School of Biological Sciences, University of Aberdeen, Aberdeen, UK.
Centre for Biodiversity Dynamics, Institutt for Biologi, NTNU, Trondheim, Norway.
J Anim Ecol. 2021 Apr;90(4):796-808. doi: 10.1111/1365-2656.13410. Epub 2021 Jan 26.
Elucidating the full eco-evolutionary consequences of climate change requires quantifying the impact of extreme climatic events (ECEs) on selective landscapes of key phenotypic traits that mediate responses to changing environments. Episodes of strong ECE-induced selection could directly alter population composition, and potentially drive micro-evolution. However, to date, few studies have quantified ECE-induced selection on key traits, meaning that immediate and longer-term eco-evolutionary implications cannot yet be considered. One widely expressed trait that allows individuals to respond to changing seasonal environments, and directly shapes spatio-seasonal population dynamics, is seasonal migration versus residence. Many populations show considerable among-individual phenotypic variation, resulting in 'partial migration'. However, variation in the magnitude of direct survival selection on migration versus residence has not been rigorously quantified, and empirical evidence of whether seasonal ECEs induce, intensify, weaken or reverse such selection is lacking. We designed full annual cycle multi-state capture-recapture models that allow estimation of seasonal survival probabilities of migrants and residents from spatio-temporally heterogeneous individual resightings. We fitted these models to 9 years of geographically extensive year-round resighting data from partially migratory European shags Phalacrocorax aristotelis. We thereby quantified seasonal and annual survival selection on migration versus residence across benign and historically extreme non-breeding season (winter) conditions, and tested whether selection differed between females and males. We show that two of four observed ECEs, defined as severe winter storms causing overall low survival, were associated with very strong seasonal survival selection against residence. These episodes dwarfed the weak selection or neutrality evident otherwise, and hence caused selection through overall annual survival. The ECE that caused highest overall mortality and strongest selection also caused sex-biased mortality, but there was little overall evidence of sex-biased selection on migration versus residence. Our results imply that seasonal ECEs and associated mortality can substantially shape the landscape of survival selection on migration versus residence. Such ECE-induced phenotypic selection will directly alter migrant and resident frequencies, and thereby alter immediate spatio-seasonal population dynamics. Given underlying additive genetic variation, such ECEs could potentially cause micro-evolutionary changes in seasonal migration, and thereby cause complex eco-evolutionary population responses to changing seasonal environments.
阐明气候变化的全部生态进化后果需要量化极端气候事件 (ECEs) 对介导对变化环境响应的关键表型特征的选择景观的影响。强烈的 ECE 诱导选择事件可能直接改变种群组成，并可能驱动微观进化。然而，迄今为止，很少有研究量化了关键特征的 ECE 诱导选择，这意味着无法立即考虑其近期和长期的生态进化意义。一个广泛表达的特征是，个体可以对变化的季节性环境做出反应，并直接塑造时空季节性种群动态，即季节性迁徙与居留。许多种群表现出相当大的个体间表型变异，导致“部分迁徙”。然而，迁徙与居留的直接生存选择的幅度变化尚未得到严格量化，也缺乏关于季节性 ECE 是否诱导、加剧、减弱或逆转这种选择的经验证据。我们设计了完整的年度周期多状态捕获-再捕获模型，允许从时空异质的个体再观测中估计迁徙者和居留者的季节性生存概率。我们将这些模型拟合到来自部分迁徙的欧洲鸬鹚（Phalacrocorax aristotelis）的 9 年广泛的全年异地重见数据中。因此，我们量化了在良性和历史极端非繁殖季节（冬季）条件下，迁徙与居留之间的季节性和年度生存选择，并测试了选择是否在雌性和雄性之间存在差异。我们发现，四个观察到的 ECE 中的两个，定义为导致整体低存活率的严重冬季风暴，与对居留的强烈季节性生存选择有关。这些事件使其他情况下的微弱选择或中立性相形见绌，因此导致了整体年度生存的选择。导致最高整体死亡率和最强选择的 ECE 也导致了性别偏置死亡率，但总体上几乎没有证据表明性别偏置选择对迁徙与居留的影响。我们的结果表明，季节性 ECEs 及其相关死亡率可以极大地塑造迁徙与居留之间的生存选择景观。这种 ECE 诱导的表型选择将直接改变迁徙者和居留者的频率，从而改变当前的时空季节性种群动态。鉴于潜在的加性遗传变异，这种 ECE 可能会导致季节性迁徙的微进化变化，并因此导致对变化的季节性环境的复杂生态进化种群反应。
