Venkataraman Yaamini R, Kelso Julia C, Payne Catlin, Freitas Heidi L, Kohler Jasmine, Tepolt Carolyn K
Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
Department of Genetics, Harvard Medical School, Boston, MA, USA.
Integr Comp Biol. 2025 Jul 17. doi: 10.1093/icb/icaf131.
Temperature is a major driver of individual performance in ectotherms, with this impact depending on stressor intensity and duration. Differences in individual response across temperature, time, and populations are shaped by the interplay between evolutionary adaptation and phenotypic plasticity. Some populations are able to thrive in novel and changing environments despite limited genetic diversity, raising the question of how plasticity and adaptation interact after significant genetic diversity loss. The European green crab (Carcinus maenas) is a textbook example of this phenomenon: invasive populations boast a broad thermal tolerance and exceptional thermal flexibility even after repeated genetic bottlenecks. Despite this loss of diversity overall, prior work has found a strong population-level association between variation at a specific extended genomic region (supergene), cold tolerance, and sea surface temperature. We conducted a series of three experiments using righting response to characterize sublethal thermal tolerance and plasticity in introduced green crab populations, then determined if these factors were associated with supergene genotype for individual adult crabs. Crabs showed signs of stress after exposure to a 30°C heat shock in one experiment. Interestingly, a second experiment exposing C. maenas to repeated 24-hour heat shocks showed that prior heat shock conferred beneficial plasticity during a subsequent event. The third experiment examined cold acclimation over multiple timepoints up to 94 hours. At 5°C, certain crabs exhibited an acclimatory response where righting slowed dramatically at first, and then gradually sped up after a longer period of cold exposure. Several crabs failed to right at 1.5°C, which could be indicative of dormancy employed to reduce energy consumption in colder conditions. There were no significant relationships between individual plasticity and supergene genotype in any experiment. Linking population-level genetic associations with individual-level physiology is complex, and reflects the impact of environmental conditions such as temperature throughout life history in shaping adult phenotype. Our results highlight the robust thermal tolerance and plasticity that adult green crabs maintain despite a substantial reduction in genetic diversity, and underscore the importance of probing population-level genotype-phenotype associations at the individual level.
温度是变温动物个体表现的主要驱动因素，这种影响取决于应激源的强度和持续时间。个体在温度、时间和种群间的反应差异是由进化适应和表型可塑性之间的相互作用所塑造的。尽管遗传多样性有限，但一些种群仍能在新颖且不断变化的环境中茁壮成长，这就引发了一个问题：在遗传多样性大幅丧失后，可塑性和适应性是如何相互作用的。欧洲绿蟹（Carcinus maenas）就是这一现象的典型例子：即使经历了多次遗传瓶颈，入侵种群仍具有广泛的热耐受性和出色的热灵活性。尽管总体上遗传多样性有所丧失，但先前的研究发现，在一个特定的扩展基因组区域（超级基因）的变异、耐寒性和海表温度之间存在很强的种群水平关联。我们进行了一系列三个实验，利用翻正反应来表征引入的绿蟹种群的亚致死热耐受性和可塑性，然后确定这些因素是否与成年个体螃蟹的超级基因基因型相关。在一个实验中，螃蟹在暴露于30°C热休克后出现了应激迹象。有趣的是，第二个将欧洲绿蟹暴露于重复24小时热休克的实验表明，先前的热休克在随后的事件中赋予了有益的可塑性。第三个实验在长达94小时的多个时间点上研究了冷驯化。在5°C时，某些螃蟹表现出一种驯化反应，即翻正一开始急剧减慢，然后在较长时间的冷暴露后逐渐加快。几只螃蟹在1.5°C时无法翻正，这可能表明它们采用了休眠来减少在较冷条件下的能量消耗。在任何实验中，个体可塑性与超级基因基因型之间均无显著关系。将种群水平的遗传关联与个体水平的生理学联系起来很复杂，这反映了温度等环境条件在整个生命史中对塑造成年表型的影响。我们的结果突出了成年绿蟹尽管遗传多样性大幅减少但仍保持的强大热耐受性和可塑性，并强调了在个体水平上探究种群水平基因型 - 表型关联的重要性。
