Genetic clustering
The assignment test analysis using STRUCTURE also showed evidence of nuclear introgression in three plots (Fig. 4). As the species were identified, the most appropriate K was K = 2 for all plots, indicating that the colonies of both Nanjing and Wuhan were appropriately divided into two species-specific genotypic clusters, although a few gene introgressions were observed. In contrast, the populations of R. flaviceps and R. chinensis in Chengdu were much more mixed and showed little evidence of species differentiation.