雄性中华大蟾蜍对交配前竞争和交配后竞争的权衡策略及其进化机制

雄性繁殖行为受交配前竞争和交配后竞争共同影响。而能量是有限的，雄性需权衡交配前后竞争，采取最佳策略，以获得最大适合度。那么，交配前后竞争关系如何？如何在它们间权衡？什么原因导致其特点和权衡的差异？雄性在整个生活史怎样调整权衡策略？其进化机制怎样？这些是性选择和进化生物学的热点问题。我们前期研究发现：不同种群、时期和年份间，不同中华大蟾蜍雄性个体状况、繁殖行为和繁殖成功率差异显著；大的雄性获得更多更好的雌性和后代，但这一关系并非线性单调递增，可能是对交配前后竞争权衡及调整的结果。本项目采用野外跟踪调查、室内实验和分子生物学技术，在多个种群和年份研究多种因素对湖南八大公山雄性中华大蟾蜍交配前后竞争的影响，它们的关系及权衡特征，多个因子对权衡的作用及雄性在不同生活史过程和年份的调整，以检验相关假设和理论假说，揭示交配前后竞争权衡策略和进化动力，探讨雄性竞争、性选择、能量分配和生活史对策进化机制。

Reproductive behaviors of males, their resource investments and fitness benefits could be influenced by pre-mating and post-mating intra-sexual competitions, simultaneously. As the limitations on energy storage and resources obtained, males should make trade-offs between pre- and post-mating competitions and perform their best energy allocation strategies to pursue the highest reproductive success. How are the relationships between pre- and post-mating competitions? What patterns of their trade-offs the males have? What factors lead to the different traits of these two competitions and how they cause the variations of the trade-offs? During the whole life-time, how the males change this trade-off at the life-history level? What are the evolutionary drivers for the above processes? These scientific questions are hot-topics in evolutionary biology and sexual selection research. Our previous studies showed that, in different populations, life-history stages, or breeding seasons, variations on body condition, breeding behaviors, and reproductive success were significant among male individuals of the Asiatic toad (Bufo gargarizans). Generally, larger males enjoyed more mating opportunities, better female mates, and greater numbers of offspring. But this trend was not monotone increasing and nonlinear, which might indicate the impacts of pre- and post-mating input trade-offs and allocation strategy adjustments by the males of this species. Using an integration method of continuous field surveys, tracking monitoring, behavior observation, controlling experiments, and molecular genetic techniques, we will study the following issues in multiple populations of the Asiatic toad within the Badagongshan National Nature Reserve, Hunan Province across years: impacts of several conditions on the traits, densities, outcomes, investments, and benefits of pre- and post-mating competitions in males; relationships between pre- and post-mating and their trade-off patterns by the males; influences of a number of body condition, population structure, ecological, environmental, life-history, and mating system factors on the trade-off strategy; trade-off modifications among life-history stages and breeding seasons at the life-time scale by the males. Our research will test the related assumptions, hypotheses, and theories, and reveal the strategies and evolutionary mechanisms of the trade-offs between pre-mating and post-mating intra-sexual competitions among males systematically. It can provide discussions and evidences on the evolutionary drivers of male-male contest, sexual selection, energy allocation, and life-history strategy, promote the explorations and theory developments in this field, and, furthermore, produce proofs on behavioral evolution, population dynamics, and species extinction pressures, and references for management and conservation of amphibians.