Tsetse fly population genetics: an indirect approach to dispersal.

Tsetse populations are distributed discontinuously, particularly the morsitans group. Dispersal among diverse populations cannot easily be measured directly because the geographical distances between them can be too great to have a reasonable expectation of recapturing experimentally released flies. Moreover, reproductive success of widely dispersed flies might be poor. The question of dispersal rates in tsetse is immediately important because area-wide eradication plans involving the sterile insect technique are under consideration. Dispersal and gene flow are important from evolutionary and historical viewpoints. An indirect method of estimating dispersal is to measure gene flow. Genetic data indicate surprisingly low rates of gene flow in the morsitans and palpalis groups studied to date. The underlying assumptions in making such estimates need to be examined carefully, however, before accepting firm conclusions, and further research is needed. Of particular interest is the question of tsetse adaptation to local environments.