棘蛙属种间渐渗杂交及物种形成

Introgressive hybridization among plant species has been seen as a potential mechanism for the spread of beneficial mutations and the formation of new taxa. In contrast, hybridization in animals has traditionally been viewed as a rare and evolutionarily destructive process leading to the prevention or reversal of divergence between incipient species. In recent years, however, hybridization has been documented across several animal groups, suggesting that this phenomenon may be more important for the evolutionary history and speciation of animals than previously thought. Our previous study found the discrepancy between the mtDNA and the morphotypes in several individuals. This discrepancy may have been caused by introgressive hybridization between Quasipaa spinosa and Q. shini. So, it is speculated that hybridization leading to speciation may has been occurred across Quasipaa species. This project will detect whether introgression of nuclear and mitochondrial genes are common participate in the introgression among these species through the acquisition of Q. spinosa, Q. shini, Q. jiulongensis and Q. exilispinosa overlapping distribution zone of the samples, using multiple gene (nuclear genes and mitochondrial) long fragment molecular markers and phylogeographic analyses. At the same time, we determine whether the fitness of hybrid offspring are fertile and is different from the non-hybrid offspring based on offspring viability, phenotype and exercise performance data from the indoor rearing breeding experiments; finally, we also determine whether the hybrid individuals and Quasipaa species exist reproductive behavior based on the sound analysis. This study is a powerful example of hybridization leading to speciation in nonmodel amphibian species, and is an excellent opportunity to understand the mechanisms leading to speciation in the context of gene flow.

植物渐渗杂交已作为进化和物种形成的方式而被广泛报道，在动物中，这种现象被认为发生较少且对生物多样性不利，但最近的一些研究挑战这一观点。我们前期研究发现，棘胸蛙和棘侧蛙存在基因渐渗，并在野外发现中间形态个体。我们推测，同域分布的棘蛙属物种可能广泛存在渐渗杂交，并对棘蛙属物种形成有重要影响。本项目拟通过采集棘胸蛙、九龙棘蛙、棘侧蛙和小棘蛙地理分布重叠区的样本，采用不同遗传背景的多基因（核基因和线粒体）长片段分子标记，运用分子系统学方法检测棘蛙属物种间是否存在基因渐渗以及两种基因渐渗的时空分布模式；同时通过室内饲养交配繁殖实验，获得后代存活率、表型和运动表现等数据，并以此判断杂交后代是否可育和具有区别于非杂交后代的适合度；最后通过鸣声学分析，确定杂种个体和棘蛙属其他物种是否存在繁殖行为的隔离。本项目不仅是非模式两栖类杂交成种的有力例证，而且对阐明种间渐渗杂交的物种形成机制有着重要意义.

植物渐渗杂交已作为进化和物种形成的方式而被广泛报道，在动物中，这种现象被认为发生较少且对生物多样性不利，但最近的一些研究挑战这一观点。渐渗杂交导致物种形成仍然缺乏充分的自然例证，尤其是在非模式两栖动物中。分子系统学及溯祖理论分析方法的发展和完善、高通量测序技术的进步带动的种群基因组学的发展为这一问题的研究带来了前所未有的机会。我们前期研究发现，棘胸蛙和棘侧蛙存在基因渐渗，并在野外发现中间形态个体。我们推测，同域分布的棘蛙属物种可能广泛存在渐渗杂交，并对棘蛙属物种形成有重要影响。本项目通过采集棘胸蛙、九龙棘蛙、棘侧蛙和小棘蛙地理分布重叠区的样本，采用不同遗传背景的多基因（核基因、线粒体和微卫星分子）长片段分子标记，运用分子系统学方法检测棘蛙属物种间是否存在基因渐渗以及两种基因渐渗的时空分布模式；同时通过室内饲养交配繁殖实验，获得后代存活率、表型和运动表现等数据，并以此判断杂交后代是否可育和具有区别于非杂交后代的适合度；最后通过鸣声学分析，确定杂种个体和棘蛙属其他物种是否存在繁殖行为的隔离。结果表明：分子生物学数据揭示棘蛙属多个个物种间存在基因渐渗现象；野外发现棘胸蛙和棘腹蛙中间形态个体；杂交饲养繁殖实验表明棘胸蛙（♀）与棘侧蛙（♂）杂交可以获得健康的杂种子代，孵化率的平均值为47.12%；杂种在一定条件下具有较高适合度。我们验证了前期的假设：棘蛙属物种杂交能产生可育后代，并且可能导致了新物种形成。本项目不仅是非模式两栖类杂交成种的有力例证，而且对阐明种间渐渗杂交的物种形成机制有着重要意义。