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

Local specialization 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 with freshwater. We show that habitat modification can alter phenotypes of native species, but local morphological specialization is associated with trade-offs that may reduce its benefits.

局部特化对个体具有增益效应，同时可增强物种应对环境变化的适应韧性。然而，形态响应、生理表现与行为之间往往存在权衡关系。本研究旨在验证三棘刺鱼（Gasterosteus aculeatus）的生境特异性形态是否会在不同盐度条件下与生理表现及行为产生交互作用。我们推翻了“高捕食压力生境中的鱼类，其较深的体型会降低运动性能”这一假说，但较深的体型与肌肉品质之间存在权衡：躯体较深的个体，其肌肉产生的力量弱于躯体较浅的盐沼生境鱼类。尽管如此，盐沼生境鱼类的游泳性能更低，推测原因是其整体肌肉量偏低，同时尾柄更小、头部更大。相较于淡水环境以及淡水生境的鱼类，盐沼生境鱼类在盐度为20ppt的水体中表现更优。不过，盐度暴露会改变所有生境鱼类的集群行为，相较于淡水组，集群的移动速度更快、个体间间距更小。本研究表明，生境改造可改变本土物种的表型特征，而局部形态特化往往伴随权衡效应，这可能削弱其原本带来的益处。