POPULATION DEMOGRAPHY OF ANTARCTIC FUR SEALS - THE COSTS OF REPRODUCTION AND IMPLICATIONS FOR LIFE-HISTORIES
POPULATION DEMOGRAPHY OF ANTARCTIC FUR SEALS - THE COSTS OF REPRODUCTION AND IMPLICATIONS FOR LIFE-HISTORIES
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DOI：
10.2307/5653
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发表时间：
1995-07-01
影响因子：
4.8
通讯作者：
REID, K
中科院分区：
文献类型：
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作者：
BOYD, IL;CROXALL, JP;REID, K
1.本研究探讨了繁殖的成本在未来的生存和繁殖的雌性南极软毛海豹从鸟岛，南格鲁吉亚。它使用了连续11年的标记-再捕获数据，其中包括3年，当时几个指数显示粮食供应远低于平均水平。人口年龄结构，结合测量的年龄特定的生存率，估计人口的增长率为每年10.7%。平均年生存率为0.83（SD = 0.10），范围为0.65 - 0.93。存活率没有显示出随时间的趋势，但与幼仔的生长速度弱相关，这表明它可能受到食物供应的影响。生存率与其他环境或人口统计学参数（包括种群规模）无关.没有衰老的迹象。在考虑了因怀孕和日历年而产生的变化后，生存率与出生年份或年龄无关。怀孕导致存活率下降，占成年女性死亡率的40-50%。这种影响在生殖产出最高的年龄组（5-8岁）中最大。平均妊娠率为0.70（SD = 0.11），年际范围为0.59-0.88。虽然雌性通常在3-4岁时生产第一只幼崽，但怀孕率在8岁时达到高峰，此后下降。否则，怀孕率与我们测试的环境或人口统计学变量无关。在幼犬饲养期间的食物供应对妊娠率没有影响。40-50%的妊娠失败与前一年妊娠的动物有关。6.繁殖给雌性带来了成本，在减少生存和未来的繁殖力方面，因此，平均而言，存活时间最长的雌性往往这样做，因为它们的繁殖力较低。
1. This study examined the costs of reproduction in terms of future survival and reproduction in female Antarctic fur seals from Bird Island, South Georgia. It used mark-recapture data from 11 consecutive years, including 3 years when several indices showed that food availability was well below average.2. Population age structures were used, in conjuction with the measured age-specific survival rates, to estimate the rate of increase of the population as 10.7% per annum.3. The average annual survival rate was 0.83 (SD = 0.10) with a range from 0.65 to 0.93. Survival rate showed no trend through time but was weakly correlated with pup growth rate, suggesting that it may be influenced by availability of food. Survival rate was unrelated to any other environmental or demographic parameter including population size.4. There was no evidence of senescence. Survival rate was not related to year of birth or age, after accounting for variation due to pregnancy and calendar year. Survival was reduced as a result of pregnancy which accounted for 40-50% of adult female mortality. This effect was greatest in the age classes with the highest reproductive output (ages 5-8 years).5. Mean pregnancy rate was 0.70 (SD = 0.11) with an interannual range of 0.59-0.88. Although females normally produced their first pups at age 3-4 years, pregnancy rate peaked at age 8 years and declined thereafter. Otherwise pregnancy rate was unrelated to the environmental or demographic variables we tested. Food availability during the pup-rearing period had no effect on pregnancy rate. 40-50% of failures to become pregnant related to animals having been pregnant in the previous year.6. Reproduction incurs costs to females, in terms of reduced survival and future fecundity, and consequently, on average, females which survive longest tend to do so because they have lower fecundity.