Browsing by Author "Bonnald, Julie"

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    Phenotypical characterization of African savannah and forest elephants, with special emphasis on hybrids: the case of Kibale National Park, Uganda
    (Cambridge University Press (CUP), 2022-06) Bonnald, Julie; Cornette, Raphaël; Pichard, Maëllie; Asalu, Edward; Krief, Sabrina
    Abstract Abstract The IUCN now recognizes the savannah Loxodonta africana and forest Loxodonta cyclotis elephants to be separate species. Despite ecological, behavioural and morphological differences, and different habitat ranges, genetic studies confirm that the two species and hybrids coexist in forest–savannah ecotones. However, the hybrid phenotypes have not yet been described. In this survey we examined whether the phenotypes of the two species and of hybrids can be distinguished. In the first step, we used a machine learning algorithm ( K -nearest neighbours) to compare 296 reference images of African elephants from five forest areas and six savannah areas where hybrids have not been recorded, confirming that six morphological criteria can be used to distinguish the species with more than 90% confidence. In the second step, we analysed 1,408 videos of elephants from 14 camera traps in Sebitoli, in Kibale National Park, Uganda, part of the main hybridization area. We used a multiple correspondence analysis and a species assignment key, highlighting the presence of three categories of phenotypes. Compared to the savannah and forest phenotypes (36.8 and 12.1%, respectively), the intermediate phenotypes, which could include hybrids, were more frequent (51.1%). Further studies combining morphology and genetics of the same individuals will be necessary to refine this species assignment key to characterize phenotypes confidently. This non-invasive, fast and inexpensive phenotypical-based method could be a valuable tool for conservation programmes.
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    Who are the elephants living in the hybridization zone? How genetics may guide conservation to better protect endangered elephants
    (Elsevier B.V, 2021-12) Bonnald, Julie; Utge, Jose; Kuhner, Mary K.; Wasser, Samuel K.; Asalu, Edward; Okimat, John Paul; Krief, Sabrina
    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.