Generalist haemosporidian parasites are better adapted to a subset of host species in a multiple host community

Parasites that can infect multiple host species are considered to be host generalists with low host specificity. However, whether generalist parasites are better adapted to a subset of their host species remains unknown. To elucidate this possibility, we compared the variation in prevalence and infection intensity among host species of three generalist parasite lineages belonging to the morphological species Haemoproteus majoris, in a natural bird community in southern Sweden. Prevalence in each host species was confirmed by nested PCR and DNA sequencing and infection intensities were quantified using lineage-specific real-time qPCR. For two of the three lineages, we detected positive correlations between prevalence and infection intensity, indicating that these generalist parasites are better adapted to a subset of host species, which may have been more frequently encountered during the evolution of the parasite; we refer to these as main host species. For both lineages, the main host ...