Dissertation Research: The Evolution of Arboreal Carabid Beetles

许多生物群体的多样性与新特征的进化有关，这些新特征有助于物种数量的爆炸性增长。在这种辐射过程中获得的适应具有特殊的功能和独特的进化史。物种日益多样化和逐渐专业化的一个例子是步甲甲虫，俗称地面甲虫，它们已经适应了树栖生活方式。研究生Karen Ober在David Maddison博士的指导下，通过调查大类群Lebiobforma的10个左右部落的代表性分类群，研究步甲在树上适应的进化。来自马来西亚和马达加斯加的新藏品(后者由同事提供)将增加博物馆藏品，并为分子和形态研究提供材料。形态特征包括颧骨和爪子结构(独立于与交配有关的结构)、腿长和胸前形状，这可能与树栖生活的适应性变化有关。为了研究树栖步行动物的起源和进化，将使用至少两个基因的分子序列数据重建树形目动物及其近亲，28S核糖体RNA基因和核基因‘无翼’。两者都显示出提供突变差异的希望，这将允许在利生物形体血统之间进行歧视。有了关系的进化史，人们可以研究栖息地从地面栖息地向树生生物转移的数量和方向，并探索与树生生物有关的生态和形态特征的变化模式。

0073273Maddison and Ober The diversity of many groups of living organisms is related to the evolution of novel features that contribute to an explosive increase in the number of species. Adaptations acquired during such a radiation posses specialized functions and a unique evolutionary history. An example of increasing diversification of species and progressive specialization can be found in carabid beetles, commonly known as ground beetles, that have adapted an arboreal lifestyle. Graduate student Karen Ober, under the direction of Dr. David Maddison, is studying the evolution of arboreal adaptations in carabid beetles by surveying representative taxa across the 10 or so tribes of the large group Lebiomorpha. New collections from Malaysia and from Madagascar (the latter supplied by colleagues) will augment museum holdings and provide materials for molecular and morphological studies. Morphological features include tarsal and claw structures (independent of those associated with mating), leg length, and prorhorax shape, which may be involved in adaptive changes to arboreal life. To investigate the origin and evolution of arboreal carabids, an evolutionary tree of lebiomorphs and their relatives will be reconstructed using molecular sequence data from minimally two genes, the 28S ribosomal RNA gene and the nuclear gene 'wingless.' Both show promise of providing mutational differences that would allow discrimination among lineages of lebiomorphs. With the evolutionary history of relationships in hand, one can study the number and direction of habitat shifts from ground-dwelling to arboreality and explore patterns of changes in ecological and morphological features presumed to be associated with arboreal life.