Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, P-2780-156, Oeiras, Portugal.
Organisms and Environment Division, School of Biosciences, Cardiff University, Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK.
Sci Rep. 2018 Jan 17;8(1):880. doi: 10.1038/s41598-017-17042-5.
The origin of the elephant on the island of Borneo remains elusive. Research has suggested two alternative hypotheses: the Bornean elephant stems either from a recent introduction in the 17th century or from an ancient colonization several hundreds of thousands years ago. Lack of elephant fossils has been interpreted as evidence for a very recent introduction, whereas mtDNA divergence from other Asian elephants has been argued to favor an ancient colonization. We investigated the demographic history of Bornean elephants using full-likelihood and approximate Bayesian computation analyses. Our results are at odds with both the recent and ancient colonization hypotheses, and favour a third intermediate scenario. We find that genetic data favour a scenario in which Bornean elephants experienced a bottleneck during the last glacial period, possibly as a consequence of the colonization of Borneo, and from which it has slowly recovered since. Altogether the data support a natural colonization of Bornean elephants at a time when large terrestrial mammals could colonise from the Sunda shelf when sea levels were much lower. Our results are important not only in understanding the unique history of the colonization of Borneo by elephants, but also for their long-term conservation.
婆罗洲岛上大象的起源仍然难以捉摸。研究提出了两种替代假说：婆罗洲象要么是在 17 世纪的最近引入的，要么是在几十万年前的古代殖民化的结果。缺乏大象化石被解释为最近引入的证据，而与其他亚洲象的 mtDNA 分化则支持古代殖民化。我们使用完全似然和近似贝叶斯计算分析研究了婆罗洲大象的种群历史。我们的结果与最近的和古代的殖民化假说都不一致，而是支持第三种中间情况。我们发现，遗传数据支持这样一种情况，即在末次冰期期间，婆罗洲大象经历了瓶颈期，这可能是由于婆罗洲的殖民化，此后它已经缓慢恢复。总的来说，这些数据支持了在海平面低得多的时候，大型陆地哺乳动物可以从巽他大陆架上殖民的情况下，婆罗洲大象的自然殖民化。我们的研究结果不仅对理解大象在婆罗洲独特的殖民历史具有重要意义，而且对它们的长期保护也具有重要意义。
