Breeding structure of Glossina pallidipes populations evaluated by mitochondrial variation

Mitochondrial DNA diversity was studied at four loci in six natural populations of the tsetse fly Glossina pallidipes from Zimbabwe, Mozambique, Kenya, and Ethiopia. Single-locus diversity varied from 0.39 at 12S to 0.65 at COII. A total of 32 haplotypes was found with a mean of 6.4 ± 2.9 per locus. To study breeding structure, diversity at two loci, COII and 16S2, was evaluated in 18 populations sampled from an area of approximately 1,611,000 km² and in three laboratory cultures. Twenty-six haplotypes were detected at the two loci and mean haplotype diversity over all natural populations was 0.63. A high degree of population subdivision was detected within and among the Ethiopian and Kenya populations. The Zimbabwe and Zambia populations showed much less variation and differentiation than the northern populations. A population in Mozambique showed high levels of haplotype variation and affinities closest to populations in eastern Kenya, some 1700 km to the north. Analysis of variance of haplotype frequencies showed that 51.5% of the total lay within populations, 13% among populations within five nested groups, and 35.5% among the five groups. Wright's F_ST was 0.485, Nel's G_ST was 0.33, and Weir and Cunningham's θ = 0.45. Ecological data show that G. pallidipes is highly vagile. The large amount of genetic differentiation may be explained by genetic drift that occurred in scattered, relict populations during the rinderpest panzootic of the late 19th and early 20th centuries.