Phylogeography and population structure of the tsetse fly Glossina pallidipes in Kenya and the Serengeti ecosystem

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 (N e) 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

An update on the distribution of Glossina (tsetse flies) at the wildlife-human-livestock interface of Akagera National Park, Rwanda

“…The abundance of G. pallidipes goes in line with the situation in several other countries in the eastern and southern Africa regions [52]; [48]; [55]. This species is the most widely distributed tsetse species in those regions, hence the main vector of AAT and potentially the vector of sleeping sickness [56]. However, recent studies highlight the genetic modi cations amid Glossina populations [57] due to environmental changes [58] ; [59]; [60] which could lead to the dominance and adaptations of certain species in a region.…”

Tsetse blood-meal sources, endosymbionts and trypanosome-associations in the Maasai Mara National Reserve, a wildlife-human-livestock interface

“…Glossina pallidipes is a widely-spread species in Kenya and intense control strategies have had limited success [56]. However, populations of G. pallidipes have been found to be clustered genetically in Kenya [57], necessitating tailor-made control and monitoring strategies for the different clusters for effective tsetse fly eradication. Unlike G. pallidipes, the geographical range of G. swynnertoni in Kenya is limited to a narrow belt within the Maasai Mara-Serengeti ecosystem, which has resulted in the prioritization of this tsetse species as a target for elimination in East Africa [58].…”

“…However, populations of G . pallidipes have been found to be clustered genetically in Kenya [ 57 ], necessitating tailor-made control and monitoring strategies for the different clusters for effective tsetse fly eradication. Unlike G .…”

An update on the distribution of Glossina (tsetse flies) at the wildlife-human-livestock interface of Akagera National Park, Rwanda

“…The abundance of G. pallidipes is in line with the situation in several other countries of the eastern and southern Africa regions [ 53 , 56 , 59 ]. This species is the most widely distributed tsetse species in those regions and hence is the main vector of AAT and potentially the vector of rhodesiense sleeping sickness [ 60 ]. However, recent studies highlight the genetic modifications amid Glossina populations [ 61 ] due to environmental changes [ 62 – 64 ], which could lead to the dominance and adaptations of certain species in a region.…”