Data from: Metabolic depression and the evolution of hypoxia tolerance in threespine stickleback, Gasterosteus aculeatus

Anthropogenic increases in global temperature and agricultural runoff are increasing the prevalence of aquatic hypoxia throughout the world. We investigated the potential for a relatively rapid evolution of hypoxia tolerance using two isolated (for <11,000 years) populations of threespine stickleback, one from a lake that experiences long-term hypoxia (Alta Lake, British Columbia) and one from a lake that does not (Trout Lake, British Columbia). Loss-of-equilibrium experiments revealed that the Alta Lake stickleback were significantly more tolerant of hypoxia than the Trout Lake stickleback, and calorimetry experiments suggest that the enhanced tolerance of Alta Lake stickleback may be associated with their ability to depress metabolic rate (as indicated by metabolic heat production) by 33% in hypoxia. The two populations showed little variation in their capacities for O2 extraction and anaerobic metabolism. These results reveal that intraspecific variation in hypoxia tolerance can develop over relatively short geological timescales, as can metabolic rate depression, a complex biochemical response that may be favoured in long-term hypoxic environments.人为活动引发的全球气温升高与农业径流，正不断加剧全球范围内水生低氧（hypoxia）的发生频率与分布范围。本研究以两个隔离时长不足11000年的三刺棘鱼（threespine stickleback）种群为实验材料，探究了低氧耐受性状快速演化的潜在可能性；其中一个种群来自长期处于低氧环境的不列颠哥伦比亚省阿尔塔湖（Alta Lake），另一个种群则来自非低氧环境的不列颠哥伦比亚省特劳特湖（Trout Lake）。失衡实验结果显示，阿尔塔湖种群的三刺棘鱼对低氧的耐受能力显著强于特劳特湖种群；量热实验结果表明，阿尔塔湖种群的低氧耐受能力提升，可能与其在低氧环境下可将代谢率（以代谢产热为衡量指标）降低33%的能力密切相关。两个种群在氧气摄取能力与无氧代谢能力方面几乎无显著差异。本研究结果揭示，低氧耐受的种内变异可在相对较短的地质时间尺度内形成；代谢率下调这一复杂的生化响应亦是如此，而该响应在长期低氧环境中可能会受到自然选择的青睐。