Cuenca Cambronero Maria, Zeis Bettina, Orsini Luisa
Environmental Genomics Group School of Biosciences the University of Birmingham Birmingham UK.
Institute of Zoophysiology University of Muenster Muenster Germany.
Evol Appl. 2017 Nov 2;11(1):112-120. doi: 10.1111/eva.12561. eCollection 2018 Jan.
Anthropogenic global warming has become a major geological and environmental force driving drastic changes in natural ecosystems. Due to the high thermal conductivity of water and the effects of temperature on metabolic processes, freshwater ecosystems are among the most impacted by these changes. The ability to tolerate changes in temperature may determine species long-term survival and fitness. Therefore, it is critical to identify coping mechanisms to thermal and hyper-thermal stress in aquatic organisms. A central regulatory element compensating for changes in oxygen supply and ambient temperature is the respiratory protein haemoglobin (Hb). Here, we quantify Hb plastic and evolutionary response in subpopulations resurrected from the sedimentary archive of a lake with known history of increase in average temperature and recurrence of heat waves. By measuring constitutive changes in crude Hb protein content among subpopulations, we assessed evolution of the Hb gene family in response to temperature increase. To quantify the contribution of plasticity in the response of this gene family to hyper-thermal stress, we quantified changes in Hb content in all subpopulations under hyper-thermal stress as compared to nonstressful temperature. Further, we tested competitive abilities of genotypes as a function of their Hb content, constitutive and induced. We found that Hb-rich genotypes have superior competitive abilities as compared to Hb-poor genotypes under hyper-thermal stress after a period of acclimation. These findings suggest that whereas long-term adjustment to higher occurrence of heat waves may require a combination of plasticity and genetic adaptation, plasticity is most likely the coping mechanism to hyper-thermal stress in the short term. Our study suggests that with higher occurrence of heat waves, Hb-rich genotypes may be favoured with potential long-term impact on population genetic diversity.
人为导致的全球变暖已成为推动自然生态系统发生剧烈变化的主要地质和环境力量。由于水的高导热性以及温度对代谢过程的影响，淡水生态系统是受这些变化影响最大的生态系统之一。耐受温度变化的能力可能决定物种的长期生存和适应性。因此，确定水生生物应对热应激和高温应激的机制至关重要。补偿氧气供应和环境温度变化的一个核心调节要素是呼吸蛋白血红蛋白（Hb）。在此，我们量化了从一个已知平均温度升高和热浪反复发生历史的湖泊沉积档案中复活的亚种群中Hb的可塑性和进化反应。通过测量亚种群中粗Hb蛋白含量的组成性变化，我们评估了Hb基因家族对温度升高的进化反应。为了量化该基因家族对高温应激反应中可塑性的贡献，我们将所有亚种群在高温应激下的Hb含量变化与非应激温度下的变化进行了量化比较。此外，我们测试了基因型的竞争能力与其Hb含量（组成性和诱导性）的函数关系。我们发现，经过一段时间的适应后，在高温应激下，富含Hb的基因型比Hb含量低的基因型具有更强的竞争能力。这些发现表明，虽然长期适应热浪发生频率的增加可能需要可塑性和遗传适应的结合，但可塑性很可能是短期内应对高温应激的机制。我们的研究表明，随着热浪发生频率的增加，富含Hb的基因型可能更受青睐，这可能对种群遗传多样性产生潜在的长期影响。
