Aninta Sabhrina Gita, Drinkwater Rosie, Carmagnini Alberto, Deere Nicolas J, Priyono Dwi Sendi, Andayani Noviar, Winarni Nurul L, Supriatna Jatna, Fumagalli Matteo, Larson Greger, Galbusera Peter H A, Macdonald Alastair, Greer Deborah, Mohamad Kusdiantoro, Prasetyaningtyas Wahono Esthi, Mustari Abdul Haris, Williams John Lewis, Barnett Ross, Shaw Darren, Semiadi Gono, Burton James, Seaman David J I, Voigt Maria, Struebig Matthew J, Brace Selina, Rossiter Stephen J, Frantz Laurent
School of Biological and Behavioural Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
Palaeogenomics Group, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität, Munich 80539, Germany.
Proc Natl Acad Sci U S A. 2025 Jul;122(26):e2422690122. doi: 10.1073/pnas.2422690122. Epub 2025 Jun 24.
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 ( spp.) and babirusa ( 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.
在较长时间尺度上，由于人口统计学随机性、遗传漂变和近亲繁殖，大型脊椎动物的岛屿种群比大陆种群经历了更高的灭绝率。虽然小岛屿种群更容易灭绝，因此可能成为诸如基因拯救等保护干预措施的目标，但与大岛屿上的种群相比，它们经历的人为栖息地退化相对较少。在这里，我们确定了长期隔离和近期人类活动对华莱士群岛特有的两种依赖森林的哺乳动物——倭水牛（属）和鹿豚（属）的岛屿种群遗传多样性的影响及保护意义。通过基因组分析和栖息地适宜性模型，我们发现，与亲缘关系相近的物种相比，苏拉威西岛大陆上的种群表现出低杂合度、高近亲繁殖率、有害等位基因比例高，且经历着高比率的人为干扰。相比之下，较小岛屿上的种群占据着质量更高的栖息地，尽管杂合度较低且近亲繁殖率较高，但有害突变较少。位点频率谱表明，这些模式反映了较小岛屿种群中更强的长期净化作用。因此，我们的结果表明，保护工作应侧重于保护小岛屿的高质量栖息地，并避免从大陆种群进行种群转移。这项研究凸显了近海小岛屿在面对大陆开发时，对华莱士群岛标志性本土哺乳动物长期生存的关键作用。
