Collaborative Research: Abandoned Elephant Seal Colonies in Antarctica: Integration of Genetic, Isotopic, and Geologic Approaches toward Understanding Holocene Environmental Change

在之前由NSF赞助的研究中，PI发现南极洲维多利亚陆地海岸(VLC)曾经存在南部象海豹群落，在那里它们不再被观察到。蜕皮的海豹皮肤和毛发出现在300公里的海岸线上，距离任何现存的殖民地超过1000公里。在前殖民地遗址发现的海豹的最后记录是在公元1600年。由于遗弃发生在亚南极封存之前，VLC殖民地的消失可能是由于环境因素，可能是由于陆地上快速的常年海冰的冷却和侵蚀，使得进入开采地点变得困难。因此，VLC沿线海豹栖息的记录有可能作为气候变化的替代指标。象海豹是一种主要分布在北极圈的亚南极物种。遗传研究揭示了种群间的显著分化，特别是在麦格理一号，这是最接近被遗弃的VLC群体的现存种群。麦格理人口不仅在基因上是独一无二的，而且在过去的50年里，它经历了2%/年的莫名其妙的下降。在一项初步研究中，遗传分析显示了VLC海豹与麦格理一号海豹之间的密切关系。了解这两个种群之间的关系，以及导致VLC海豹种群灭绝的环境压力，将有助于更好地了解当今种群的遗传结构，环境变化对海豹种群的影响，这个项目解决了几个关键的研究问题：(1)为什么象海豹会定居，然后放弃VLC？(2)象海豹的记录揭示了全新世气候变化和海冰条件的哪些信息？(3)海豹的觅食策略是什么，这些策略是否随着气候的变化而改变？(4)VLC海豹的遗传结构与现有种群有什么关系？(5)遗传多样性如何随着时间的推移和种群的减少而变化？(6)使用古代样本来估计mtDNA突变率，关于VLC种群随时间的变化，我们能了解到什么？(7)占据相同地点，但明显处于不同时间的象海豹和阿德利企鹅之间的生态关系是什么？拟议的工作包括对年轻研究人员进行专业培训，并将数据纳入研究生和本科课程。

During previous NSF-sponsored research, the PI's discovered that southern elephant seal colonies once existed along the Victoria Land coast (VLC) of Antarctica, a region where they are no longer observed. Molted seal skin and hair occur along 300 km of coastline, more than 1000 km from any extant colony. The last record of a seal at a former colony site is at ~A.D. 1600. Because abandonment occurred prior to subantarctic sealing, disappearance of the VLC colony probably was due to environmental factors, possibly cooling and encroachment of land-fast, perennial sea ice that made access to haul-out sites difficult. The record of seal inhabitation along the VLC, therefore, has potential as a proxy for climate change. Elephant seals are a predominantly subantarctic species with circumpolar distribution. Genetic studies have revealed significant differentiation among populations, particularly with regard to that at Macquarie I., which is the extant population nearest to the abandoned VLC colony. Not only is the Macquarie population unique genetically, but it is has undergone unexplained decline of 2%/yr over the last 50 years3. In a pilot study, genetic analyses showed a close relationship between the VLC seals and those at Macquarie I. An understanding of the relationship between the two populations, as well as of the environmental pressures that led to the demise of the VLC colonies, will provide a better understanding of present-day population genetic structure, the effect of environmental change on seal populations, and possibly the reasons underlying the modern decline at Macquarie Island.This project addresses several key research problems: (1) Why did elephant seals colonize and then abandon the VLC? (2) What does the elephant seal record reveal about Holocene climate change and sea-ice conditions? (3) What were the foraging strategies of the seals and did these strategies change over time as climate varied? (4) How does the genetic structure of the VLC seals relate to extant populations? (5) How did genetic diversity change over time and with colony decline? (6) Using ancient samples to estimate mtDNA mutation rates, what can be learned about VLC population dynamics over time? (7) What was the ecological relationship between elephant seals and Adelie penguins that occupied the same sites, but apparently at different times? The proposed work includes the professional training of young researchers and incorporation of data into graduate and undergraduate courses.