Who are the elephants living in the hybridization zone? How genetics may guide conservation to better protect endangered elephants

Abstract

After a long-standing debate, African elephants are now considered by the IUCN as two distinct species: savannah elephants ( Loxodonta africana ), listed as endangered on the IUCN Red List of Threatened Species, and forest elephants ( Loxodonta cyclotis ), critically endangered. Both are severely threatened by forest loss, fragmentation and degradation due to agriculture expansion, as well as by illegal ivory trade. Although the two species have different habitat preferences, their range overlaps in some ecotones; despite an ancient separation between these two species, hybrids have been reported in five locations. The main hybrid hotspot is located on the Democratic Republic of Congo-Uganda border and still remains understudied. Using 15 microsatellites, we investigated this hybridization zone by determining the species and hybrid status of 177 fecal samples collected in the area of Sebitoli, at the extreme North of Kibale National Park. Surprisingly for a forest area, no pure forest elephants were detected. Out of the 91 individuals sampled, a very large proportion (81.3%) were hybrid individuals mainly from a second generation or more. Only 18.7% of pure savannah elephants were detected, all originating from the DRC-Uganda border. Further analyses are necessary to assess the age of this hybridization zone. Our results emphasize that hybrids and savannah elephants can successfully range in forested area. They also show that forest elephants are rare even in their native habitat. In the current context of high threat faced by African elephant species, it is crucial to strengthen conservation efforts for these species before it is too late. • 91 individuals were sampled in the Ugandan elephant hybridization zone. • No forest elephants were detected in the sampled forested area. • 81% of the sampled elephants were hybrids. • Hybrids are fertile with 98.6% of hybrids belonging to second generation or more. • Pure savannah elephants seem to originate from the DRC-Uganda border.