Population genetic patterns of the solitary tunicate, Molgula manhattensis, in invaded Chinese coasts: large-scale homogeneity but fine-scale heterogeneity

Frequent anthropogenic activities and rapid microevolution associated with rapidly changing environments have complicated the population genetic patterns of invasive species in invaded ranges. In order to deeply understand the mechanisms of invasion success, it is crucial to illuminate population genetic patterns at varied geographical scales in invaded ranges, as well as potential influential factors contributing to observed patterns. In this study, we used both the mitochondrial cytochrome c oxidase subunit I (COI) gene and nuclear microsatellites to investigate the population genetic patterns of a hermaphroditic solitary tunicate, Molgula manhattensis, in invaded Chinese coasts. Our results showed a low level of genetic diversity based on both types of genetic markers. Multiple analyses exhibited a high level of population genetic homogeneity across a wide geographical range. Interestingly, we detected significant population genetic structure at fine geographical scales, particularly for two populations sampled from the Bohai Sea (Laoting and Laizhou). The complex genetic patterns observed in this study, together with multiple putative factors responsible for such patterns, are expected to help understand the invasion success and dispersal dynamics of M. manhattensis along Chinese coasts.