Laidre Kristin L, Born Erik W, Atkinson Stephen N, Wiig Øystein, Andersen Liselotte W, Lunn Nicholas J, Dyck Markus, Regehr Eric V, McGovern Richard, Heagerty Patrick
Polar Science Center Applied Physics Laboratory University of Washington Seattle WA USA.
Greenland Institute of Natural Resources Nuuk Greenland.
Ecol Evol. 2018 Jan 18;8(4):2062-2075. doi: 10.1002/ece3.3809. eCollection 2018 Feb.
Climate change is expected to result in range shifts and habitat fragmentation for many species. In the Arctic, loss of sea ice will reduce barriers to dispersal or eliminate movement corridors, resulting in increased connectivity or geographic isolation with sweeping implications for conservation. We used satellite telemetry, data from individually marked animals (research and harvest), and microsatellite genetic data to examine changes in geographic range, emigration, and interpopulation connectivity of the Baffin Bay (BB) polar bear () subpopulation over a 25-year period of sea-ice loss. Satellite telemetry collected from = 43 (1991-1995) and 38 (2009-2015) adult females revealed a significant contraction in subpopulation range size (95% bivariate normal kernel range) in most months and seasons, with the most marked reduction being a 70% decline in summer from 716,000 km (SE 58,000) to 211,000 km (SE 23,000) ( < .001). Between the 1990s and 2000s, there was a significant shift northward during the on-ice seasons (2.6 shift in winter median latitude, 1.1 shift in spring median latitude) and a significant range contraction in the ice-free summers. Bears in the 2000s were less likely to leave BB, with significant reductions in the numbers of bears moving into Davis Strait (DS) in winter and Lancaster Sound (LS) in summer. Harvest recoveries suggested both short and long-term fidelity to BB remained high over both periods (83-99% of marked bears remained in BB). Genetic analyses using eight polymorphic microsatellites confirmed a previously documented differentiation between BB, DS, and LS; yet weakly differentiated BB from Kane Basin (KB) for the first time. Our results provide the first multiple lines of evidence for an increasingly geographically and functionally isolated subpopulation of polar bears in the context of long-term sea-ice loss. This may be indicative of future patterns for other polar bear subpopulations under climate change.
气候变化预计将导致许多物种的分布范围变化和栖息地破碎化。在北极地区，海冰的消失将减少物种扩散的障碍或消除移动通道，从而导致连通性增加或地理隔离，这对物种保护具有广泛影响。我们利用卫星遥测技术、个体标记动物（研究和捕获）的数据以及微卫星基因数据，研究了巴芬湾（BB）北极熊（）亚种群在25年海冰损失期间地理范围、迁徙和种群间连通性的变化。从43只（1991 - 1995年）和38只（2009 - 2015年）成年雌性北极熊收集的卫星遥测数据显示，在大多数月份和季节，亚种群范围大小（95%双变量正态核范围）显著收缩，最明显的减少是夏季范围从716,000平方千米（标准误差58,000）下降了70%至211,000平方千米（标准误差23,000）（<0.001）。在20世纪90年代至21世纪初期间，在冰上季节有显著向北移动（冬季中位纬度移动2.6，春季中位纬度移动1.1），在无冰夏季范围显著收缩。21世纪的北极熊离开BB的可能性较小，冬季进入戴维斯海峡（DS）和夏季进入兰开斯特海峡（LS）的北极熊数量显著减少。捕获回收表明，在这两个时期，对BB的短期和长期忠诚度都很高（83 - 99%的标记北极熊仍留在BB）。使用八个多态微卫星的基因分析证实了之前记录的BB、DS和LS之间的分化；但首次微弱地将BB与凯恩盆地（KB）区分开来。我们的结果首次提供了多条证据，证明在长期海冰损失的背景下，北极熊亚种群在地理和功能上日益隔离。这可能预示着气候变化下其他北极熊亚种群的未来模式。
