Data from: Morphological differences between habitats are associated with physiological and behavioural trade-offs in stickleback (Gasterosteus aculeatus)

Local specialisation can be advantageous for individuals, and may increase the resilience of the species to environmental change. However, there may be trade-offs between morphological responses and physiological performance and behaviour. Our aim was to test whether habitat-specific morphology of stickleback (Gasterosteus aculeatus) interacts with physiological performance and behaviour at different salinities. We rejected the hypothesis that deeper body shape of fish from habitats with high predation pressure led to decreases in locomotor performance. However, there was a trade-off between deeper body shape and muscle quality. Muscle of deeper-bodied fish produced less force than that of shallow-bodied saltmarsh fish. Nonetheless, saltmarsh fish had lower swimming performance, presumably because of lower muscle mass overall coupled with smaller caudal peduncles and larger heads. Saltmarsh fish performed better in saline water (20 ppt) relative to freshwater, and relative to fish from freshwater habitats. However, exposure to salinity affected shoaling behaviour of fish from all habitats, and shoals moved faster and closer together compared to freshwater. We show that habitat modification can alter phenotypes of native species, but local morphological specialisation is associated with trade-offs that may reduce its benefits.生境特化对个体具有优势，且可提升物种应对环境变化的恢复力。然而，形态响应、生理性能与行为之间往往存在权衡关系。本研究旨在验证：棘鱼（Gasterosteus aculeatus）的生境特异性形态，是否会在不同盐度条件下与生理性能及行为产生交互效应。我们拒绝了“高捕食压力生境中鱼类的躯体更深形态会降低运动性能”这一假说。不过，躯体更深的形态与肌肉品质之间存在权衡：躯体更高的鱼类，其肌肉产生的肌力低于浅躯体形态的盐沼生境鱼类。尽管如此，盐沼生境鱼类的游泳性能仍相对更低，推测其原因为整体肌肉量偏少，同时尾柄更短小、头部相对更大。相较于淡水生境鱼类，盐沼生境鱼类在20ppt盐度的水体中表现更优。但盐度暴露会改变所有生境来源鱼类的集群行为：相较于淡水环境，鱼群的移动速度更快、集群聚合度更高。本研究证实，生境改造可改变本土物种的表型特征，但局部形态特化所伴随的权衡效应，可能会削弱其原本带来的益处。