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Ignoring species hybrids in the IUCN Red List assessments for African elephants may bias conservation policy

Nature Ecology & Evolution volume 5, pages 1050–1051 (2021)Cite this article

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To the Editor — Elephants in Africa can be assigned to two different species, savanna elephants (Loxodonta africana) and forest elephants (L. cyclotis)1. The International Union for Conservation of Nature (IUCN) recently recognized this taxonomic consensus by publishing Red List assessments for both species2,3. Red List assessments are widely regarded as authoritative and they inform and influence conservation policy. Species assessors are experts selected by the respective Red List Authority for the species to be assessed. Although assessors follow the IUCN’s detailed and transparent criteria4, there is always an element of interpretation — in this case, we are concerned that the way assessors assigned elephant populations to either species will be detrimental to elephant conservation policy.

An individual elephant can be assigned to either elephant species based on just a few genetic markers5. Where populations have yet to be sampled, species assignments can be done with a ‘nearest neighbour’ model6; the IUCN assessors used this for a strict interpretation of binary species assignments for elephants. However, genetic screening has detected hybridization between African elephant populations in suture zones, with hybrids reported in at least 10 extant populations5,6. The nearest-neighbour model ignored hybrids, both as an input and output category, as can be seen from the occurrence of hybrids inside the polygon where the probability of a forest species assignment is supposedly absolute (fig. 4 in ref. 6). This figure also shows an east–west gradient in West Africa, where ecological gradients are generally north–south. This report is written by two authorities in this field and may be the best evidence there is for the assessment, but we note that it has not been peer reviewed and that it hinges on precarious data: by our calculations, the addition or subtraction of a single savanna elephant in Senegal could change the model outcome substantially. Until field samples from these populations are analysed, we suggest that museum samples could be considered to bring the nearest-neighbour model more in line with the natural history of the species in the region.

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Authors and Affiliations

  1. Wildlife Conservation Research Unit, Recanati-Kaplan Centre, Zoology, University of Oxford, Oxford, UK

    Hans Bauer & Claudio Sillero-Zubiri

  2. Evolutionary Ecology Group, Biology, University of Antwerp, Antwerp, Belgium

    Hans Bauer

  3. Laboratory for Applied Ecology, Natural Resource Conservation, University of Abomey-Calavi, Cotonou, Benin

    Aristide Comlan Tehou

  4. Department of HydroSciences and Environment, University Iba Der Thiam, Thiès, Sénégal

    Mallé Gueye

  5. Direction de la Faune, de la Chasse et des Parcs et Réserves, Ministère de l’Environnement de la Salubrité Urbaine et du Développement Durable, Niamey, Niger

    Hamissou Garba

  6. Direction de la Faune et des Chasses, Ministère de l’Environnement et du Développement Durable, Ouagadougou, Burkina Faso

    Benoit Doamba

  7. National Parks Directorate, Ministry of Environment and Sustainable Development, Dakar, Senegal

    Djibril Diouck

  8. The Born Free Foundation, Horsham, UK

    Claudio Sillero-Zubiri

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  1. Hans Bauer
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  2. Aristide Comlan Tehou
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Correspondence to Hans Bauer.

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Bauer, H., Tehou, A.C., Gueye, M. et al. Ignoring species hybrids in the IUCN Red List assessments for African elephants may bias conservation policy. Nat Ecol Evol 5, 1050–1051 (2021). https://doi.org/10.1038/s41559-021-01491-3

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