Temperature-dependent variation in alternative migratory tactics and its implication for fitness and population dynamics in a salmonid fish
Temperature-dependent variation in alternative migratory tactics and its implication for fitness and population dynamics in a salmonid fish
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替代性迁徙策略的温度依赖性变化及其对鲑鱼健康和种群动态的影响
DOI：
10.1111/1365-2656.12240
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发表时间：
2014
影响因子：
4.8
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Morita;K.;Tamate;T.;Kuroki;M.;Nagasawa;T.
温度驱动的生活史适应性变化发生在外温动物中，因此，在预测种群对气候变化的反应时，需要考虑适应性生活史变化。部分迁移是生活史多样性的一种常见形式，其中种群包含迁移和定居行为。鲑科鱼类表现出广泛的生活史多样性，特别是部分迁移。通过野外观察和理论模型，研究了温度驱动的生活史改变对部分洄游的马苏鲑（Oncorhynchus masou）种群动态的影响，结果表明，不同洄游策略的空间格局与温度梯度有关。随着温度的升高，以及早期生长条件的改善，留居雄性的出现率增加，而迁徙雄性的比例和延迟迁徙的比例（包括两性）则下降。在早期生长条件较好的情况下采用留居策略，在早期生长条件中等的情况下采用早期迁移策略，在早期生长条件较差的情况下采用延迟迁移策略，使个体适合度最大化。研究结果表明，个体在迁徙过程中表现出一种依赖于地位的条件策略，即个体地位影响个体采取不同的迁徙策略，以最大限度地利用环境;模拟模型表明，随着温度升高，雄性的居住量增加，导致迁徙数量大幅减少。此外，随着温度的升高，延迟（老年）移民数量的减少放大了丰度的波动。我们的研究结果表明，温度驱动的生活史修改对于预测气候变暖下自然种群的动态具有重要意义。
Temperature‐driven life‐history modifications by adaptation occur in ectotherms, and therefore, life‐history modifications by adaptation need to be taken into consideration when predicting population responses to the climate change.Partial migration is a common form of life‐history diversity in which a population contains both migratory and resident behaviours. Salmonid fish exhibit a wide range of life‐history diversity and, in particular, partial migration. We evaluated the effect of temperature‐driven life‐history modifications on population dynamics in partially migratory masu salmon (Oncorhynchus masou) by field observations and theoretical models.Field observations revealed that spatial patterns of alternative migratory tactics were associated with temperature gradients. The occurrence of resident males increased, whereas the proportion of migrant males and the proportion of delayed migrants including both sexes decreased with increasing temperature and, thereby, with improved early growth conditions.The expected fitness for each migratory tactic was computed in a life‐history model with early growth conditions as a function. Individual fitness was maximized by adopting resident tactics under favourable early growth conditions, early migrant tactics under intermediate early growth conditions and delayed migrant tactics under unfavourable early growth conditions. The results suggest that individuals exhibited a status‐dependent conditional strategy, that is, the adoption of alternative migratory tactics is influenced by the status of individuals to make the best of a situation.A simulation model suggests that increased residency by males to increased temperature leads to a substantial decrease in the number of migrants. Moreover, the decrease in the number of delayed (older) migrants with increasing temperature magnified fluctuations in abundance. Our findings indicate the importance of temperature‐driven life‐history modifications for predicting dynamics of natural populations under climate warming.