The population genetics of host specificity: genetic differentiation in dove lice (Insecta: Phthiraptera)

Abstract

Some species of parasites occur on a wide range of hosts while others are restricted to one or a few host species. The host specificity of a parasite species is determined, in part, by its ability to disperse between host species. Dispersal limitations can be studied by exploring the genetic structure of parasite populations both within a single species of host and across multiple host species. In this study we examined the genetic structure in the mitochondrial cytochrome oxidase I (COI) gene of two genera of lice (Insecta: Phthiraptera) occurring on multiple sympatric species of doves in southern North and Central America. One genus, Columbicola, is generally less host-specific than the other, Physconelloides. For both genera we identified substantial genetic differentiation between populations of conspecific lice on different host species, generally 10-20% sequence divergence. This level of divergence is in the range of that often observed between species of these two genera. We used nested clade analysis to explore fine scale genetic structure within species of these feather lice. We found that species of Physconelloides exhibited more genetic structure, both among hosts and among geographical localities, than did species of Columbicola. In many cases, single haplotypes within species of Columbicola are distributed on multiple host species. Thus, the population genetic structure of species of Physconelloides reveals evidence of geographical differentiation on top of high host species specificity. Underlying differences in dispersal biology probably explain the differences in population genetic structure that we observed between Columbicola and Physconelloides.

Community interactions govern host-switching with implications for host–parasite coevolutionary history

“…Body lice are significantly more host-specific, and exhibit more population genetic structure than wing lice (21). The evolutionary history of body lice also parallels that of the host more closely than does the evolutionary history of wing lice.…”

Parasite co-structure: broad and local scale approaches

“…For instance, trematode species that cycle exclusively in freshwater hosts are much more genetically subdivided among rivers than another fluke from the same locations, but whose life cycle includes highly mobile terrestrial hosts (Criscione & Blouin, 2004). Johnson et al (2002) found differences in genetic structure among species of dove lice. In part, these patterns may be due to the ability of some louse species to hitch-hike on hippoboscid flies.…”

Are lice good proxies for host history? A comparative analysis of the Australian magpie, Gymnorhina tibicen, and two species of feather louse

“…Several B. semiannulata and two Philopterus sp. individuals that were sequenced were highly divergent to all other samples and were in the range observed between species in the louse genus Physconelloides (Johnson et al, 2002) or among species of Columbicola that use different hosts (Whiteman et al, 2004). These lice possibly represent host transfer from their regular host to the Australian magpie.…”

“…to gain access to a new host through host to host contact. Some species of lice that share a host but live in different habitats also display differences in dispersal potential (Johnson et al, 2002). The differences in dispersal potential among the two louse species are expected to result in greater levels of gene flow among populations of B. semiannulata and possibly higher concordance of genetic variation with the host in Philopterus sp.…”