冷血脊椎动物中极少存在高度分化的异形性染色体，96%的物种表现为相同形态。这一有悖于性染色体进化理论的现象如何解释？新的假说认为，因性反转XY雌性个体偶然的出现，X和Y之间再次发生重组而维持了性染色体形态不变。然而，现有研究所涉类群非常有限，尤其缺乏异形性染色体物种为参照而显不足。本研究拟选择兼有同形和异形性染色体的四川湍蛙及其近缘物种群为材料，借助于基因组测序、染色体显微切割、WGA扩增及涂染FISH技术等进行性别连锁标记筛选及定位，运用新兴的近似贝叶斯计算等多重分析方法，重点：（1）检测X和Y性染色体间的基因重组是否受到高度抑制；（2）基于性别连锁标记构建分子树，检测X和Y间是否再次发生基因重组；（3）检测X和Y序列之间相似性存在与否推导重组是否再次发生；（4）检测X和Y之间偶然的基因重组是否以极低的频率出现。期望通过多层次多侧面的分析进行假说求证，以期对这一令人迷惑的话题进行诠释。

In sharp contrast with birds and mammals, highly differentiated Y chromosome are rarely observed in cold-blooded vertebrates. Sex chromosomes have been described as homomorphic in about 96% of amphibians and fishes studied so far. Why is that so? The ‘‘fountain-of-youth’’ hypothesis advocates that sex-chromosome integrity can be maintained over long times by occasional recombination in XY females. However, this view is not enough to be evidenced, especially when the species with the heteromorphic sex-chromosome is the third reference. In this study, we assess the X-Y recombination at population level, by a case study on Amolops mantzorum sister species (Anura, Ranidae), these involving homomorphic or heteromorphic sex-chromosome. First, we try to assess whether the recombination is suppressed by employing a series of microsatellite loci to check the recombination rate between autosomes, X-X and X-Y chromosomes. Second, we will try to detect the X-Y recombination by reconstructing gene tree with the sex linked loci through isolating Y chromosome in the light microscope, then mapping loci to Y chromosome by FISH. Third, we try to decipher the X-Y recombination based on the analysis of X-Y similarity. Fourth, we try to estimate the X-Y recombination rate relative to that between X chromosomes in all species by employing Approximate Bayesian Computation.