Data from: Plasticity of thermal tolerance and its relationship with growth rate in juvenile mussels (Mytilus californianus)

Complex life cycles characterized by uncertainty at transitions between larval/juvenile and adult environments could favor irreversible physiological plasticity at such transitions. To assess whether thermal tolerance of intertidal mussels (Mytilus californianus) adjusts to post-settlement environmental conditions, we collected juveniles from their thermally buffered microhabitat from high and low-shore locations at cool (wave-exposed) and warm (wave-protected) sites. Juveniles were transplanted to unsheltered cages at the two low sites or placed in a common garden. Juveniles transplanted to the warm site for one month in summer had higher thermal tolerance, regardless of origin site. In contrast, common-garden juveniles from all sites had lower tolerance indistinguishable from exposed-site transplants. After six months in the field plus a common garden period, there was a trend for higher thermal tolerance at the protected site, while reduced thermal tolerance at both sites indicated seasonal acclimatization. Thermal tolerance and growth rate were inversely related after one but not six months; protected-site transplants were more tolerant but grew more slowly. In contrast to juveniles, adults from low-shore exposed and protected sites retained differences in thermal tolerance after common garden treatment in summer. Both irreversible and reversible forms of plasticity must be considered in organismal responses to changing environments.

以幼虫/稚贝与成体栖息环境转换阶段存在不确定性为典型特征的复杂生活史，可能会促使该类转换阶段产生不可逆的生理可塑性。为评估潮间带贻贝（*Mytilus californianus*）的热耐受性是否会因定居后的环境条件发生适应性调整，我们从冷凉（浪击暴露）与温暖（波影庇护）样地的高潮带与低潮带区域，采集了栖息于热缓冲微生境中的稚贝。随后将这些稚贝移植至两个低潮带样地的无遮蔽笼具中，或安置于同质园（common garden）环境中培育。在夏季移植至温暖样地培育一个月的稚贝，其热耐受性显著更高，且与稚贝的原始采集样地无关。与之相反，所有样地采集后置于同质园培育的稚贝，其热耐受性均较低，且与浪击暴露样地移植组的稚贝无显著差异。在野外培育六个月并辅以一段同质园培育周期后，庇护样地组稚贝的热耐受性呈现升高趋势；而两个样地组稚贝的热耐受性均出现下降，这一现象表明存在季节性驯化适应。培育一个月后，稚贝的热耐受性与生长速率呈负相关关系，但该相关性在培育六个月后不复存在；庇护样地移植组的稚贝热耐受性更强，但生长速率更为缓慢。与稚贝不同，夏季经同质园处理后，低潮带浪击暴露样地与庇护样地的成体贻贝仍保留了热耐受性的差异。在解析生物应对环境变化的响应机制时，必须同时考虑不可逆与可逆两种形式的可塑性。