DISSERTATION RESEARCH: Colonization History and Genetic Structure of Incipient Sexual Isolation Between USA and Caribbean Populations of Drosophila Melanogaster

这项研究解决了人类如何改变人类相关物种的进化历史和生物学的基本问题。 在人类不断扩大世界各地物种的地理范围的时候，很少有人知道这将如何影响物种的遗传和表型构成。 由于人类运输导致生殖隔离（种族形成）的第一阶段，物种扩大其范围的情况很少被描述或很好地描述。 在加勒比群岛对果蝇Drosophila melanogaster的研究为研究这一案例提供了前所未有的机会。 这是因为有人假设，由于历史上的非洲奴隶贸易，这种非洲物种殖民了加勒比海。 这项研究将深入了解物种范围的扩大如何导致祖先和衍生种群之间的行为隔离。 该研究将确定美国和加勒比海苍蝇种群之间观察到的形态，信息素和行为差异是否是由于：1）不同的殖民事件，美国苍蝇在19世纪从欧洲殖民，加勒比苍蝇在17世纪从非洲殖民，或2）美国苍蝇殖民加勒比海，随后适应性地收敛到非洲一样的热带特征。 这项研究也将为未来鉴定导致观察到的表型分化和性隔离的基因铺平道路。除了智力影响外，该项目还将产生更广泛的影响。 这项研究将继续涉及本科生和高中生。 七名大学生（包括一名代表性不足的少数民族成员和四名妇女）目前正在从事这一项目，预计将成为未来出版物的共同作者。 去年夏天，一名高中生在著名的西门子-西屋科学竞赛（2005-2006）中获得全国第二名，以表彰他们对该项目的研究。 首席研究员真使用巴哈马苍蝇广泛教学本科分子多样性实验室课程。 最后，还与巴哈马拿骚农业部的生物学家建立了联系，这将促进美国和巴哈马学术界之间更多地交流意见。

This study addresses fundamental questions concerning how humans may alter the evolutionary history and biology of human-associated species. In a time when humans are constantly expanding the geographical ranges of species all over the world, very little is known about how this will affect the genetic and phenotypic constitution of species. Cases in which species expanded their ranges due to human transport resulting in the first stages of reproductive isolation (race formation) are rarely described or well characterized. Research on the fruit fly Drosophila melanogaster in the Caribbean islands offers an unprecedented opportunity to study just such a case. This is because it is hypothesized that this African species colonized the Caribbean as a result of historical African slave trades. The study will provide insight into how a species range expansion leads to behavioral isolation between ancestral and derived populations. The research will determine whether the observed morphological, pheromonal and behavioral differences between United States and Caribbean fly populations are due to either: 1) distinct colonization events, the U.S. flies being colonized from Europe in the 1800s and the Caribbean flies being colonized from Africa during the 1600s slave trades, or 2) U.S. flies colonizing the Caribbean and subsequently adaptively converging onto African-like tropical traits. This research will also pave the way toward future work on the identification of genes responsible for the observed phenotypic divergence and sexual isolation.This project will have substantial broader impacts in addition to its intellectual impacts. The research will continue to involve both undergraduates and high school students. Seven undergraduates (including one under-represented minority member and four women) are presently working on this project and are expected to be co-authors of future publications. This past summer a high school student finished second place nationwide in the prestigious Siemens-Westinghouse Science Competition (2005-2006) for their research on this project. Principal Investigator True uses the Bahamas flies extensively in teaching an undergraduate Molecular Diversity Laboratory course. Finally, contacts have been established with biologists in the Department of Agriculture in Nassau, Bahamas, which will facilitate a greater exchange of ideas between the United States and Bahamian academic communities.