The genetic diversity of two invasive sympatric bivalves (Corbicula fluminea and Dreissena polymorpha) from Lakes Garda and Maggiore, Northern Italy

Corbicula fluminea and Dreissena polymorpha are two non-indigenous species (NIS), known to provoke biodiversity loss of the existent native communities and alterations in the ecosystem functioning structure. Both of these NIS have successfully founded well established populations in Lakes Maggiore and Garda (Northern Italy). Here, we evaluated the mitochondrial COI genetic diversity of C. fluminea and D. polymorpha populations from the aforementioned lakes. The COI gene analysis revealed one C. fluminea haplotype, belonging to the FW5 androgenetic invasive lineage. Two D. polymorpha haplotypes - LM1 and LM2 - were detected in Lake Maggiore. The D. polymorpha comparative phylogeographical haplotype analysis between Lake Maggiore and the retrieved COI data available from Lake Garda revealed that LM1 is the dominant haplotype in both populations, whereas LM2 a rare haplotype was only detected in Lake Maggiore. These findings contribute for a better understanding of the demographic history of these highly invasive species in these Italian lakes, thus suggesting that C. fluminea and D. polymorpha populations present a similar genetic pattern. The low genetic diversity detected in both of these bivalve populations seems to reflect a pre-existent low genetic pool prevenient from the introductory source(s).