Life history variation in pinnipeds

我研究的长期目标是了解影响海豹觅食和繁殖策略的进化和生态因素。在接下来的五年里，我和我的学生计划建立在我们对灰海豹（Halichoerus grypus）的生活史和觅食生态学的长期研究基础上。在相对较少的大型长寿脊椎动物中，生殖表现在个体内部和个体之间的可变性已被记录。对特征的平均估计掩盖了个体对环境变化和趋势的反应中潜在的重要变异性。我们计划继续收集来自>1700只单独标记的已知年龄雌性的长期数据（2017年为>30年），以研究生殖性能和存活率个体差异的内在和外在来源，并评估这种差异对后代存活率和断奶时大小的影响。这些数据还将用于测试性能的异质性（固定与动态）的性质以及首次生育年龄与终生生殖成功率之间的关系。我们还将使用永久标记的雄性（~600）和雌性（如上所述）的观察历史来检验有关性别特异性发病、存活率和生殖衰老的假设，以及生存模式如何随着种群丰度和环境可变性的变化而变化。虽然后代的大小通常被用作雌性和后代健康的代表，但这种假设很少在大型、长寿（bb0 - 20岁）的哺乳动物中得到验证。研究人员测量了1998年至2002年出生的大约2400只永久标记的灰海豹幼崽和2014年至2016年出生的2100只幼崽的体型和其他后代特征。我们将在招募这些幼崽的幸存者时测量它们的体型和年龄，以测试后代体型、存活率和长期繁殖表现之间的关系。我们将使用配有两个三轴加速度计的灰海豹的精细GPS轨迹来开发算法来区分行为，包括觅食，以验证从状态空间运动模型中估计的行为状态。与动物携带的相机一起，我们寻求更好地了解在营养水平较高的海洋捕食者觅食的空间和时间模式。

The long-term objective of my research is to understand the evolutionary and ecological factors that have shaped the foraging and reproductive strategies of seals. During the next five years, my students and I to plan build upon our long-term studies of life history and foraging ecology of grey seals (Halichoerus grypus). Variability in reproductive performance within and among individuals over their reproductive life has been documented for relatively few large long-lived vertebrates. Mean estimates of traits obscure potentially important variability in the response of individuals to environmental variability and trends. We plan to continue the collection of long-term data (>30 years in 2017) from >1700 individually marked, known-age females to investigate intrinsic and extrinsic sources of individual variability in reproductive performance and survival and to evaluate the consequences of this variability on offspring survival and size at weaning. These data will also be used to test for the nature of heterogeneity (fixed vs dynamic) in performance and the relationship between age at first birth and lifetime reproductive success. We will also use the sighting histories of permanently marked males (~600) and females (as above) to test hypotheses concerning sex-specific onset and rate of survival and reproductive senescence and how patterns of survival vary with changes in population abundance and environmental variability. Although offspring size is often used as a proxy for female and offspring fitness, this hypothesis has rarely been tested in large, long-lived (>20 yr) mammals. Size and other offspring traits were measured for about 2400 permanent-marked grey seals pups that were born from 1998 to 2002 and another 2100 pups from 2014 to 2016. We will measure size and age at recruitment of the survivors of those pups to test the relationship between offspring size, survival, and long-term reproductive performance. We will use fine-scale GPS tracks from grey seals fitted with two tri-axial accelerometers to develop algorithms to distinguish behaviours, including foraging, to validate behavioural states estimated from state-space movement models. Along with animal-borne cameras we seek to better understand the spatial and temporal pattern of foraging in an upper trophic-level marine predator.