Description | Species colonizations (both natural and anthropogenic) can be associated with genetic
founder effects, where founding populations demonstrate significant genetic bottlenecks compared to native populations. Yet, many successfully established free‐living
species exhibit little reduction in genetic diversity—possibly due to multiple founding events and/or high propagule pressure during introductions. Less clear, however, is whether parasites may show differential signatures to their free‐living hosts.
Parasites with indirect life cycles may particularly be more prone to founder effects
(i.e., more genetically depauperate) because of inherently smaller founding populations and complex life cycles. We investigated this question in native (east coast) and
introduced (west coast) North American populations of a host snail Tritia obsoleta
(formerly Ilyanassa obsoleta, the eastern mudsnail) and four trematode parasite species that obligately infect it. We examined genetic diversity, gene flow, and population structure using two molecular markers (mitochondrial and nuclear) for the host
and the parasites. In the host snail, we found little to no evidence of genetic founder
effects, while the trematode parasites showed significantly lower genetic diversity
in the introduced versus native ranges. Moreover, the parasite's final host influenced
infection prevalence and genetic diversity: Trematode species that utilized fish as
final hosts demonstrated lower parasite diversity and heightened founder effects in
the introduced range than those trematodes using birds as final hosts. In addition,
inter‐regional gene flow was strongest for comparisons that included the putative
historical source region (mid‐Atlantic populations of the US east coast). Overall, our
results broaden understanding of the role that colonization events (including recent
anthropogenic introductions) have on genetic diversity in non‐native organisms by
also evaluating less studied groups like parasites. | en_US |