Genomic dissection of climate change impacts on a declining Antarctic top predator population

预测物种将如何应对气候变化需要了解个体适应性变化的遗传基础。这对寿命长的物种特别重要，因为它们只有相对较少的几代人可以作出反应，而且对生活在极地的物种也特别重要，因为那里正在发生许多最迅速和最深刻的环境变化。 然而，由于在具有挑战性的野外条件下从大量个体中收集基于个体的表型和遗传数据的困难和费用，对极地脊椎动物的长期研究很少，快速的气候变化可能会对对适应性重要的性状施加强大的选择压力，然而，很少有实证研究能够直接量化气候变化下改变的选择机制及其人口后果。 此外，大多数研究都集中在气候变化的加性遗传效应（即等位基因频率变化）上。 然而，人们越来越意识到，杂合性也可以是一个重要组成部分的个人健身饲料到人口增长和灭绝probability.An突出的机会，阐明气候变化下改变选择制度的基因组和表型的后果是由南极海狗在南大西洋的研究。 我们最近报告说，自20世纪80年代以来，由于当地磷虾供应减少，繁殖雌性数量下降了25%，幼崽出生质量下降了8%。 与此同时，育种雌性杂合性增加了17%，在过去的二十年，这表明对纯合子幼崽的生存力选择的强度一直在增加。 然而，由于杂合性仅从9个遗传标记中定量，因此尚不清楚这些模式是否可以反映近交衰退或个体标记与生物学相关基因的偶然连锁。 阐明这些机制的重要性，并确定相关的基因是至关重要的理解选择的性质，适应性相关性状的遗传结构及其在不断变化的世界中的生态和进化动力学。我们将通过对576个个体进行基因分型来解决这个问题，这些个体跨越30年，分布在全基因组范围内的80，000个单核苷酸多态性。 由此产生的数据集将提供巨大的力量来量化近交衰退对适应度变化的贡献，同时还将采取几种补充方法来评估基因组特定部分的解释力和关键候选基因的可能参与。 最后，我们将通过测试杂合性是否会影响个体幼崽在从出生到营养独立的关键时期获得体重的能力，更深入地研究早期适应性变化。 因此，该项目将为气候变化对南极顶级捕食者的影响提供一个前所未有的窗口。

Predicting how species will respond to climate change requires an understanding of the genetic basis of variation in individual fitness. This is particularly important for long-lived species, which have relatively few generations in which to respond, and species inhabiting polar regions where many of the most rapid and profound environmental changes are occurring. However, long-term studies of polar vertebrates are rare owing to the difficulty and expense of collecting individual-based phenotypic and genetic data from large numbers of individuals under challenging field conditions.Rapid climate change is likely to impose strong selection pressures on traits that are important to fitness, yet few empirical studies have been able to directly quantify altered selective regimes under climate change and their demographic consequences. Furthermore, most studies have focused on additive genetic effects (i.e. allele frequency changes) in response to climate change. However, there is a growing awareness of the fact that heterozygosity can also be a major component of individual fitness that feeds into population growth and extinction probability.An outstanding opportunity to elucidate the genomic and phenotypic consequences of altered selective regimes under climate change is provided by a study of Antarctic fur seals in the South Atlantic. We recently reported a 25% decline in the number of breeding females and an 8% fall in pup birth mass since the 1980s due to locally reduced krill availability. Concurrently, breeding female heterozygosity has increased by 17% over two decades, suggesting that the strength of viability selection against homozygous pups has been increasing over time. However, because heterozygosity was only quantified from nine genetic markers, it remains unclear whether these patterns could reflect inbreeding depression or chance linkage of individual markers to biologically relevant genes. Elucidating the importance of these mechanisms and identifying the genes involved is crucial for understanding the nature of selection, the genetic architecture of fitness-relevant traits and their ecological and evolutionary dynamics in a changing world.We will tackle this question by genotyping 576 individuals spanning three decades at 80,000 genome-wide distributed single nucleotide polymorphisms. The resulting dataset will offer great power to quantify the contribution of inbreeding depression to fitness variation, while several complementary approaches will also be taken to evaluate the explanatory power of specific parts of the genome and the possible involvement of key candidate genes. Finally, we will delve deeper into early acting fitness variation by testing whether heterozygosity influences the ability of individual pups to gain body mass during the critical period from birth to nutritional independence. This project will thereby provide an unprecedented window on the impacts of climate change on an Antarctic top predator.