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

这项研究解决了有关人类如何改变与人类相关的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，人们对这将如何影响物种的遗传和表型构成知之甚少。由于人类运输，物种范围扩大，导致生殖隔离(小种形成)的第一阶段的案例很少被描述或很好地描述。在加勒比海群岛对果蝇黑腹果蝇的研究为研究这种情况提供了一个前所未有的机会。这是因为据推测，这一非洲物种殖民加勒比海是历史上非洲奴隶贸易的结果。这项研究将深入了解物种范围的扩大如何导致祖先和派生种群之间的行为隔离。这项研究将确定观察到的美国和加勒比海苍蝇种群在形态、信息素和行为上的差异是否源于：1)不同的殖民事件，美国苍蝇在19世纪从欧洲殖民，加勒比海苍蝇在17世纪奴隶贸易期间从非洲殖民，或者2)美国苍蝇在加勒比海殖民，随后适应性地融合为类似非洲的热带特征。这项研究还将为未来识别导致观察到的表型差异和性别隔离的基因铺平道路。这个项目除了对智力的影响外，还将产生实质性的更广泛的影响。这项研究将继续包括本科生和高中生。7名本科生(包括1名代表不足的少数族裔成员和4名妇女)目前正在参与这一项目，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)上获得了全国第二名，因为他们对这个项目的研究。首席研究员True在教授本科生分子多样性实验室课程时广泛使用巴哈马苍蝇。最后，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大程度的思想交流。

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.