Data from: Dispersal propensity in Tetrahymena thermophila ciliates – a reaction norm perspective

Dispersal and phenotypic plasticity are two main ways for species to deal with rapid changes of their environments. Understanding how genotypes (G), environments (E) and their interaction (genotype and environment; G x E) each affects dispersal propensity is therefore instrumental for predicting the ecological and evolutionary responses of species under global change. Here we used an actively dispersing ciliate to quantify the contributions of G, E, and G x E on dispersal propensity, exposing 44 different genotypes to three different environmental contexts (densities in isogenotype populations). Moreover, we assessed the condition-dependence of dispersal, i.e. whether dispersal is related to morphological, physiological or behavioral traits. We found that genotypes showed marked differences in dispersal propensity and that dispersal is plastically adjusted to density, with the overall trend for genotypes to exhibit negative density-dependent dispersal. A small, but significant G x E interaction indicates genetic variability in plasticity and therefore some potential for dispersal plasticity to evolve. We also show evidence consistent with condition-dependent dispersal suggesting that genotypes also vary in how individual condition is linked to dispersal under different environmental contexts thereby generating complex dispersal behavior due to only three variables (genes, environment, and individual condition).

扩散（dispersal）与表型可塑性（phenotypic plasticity）是物种应对环境快速变化的两种核心策略。解析基因型（genotype，G）、环境（environment，E）及其互作（基因型与环境互作，即G×E）分别对扩散倾向的影响机制，对于预测全球变化下物种的生态与进化响应至关重要。本研究以一种主动扩散的纤毛虫（ciliate）为实验材料，量化了G、E及G×E对扩散倾向的贡献：将44种不同基因型暴露于三种不同的环境情境，即同基因型种群的密度梯度中。此外，我们还评估了扩散的条件依赖性，即扩散是否与个体的形态、生理或行为性状相关。研究结果显示，不同基因型的扩散倾向存在显著差异，且扩散会随种群密度发生可塑性调整，整体呈现负密度依赖扩散的趋势。微弱但显著的G×E互作结果表明，扩散可塑性存在遗传变异，因此具备一定的进化潜力。本研究还提供了支持条件依赖性扩散的证据，表明不同基因型在个体条件与不同环境情境下的扩散关联模式上同样存在差异，仅通过基因、环境与个体条件这三个变量，即可催生复杂的扩散行为模式。