School of Marine and Tropical Biology, James Cook University Townsville, Queensland, 4810, Australia ; Centre for Tropical Water and Aquatic Ecosystem Research, James Cook University Townsville, Queensland, 4810, Australia ; Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University Townsville, Queensland, 4810, Australia.
School of Marine and Tropical Biology, James Cook University Townsville, Queensland, 4810, Australia.
Ecol Evol. 2014 Mar;4(5):606-22. doi: 10.1002/ece3.968. Epub 2014 Feb 11.
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 (∼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. 4.73 Ma, 95% higher posterior density (HPD) 2.08-8.16 Ma) 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.
更新世气候循环对南半球生物群的影响尚未得到很好的理解。澳大利亚东部沿海边缘为研究景观发育、海平面波动和周期性气候干旱对淡水生物多样性进化的相对影响提供了理想的环境。我们利用广泛的采样（代表 11 个流域的 18 个地点的 649 个个体）和线粒体序列（约 1.3kb 的控制区和 ND4）和核微卫星（12 个多态性位点）分析，研究了广布的克里夫特河龟（Emydura macquarii krefftii）的进化历史受到气候振荡和物理生物地理障碍的影响。进行了一系列系统发育（单倍型网络、分子年代学）、种群统计（中性检验、不匹配分布）和种群遗传分析（成对 F ST、分析分子方差、贝叶斯聚类分析），以区分竞争的种群统计（局部持续与范围扩张）和生物地理（干旱走廊与流域分水岭）情景。遗传数据表明，克里夫特河龟的种群遗传结构主要反映了流域分水岭的隔离。引人注目的南北区域分化（2.2%ND4 p-distance；c. 4.73 Ma，95%高 posterior density（HPD）2.08-8.16 Ma）与长期跨越主要分水岭的隔离一致，而不是与相邻的干旱走廊。区域谱系之间的古老分化意味着北部克里夫特种群尽管经历了严重的局部干旱的反复阶段，但仍能持续存在，但当代遗传多样性非常低。南部种群的稳定人口统计学和高水平的遗传多样性推断，因为那里的干旱程度不那么极端。克里夫特河龟的广泛范围遗传结构反映了当代和历史流域结构，尽管上新世-更新世气候干旱的程度在区域上存在差异，但可能反映在当前的遗传多样性水平上。
