Linking the energetics of reproduction to population demography in a marine apex predator

人口的变化是由于出生率、死亡率和/或移民率的变化。更深入地了解影响这些生命率的基本机械过程对于更好地估计人口增长率至关重要。这反过来又将有助于对环境变化可能对人口产生的影响进行先验评估。我们提出了这样一个自下而上的方法来了解环境变化之间的联系，哺乳期和随后的变化在少年生存和女性生育力的海洋顶端捕食者，加拉帕戈斯海狮（Zalophus wollebaeki）的人口的能量。建立在我们的长期，以个人为基础的研究，自2003年以来一直在运行，我们建议结合稳定同位素分析的一岁鸽的双标记水的方法来测量泌乳的能量。这将使我们能够了解一岁鸽觅食行为的变化与哺乳行为的变化之间的关系。在母亲方面，我们将能够估计哺乳的能量成本，以及这与生育时间表的相关性。这将为我们提供一个异常详细的洞察力，如何在生命率的变化引起的近端过程。我们将把这种变化的生命率在年龄结构的矩阵模型中的生命率条目是环境变化的函数。在随后的第二个模型步骤中，我们将纳入强大的队列效应，并测试人口稳定性的假设，主要是由于一些队列的生存和繁殖比平均水平好得多，这些平均生命率估计因此没有捕捉到驱动人口增长的过程。因此，我们对海狮的长期研究处于独特的位置，可以将联合收割机的近似和最终因素结合起来，因为人口数据和大的环境扰动使我们能够深入了解驾驶过程。

Changes in a population are due to changes in birth, death and/or immigration rates. A deeper understanding of the underlying mechanistic processes affecting these vital rates is essential for better estimation of population growth rates. This in turn, will allow the a priori assessment of the likely impact of environmental change on populations. We propose such a bottom-up approach to understand the linkage between environmental variation, the energetics of lactation and subsequent variation in juvenile survival and female fertility in a population of a marine apex predator, the Galapagos sea lion (Zalophus wollebaeki). Building on our long-term, individual-based study that has been running since 2003, we propose to measure the energetics of lactation by the doubly-labelled water method in combination with stable isotope analyses of yearlings. This will allow us to understand how variation in foraging behaviour of yearlings relates to variation in suckling behaviour. On the maternal side, we will be able to estimate the energetic cost of lactation and how this covaries with fertility schedules. This will provide us with an unusually detailed insight into how variation in vital rates arises from proximate processes. We will incorporate this variation in vital rates in age-structured matrix models where vital rate entries are functions of environmental variation. In a subsequent second model step, we will incorporate strong cohort effects and test the hypothesis that population stability is mainly due to some cohorts surviving and reproducing much better than average and that these average vital rate estimates do hence not capture the processes driving population growth. Our long-term sea lion study is hence in a unique position to combine proximate and ultimate factors because the population data and the large environmental perturbations allow us to gain a deep insight into the driving processes.