峨眉树蛙求偶场婚配制度的进化机制

The lek is an unusual mating system which refers to multiple males of a species aggregate into a certain field displaying elaborate performance in order to mate with females visiting to leks. It has attracted much attention due to its uniqueness, and has become a hotspot in the research of behavioral ecology and evolutionary biology in the 1980s. However the mechanism of forming a lek is still the most controversial puzzle. Many amphibian species are known to form leks during breeding season, yet it has seldom been tested on the evolutionary forces acting on the lek formation in this taxon. We have found that there is a typical lek mating system in omei treefrog (Rhacophorus omeimontis) with significant difference in the reproductive success among males, which means that this species is an ideal model to study the evolutionary mechanism of lek mating system. Therefore, we intend to combine the behavioral observation with experimental analysis to study the lek in omei treefrog. In this study, we will 1) investigate the correlation between the size of males aggregations and the number of females, 2) research the correlation between the size of males aggregations and the intensity of sexual selection, 3) evaluate the relationship between the males' breeding success and the index of kinship. Our purpose is to test the "female passive attraction", "female preference " and "kin selection" hypotheses in the lek mating system, to reveal the evolutionary mechanism of lek in omei treefrog, and to promote the development of mating system theory in amphibian.

求偶场婚配制度是指一个物种的多个雄性聚集于某一领域，通过炫耀表演，以吸引雌性到表演场进行交配的婚配制度。它因其独特性而受到广泛关注，在上世纪80年代就已成为行为生态学和进化生物学的研究热点，然而关于它的形成机制至今仍然是最具争议的未解之谜。许多两栖动物在繁殖季节会形成求偶场，但是很少有关于它们求偶场婚配制度进化机制的研究。我们的研究发现：峨眉树蛙具有典型的求偶场婚配制度，雄性繁殖成功率具有显著的差异，是一个很好研究求偶场婚配制度进化机制的模式动物。因此，我们拟利用行为观察和实验分析相结合的方法，研究峨眉树蛙求偶场：1）雄性群体大小与雌性数量之间的相关性；2）雄性群体大小与性选择强度之间的相关性；3）雄性亲缘关系指数与繁殖成功率之间的相关性，验证求偶场婚配制度的"雌性被动吸引假说"、"雌性偏好假说"和"亲缘选择假说"，揭示峨眉树蛙求偶场婚配制度的进化机制，促进两栖动物婚配制度理论的发展。

为了验证两栖类求偶场婚配制度进化机制的雌性被动吸引假说、雌性偏好假说和亲缘选择假说，我们利用野外行为观察和微卫星、MHC分子标记实验分析相结合的方法调查了峨眉数蛙（Rhacophorus omeimontis）求偶场雄性群体大小与雌性数量之间的相关性、雄性群体大小与性选择强度之间的相关性，以及雄性亲缘关系指数与繁殖成功率之间的相关性。研究发现峨眉数蛙在四个繁殖季节求偶场雄性群体大小与雌性数量和性选择强度之间均存在显著的正相关，而雄性亲缘关系指数与繁殖成功率之间不存在显著的相关性。结果支持两栖类求偶场婚配制度进化机制的雌性被动吸引假说和雌性偏好假说，而不支持亲缘选择假说。因此，我们认为雌性被动吸引和雌性偏好在峨眉树蛙求偶场婚配制度的进化过程中起着重要的作用。

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