Mitochondrial and nuclear genetic structure in Rhodeus ocellatus (Teleostei: Cyprinidae) with approximate Bayesian computation

Abstract

The rosy bitterling, Rhodeus ocellatus, is a small freshwater fish belonging to the family Cyprinidae. This species lives in ponds where freshwater mussels are abundant and female lays eggs inside mussels. To understand whether the reproduction mode influenced the phylogeography, our study examined the genetic structure of R. ocellatus using sequences from the mitochondrial DNA (cytochrome b gene and control region) and nuclear DNA (the first intron of ribosomal protein S7 gene). In total, 213 specimens were collected from twelve populations in south of Yangtze River, including Yangtze River, Taiwan and Hainan Islands. The phylogenetic analyses based on mitochondrial and nuclear sequences both showed the lack of a population genetic structure, but all results, including the approximate Bayesian computation approaches, showed that these two markers revealed incongruent historical signals. Our study found that (1) the discordance between these two markers were accounted for admixtures by introduced; (2) the phylogeographic pattern of R. ocellatus and that of other freshwater fish were identical; (3) the reproduction mode was due to that the gene flows among populations were limited; and (4) R. ocellatus colonized in south of the Yangtze River (including) after southeast coastal districts formed and before Taiwan Island reached its present shape by comparing our results with that of the previous studies.