Biogeography and host‐related factors trump parasite life history: limited congruence among the genetic structures of specific ectoparasitic lice and their rodent hosts

Abstract

Parasites and hosts interact across both micro- and macroevolutionary scales where congruence among their phylogeographic and phylogenetic structures may be observed. Within southern Africa, the four-striped mouse genus, Rhabdomys, is parasitized by the ectoparasitic sucking louse, Polyplax arvicanthis. Molecular data recently suggested the presence of two cryptic species within P. arvicanthis that are sympatrically distributed across the distributions of four putative Rhabdomys species. We tested the hypotheses of phylogeographic congruence and cophylogeny among the two parasite lineages and the four host taxa, utilizing mitochondrial and nuclear sequence data. Despite the documented host-specificity of P. arvicanthis, limited phylogeographic correspondence and nonsignificant cophylogeny was observed. Instead, the parasite-host evolutionary history is characterized by limited codivergence and several duplication, sorting and host-switching events. Despite the elevated mutational rates found for P. arvicanthis, the spatial genetic structure was not more pronounced in the parasite lineages compared with the hosts. These findings may be partly attributed to larger effective population sizes of the parasite lineages, the vagility and social behaviour of Rhabdomys, and the lack of host-specificity observed in areas of host sympatry. Further, the patterns of genetic divergence within parasite and host lineages may also be largely attributed to historical biogeographic changes (expansion-contraction cycles). It is thus evident that the association between P. arvicanthis and Rhabdomys has been shaped by the synergistic effects of parasite traits, host-related factors and biogeography over evolutionary time.

Phylogenetic congruence of lichenised fungi and algae is affected by spatial scale and taxonomic diversity

“…With asexual reproduction, the fungus and alga disperse together, and so, a predominance of asexual reproduction may be one of the reasons we see such a strong co-diversification signal in these taxa. However, the results of this study suggest that the spatial distributions of the fungi and algae may also be important in determining the nature of the symbiosis, particularly at larger spatial scales, as has been observed in some parasite lineages (e.g., du Toit et al, 2013). Thus, we need to do more work on algal and fungal availability to determine if habitat preferences and/or dispersal limitation led to some of the spatial patterns that we see.…”

Ciliate species diversity and host-parasitoid codiversification in Pseudocollinia infecting krill, with description of Pseudocollinia similis sp. nov.

“…Parasites often codiversify or coevolve with their hosts, and recently gene sequences and inferred tree topologies have been used to test these hypotheses of codiversification (Johnson et al 2004, Kuo et al 2008, Cruaud et al 2012, Rosenblueth et al 2012, Du Toit et al 2013. While event-based reconciliation tools show some codiversification of Pseudocollinia species with their host euphausiids, the AU/SH tests rejected absolute codiversification.…”

Comparative phylogeography of parasitic Laelaps mites contribute new insights into the specialist-generalist variation hypothesis (SGVH)

“…The individual Rhabdomys species, however, differ in their phylogeographic structure (genetic connectivity among geographic populations). For example, the solitary R. dilectus that occurs on the eastern area of southern Africa has haplotype sharing throughout the region (indicative of higher dispersal capabilities) while the arid adapted R. bechuanae has strong intraspecific population differentiation among sampling sites, indicative of lower dispersal among sampling sites [11]. …”