Effects of pup age, maternal age, and birth date on pre-weaning survival rates of Weddell seals in Erebus Bay, Antarctica
Effects of pup age, maternal age, and birth date on pre-weaning survival rates of Weddell seals in Erebus Bay, Antarctica
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南极洲埃里伯斯湾幼崽年龄、母亲年龄和出生日期对威德尔海豹断奶前存活率的影响
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
R. Garrott
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作者：
K. Proffitt;J. Rotella;R. Garrott
确定影响幼年生存的因素对于了解种群动态非常重要，也可能为生活史理论和塑造进化的选择力提供见解。量化的相对影响的各种潜在的选择力的出生后，母亲的依赖，和独立的时期是困难的，往往限制调查人员估计一个单一的青少年存活率的第一年的生活，或从出生到招聘。我们研究了2005年至2007年在南极洲埃里伯斯湾的母亲依赖期内，单独标记的威德尔海豹Leptonychotes weddellii幼崽的生存。我们使用标记-再捕获模型来评估关于前42天日龄期间每日断奶前存活率（WSD）变化的竞争性先验假设。从数据中获得最多支持的先验模型支持了我们的几个预测：随着幼犬年龄的增长，出生时间较晚和母亲年龄较大的幼犬的体重增加。随着幼犬年龄的增加，体重增加可能是由于对环境的适应能力提高，对最虚弱幼犬的表型选择，或两者兼而有之。母亲的年龄比母亲的经验或生育年龄更重要，可能表明，年龄相关的体重增加允许更大的后代供应，或年龄相关的竞争能力的改善有利于后代在产妇护理期间。根据出生时间和母亲的年龄，142天的范围从0.79（SE = 0.05）到0.98（SE = 0.01）。这些异常高的断奶前存活率与其他大型陆地和海洋哺乳动物物种的新生儿存活率相当低的估计相反，并表明在具有相似生活史的物种中，断奶前的存活概率可能会受到捕食者和环境波动的缓冲，在此期间的孕产妇营养依赖。气候变化影响冰的稳定性用于幼犬基板或程度的快速冰缓冲幼犬殖民地从捕食者有可能减少断奶前的生存，并可能有重要的影响人口增长率。
Identifying factors affecting juvenile survival is important to understanding the dynamics of populations and may also provide insights into life history theory and the selective forces shaping evolution. Quantifying the relative influence of the various potential selective forces for the post-birth, maternal dependency, and independent periods is difficult and often limits investigators to estimating a single juvenile survival rate for the first year of life, or from birth to recruitment. We examined survival of individually marked Weddell seal Leptonychotes weddellii pups during the maternal dependency period in Erebus Bay, Antarctica from 2005-2007. We used mark-recapture models to evaluate competing a priori hypotheses regarding variation in daily pre-weaning survival rates (ϕ) during the first 42 days of age. The a priori model receiving the most support from the data supported several of our predictions: ϕ increased with pup age and was higher for pups born later in the season and to older mothers. Increases in ϕ with increasing pup age may have been due to improved resilience to the environment, phenotypic selection against the frailest pups, or both. Maternal age was more important to ϕ than was maternal experience or age of primiparity, potentially indicating that age-related increases in body mass allow greater offspring provisioning, or age-related improvements in competitive abilities benefit offspring during the period of maternal care. Depending on the timing of birth and the age of the mother, ϕ 42 days ranged from 0.79 (SE = 0.05) to 0.98 (SE = 0.01). These exceptionally high pre-weaning survival rates contrast with estimates from other large terrestrial and marine mammal species where neonate survival is considerably lower and suggest that in species with similar life histories, pre-weaning survival probability may be buffered from both predators and environmental fluctuations during the period of maternal nutritional dependency. Climatic changes affecting stability of ice used for pupping substrate or extent of fast-ice buffering pupping colonies from predators have the potential to reduce pre-weaning survival and may have important implications for population growth rates.