Dissertation Research: Conspecific Sperm Precedence in Drosophila

Coyne9801476在自然界中的许多生物中，雄性和雌性在交配中经常表现出与适合度相关的差异。 雌性可能会受益于只允许她接受的某些精子使她的卵子受精，而雄性则会受益于鼓励雌性尽可能多地使用他的精子，而牺牲其他雄性。 当这些利益冲突时，雄性和雌性之间的进化斗争就产生了。 这种斗争可以在内部生殖解剖学和生理学上产生永久性的变化，例如雄性和雌性相遇时经常进化出彼此微调的生殖系统，但与其他密切相关的动物的生殖系统不同。 这种内部生殖系统的差异可能会阻止群体之间的杂交，从而导致新物种的起源。研究人员在广泛研究的果蝇属中发现了这一过程的证据。 当两个亲缘关系密切的果蝇物种的精子竞争同一个雌性的卵子时，来自同一物种的雄性果蝇的精子总是比来自亲缘关系较远的雄性果蝇的精子竞争得多。这项研究将调查1）所描述的过程在果蝇属中的广泛证据，2）内部生殖系统中所描述的差异进化的速度有多快，3）精子相对于其他物种精子获得竞争优势的机制，以及4）同一物种雄性精子之间的竞争机制。 这个项目将进一步加深我们对内部生殖现象在物种差异起源中的重要性的理解。

Coyne9801476In many organisms occurring in nature, males and females often demonstrate fitness-related differences in mating. A female may benefit by allowing only certain of the sperm she receives to fertilize her eggs, while a male benefits by encouraging the female to use as many of his sperm as possible, at the expense of other males. When these interests conflict, an evolutionary struggle between males and females results. This struggle can create perpetual change in internal reproductive anatomy and physiology, such that males and females that encounter one another often evolve reproductive systems that are finely tuned to one another, but are different from the reproductive systems of other closely related animals. Such differences in internal reproductive systems may then prevent subsequent interbreeding between groups, contributing to the differences that lead to the origin of new species.The investigators have discovered evidence of this process within the widely studied genus of fruit flies, Drosophila. When sperm from two closely related species of Drosophila compete for the eggs of a single female, those sperm from a male of the same species as the female invariably out-compete the sperm from the more distantly related male. The proposed research will investigate 1) how widespread evidence of the described process is in the Drosophila genus, 2) how rapidly the described differences in internal reproductive systems can evolve, 3) the mechanism by which sperm gain a competitive advantage over sperm of other species, and 4) the mechanisms of competition among sperm from males of the same species. This project will further our understanding of the importance of internal reproductive phenomena in the origin of differences among species.