近缘和远缘杂交现象在龟鳖目（Testudines）中十分普遍，一些龟鳖类物种甚至被认为是起源于古老的杂交事件。地龟科的乌龟（Mauremys reevesii）和黄喉拟水龟（M. mutica）的杂交现象较为特殊，其正、反交产生的大头乌龟和腊戌拟水龟表型差异大，且大头乌龟为全雌单性。本项目以可频繁进行种间杂交的乌龟和黄喉拟水龟为对象，拟在繁殖生物学研究的基础上，整合基因组DNA甲基化、全基因组测序、比较转录组学及免疫共沉淀等技术，从表观遗传学、进化生物学等多方面探讨乌龟和黄喉拟水龟正、反交杂种表型出现差异和大头乌龟全雌单性形成的原因；从系统进化和蛋白相互作用等角度，研究龟类频繁种间杂交的分子机制；通过比较亲本种和杂种的全基因组图谱，分析亲本和杂种子代间的基因组差异，鉴别出高度分化的“基因组岛”。以期深入探讨乌龟和黄喉拟水龟的生殖隔离，为乌龟和黄喉拟水龟的物种有效性及保护提供重要参考。

Hybridization between closely related and distantly related taxa occurs regularly in Testudines, and certain turtles might have originated from ancient hybridization events. It’s reported that there are massive hybridizations within Geoemydidae and the hybridization between the Chinese pond turtle Mauremys reevsii and the yellow pond turtle M. mutica, which is of longstanding interest to evolutionary biologists. In particular, reciprocal crosses between this two species will generate two other independent F1 hybrid with significant phenotypic differentiation, i.e., Chinese broad-headed pond turtle (M. megalocephala) and Pritchard's Pond Turtle (M. pritchardi). In addition, nearly all the Chinese broad-headed pond turtles observed in wild and turtle farms are female. In the present study, we propose to investigate the hybrid mechanism of turtles by the help of knowledge from reproduction biology of Chinese pond turtle and the yellow pond turtle. We plan to employ the integrated whole genome bisulfite sequencing, whole genome sequencing, comparative transcriptome and Co-immunoprecipitation assayas technologies, to 1) investigate the epigenetic and trancriptomic responses to phenotypic differentiation in Chinese broad-headed pond turtle and Pritchard's Pond Turtle; 2) analyze the coevolution and Protein-Protein interaction of genes that are vital for sperm-egg fusion; and 3) survey the divergence genomic islands across genome and genome compatibility in Chinese broad-headed pond turtle and Pritchard's Pond Turtle. Our study will provide insights into mechanism of reproduction isolation in turtles and valuable information for species delimitation and conservation of Mauremys species.