Abstract：
The success of maternal foraging strategies during the rearing period can greatly impact the physiology and survival of dependent offspring. Surprisingly though, little is known on the fitness consequences of foraging strategies during the foetal period. In this study, we characterized variation in maternal foraging strategy throughout pregnancy in a marine top predator (South American fur seal, Arctocephalus australis), and asked if these shifts predicted neonatal health and postnatal survival. We found that during early pregnancy all pregnant females belonged to a single, homogenized foraging niche without evident clusters. Intriguingly though, during late pregnancy, individual fur seal mothers diverged into two distinct foraging niches characterized by a benthic-nearshore and a pelagic-offshore strategy. Females that shifted towards the benthic-nearshore strategy gave birth to pups with greater body mass, higher plasmatic levels of glucose and lower levels of blood urea nitrogen. The pups born to these benthic females were eight times more likely to survive compared to females using the pelagic-offshore foraging strategy during late pregnancy. These survival effects were mediated primarily by the impact of foraging strategies on neonatal glucose independent of protein metabolic profile and body mass. Benthic-nearshore foraging strategies during late pregnancy potentially allow for the greater maternal transfer of glucose to the foetus, leading to higher chances of neonatal survival. These results call for a deeper understanding of the balance between resource acquisition and allocation provided by distinct foraging polymorphisms during critical life-history periods, and how this trade-off may be adaptive under certain environmental conditions.
摘要：
在饲养期间，母体觅食策略的成功会极大地影响依赖后代的生理和生存。但令人惊讶的是,对胎儿时期觅食策略的适应性后果知之甚少。在这项研究中,我们描述了海洋顶级捕食者在整个怀孕期间母体觅食策略的变化（南美海豹，北角牛)，并询问这些变化是否可以预测新生儿健康和产后存活。我们发现在怀孕早期，所有怀孕的女性都属于单身，均质化觅食生态位，无明显集群。不过有趣的是，在怀孕后期，个别海豹母亲分为两个不同的觅食生态位，其特征是底栖近岸和远洋近海策略。转向海底近岸策略的雌性生出了体重更大的幼崽，血浆葡萄糖水平较高，血液尿素氮水平较低。与怀孕后期使用远洋-近海觅食策略的雌性相比，这些底栖雌性所生的幼崽存活的可能性是雌性的八倍。这些存活效应主要由觅食策略对新生儿葡萄糖的影响介导，而与蛋白质代谢谱和体重无关。怀孕后期的底栖近岸觅食策略可能会使母体将葡萄糖更大程度地转移到胎儿中，导致新生儿存活的机会更高。这些结果要求对关键生活史期间不同的觅食多态性提供的资源获取和分配之间的平衡有更深入的了解。以及这种权衡在某些环境条件下如何适应。
