The importance of small-island populations for the long-term survival of endangered large-bodied insular mammals

Aninta, Sabhrina Gita, Drinkwater, Rosie, Carmagnini, Alberto, Deere, Nicolas J., Priyono, Dwi Sendi, Andayani, Noviar, Winarni, Nurul L., Supriatna, Jatna, Fumagalli, Matteo, Larson, Greger, and others. (2025) The importance of small-island populations for the long-term survival of endangered large-bodied insular mammals. Proceedings of the National Academy of Sciences, 122 (26). Article Number e242269012. ISSN 0027-8424. (doi:10.1073/pnas.2422690122) (KAR id:110465)

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Official URL: https://doi.org/10.1073/pnas.2422690122

Abstract

Island populations of large vertebrates have experienced higher extinction rates than mainland populations over long timescales due to demographic stochasticity, genetic drift, and inbreeding. While being more susceptible to extinction and as such potentially targeted for conservation interventions such as genetic rescue, small-island populations can experience relatively less anthropogenic habitat degradation than those on larger islands. Here, we determine the consequences and conservation implications of long-term isolation and recent human activities on genetic diversity of island populations of two forest-dependent mammals endemic to the Wallacea archipelago: the anoa (Bubalus spp.) and babirusa (Babyrousa spp.). Using genomic analyses and habitat suitability models, we show that, compared to closely related species, populations on mainland Sulawesi exhibit low heterozygosity, high inbreeding, a high proportion of deleterious alleles, and experience a high rate of anthropogenic disturbance. In contrast, populations on smaller islands occupy higher-quality habitats, possess fewer deleterious mutations despite exhibiting lower heterozygosity and higher inbreeding. Site frequency spectra indicate that these patterns reflect stronger, long-term purging in smaller-island populations. Our results thus suggest that conservation efforts should focus on protecting small-island high-quality habitats and avoiding translocations from mainland populations. This study highlights the crucial role of small offshore islands for the long-term survival of Wallacea’s iconic and indigenous mammals in the face of development on the mainland.

Item Type:	Article
DOI/Identification number:	10.1073/pnas.2422690122
Uncontrolled keywords:	conservation, genetic rescue, genetic load, inbreeding, habitat suitability modeling
Subjects:	G Geography. Anthropology. Recreation G Geography. Anthropology. Recreation > GN Anthropology
Institutional Unit:	Schools > School of Natural Sciences > Conservation Institutes > Durrell Institute of Conservation and Ecology
Former Institutional Unit:	There are no former institutional units.
Funders:	Natural Environment Research Council (https://ror.org/02b5d8509)
Depositing User:	Matthew Struebig
Date Deposited:	01 Jul 2025 09:57 UTC
Last Modified:	15 Oct 2025 02:45 UTC
Resource URI:	https://kar.kent.ac.uk/id/eprint/110465 (The current URI for this page, for reference purposes)

University of Kent Author Information

Deere, Nicolas J..

Creator's ORCID:	https://orcid.org/0000-0003-1299-2126
CReDIT Contributor Roles:

Seaman, David James Ian.

Creator's ORCID:	https://orcid.org/0000-0002-6616-7001
CReDIT Contributor Roles:

Struebig, Matthew J..

Creator's ORCID:	https://orcid.org/0000-0003-2058-8502
CReDIT Contributor Roles:

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