Résumé
Theoretical dates of isolation inferred from genetic data can display discrepancies with estimated dates from historical data that mostly come from underestimate of effective population sizes. Improving sampling design and genetic markers quality seem to be the best solutions to avoid such caveats.
•Isolated tsetse populations are easy targets for control.•We studied several examples of totally isolated tsetse populations.•Theoretical dates of isolation were inferred from genetic data.•Discrepancies mostly come from underestimate of effective population sizes.•Improving sampling design and genetic markers quality seem to be the best solutions.
Isolated tsetse populations constitute a target for tsetse control programmes in endemic countries, since their isolation, if demonstrated, allows control without reinvasion risk from neighbouring populations. Population genetic parameters, such as the fixation index, have proven useful to assess isolation status, and should also give important information on the divergence time since isolation. We gathered results obtained from different datasets regarding several examples of putatively totally isolated tsetse populations of different tsetse species: Glossina palpalis gambiensis in Guinea, in the Niayes of Senegal, and in the sacred wood of Bama in Burkina Faso; G. tachinoides from Bitou and Pama in South-East Burkina Faso. The different levels of isolation were compared to differentiation between the two subspecies G. p. gambiensis and G. p. palpalis which both occur allopatrically along the Comoe River in Ivory Coast. We also use some historical evidence to calibrate differentiation speed and give estimates of time since separation for the different cases studied. Discrepancies mostly come from underestimate of effective population sizes, and we propose improving sampling design and genetic markers quality to circumvent such caveats.