Abstract:
A comparative phylogeographic study on two economically important African tick species, Amblyomma hebraeum
and Hyalomma rufipes was performed to test the influence of host specificity and host movement on dispersion.
Pairwise AMOVA analyses of 277 mtDNA COI sequences supported significant population differentiation among the
majority of sampling sites. The geographic mitochondrial structure was not supported by nuclear ITS-2 sequencing,
probably attributed to a recent divergence. The three-host generalist, A. hebraeum, showed less mtDNA geographic
structure, and a lower level of genetic diversity, while the more host-specific H. rufipes displayed higher levels of
population differentiation and two distinct mtDNA assemblages (one predominantly confined to South Africa/Namibia
and the other to Mozambique and East Africa). A zone of overlap is present in southern Mozambique. A mechanistic
climate model suggests that climate alone cannot be responsible for the disruption in female gene flow. Our findings
furthermore suggest that female gene dispersal of ticks is more dependent on the presence of juvenile hosts in the
environment than on the ability of adult hosts to disperse across the landscape. Documented interspecific
competition between the juvenile stages of H. rufipes and H. truncatum is implicated as a contributing factor towards
disrupting gene flow between the two southern African H. rufipes genetic assemblages.
