Molecular Systematics and the Evolution of Habitat Specificity

克兰德尔9702338 系统发生学是一个研究领域，对其他学科如生态学、分子生物学、系统学和进化生物学具有核心重要性。随着遗传学应用的增加，这些应用的广度也在增加。从对基因生化功能的分子研究到对人类的研究，例如对HIV-1传播模式的研究，“系统发育思维”导致了广泛学科的重大发现。本研究的目的是通过高中外展、博物馆展览和本科/研究生教育，将遗传学带给更广泛的人群。此外，系统发育思维在我的研究计划中无处不在。本研究的主要目的是建立淡水螯虾科（Cambaridae）两个姊妹亚属（Jug cambarus和Glareocola）24个种之间的系统发育关系。一旦建立了系统发育关系，PI将测试这两个亚属相对于来自Cambarus属内其他五个亚属的代表的单系性。系统发育的估计将基于线粒体基因组16 S区和核基因astacin的核苷酸序列。 一旦估计了单系发生并建立了单系，PI将使用比较方法探索栖息地特异性的进化生物学。这组淡水小龙虾的美丽之处在于它们分布在发现小龙虾的四个主要生态类型中：激流沃茨（8种），静水沃茨（5种），初级穴居者（半陆地，5种）和洞穴（地下，6种）。因此，他们提供了一个独特的机会来研究小龙虾栖息地特异性的演变。小龙虾会入侵一个栖息地并在该栖息地内辐射吗？是否有一个重复的进化序列的栖息地特异性，如lotic到lentic，穴居人，洞穴？或者是栖息地特定的城市随机分布在整个人类史上？PI的研究将解决这些问题，并使用答案作为在我的教育计划中使用系统发育方法的例子。

Crandall 9702338 Phylogenetics is a field of study that is of central importance to others such as ecology, molecular biology, systematics, and evolutionary biology. As applications of phylogenetics increase, so too does the breadth of ~ese applications. From molecular studies of the biochemical function of genes, to human studies such as transmission patterns in HIV-I, "phylogenetic thinking" has lead to major discoveries in a broad array of disciplines. The object of this study is to bring phylogenetics to a broader array of peop e through high school outreach, museum displays, and undergraduate/graduate education. In addition, phylogenetic thinking is pervasive in my research program. The primary research goal is to establish phylogenetic relationships among the 24 species within the two sister subgenera of freshwater crayfishes, Jug~cambarus and Glareocola (Decapoda: Cambaridae). Once phylogenetic relationships are established, the PI will test the monophyly of these two subgenera relative to representatives from five other subgenera within the genus Cambarus. Phylogenetic estimates will be based on nucleotide sequences from the 1 6S region of the mitochondrial genome and the nuclear gene astacin. Once,a phylogeny is estimated and monophyly is established, the PI will explore the evolutionary biology of habitat specificity using comparative methods. The beauty of this group of freshwater crayfishes is that they are distributed into the four main ecotypes within which crayfishes are found: lotic waters (8 species), lentic waters (5 species), primary burrowers (semi-terrestrial, 5 species), and caves (subterranean, 6 species). Therefore, they provide a unique opportunity to study the evolution of habitat specificity in crayfishes. Do crayfishes invade a habitat and radiate within that habitat? Is there a repeated evolutionary sequence of habitat specificity, such as lotic to lentic, to burrower, to cave? Or are habitat specif~cities randomly distributed over the phylogeny? The PI's research will address these questions and use the answers as examples of the utility of the phylogenetic approach in my educational programs.