# Unravelling genetic differentiation between Glossina brevipalpis populations from two distant National Parks in Mozambique

## TL;DR

This study examines the genetic differences between tsetse fly populations in two Mozambican national parks, finding strong isolation and suggesting human activity might explain limited gene flow.

## Contribution

The study reveals strong genetic isolation between G. brevipalpis populations in Gorongosa and Maputo National Parks, suggesting undocumented pocket populations or human-driven translocation.

## Key findings

- The two G. brevipalpis populations in Gorongosa and Maputo National Parks are strongly isolated with minimal gene flow.
- Average dispersal within parks reaches 30 km per generation.
- Human-driven animal transportation is suggested as a possible cause for limited gene exchange between the parks.

## Abstract

African trypanosomosis (AT), caused by protozoan parasites of the genus Trypanosoma, has plagued the African continent for centuries, affecting both humans and animals. Its principal vector, tsetse flies, can be found across sub-Saharan Africa. Vector control represents an efficient way to reduce the burden of AT. In Mozambique, control campaigns reshaped tsetse fly distribution to what it is today, with four species presently found: Glossina brevipalpis, G. pallidipes, G. morsitans and, G. austeni. Additionally, G. brevipalpis can be observed in two National parks, Gorongosa National Park in the Centre and Maputo National Park in the South, with an 840 km wide tsetse-free zone between them. In order to improve our knowledge on the genetic diversity in these populations, and their probable isolation, we undertook a population genetics study with 11 microsatellite loci. We found that these two zones behave as strongly isolated subpopulations, only exchanging a few individuals per year. To explain this finding, we suggest the existence of undocumented pocket populations between the two parks, or, in the absence of these, the accidental translocation of tsetse flies during human-driven animal transportation. We suggest that translocation through human-driven animal movement should be explored in future studies investigating Glossina populations. If eradication were to be attempted, re-invasion of the tsetse via motorized human transport should be considered in conjunction with the exploration of other sites within a 30 km radius to validate that no sources of re-invasion exist around these parks.

African trypanosomoses (AT), is caused by single celled parasites of the genus Trypanosoma. These have plagued the African continent for centuries, affecting both humans and animals. Its principal vector, tsetse flies, can be found across sub-Saharan Africa. Vector control represents an efficient way to reduce the burden of AT. In Mozambique, control campaigns reshaped tsetse fly distribution to what it is today, with four species presently found: Glossina brevipalpis, G. pallidipes, G. morsitans and, G. austeni. Additionally, G. brevipalpis can be observed in two National parks, Gorongosa National Park in the Centre and Maputo National Park in the South, with an 840 km wide tsetse-free zone between them. In the present work, we have analysed the genetic variation of this tsetse fly within and across these two parks. We found that these two zones behave as strongly isolated subpopulations, only exchanging a few individuals per year. Within parks, average dispersal appeared to reach 30 km per generation. To explain this finding, we suggest the existence of undocumented pocket populations between the two parks. In the absence of such pockets, the most probable explanation is the accidental translocation of tsetse flies during human-driven animal transportation. If eradication were to be attempted, re-invasion of the tsetse via motorized human transport should be considered in conjunction with the exploration of other sites within a 30 km radius to validate that no sources of re-invasion exist around these parks.