School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, Scotland.
Centre for Biodiversity Dynamics, Institutt for Biologi, NTNU, Trondheim, Norway.
Proc Biol Sci. 2020 Jul 29;287(1931):20200928. doi: 10.1098/rspb.2020.0928. Epub 2020 Jul 22.
Within-individual and among-individual variation in expression of key environmentally sensitive traits, and associated variation in fitness components occurring within and between years, determine the extents of phenotypic plasticity and selection and shape population responses to changing environments. Reversible seasonal migration is one key trait that directly mediates spatial escape from seasonally deteriorating environments, causing spatio-seasonal population dynamics. Yet, within-individual and among-individual variation in seasonal migration versus residence, and dynamic associations with subsequent reproductive success, have not been fully quantified. We used novel capture-mark-recapture mixture models to assign individual European shags () to 'resident', 'early migrant', or 'late migrant' strategies in two consecutive years, using year-round local resightings. We demonstrate substantial among-individual variation in strategy within years, and directional within-individual change between years. Furthermore, subsequent reproductive success varied substantially among strategies, and relationships differed between years; residents and late migrants had highest success in the 2 years, respectively, matching the years in which these strategies were most frequently expressed. These results imply that migratory strategies can experience fluctuating reproductive selection, and that flexible expression of migration can be partially aligned with reproductive outcomes. Plastic seasonal migration could then potentially contribute to adaptive population responses to currently changing forms of environmental seasonality.
个体内和个体间关键环境敏感性状表达的变化，以及个体内和个体间适应度成分的变化，决定了表型可塑性和选择的程度，并塑造了种群对不断变化的环境的反应。可逆季节性迁移是一种关键性状，它直接介导了从季节性恶化环境中的空间逃逸，导致了时空种群动态。然而，季节性迁移与居留之间的个体内和个体间变化，以及与随后生殖成功的动态关联，尚未得到充分量化。我们使用新的捕获-标记-再捕获混合模型，通过全年的本地重见，将两只连续两年的欧洲海雀（）分配为“居留”、“早期迁移”或“晚期迁移”策略。我们证明了个体内策略在年内存在大量的个体间变异性，并且在年际间存在方向性的个体内变化。此外，后续的生殖成功在策略之间存在很大差异，并且这种关系在年际间也不同；居民和晚期移民在这两年的成功率最高，与这两年最常表达这些策略的情况相匹配。这些结果表明，迁徙策略可能会经历不断变化的生殖选择，而迁徙的灵活表达可以部分与生殖结果相吻合。因此，可塑性季节性迁移可能有助于适应种群对当前不断变化的环境季节性形式的反应。
