臭蛙属物种同域共存机制及进化模式研究

Allopatric speciation are generally caused by geographic barriers, and closely related sympatric species can not share the same ecological niche for long. However, our previous studies showed that sympatric distributions existed between sister species, closely related species and distantly related species in the asian edemic Odorrana. How do the sympatric species coexist? Whether there are differences between the mechanisms underlying their sympatric distribution among different taxonomic level? Those issues have become one of the hotspots in evolutionary ecology and ecology. .To answer those questions, we investigated the Odorrana schmackeri species complex and O. graminea species complex, and widespread sympatric distributions occurred in both of the species complex. Three null hypotheses were tested in this project to explore the level of sympatry among different species complex, closely related species, and sister species with different methods of comparative morphology, molecular ecology and comparative phylogeography. The aims were to (1) detect the character displacement, gene flow and introgression of sympatric species in Odorrana; (2) explore the evolutionary mechanisms underlying the sympatry of different populations and their patterns; (3) reveal the geological events leading to the current sympatric distribution patterns and the population history dynamics. The results will provide scientific basis for preventing and controlling invasive species, and protecting the endangered animals and their genetic diversity.

近缘物种通常在相互隔离的地理环境中分化形成，同域分布的近缘物种无法长期共享同一生态位。然而前期研究结果显示，亚洲特有的臭蛙属两栖类，在姊妹种、近缘种及远缘物种间存在普遍的同域分布现象。.针对以上问题，本研究提出三个零假设，以同域现象较为集中的花臭蛙复合体（Odorrana schmackeri species complex）和大绿臭蛙复合体（O. graminea species complex）为主要研究对象，运用比较形态学、分子生态学和比较谱系地理学的方法，基于种组间、近缘种间、姊妹种间的多物种共存不同层次，（1）检测臭蛙属同域分布物种的性状替换、基因交流和渐渗杂交；（2）探讨同域分布种群的进化机制及模式；（3）揭示导致现有同域分布格局的地质变迁和种群历史动态。为防控入侵物种、保护濒危动物及遗传多样性提供科学依据。

性状替换和生殖隔离强化被认为是促进物种共存的主要机制。臭蛙属内大绿臭蛙、花臭蛙及近缘物种存在广泛的分布重叠及同域分布现象，分布范围涵盖中国第二阶梯至第三阶梯不同地势和环境梯度。不同的系统关系及分布重叠程度，使其成为研究同域共存机制的理想对象。本项目以同域现象较为集中的花臭蛙复合体(Odorrana schmackeri species complex)和大绿臭蛙复合体(O. graminea species complex) 为主要研究对象，从种组间、近缘种间、姊妹种间不同共存层次，1)基于形态数据、食性和环境数据，进行生态位及生态性状替换分析; 2)基于雄性鸣声及雌性性选择偏好，检测合子前生殖隔离; 3)运用简化基因组数据，明确同域分布近缘种遗传分化格局及基因流空间分布，揭示种群历史动态，检测同域分布近缘种是否存在生殖隔离强化。.花臭蛙与同域分布近缘种间具有生态位保守性，没有明显的性状替换，种间的性状变异主要受环境因素的影响。花臭蛙与同域分布近缘物种的雄性鸣声存在显著差异，物种内同域分布种群通过改变鸣声特征加强合子前生殖隔离促进同域共存。广义花臭蛙、广义大绿臭蛙物种间的基因流存在明显的空间模式，东部第三阶梯分布毗邻的物种间存在基因流和渐渗杂交，西南山地第二、三阶梯交界处的花臭蛙及同域分布近缘物种具有较强的生殖隔离、不存在渐渗杂交。西南山地花臭蛙与同域分布近缘种遗传分化模式显示选择清除的特征，同域分布未导致生殖隔离强化。青藏高原隆升及气候波动对广义花臭蛙、广义大绿臭蛙的遗传分化以及现有分布格局的形成均具有重要作用。.本研究提示历史事件、种群历史动态是导致同域分布格局形成的重要因素，环境过滤及完善的生殖隔离是花臭蛙与近缘种实现共存的主要机制。