Comparison of southern elephant seal populations, and observations of a population on a demographic knife-edge
Comparison of southern elephant seal populations, and observations of a population on a demographic knife-edge
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南象海豹种群的比较以及对人口统计边缘种群的观察
DOI：
10.3354/meps288273
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发表时间：
2005
影响因子：
2.5
通讯作者：
M. Bester
中科院分区：
文献类型：
--
作者：
C. McMahon;M. Hindell;H. Burton;M. Bester
动物种群的动态由几个关键的人口统计参数决定，这些参数随着时间的推移而变化，从而导致种群状况的变化。在管理种群下降时，确定驱动这种变化的参数是一个高度优先的问题，但对于大型和长寿物种来说，很少能做到这一点。在过去的50年里，南印度洋和南太平洋的南部象海豹的数量减少了50%。这些下降的原因尚不清楚。这项研究使用了基于长期人口统计数据的随机莱斯利矩阵预测模型，以检验几个生活史参数在导致这种下降中的潜在作用。这些模型模拟了从年度丰度调查中独立得出的观察到的种群趋势。存活率和繁殖力的微小变化对种群增长率有显著影响。例如，在麦格理岛，存活率和生育率的微小变化(约5%)就会导致人口从减少的人口恢复到增加的人口。对适合度影响最大的存活率依次为：(1)幼体存活率，(2)成体存活率，(3)成体繁殖力，(4)幼体繁殖力。种群生存能力分析(PVA)显示，马里恩岛种群在未来150年内灭绝的可能性很高，而麦夸里岛种群灭绝的概率很低。马里恩岛每个种群的平均灭绝时间估计为134年(95%可信区间：105年至332年)，麦考里岛为564年(最早灭绝时间为307年)。
The dynamics of animal populations are determined by several key demographic parameters, which vary over time with resultant changes in the status of the population. When managing declining populations, the identificationof the parameters that drive such change are a high priority, but are rarely achieved for large and long-lived species. Southern elephant seal populations in the South Indian and South Pacific oceans have decreased by as much as 50 % during the past 50 yr. The reasons for these decreases remained unknown. This study used a projected stochastic Leslie-matrix model based on long-term demographic data to examine the potential role of several life-history parameters in contributing to the declines. The models simulated the observed population trends that were independently derived from annual abundance surveys. Small changes in survival and fecundity had dramatic effects on population growth rates. At Macquarie Island for example, a small change (ca. 5%) in survival and fecundity rates resulted in the population reverting from a decreasing one to a population that increased. The vital rates that had the greatest impact on fitness were, in order of importance: (1) juvenile survival, (2) adult survival, (3) adult fecundity and (4) juvenile fecundity. Population viability analysis (PVA) for each of the 2 decreasing populations revealed that there was a high probability of the Marion Island population becoming extinct within the next 150 yr, while the probability of extinction at Macquarie Island was low. The estimated mean times to extinction for each population was 134 yr (95% confidence intervals: 105 to 332 yr) at Marion Island and 564 yr at Macquarie Island (the earliest time to extinction was 307 yr).