Eastern Arc Mountains Block Gene Flow in Elephants and Giraffes, New Genetic Study Reveals

A new study published in the African Journal of Wildlife Research provides clear genetic evidence that Tanzania’s Eastern Arc Mountains act as a major natural barrier separating populations of two iconic species: the African savanna elephant (Loxodonta africana) and the Masai giraffe (Giraffa tippelskirchi). The research team analyzed mitochondrial DNA from 450 elephants and 100 giraffes across the Ruaha–Rungwa, Katavi–Rukwa, and Nyerere–Selous ecosystems, uncovering a strong east–west genetic divide.

This work was made possible through a collaboration among researchers from Penn State University, the Research and Innovation for the Serengeti Ecosystem (RISE) at the Grumeti Fund, the Department of Fisheries, Wildlife, and Conservation Sciences at Oregon State University, the Wild Nature Institute, the Department of Evolutionary Biology and Environmental Studies at the University of Zurich, and the Ministry of Natural Resources and Tourism in Dodoma, Tanzania.

The study found no shared haplotypes between giraffe populations on either side of the Eastern Arc Mountains, indicating long-term isolation. In elephants, researchers detected only minimal historical female-mediated gene flow, with a single shared haplotype across the mountain chain.

Lead author Dr. George Lohay highlighted the importance of these findings for understanding wildlife evolution:
“We found no genetic evidence that giraffes ever crossed the Eastern Arc Mountains, and elephants show only minimal past movement.”

The mountains naturally restrict movement, but research indicates that ongoing habitat loss and the decline of miombo woodlands are now jeopardizing the remaining wildlife corridors. This makes their protection more urgent than ever. Additionally, there is evidence that other species, such as sable antelopes and lions, are also separated by the Eastern Arc Mountains.

Download the study here