Dissertation Research: Phylogeography of Salamanders of the Plethodon Jordani Complex in the Southern Appalachian Mountains

项目描述Plethodon jordani复合体是7个高海拔山区物种的组合，这些物种的形态分化很小，但根据蛋白质变异的调查，它们具有高水平的遗传分化。 在最近的冰河时期，温度变化的周期被预测会导致蝾螈在追踪它们的有利环境时反复发生种群隔离和接触。 这些截然不同的事件可能导致了隔离时的遗传融合和接触时的遗传混合。 在许多情况下，尚不清楚这些力量的相互作用如何影响这一物种复合体中的物种形成。 本研究的目的是利用线粒体DNA序列与现有的蛋白质变异数据，以测试假设的遗传分化和杂交形成之间的片段化种群P. jordani复杂通过系统发育analysis.Project意义很少有culturegeographic研究有足够的采样，以检测在一个精细的地理尺度上的遗传片段化和自然种群之间的二次接触的模式。 本研究旨在提供一个详细的和精细规模的物种假说，从蛋白质变异的地理学测试。 乔氏刺齿鱼复合体的分布相对有限，因此可以在其分布范围内进行广泛的采样，从而几乎完全表征线粒体基因的遗传多样性。 大样本量和线粒体DNA序列使我们能够区分种群之间正在进行的动态基因交换与历史上不连续的基因交换模式。 此外，蛋白质变异的广泛调查的存在提供了一个理想的情况下，检查组合的数据源，以量化种群和物种形成之间的进化分歧。

Project DescriptionThe Plethodon jordani complex is an assemblage of seven high-elevation mountain species that show little morphological differentiation, but contain high levels of genetic differentiation according to surveys of protein variation. Cycles of temperature change during the most recent ice ages are predicted to have caused repeated episodes of population isolation and contact as salamanders tracked their favorable environments. These contrasting episodes may have caused genetic ivergence when isolated and genetic mixing while in contact. In many cases it is unclear how the interplay of these forces has affected species formation in this species complex. Objectives of this research are to utilize mitochondrial DNA sequences in tandem with the existing protein variation data to test hypotheses of genetic differentiation and hybrid formation among fragmented populations in the P. jordani complex through phylogenetic analyses.Project Significance Few phylogeographic studies have sufficient sampling to detect on a fine geographic scale the patterns of genetic fragmentation and secondary contact among natural populations. This study seeks to provide a detailed and fine-scale phylogeographic test of species hypotheses that were generated from protein variation. The relatively limited distribution of the Plethodon jordani complex allows extensive sampling across its distribution and, therefore, near complete characterization of genetic diversity for a mitochondrial gene. The large sample sizes and mitochondrial DNA sequences allow us to distinguish ongoing dynamic gene exchange among populations versus historically discontinuous patterns of gene exchange. Furthermore, the existence of extensive surveys of protein variation provides an ideal situation for examining combined data sources for quantifying evolutionary divergence among populations and species formation.