Abstract
Glossina pallidipes is the main vector of animal African trypanosomiasis and a potential vector of human African trypanosomiasis in eastern Africa where it poses a large economic burden and public health threat. Vector control efforts have succeeded in reducing infection rates, but recent resurgence in tsetse fly population density raises concerns that vector control programs require improved strategic planning over larger geographic and temporal scales. Detailed knowledge of population structure and dispersal patterns can provide the required information to improve planning. To this end, we investigated the phylogeography and population structure of G. pallidipes over a large spatial scale in Kenya and northern Tanzania using 11 microsatellite loci genotyped in 600 individuals. Our results indicate distinct genetic clusters east and west of the Great Rift Valley, and less distinct clustering of the northwest separate from the southwest (Serengeti ecosystem). Estimates of genetic differentiation and first-generation migration indicated high genetic connectivity within genetic clusters even across large geographic distances of more than 300 km in the east, but only occasional migration among clusters. Patterns of connectivity suggest isolation by distance across genetic breaks but not within genetic clusters, and imply a major role for river basins in facilitating gene flow in G. pallidipes. Effective population size (Ne) estimates and results from Approximate Bayesian Computation further support that there has been recent G. pallidipes population size fluctuations in the Serengeti ecosystem and the northwest during the last century, but also suggest that the full extent of differences in genetic diversity and population dynamics between the east and the west was established over evolutionary time periods (tentatively on the order of millions of years). Findings provide further support that the Serengeti ecosystem and northwestern Kenya represent independent tsetse populations. Additionally, we present evidence that three previously recognized populations (the Mbeere-Meru, Central Kenya and Coastal “fly belts”) act as a single population and should be considered as a single unit in vector control.
Highlights
Tsetse flies are restricted to Sub-Saharan Africa and inhabit patchy and discontinuous habitat within their distribution [1,2]
Tsetse flies are responsible for transmission of trypanosomes that cause human African trypanosomiasis (HAT) and animal African Trypanosomiasis (AAT) in sub-Saharan Africa, and are of economic importance in the regions they inhabit
Findings from Approximate Bayesian Computation (ABC) simulations suggest that the east/west divergence reflects the biogeographic break across the Great Rift Valley, and the northwest/southwest divergence reflects the biogeographic break between low elevation savannah and the Kenyan highlands, both biogeographic breaks previously observed in savannah animals with similar ranges
Summary
Tsetse flies (genus Glossina) are restricted to Sub-Saharan Africa and inhabit patchy and discontinuous habitat within their distribution [1,2]. Geographical Information System (GIS) prediction models have been used to show areas of tsetse abundance and expansion [13,15], and these models suggest that several human and natural disturbance have impacted tsetse distribution at various times. This finding is supported by population genetic analyses that indicated genetic shifts [16] especially in regions where human activities have altered conditions [17,18]. Understanding the relative impact of these various biogeographic forces is important for the development and coordination of effective and feasible vector control strategies in Kenya and Tanzania, two countries that are heavily burdened by the economic cost of AAT
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
