering analysis) were implemented to differentiate between competing demographic (local persistence vs. range expansion) and biogeographic (arid corridor vs. drainage divide) scenarios. Genetic data reveal population genetic structure in Krefft's river turtles primarily reflects isolation across drainage divides. Striking north-south regional divergence (2.2% ND4 p-distance; c. 4.73Ma, 95% higher posterior density (HPD) 2.08-8.16Ma) was consistent with long-term isolation across a major drainage divide, not an adjacent arid corridor. Ancient divergence among regional lineages implies persistence of northern Krefft's populations despite the recurrent phases of severe local aridity, but with very low contemporary genetic diversity. Stable demography and high levels of genetic diversity are inferred for southern populations, where aridity was less extreme. Range-wide genetic structure in Krefft's river turtles reflects contemporary and historical drainage architecture, although regional differences in the extent of Plio-Pleistocene climatic aridity may be reflected in current levels of genetic diversity.

Item ID: 32925
Item Type: Article (Research - C1)
ISSN: 2045-7758
Keywords: Burdekin Gap, chelidae, cyclic aridity, drainage divide, phylogeography, population genetics
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© 2014 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Funders: James Cook University
Date Deposited: 30 Apr 2014 09:26
FoR Codes: 06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060302 Biogeography and Phylogeography @ 50%
06 BIOLOGICAL SCIENCES > 0604 Genetics > 060411 Population, Ecological and Evolutionary Genetics @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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