一项最新研究显示，在约8000年前的一次气候变化过程中，南极象海豹获得了一块新的栖息地，而约1000年前气候再次变化时，这一大型栖息地上的象海豹几乎完全灭绝。

英国达勒姆大学10日发布新闻公报说，由该校研究人员领头的一个国际科研小组利用基因技术，分析了在南极维多利亚沿岸发现的一些象海豹残余物。结果发现，样本中的DNA（脱氧核糖核酸）具有高度多样性，说明这一地区曾是一个相当大规模的象海豹栖息地。

但现在这一地区并没有象海豹生存，最近的象海豹栖息地离这里足有2500公里。

进一步分析显示，这是因为约8000年前的一次气候变化使得南极冰盖缩小，形成了这块栖息地。由于环境良好、食物充足，象海豹很快迁徙到这里并形成一个大规模种群。但是，约1000年前，气候再次变化，冰盖“卷土重来”，除少数象海豹回到原有家园外，这一地区的大多数象海豹都随环境变化而灭绝。

研究人员说，这说明了气候变化对生物种群的深远影响，也为如何应对未来可能的气候变化提供了参考。这一研究报告发表在最新一期美国《公共科学图书馆·遗传学》月刊上。

象海豹是大型动物之一，雄性象海豹体重可达几千公斤。象海豹可长时间生活在海洋中，但在换毛、繁殖等时期需要移至陆地。

推荐原始出处：

PLoS Genet 5(7): e1000554. doi:10.1371/journal.pgen.1000554

Rapid Response of a Marine Mammal Species to Holocene Climate and Habitat Change

Mark de Bruyn1¤*, Brenda L. Hall2, Lucas F. Chauke3, Carlo Baroni4, Paul L. Koch5, A. Rus Hoelzel1*

1 School of Biological Sciences, University of Durham, Durham, United Kingdom, 2 Climate Change Institute and Department of Earth Sciences, University of Maine, Orono, Maine, United States of America, 3 Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa, 4 Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy, 5 Department of Earth and Planetary Sciences, University of California, Santa Cruz, California, United States of America

Environmental change drives demographic and evolutionary processes that determine diversity within and among species. Tracking these processes during periods of change reveals mechanisms for the establishment of populations and provides predictive data on response to potential future impacts, including those caused by anthropogenic climate change. Here we show how a highly mobile marine species responded to the gain and loss of new breeding habitat. Southern elephant seal, Mirounga leonina, remains were found along the Victoria Land Coast (VLC) in the Ross Sea, Antarctica, 2,500 km from the nearest extant breeding site on Macquarie Island (MQ). This habitat was released after retreat of the grounded ice sheet in the Ross Sea Embayment 7,500–8,000 cal YBP, and is within the range of modern foraging excursions from the MQ colony. Using ancient mtDNA and coalescent models, we tracked the population dynamics of the now extinct VLC colony and the connectivity between this and extant breeding sites. We found a clear expansion signal in the VLC population ~8,000 YBP, followed by directional migration away from VLC and the loss of diversity at ~1,000 YBP, when sea ice is thought to have expanded. Our data suggest that VLC seals came initially from MQ and that some returned there once the VLC habitat was lost, ~7,000 years later. We track the founder-extinction dynamics of a population from inception to extinction in the context of Holocene climate change and present evidence that an unexpectedly diverse, differentiated breeding population was founded from a distant source population soon after habitat became available.