Parasite infection reflects host genetic diversity among non-native populations of pumpkinseed sunfish in Europe

Species introductions often coincide with loss of genetic diversity and natural enemies. Anthropogenic translocation of the North-American pumpkinseed Lepomis gibbosus (L., 1758) (Centrarchidae) and its further spread have resulted in recent species establishment in most European countries. This study determines genetic differentiation of non-native European pumpkinseed populations and identifies how their genetic structure relates to the distribution and abundance of parasite species. Microsatellite analysis indicated presence of three genetic lineages, which were well supported by discriminant analysis based on parasite abundance data. The first lineage clustered pumpkinseed populations from northern and southern France and showed high allelic richness, heterozygosity and parasite richness. The second included populations along the “Southern invasion corridor” connecting the rivers Rhine, Main and Danube. The fish exhibited low to high genetic and parasite diversity and generally high parasite abundance. The third lineage clustered populations with low genetic and parasite diversity, located in Portuguese reservoirs and water bodies along the upper Elbe. Parasite species richness was significantly associated with host microsatellite heterozygosity and allelic richness, a trend partially affected by richness of North-American parasites. Furthermore, our results indicate that parasite community composition may serve as a useful biological tool to discriminate non-native fish populations and their inter-relationships.