Oral Presentation- Symposium 12th International Mammalogical Congress

Limited dispersal in an ectoparasitic mite, Laelaps giganteus, contributes to significant phylogeographic congruence with the rodent host, Rhabdomys (#263)

Adriaan Engelbrecht 1 2 3 , Sonja Matthee 1 , Nina du Toit 1 2 , Conrad A Matthee 2
  1. Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch, Western Cape, South Africa
  2. Evolutionary Genomics Group, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape, South Africa
  3. University of the Western Cape, Bellville, Cape Town, Western Cape, South Africa

Exploring how biogeography, parasite life history and host vagility influences evolutionary codivergence, we followed a comparative phylogeography approach using a host-specific non-permanent mite, Laelaps giganteus, that occurs on four rodent species within the genus Rhabdomys. A mtDNA COI haplotype network derived for 278 parasite specimens showed marked phylogeographic congruence with host distributions. Analysis of the less variable nuclear intron Tropomyosin was partially consistent with these results. Although distance-based cophylogenetic analyses in AXPARAFIT failed to support significant mtDNA codivergences (P ≥ 0.02), event-based analyses revealed significant cophylogeny between sampling localities of Rhabdomys and Laelaps using CORE-PA (P = 0.046) and JANE (P = 0.026; P = 0.00). These findings, in conjunction with the weak congruence previously reported among the permanent ectoparasitic lice Polyplax and Rhabdomys, suggest that host–parasite intimacy is not the most important driver of significant codivergence in our study system. Instead, the more restricted dispersal ability of L. giganteus, when compared to Polyplax, resulted in stronger spatial structuring and this could have resulted in significant codivergence. Host switching occurred predominantly on the edges of host distributions and was probably facilitated by climate-induced range shifts. When host ranges shift, the phylogeographic structure of L. giganteus is not reflecting the host movements as most of the nest bound parasites do not disperse with the host (they miss the boat) and the genetic contribution of the few dispersing mite individuals is often overwhelmed by the large number of individuals already present in nests within the new environment (causing them to drown on arrival).