论文标题： All-Male Groups in Asian Elephants: A Novel, Adaptive Social Strategy in Increasingly Anthropogenic Landscapes of Southern India

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作者：Nishant Srinivasaiah, Vinod Kumar, Srinivas Vaidyanathan, Raman Sukumar, Anindya Sinha

发表时间：2019/07/04

数字识别码： 10.1038/s41598-019-45130-1

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根据《app手机版》发表的一项研究 All-Male Groups in Asian Elephants: A Novel, Adaptive Social Strategy in Increasingly Anthropogenic Landscapes of Southern India，在被人类活动分割的地区，高度濒危的幼年亚洲象形成了全雄性象群。作者推测这可能是雄象的一种适应性行为，旨在提高其在人类接触风险高的地区的生殖适度。

图1: 一头较年轻雄象和年长雄象的社会互动。图源：FEP, Nishant Srinivasaiah

印度国立高等研究院的Nishant Srinivasaiah及同事用时23个月，在印度南部收集了248头雄象的1445张照片，并对照片进行了分析。他们发现，当幼年雄象生活在非森林地区或人类改造地区（如耕地地区）时，它们会形成大规模的全雄性象群。与此相对的是，通常未达到性成熟的幼年雄象主要生活在雌雄混合的象群中，而性成熟的成年雄象主要是独居。最大的幼年亚洲象群被发现于作物可得性高的地区，象群中的个体比起独居成年象更倾向于拥有更健康的身体条件。这一发现表明，幼年雄性亚洲象象群的形成可能是一种适应性行为，旨在提高其在资源丰富但与人类接触风险高的地区的繁殖适应度。

图2：一个全雄性象群穿过研究区域的人类居住地区。图源：FEP, Vinod Kumar

作者表明，在耕地上觅食的大型全雄性象群倾向于在一起共同生活多年，这意味着这种行为可能是为了应对栖息地受到威胁的境况而采取的一种风险管理策略。他们认为理解那些生活在人类活动较多地区的大象的演化行为，或有助于减少人象冲突，防止这些濒危动物进一步减少。

摘要：Male Asian elephants are known to adopt a high-risk high-gain foraging strategy by venturing into agricultural areas and feeding on nutritious crops in order to improve their reproductive fitness. We hypothesised that the high risks to survival posed by increasingly urbanising and often unpredictable production landscapes may necessitate the emergence of behavioural strategies that allow male elephants to persist in such landscapes. Using 1445 photographic records of 248 uniquely identified male Asian elephants over a 23-month period, we show that male Asian elephants display striking emergent behaviour, particularly the formation of stable, long-term all-male groups, typically in non-forested or human-modified and highly fragmented areas. They remained solitary or associated in mixed-sex groups, however, within forested habitats. These novel, large all-male associations, may constitute a unique life history strategy for male elephants in the high-risk but resource-rich production landscapes of southern India. This may be especially true for the adolescent males, which seemed to effectively improve their body condition by increasingly exploiting anthropogenic resources when in all-male groups. This observation further supports our hypothesis that such emergent behaviours are likely to constitute an adaptive strategy for male Asian elephants that may be forced to increasingly confront anthropogenically intrusive environments.

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