Host specificity shapes population structure of pinworm parasites in Caribbean reptiles

Abstract

Host specificity is one of the potential factors affecting parasite diversification because gene flow may be facilitated or constrained by the number of host species that a parasite can exploit. We test this hypothesis using a costructure approach, comparing two sympatric pinworm parasites that differ in host specificity - Parapharyngodon cubensis and Spauligodon anolis - on the Puerto Rican Bank and St. Croix in the Caribbean. Spauligodon anolis specializes on Anolis lizards, whereas P. cubensis parasitizes Anolis lizards as well as many other species of lizards and snakes. We collected lizards from across the Puerto Rican Bank and St. Croix, sampled them for S. anolis and P. cubensis and generated nuclear and mitochondrial sequence data from the parasites. We used these data to show that P. cubensis is comprised of multiple cryptic species that exhibit limited population structure relative to S. anolis, which is consistent with our prediction based on their host specificity. We also provide evidence that the distribution of P. cubensis species is maintained by competitive exclusion, and in contrast to previous theoretical work, the parasites with the greatest number of host species also reach the highest prevalence rates. Overall, our results are consistent with the hypothesis that host specificity shapes parasite diversification, and suggest that even moderate differences in host specificity may contribute to substantial differences in diversification.

Getting there and around: Host range oscillations during colonization of the Canary Islands by the parasitic nematode Spauligodon

“…In reality, the mechanisms of parasite diversification are still unclear, and other factors such as host density and host defence have also been linked with parasite diversification (Morand, ). Previous studies on Spauligodon nematodes have reported high population structure on islands, as a direct consequence of their specificity and diversification (Falk & Perkins, ). However, it remained unclear whether Spauligodon is in fact prevented by specificity barriers from expanding its host range, if it is somehow immune to the parasite island syndrome, or if sample bias had a strong influence on the observed patterns.…”

Contrasting definitive hosts as determinants of the genetic structure in a parasite with complex life cycle along the south‐eastern Pacific

“…, ; Miura et al . ; Falk & Perkins ). We demonstrated that N. georgenascimentoi corresponds to a species complex that includes at least three Neolebouria spp.…”

“…). Similarly, Falk & Perkins () (using 18S and COI) suggested that the differences in population structure between two Nematoda species ( Spauligodon anolis and Parapharyngodon cubensis ) are associated with a greater number of hosts, providing more opportunities for dispersal.…”

“…In addition, some authors have proposed that host specificity might affect parasite diversification (Nadler ; Criscione et al . ) because gene flow might be facilitated or constrained by the number of host species that a parasite can use (Nadler ; Blasco‐Costa & Poulin ; Falk & Perkins ). Based on the cytochrome oxidase subunit I gene (COI), Johnson et al .…”

Influence of life history traits on the population genetic structure of parasitic helminths: a minireview

“…However, if the hosts are particularly abundant, widespread and have high dispersal/mobility, the possibilities of gene flow for the parasites increase. In contrast, populations of parasites with a broad host range may show relatively high genetic variation and low differentiation because of a greater number of opportunities for gene flow (Archie andEzenwa 2011, Falk andPerkins 2013). Ecological or behavioural differences between host species may also influence the population genetic structure.…”