Eberhard William G, Gelhaus Jon K
Smithsonian Tropical Research Institute and Escuela de Biología, Universidad de Costa Rica, Ciudad Universitaria, Costa Rica, and Museum of Natural Science, Louisiana State University, Baton Rouge, LA 70808, USA.
Department of Biodiversity, Earth and Environmental Sciences, The Academy of Natural Sciences, Drexel University, 1900 Ben Franklin Parkway, Philadelphia, PA 19103-1195, USA.
Insects. 2024 Sep 9;15(9):680. doi: 10.3390/insects15090680.
Male genitalia have been hypothesized to function as courtship devices during copulation, but it is difficult to use behavioral observations to test this hypothesis because male genitalia are usually hidden inside the female during copulation. In tipuloid flies, however, nearly all of the male's complex genital structures remain outside the female. Copulation behavior and genital morphology in () and . () suggest that some male genital structures function to stimulate the female: male structures that contact the female bear tufts or dense arrays of modified setae on precisely the surfaces that contact the female; contact involves repeated, stereotyped rhythmic movements that include brushing, vibrating, scraping, and tapping; the movements are appropriately designed to utilize the morphology of the modified setae to stimulate the female; and the movements have little or no other perceptible mechanical effects on the female. The female structures contacted by these male genital movements fail to show the defensive designs predicted by the theories of genital evolution that are based on morphological species isolation or male-female morphological conflicts of interest; also unexplained by the conflict of interest hypothesis are female movements that seem designed to increase rather than avoid stimulation by the male.
雄性生殖器被推测在交配过程中起到求偶工具的作用，但由于在交配时雄性生殖器通常藏于雌性体内，因此很难通过行为观察来验证这一假设。然而，在大蚊科的蝇类中，几乎所有雄性复杂的生殖器结构都露在雌性体外。对（）和（）中的交配行为及生殖器形态的研究表明，一些雄性生殖器结构具有刺激雌性的功能：与雌性接触的雄性结构在与雌性接触的精确表面上长有簇状或密集排列的特化刚毛；接触包括反复、刻板的有节奏动作，如刷洗、振动、刮擦和轻敲；这些动作经过适当设计，利用特化刚毛的形态来刺激雌性；并且这些动作对雌性几乎没有或没有其他明显的机械影响。这些雄性生殖器动作所接触的雌性结构并未表现出基于形态物种隔离或雌雄形态利益冲突的生殖器进化理论所预测的防御性设计；利益冲突假说也无法解释雌性那些似乎旨在增加而非避免雄性刺激的动作。
