Data from: Temperature-dependent growth and fission rate plasticity drive seasonal and geographic changes in body size in a clonal sea anemone

The temperature-size rule is a commonly observed pattern where adult body size is negatively correlated with developmental temperature. In part, this may occur as a consequence of allometric scaling, where changes in the ratio of surface area to mass limit oxygen diffusion as body size increases. As oxygen demand increases with temperature, a smaller body should be favored as temperature increases. For clonal animals, small changes in growth and/or fission rate can rapidly alter the average body size of clonal descendants. Here I test the hypothesis that the clonal sea anemone Diadumene lineata is able to track an optimal body size through seasonal temperature changes using fission rate plasticity. Individuals from three regions (Florida, Georgia, and Massachusetts) across the species’ latitudinal range were grown in a year-long reciprocal common garden experiment mimicking seasonal temperature changes at three sites. Average body size was found to be smaller and fission rates higher in warmer conditions, consistent with the temperature-size rule pattern. However, seasonal size and fission patterns reflect a complex interaction between region-specific thermal reaction norms and the local temperature regime. These details provide insight into both the range of conditions required for oxygen limitation to contribute to a negative correlation between body size and temperature and the role that fission rate plasticity can play in tracking a rapidly changing optimal phenotype.

温度-体型法则（temperature-size rule）是一种被广泛观测到的生态模式，即成体体型与发育温度呈负相关。该现象在一定程度上可能源于异速生长缩放（allometric scaling）：当体型增大时，表面积与质量比的变化会限制氧气扩散。由于氧气需求随温度升高而增加，温度上升时更小的体型应更受青睐。对于无性繁殖动物（clonal animals）而言，生长速率和/或分裂速率的微小变化，可快速改变无性繁殖后代的平均体型。
本研究检验了如下假说：无性繁殖的海葵纵条矶海葵（Diadumene lineata）能够通过分裂速率可塑性，追踪季节性温度变化带来的最优体型。研究选取了该物种纬度分布范围内的三个区域（佛罗里达、佐治亚与马萨诸塞）的个体，开展了为期一年的双向互置共同花园实验，模拟三个采样位点的季节性温度变化。
结果发现，在较温暖的环境中，个体平均体型更小且分裂速率更高，这与温度-体型法则的模式相符。然而，季节性体型与分裂模式反映了区域特异性热反应规范（thermal reaction norms）与当地温度格局之间的复杂互作。这些细节既揭示了氧气限制参与介导体型与温度负相关所需的条件范围，也阐明了分裂速率可塑性在追踪快速变化的最优表型过程中所发挥的作用。