Extensions of species’ geographical distributions, or range extensions, are among the primary ecological responses to climate change in the oceans. Considerable variation across the rates at which species’ ranges change with temperature hinders our ability to forecast range extensions based on climate data alone. To better manage the consequences of ongoing and future range extensions for global marine biodiversity, more information is needed on the biological mechanisms that link temperatures to range limits. This is especially important at understudied, low relative temperatures relevant to poleward range extensions, which appear to outpace warm range edge contractions four times over. Here, we capitalized on the ongoing range extension of a teleost predator, the Australasian snapper Chrysophrys auratus, to examine multiple measures of ecologically relevant physiological performance at the population’s poleward range extension front. Swim tunnel respirometry was used to determine how mid-range and poleward range edge winter acclimation temperatures affect metabolic rate, aerobic scope, swimming performance and efficiency and recovery from exercise. Relative to ‘optimal’ mid-range temperature acclimation, subsequent range edge minimum temperature acclimation resulted in absolute aerobic scope decreasing while factorial aerobic scope increased; efficiency of swimming increased while maximum sustainable swimming speed decreased; and recovery from exercise required a longer duration despite lower oxygen payback. Cold-acclimated swimming faster than 0.9 body lengths sec⁻¹ required a greater proportion of aerobic scope despite decreased cost of transport. Reduced aerobic scope did not account for declines in recovery and lower maximum sustainable swimming speed. These results suggest that while performances decline at range edge minimum temperatures, cold-acclimated snapper are optimized for energy savings and range edge limitation may arise from suboptimal temperature exposure throughout the year rather than acute minimum temperature exposure. We propose incorporating performance data with in situ behaviour and environmental data in bioenergetic models to better understand how thermal tolerance determines range limits.

中文翻译：

---

将寒冷驯化与分布范围扩大的海洋鱼类的极地分布限制联系起来的生理机制。


物种地理分布的扩展或范围的扩展是对海洋气候变化的主要生态反应之一。物种分布范围随温度变化的速率存在相当大的变化，这阻碍了我们仅根据气候数据预测分布范围扩展的能力。为了更好地管理当前和未来范围扩大对全球海洋生物多样性的影响，需要更多有关将温度与范围限制联系起来的生物机制的信息。这在与极地范围延伸相关的尚未充分研究的相对较低温度下尤其重要，其速度似乎超过了温暖范围边缘收缩的四倍。在这里，我们利用硬骨鱼捕食者——澳大利亚笛鲷Chrysophrys auratus的持续活动范围扩展，来研究该种群向极地活动范围扩展前沿的生态相关生理表现的多种测量指标。游泳隧道呼吸测量法用于确定中范围和极地范围边缘冬季适应温度如何影响代谢率、有氧范围、游泳表现和效率以及运动恢复。相对于“最佳”中范围温度驯化，随后的范围边缘最低温度驯化导致绝对有氧范围减小，而阶乘有氧范围增加；游泳效率提高，最大可持续游泳速度降低；尽管氧气回报较低，但从运动中恢复需要更长的时间。尽管运输成本降低，但冷适应游泳速度超过 0.9 体长秒^-1需要更大比例的有氧范围。 有氧范围的减少并不能解释恢复的下降和最大可持续游泳速度的降低。这些结果表明，虽然在范围边缘最低温度下性能下降，但冷驯化的鲷鱼针对节能进行了优化，并且范围边缘限制可能是由于全年的次优温度暴露而不是急性最低温度暴露引起的。我们建议将性能数据与生物能模型中的原位行为和环境数据结合起来，以更好地理解热耐受性如何确定范围限制。