Interspecies introgressive hybridization in spiny frogs (Family Dicroglossidae) revealed by analyses on multiple mitochondrial and nuclear genes.

Introgression may lead to discordant patterns of variation among loci and traits. For example, previous phylogeographic studies on the genus detected signs of genetic introgression from genetically and morphologically divergent or . In this study, we used mitochondrial and nuclear DNA sequence data to verify the widespread introgressive hybridization in the closely related species of the genus , evaluate the level of genetic diversity, and reveal the formation mechanism of introgressive hybridization. In Longsheng, Guangxi Province, signs of asymmetrical nuclear introgression were detected between and . Unidirectional mitochondrial introgression was revealed from to . By contrast, bidirectional mitochondrial gene introgression was detected between and in Lushan, Jiangxi Province. Our study also detected ancient hybridizations between a female and a male in Zhejiang Province. Analyses on mitochondrial and nuclear genes verified three candidate cryptic species in , and a cryptic species may also exist in . However, no evidence of introgressive hybridization was found between and . from all the sampling localities appeared to be deeply divergent from other communities. Our results suggest widespread introgressive hybridization in closely related species of and provide a fundamental basis for illumination of the forming mechanism of introgressive hybridization, classification of species, and biodiversity assessment in .