Nina Du Toit
Comparative phylogeography of the four-striped mouse, Rhabdomys pumilio (Rodentia: Muridae) and its host-specific parasite, the sucking louse Polyplax arvicanthis (Phthiraptera: Anoplura)
Co-evolution in parasite-host systems is driven by the reciprocal selective pressures of parasite infectivity and host resistance. Most studies on host-parasite systems to date have been conducted above the species level and have focussed on macro-evolutionary patterns such as co-speciation perspective and studies on the comparative phylogeography of hosts and parasites are needed to investigate micro-evolutionary processes which take place at the population level and ultimately reinforce macro-evolutionary trends.
Parasites and hosts share an intimate biological relationship and therefore it can be expected that they will have a similar genealogical history due to shared co-speciation or co-differentiation events. A growing body of literature has shown that parasites and hosts often display congruent phylogeographic structures and that the structure of the parasite is often much more diversified than that of the host. This has allowed for parasites to be utilized as “biological magnifying glasses” to reveal several cryptic features of the evolutionary history of the host species that would not be evident from simply studying the host directly.
For my research, the four-striped mouse, Rhabdomys pumilio (Rodentia: Muridae) and its species-specific sucking louse Polyplax arvicanthis (Phthiraptera: Anoplura)
will be used to investigate theco-phylogeographic patterns of a host-parasite system in southern Africa. This will be the first such study to be conducted within South Africa and also the first population genetic study on P. arvicanthis. Observed patterns within R. pumilio will be compared with those of other studies to assess whether previously identified gene flow barriers for other organisms of the region similarly act as barriers for R. pumilio. This will contribute to the identification of general phylogeographic patterns within southern Africa as well as areas with high levels of genetic diversity across many species, which can be prioritized for conservation management. The findings will also contribute towards resolving the taxonomy of R. pumilio which remains uncertain due to a disagreement within the literature regarding the number of species and/or subspecies which should be recognized. Finally, the phylogeographic structures of R. pumilio and P. arvicanthis will be compared to search for spatial and temporal congruence. It is expected that there will be a high level of congruence between the phylogeographies of the host and parasite since P. arvicanthis possesses several characteristics which has been found to correlate with congruence in previous studies.
The outcomes of this study will enhance our current understanding of the biological diversity in the region and yield novel information of the interactions within a host-parasite system in the Southern African context.
Supervisors: Prof. CA Matthee, Prof. B van Vuuren, Dr. S Matthee