Data from: Phenotypic and genomic plasticity of alternative male reproductive tactics in sailfin mollies

A major goal of modern evolutionary biology is to understand the causes and consequences of phenotypic plasticity, the ability of a single genotype to produce multiple phenotypes in response to variable environments. While ecological and quantitative genetic studies have evaluated models of the evolution of adaptive plasticity, some long-standing questions about plasticity require more mechanistic approaches. Here, we address two of those questions: does plasticity facilitate adaptive evolution? And do physiological costs place limits on plasticity? We examine these questions by comparing genetically and plastically regulated behavioural variation in sailfin mollies (Poecilia latipinna), which exhibit striking variation in plasticity for male mating behaviour. In this species, some genotypes respond plastically to a change in the social environment by switching between primarily courting and primarily sneaking behaviour. In contrast, other genotypes have fixed mating strategies (either courting or sneaking) and do not display plasticity. We found that genetic and plastic variation in behaviour were accompanied by partially, but not completely overlapping changes in brain gene expression, in partial support of models that predict that plasticity can facilitate adaptive evolution. We also found that behavioural plasticity was accompanied by broader and more robust changes in brain gene expression, suggesting a substantial physiological cost to plasticity. We also observed that sneaking behaviour, but not courting, was associated with upregulation of genes involved in learning and memory, suggesting that sneaking is more cognitively demanding than courtship.现代进化生物学的核心目标之一，是阐明表型可塑性（phenotypic plasticity）的成因与效应——即单一基因型在多变环境中产生多种表型的能力。尽管生态学与数量遗传学（quantitative genetics）研究已对适应性可塑性的演化模型开展了系统性评估，但有关可塑性的若干长期悬而未决的问题，仍需借助更具机制阐释性的研究方法加以解答。本文针对其中两个核心问题展开探讨：其一，可塑性是否会促进适应性演化？其二，生理代价是否会对可塑性的表达形成限制？我们以帆鳍摩丽鱼（Poecilia latipinna）为研究对象，通过比较其遗传调控与可塑性调控的行为变异，解答上述问题；该物种的雄性交配行为展现出显著的可塑性差异。在该物种中，部分基因型可通过在主要求偶行为与主要偷袭交配行为之间切换，对社会环境的变化作出可塑性响应；与之相对，另有部分基因型的交配策略固定不变（仅实施求偶或仅实施偷袭交配），不表现出任何可塑性。研究结果显示，行为层面的遗传变异与可塑性变异，均伴随有大脑基因表达的部分（但非完全）重叠变化，这为“可塑性可促进适应性演化”的模型预测提供了部分支持。同时我们发现，伴随行为可塑性出现的大脑基因表达变化，其范围更广、调控更为显著，这表明可塑性需付出可观的生理代价。此外我们还观察到，仅偷袭交配行为（而非求偶行为）与学习记忆相关基因的上调表达存在显著关联，这表明偷袭交配行为比求偶行为对认知能力的要求更高。