School of BioSciences, University of Melbourne, Parkville, Vic., Australia.
Department of Environment, Land, Water and Planning, Applied Aquatic Ecology, Arthur Rylah Institute for Environmental Research, Heidelberg, Vic., Australia.
J Anim Ecol. 2021 Nov;90(11):2560-2572. doi: 10.1111/1365-2656.13561. Epub 2021 Aug 7.
Directional or stabilising selection should drive the expression of a dominant movement phenotype within a population. Widespread persistence of multiple movement phenotypes within wild populations, however, suggests that individuals that move (movers) and those that do not (residents) can have commensurate performance. The costs and benefits of mover and resident phenotypes remain poorly understood. Here, we explored how the presence and timing of movements are correlated with annual somatic growth rates, a useful proxy for performance because it is easily measured and rapidly reflects environmental changes. We used otolith growth measurements and stable isotope analyses to recreate growth and among-reach movement histories of a partially migrating, long-lived freshwater fish, golden perch Macquaria ambigua. We compared the association between movement and growth at two temporal scales: (a) short-term (annual) differences in growth, in the years preceding, during or following movement; and (b) long-term (lifetime) differences in growth. Overall, 59% of individuals performed at least one among-reach movement, with these individuals subsequently more likely to move repeatedly throughout their lives. Movers grew faster than residents, with this difference most pronounced in the juvenile and early adult stages, when most movements occurred. Annual growth did not, however, change immediately prior to or following a specific movement event. Among-individual variation in growth was initially higher for residents than for movers but decreased with age, at a faster rate for residents than for movers, such that levels conformed after 5 years of age. Our results indicate that lifetime movement is linked to faster growth in the early years of a fish's life. These faster growing movers are likely to be larger at a given age, leading to numerous potential benefits. However, the persistence of resident phenotypes suggests that there is likely a cost-benefit trade-off to moving. The presence of multiple movement phenotypes may contribute to the resilience of populations by buffering against naturally and anthropogenically exacerbated environmental variability.
定向或稳定选择应该会促使一个种群中表现出显性运动表型。然而，在野生种群中广泛存在多种运动表型，这表明运动的个体（移动者）和不运动的个体（居住者）可能具有相当的表现。移动者和居住者表型的成本和收益仍然知之甚少。在这里，我们探讨了运动的出现和时间与年度体生长率之间的相关性，体生长率是衡量表现的有用指标，因为它易于测量且能快速反映环境变化。我们使用耳石生长测量和稳定同位素分析来重建部分迁徙、长寿淡水鱼——金黄鲈 Macquaria ambigua 的生长和单次洄游运动的历史。我们比较了在两个时间尺度上运动和生长之间的关系：（a）在移动之前、期间或之后的几年中，生长的短期（年度）差异；（b）生长的长期（终生）差异。总体而言，59%的个体进行了至少一次单次洄游运动，这些个体随后更有可能在其一生中多次移动。移动者的生长速度比居住者快，这种差异在幼鱼和成鱼阶段最为明显，此时大多数运动发生。然而，在特定的运动事件之前或之后，生长并没有立即发生变化。居住者的个体间生长差异最初高于移动者，但随着年龄的增长而降低，居住者的下降速度快于移动者，因此在 5 岁以后水平趋于一致。我们的结果表明，终生运动与鱼类生命早期的快速生长有关。这些生长更快的移动者在给定年龄可能更大，从而带来许多潜在的好处。然而，居住者表型的存在表明移动可能存在成本效益权衡。多种运动表型的存在可能通过缓冲自然和人为加剧的环境变异性，有助于种群的恢复力。
