Collaborative Research: Phylogeny and Montane Species Richness in Plethodontid Salamanders

研究人员将利用形态和分子数据重建剑齿类火蜥蜴的系统发育，然后利用系统发育图探索物种多样性如何随海拔变化，以及物种丰富度模式的进化原因。蜥蜴科是火蜥蜴中最大的一科，约占所有460种火蜥蜴的三分之二。拟齿动物可能是北美东部最丰富的脊椎动物，也是许多不同生物学领域(如生态学、行为学、形态学、进化论、发展学)的科学家研究的重点。这些研究中的许多(如果不是大多数的话)在很大程度上依赖于拥有一个强大的系统发育框架。然而，使用现代方法进行全面研究的对象从来不是多齿类动物之间更高层次的关系。在一项为期三年的合作研究中，PI将利用形态特征和来自两个线粒体基因和一个核基因的DNA序列重建112种多齿类火蜥蜴(加上代表其他五个科的外群)的系统发育。该系统发展图将以阿巴拉契亚山脉异常丰富的火蜥蜴动物群为模式系统，探索物种多样性如何以及为什么会随海拔变化而变化。与低地地区相比，许多生物群体在山地地区表现出更多的物种多样性，这种普遍的模式仍然难以解释。本文认为，这种格局是山地生境的分离性质和高原物种的海拔生境专一性所导致的山地地区物种多样性增加的结果。这一模型的三个关键预测将使用系统发生学方法进行检验。这项研究将在对形态和分子数据进行严格分析的基础上，首次提供多齿蜥蜴的系统发育。在生态学、行为学、进化论、发展学和其他生物学领域的研究中，使用多齿动物作为模型系统的数十名研究人员，其系统发育将至关重要。这项研究还将首次从系统发育的角度探讨物种丰富度的海拔模式。这些对山地物种丰富度的分析应该对生态学、进化论、生物地理学和保护生物学领域具有重要的意义。例如，对海拔特性(一个物种对给定海拔范围及其相关气候的适应程度)的分析，对于预测与全球变暖或其他气候变化有关的山地物种的持续或灭绝可能很重要。这项研究将为本科生、研究生和博士后提供分子技术方面的培训，以及对系统发育、生态学和进化论的综合分析。

The investigators will reconstruct the phylogeny of plethodontid salamanders using morphological and molecular data and then use the phylogeny to explore how species diversity changes with elevation, and the evolutionary reasons for patterns of species richness. Plethodontidae is the largest family of salamanders, containing about two-thirds of all 460+ species of salamanders. Plethodontids are possibly the most abundant vertebrates in eastern North America and are the focus of research by dozens of scientists in many diverse fields of biology (e.g., ecology, behavior, morphology, evolution, development). Many (if not most) of these studies depend critically on having a robust phylogenetic framework. However, higher-level relationships among plethodontids have never been the subject of a comprehensive study using modern methods. In a three-year collaborative study, the PIs will reconstruct the phylogeny of 112 species of plethodontid salamanders (plus outgroups representing five other families) using morphological characters and DNA sequences from two mitochondrial genes and one nuclear gene. The phylogeny will be used to explore how and why species diversity changes with elevation, using the unusually rich salamander fauna of the Appalachian Mountains as a model system. Many groups of organisms exhibit increased species diversity in montane areas relative to lowland areas, a widespread pattern that remains poorly explained. It is suggested herein that this pattern results from increased speciation in montane regions caused by the disjunctive nature of montane habitats and the elevational habitat specificity of highland species. Three key predictions of this model will be tested using phylogenetic methods. The study will provide the first phylogeny of plethodontid salamanders based on a rigorous analysis of morphological and molecular data. The phylogeny will be critical to dozens of researchers who use plethodontids as a model system in studies of ecology, behavior, evolution, development, and other areas of biology. The study will also be the first to address elevational patterns of species richness from a phylogenetic perspective. These analyses of montane species richness should have important implications for the fields of ecology, evolution, biogeography, and conservation biology. For example, the analyses of elevational specificity (how narrowly adapted a species is to a given elevational range and its associated climate) may be important for predicting the persistence or extinction of montane species in relation to global warming or other changes in climate. The study will provide training for undergraduate and graduate students and a postdoctoral fellow in molecular techniques and in integrated analyses of phylogeny, ecology, and evolution.