Hybridization, natural selection and evolution of reproductive isolation: a 25-years survey of an artificial sympatric area between two mosquito sibling species of the Aedes mariae complex

Natural selection can act against maladaptive hybridization between co-occurring divergent populations leading to evolution of reproductive isolation among them. A critical unanswered question about this process that provides a basis for the theory of speciation by reinforcement, is whether natural selection can cause hybridization rates to evolve to zero. Here we investigated this issue in two sibling mosquitoes species, Aedes mariae and Ae. zammitii, that show post-mating reproductive isolation (F1 males sterile) and partial pre-mating isolation (different height of mating swarms) that could be reinforced by natural selection against hybridization. In 1986, we created an artificial sympatric area between the two species and sampled about 20,000 individuals over the following 25 years. Between 1986 to 2011, the composition of mating swarms and the hybridization rate between the two species were investigated across time in the sympatric area. Our results showed that Ae. mariae and Ae. z...自然选择可对同域分布的分化种群间的适应不良杂交（maladaptive hybridization）产生抑制作用，进而推动种群间生殖隔离（reproductive isolation）的演化。作为支撑强化物种形成（speciation by reinforcement）理论的核心基础问题，该过程中仍存在一个关键未解之谜：自然选择能否使杂交率（hybridization rate）演化至零。本研究以两种姊妹物种（sibling species）——玛丽伊蚊（Aedes mariae）与扎姆米蒂伊蚊（Ae. zammitii）——为研究对象，二者已具备交配后生殖隔离（post-mating reproductive isolation，表现为F1雄性不育（F1 males sterile））与部分交配前生殖隔离（pre-mating isolation，体现为交配群（mating swarms）高度存在差异），且该隔离机制可通过针对杂交的自然选择得到强化。1986年，我们构建了二者的人工同域区域（artificial sympatric area），并在后续25年间累计采样约20000只个体。1986年至2011年间，我们对该同域区域内的交配群组成与物种间杂交率开展了跨时间尺度的监测分析。本研究结果显示，玛丽伊蚊（Aedes mariae）与扎姆米蒂伊蚊（Ae. z...