Dissertation Research: An Experimental and Genetic Analysis of Two Salamander Contact Zones: Adaptive, Biogeographic, and Systematic Implications

0072869 Wake和Kuchta接触区，曾经在地理上分离的生物谱系重新聚集在一起，是进化过程的窗口，可以研究不同的进化现象。 在大卫威克博士的指导下，研究生肖恩·库赫塔将利用分子技术和野外实验来研究两个不相关的蝾螈类群中的两个神秘接触区。 在Ensatina eschscholtzii（尾：Plethodontidae）复合体，两个不同的亚种（oregonensis和xanthoptica）在北方加州接触。 早期对颜色模式的详细分析将这种相互作用描述为广泛的过渡，但新的分子数据表明存在紧密的遗传边界。 测试的假设是，颜色模式的“intergradation”是渗入整个杂交区，因为xanthoptica颜色模式是一个潜在的模仿属Taricha的剧毒蝾螈。 俄勒冈州和xanthoptica之间的接触区的特点是遗传使用线粒体（mt）DNA分子序列数据，等位酶，和限制性片段长度多态性（RFLP）的核DNA。鸟类捕食的测试将采用粘土模型在现场实验，旨在测试之间的模仿系统xanthoptica和Taricha的可能性。 第二个接触带位于内华达州山脉南部，加州蝾螈的两个分支Taricha torosa在那里接触。 这个边界是真正的神秘：似乎T。来自海岸山脉的torosa在Sierra内华达州南部定居，然后获得Sierra内华达州种群的表型特征。 这种表型转变的原因尚不清楚。核和线粒体DNA标记将被用来表征接触区，并调查的原因，南部塞拉利昂内华达州人口的表型进化。 这两项研究都是基于种群水平的遗传学和物种形成和分化研究的经验方法。

0072869Wake and KuchtaContact zones, where biological lineages once geographically separated come back together, are windows to the evolutionary process that enable the study of diverse evolutionary phenomena. Graduate student Shawn Kuchta, under the direction of Dr. David Wake, will use molecular techniques and field experiments to study two cryptic contact zones in two unrelated salamander taxa. In the Ensatina eschscholtzii (Caudata: Plethodontidae) complex, two distinct subspecies (oregonensis and xanthoptica) contact in northern California. An earlier detailed analysis of color pattern characterized the interaction as broad intergradation, but new molecular data suggest a tight genetic border. The hypothesis under test is that the "intergradation" of color pattern is introgression across a hybrid zone because the xanthoptica color pattern is a potential mimic of the extremely toxic newts of the genus Taricha. The contact zone between oregonensis and xanthoptica will be characterized genetically using mitochondrial (mt) DNA molecular sequence data, allozymes, and Restriction Fragment Length Polymorphisms (RFLPs) of nuclear DNA. Tests of bird predation will employ clay models in field experiments designed to test the possibility of a mimicry system between xanthoptica and Taricha. The second contact zone is located in the southern Sierra Nevada, where two clades of the California Newt, Taricha torosa, contact. This border is truly cryptic: it appears that T. torosa from the coast ranges colonized the southern Sierra Nevada, then acquired the phenotypic characteristics of Sierra Nevada populations. The causes of this phenotypic shift are unclear. Nuclear and mtDNA markers will be used to characterize the contact zone, and to investigate the cause of the phenotypic evolution of the southern Sierra Nevada populations. Both of these studies are grounded in population-level phylogenetics and an empirical approach to the study of species formation and differentiation.