Genetic characterization of the Asian clam species complex (Corbicula) invasion in the Iberian Peninsula

Abstract

The Asian clam (Corbicula sp.) is an invasive freshwater bivalve native to Asia, the Middle East, Australia, and Africa. It is now widely distributed around the world producing large ecological and economic impacts. Three well-described invasive lineages form a cryptic species complex with asexual reproduction based on androgenesis. In this study, we collected 175 individuals from different Iberian, European, and North American locations to genetically study Corbicula invasion in the Iberian Peninsula using COI and 28S genes. The use of mitochondrial and nuclear markers allows us to characterize both maternal and paternal inheritance from androgenetic Corbicula locations and to deal with the incongruences caused by egg parasitism. We identified 7 COI and 10 28S haplotypes that grouped individuals within the three invasive Corbicula lineages. Haplotype distribution of mitochondrial and nuclear markers detected genetic divergence between the Ebro Delta location and the rest of Iberian sites, suggesting that at least two invasion episodes occurred in the Iberian Peninsula. Haplotype distribution also suggested secondary contacts between Iberian and other European invaded regions. Additionally, results revealed that nuclear hybridization, a feature more widespread than previously reported, contributes to retain gene diversity in the Corbicula invasion