Molecular Systematics and the Evolution of Habitat Specificity

系统发育学是对生态学、分子生物学、系统学和进化生物学等其他学科至关重要的一个研究领域。随着系统发育学应用的增加，这些应用的广度也在增加。从基因生化功能的分子研究，到人类研究，如hiv - 1的传播模式，“系统发育思维”已经在广泛的学科领域带来了重大发现。本研究的目的是通过高中外展、博物馆展示和本科/研究生教育，将系统遗传学带给更广泛的人群。此外，系统发育思维在我的研究项目中也很普遍。本研究的主要目的是建立淡水小龙虾两个姊妹亚属——壶螯虾和小螯虾（十足目：壶螯虾科）24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其他五个亚属的代表的单系性。系统发育估计将基于线粒体基因组16s区域的核苷酸序列和核基因astacin。一旦系统发育被估计，单系性被建立，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，它们分布在四种主要的生态类型中：深水（8种），深水（5种），初级穴居（半陆地，5种）和洞穴（地下，6种）。因此，它们为研究小龙虾栖息地特异性的进化提供了一个独特的机会。小龙虾会入侵栖息地并在栖息地内辐射吗？栖息地特异性是否有一个重复的进化序列，比如从陆生到陆生，从穴居到穴居？还是栖息地的特定城市在系统发育中是随机分布的？PI的研究将解决这些问题，并将答案作为系统发育方法在我的教育计划中的应用实例。

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.