Niche similarity accompanying COI genetic differentiations in asexual and sexual Corbicula lineages within East and Southeast Asia

Asexual eukaryotes tend to occupy broader geographical ranges than their sexually reproducing relatives, with this phenomenon seemingly linked to ecological differentiation among closely related asexual and sexual lineages. Here, we used sympatric asexual and sexual Corbicula lineages to assess their ecological niche divergence and genetic differentiation within East and Southeast Asia. The predicted suitable area for asexual lineages was concentrated to Southern China, South Korea, Japan and a small region in Thailand and Vietnam, while that for sexual lineages mainly covered the middle and lower reaches of the Yangtze River in China, Japan, Malaysia, Philippines as well as Indonesia. Potential sympatric distribution of both lineages was found in the Yangtze River Basin in China, the Central and Southern Japan. Anthropogenic activity was an important variable for the distribution of asexual lineages, while precipitation variables underpinned that of sexual lineages. Although both lineages had distinct distribution patterns, the identity and similarity tests overall indicated that the asexual and sexual lineages had similar niche. Genetic analyses suggested that 348 COI sequences from 47 populations were separated into two major clusters; one consisted of sexual lineages, and the other comprised asexual lineages across all studied regions and minor sexual lineages from China. The present study suggests that sexual and asexual Corbicula lineages have similar ecological niches accompanying COI genetic differentiations in East and Southeast Asia.