DISSERTATION RESEARCH: Detecting ecomorphological convergence in the salamander genus Desmognathus: A phylogenetic approach using molecular and geometric morphometric analyses

黑蝾螈属是一种种类丰富的两栖动物，分布在北美东部。虽然许多物种占据了落叶林的溪流，但这个群体展示了显著的生态广度，从云杉林到沿海沼泽的栖息地都有。尽管它们的生态多样性，但暗色蝾螈的物种在外观上非常相似，并且都有一个棕色的斑驳图案，这使得物种识别非常困难。因此，关于物种的确切数量（以及它们之间的关系）的解释仍然存在争议和问题。本研究将通过以下方法来解决暗蝾螈的进化关系：1)在非常精细的地理尺度上对蝾螈进行采样；2)利用分子特征（几种基因的DNA序列）而不是形态特征来评估这些采样种群之间的差异。初步结果证实了某些物种的有效性，但也揭示了其他未描述的物种。此外，使用一种新的几何方法进行形态学分析的初步工作表明，头部形状的细微变化可能在该群体观察到的生态多样性中发挥重要作用，因为它允许不同种类的暗蝾螈以略微不同的方式觅食。这项研究将产生一个大型数据库，其中包括数千个标本（将存放在芝加哥菲尔德自然历史博物馆）和DNA序列（将存放在Genbank），这将供全世界的生物学家使用。精细取样将有助于识别该群体中的所有物种并划定其地理分布，这些发现对保护和土地管理很重要。

The dusky salamander genus Desmognathus is a species-rich group of amphibians distributed across eastern North America. Although many species occupy deciduous forest streams, the group demonstrates remarkable ecological breadth, ranging in habitats from spruce forests to coastal swamps. Despite their ecological diversity, the species of dusky salamanders are quite similar in appearance and all share a pattern of brown, mottled markings that makes species identification notoriously difficult. As a result, interpretations regarding the exact number of species (and relationships among them) remain controversial and problematic. This study will work to resolve evolutionary relationships of dusky salamanders by: 1) sampling salamanders on a very fine geographic scale, and 2) assessing variation among these sampled populations using molecular characters (DNA sequences for several genes) as opposed to morphological characters. Preliminary results confirm the validity of certain species but also have revealed additional, undescribed species. Moreover, preliminary work using a new geometric approach to morphological analysis suggests that subtle variation in head shape may play an important role in the group's observed ecological diversity by allowing various species of dusky salamanders to forage in slightly different ways. This study will generate a large database including several thousand specimens (to be deposited in the Field Museum of Natural History, Chicago) and DNA sequences (to be deposited in Genbank), which will be available to biologists worldwide. The fine-scale sampling will help to identify all species in the group and delimit their geographic distributions, findings important to conservation and land management.