Data from: Ancient DNA reveals differences in behaviour and sociality between brown bears and extinct cave bears.

Ancient DNA studies have revolutionised the study of extinct species and populations, providing insights on phylogeny, phylogeography, admixture and demographic history. However, inferences on behaviour and sociality have been far less frequent. Here, we investigate the complete mitochondrial genomes of extinct Late Pleistocene cave bears and middle Holocene brown bears that each inhabited multiple geographically proximate caves in northern Spain. In cave bears, we find that, although most caves were occupied simultaneously, each cave almost exclusively contains a unique lineage of closely related haplotypes. This remarkable pattern suggests extreme fidelity to their birth site in cave bears, best described as homing behaviour, and that cave bears formed stable maternal social groups at least for hibernation. In contrast, brown bears do not show any strong association of mitochondrial lineage and cave, suggesting that these two closely related species differed in aspects of their behaviour and sociality. This difference is likely to have contributed to cave bear extinction, which occurred at a time in which competition for caves between bears and humans was likely intense and the ability to rapidly colonise new hibernation sites would have been crucial for the survival of a species so dependent on caves for hibernation as cave bears. Our study demonstrates the potential of ancient DNA to uncover patterns of behaviour and sociality in ancient species and populations, even those that went extinct many tens of thousands of years ago.

古DNA（Ancient DNA）研究彻底革新了灭绝物种与种群的研究范式，为系统发育、系统地理学、遗传混合以及种群历史动态提供了全新认知。然而，针对行为与社会结构的相关推断却相对少见。本研究针对两类已灭绝类群的完整线粒体基因组（mitochondrial genome）展开分析：分别是栖息于西班牙北部多处地理邻近洞穴的晚更新世洞熊（cave bear）与中全新世棕熊（brown bear）。针对洞熊的分析显示，尽管多数洞穴的定居时间大致同步，但每处洞穴几乎仅存在一类独特的、亲缘关系紧密的单倍型（haplotype）谱系。这一独特模式表明洞熊对其出生洞穴存在极强的定居忠实性，该行为可被精准定义为归巢行为，同时说明洞熊至少在冬眠（hibernation）时期会形成稳定的母系社会集群。与之形成鲜明对比的是，棕熊并未呈现出线粒体谱系与洞穴之间的显著关联，这表明这两种亲缘关系紧密的物种在行为与社会结构层面存在差异。这一差异或许是洞熊灭绝的重要诱因之一：洞熊灭绝时期，熊类与人类之间的洞穴资源竞争已然十分激烈，而对于依赖洞穴冬眠的洞熊而言，快速占据新冬眠位点的能力对其种群存续至关重要。本研究证实，古DNA技术能够用于揭示远古物种与种群的行为与社会结构模式，即便是那些已于数万年前灭绝的类群。