Cryptic Speciation And Interspecies Hybridization In Paa:the Evidence From Phylogeographic Analyses

The genus Paa is subordinated to the Ranidae of the order Anura of Amphibian. This genus is known only from Asia, the phylogenetic relationships and the taxonomic recognition of species are controversial. This article used mtDNA as genetic marker and phylogeographic analyses as the method, found that there is cryptic species and interspecies hybridization in Paa. In this study,257individuals representing species of the genus Paa were investigated along the entire range of P. spinosa:196specimens of P. spinosa,8specimens of P. jiulongensis,5specimens of P. boulengeri,20specimens of P. exilispinosa,25specimens of P. shini and3specimens of P. yunnanensis. Approximately1333bp of mtDNA sequence data (genes12S rRNA and16S rRNA) were used. Phylogenetic analyses were conducted using maximum parsimony, Neighbour joining and Bayesian inference. BEAST was used to estimate divergence dates of major clades. Results suggest that P. spinosa can be divided into three distinct major lineages, each major lineage totally corresponds to geographical regions. Great genetic distances between the lineages from east of China, centre of China, west of China are close or larger than genetic distances interspecies, revealing the presence of three candidate cryptic species. The bifurcating phylogenetic pattern also suggests an east-west dispersal trend during historic cryptic speciation of Paa. After identifying cryptic lineages, we then determine one P. spinosa individual in contact zone is observed which has mtDNA genotype of P. shini. One P. shini has mtDNA genotype of P. spinosa. This discrepancy may have been caused by introgressive hybridization between P. spinosa and P. shini. Additionally, we found2of P. yunnanensis individuals have the haplotpe of P. boulengeri, but none of P. boulengeri has the haplotpe of P. yunnanensis, this may caused by asymmetrical introgress of P. boulengeri genes into P. yunnanensis in the hybrid zone.