长寿哺乳动物觅食成功与终生健康之间的生理临界点
Physiological tipping points in the relationship between foraging success and lifetime fitness of a long‐lived mammal
作者：Roxanne S. Beltran, Keith M. Hernandez, Richard Condit, Patrick W. Robinson, Daniel E. Crocker, Chandra Goetsch, A. Marm Kilpatrick, Daniel P. Costa
期刊：Ecology Letters
Although anthropogenic change is often gradual, the impacts on animal populations may be precipitous if physiological processes create tipping points between energy gain, reproduction or survival. We use 25 years of behavioural, diet and demographic data from elephant seals to characterise their relationships with lifetime fitness. Survival and reproduction increased with mass gain during long foraging trips preceding the pupping seasons, and there was a threshold where individuals that gained an additional 4.8% of their body mass (26 kg, from 206 to 232 kg) increased lifetime reproductive success three-fold (from 1.8 to 4.9 pups). This was due to a two-fold increase in pupping probability (30% to 76%) and a 7% increase in reproductive lifespan (6.0 to 6.4 years). The sharp threshold between mass gain and reproduction may explain reproductive failure observed in many species and demonstrates how small, gradual reductions in prey from anthropogenic disturbance could have profound implications for animal populations.
FIGURE 1 Mass gain is positively correlated with mean foraging depth, and diet and distance from the coast are positively correlated. Probability density plots of behavioural strategies (diagonal panels), correlations and p values of behavioural strategies (upper panels) and relationships between behavioural strategies (bottom panels). Blue colour indicates statistically significant relationships, and the shaded band around the linear model is a pointwise 95% confidence interval on the fitted values.
尽管人类活动的变化通常是渐进的，但如果在生理过程中能在获得能量、繁殖或生存之间产生临界点，则很有可能对动物种群产生巨大的影响。我们使用象海豹25年的行为、饮食和种群数据来描述这些与其终身健康的关系。在幼崽繁殖季节之前的长时间觅食旅行中，象海豹的存活率和繁殖率随着体重的增加而增加，并且有一个阈值，即体重增加4.8%（26公斤，从206公斤增加到232公斤）的个体，其终身繁殖成功率增加了三倍（从1.8只幼崽增加到4.9只幼崽）。这是由于幼崽出生概率增加了两倍（30%至76%），繁殖寿命增加了7%（6.0至6.4年）。体重增加和繁殖之间明确阈值的存在可能用于解释在许多物种中观察到的繁殖失败现象，并表明人类干扰导致的猎物数量小幅的逐渐减少可能对动物种群产生深远影响。
（实习生齐千萌编译）
