Data from: Quick-change artists: male guppies pay no cost to repeatedly adjust their sexual strategies

Sexually selected traits involved in mate acquisition and fertilization success are usually costly and males often plastically adjust their reproductive investment in response to social conditions. Phenotypic plasticity in male sexual traits is generally assumed to be adaptive, yet its costs are rarely investigated. Male guppies (Poecilia reticulata) adjust their ejaculate production and sexual behavior in response to perceived mating opportunities. In natural populations mating opportunities can fluctuate continuously, and the iterated activation of plastic responses may impose a cost on males. To determine such costs, we experimentally manipulated male social environment by exposing males either to a constant number of females, or to weekly oscillations in female number. We measured traits linked to condition and reproductive success throughout male life. We found no significant difference in the expression of these traits nor in male lifespan between the two groups. Our results suggest that male guppies pay negligible costs for the iterated activation of plastic responses, possibly as a consequence of selection to minimize them.与求偶交配及受精成功相关的性选择性状通常具有适应性代价，而雄性往往会根据社会环境可塑性地调整其繁殖投入。雄性性性状的表型可塑性（phenotypic plasticity）通常被认为具有适应性，但该可塑性的适应性代价却极少被研究。雄性孔雀鱼（Poecilia reticulata）会根据感知到的交配机会，调整其精子产出量与性行为。在自然种群中，交配机会往往持续波动，而反复激活可塑性响应可能会使雄性付出适应性代价。为明确此类代价，我们通过两种方式操控雄性的社会环境：一是将雄性暴露于固定数量的雌性环境中，二是让雌性数量每周周期性波动。我们在雄性的整个生命周期中，测量了与其健康状态及繁殖成功相关的各项性状。我们发现，两组雄性的上述性状表达量以及寿命均无显著差异。我们的研究结果表明，雄性孔雀鱼在反复激活可塑性响应过程中所付出的代价可忽略不计，这或许是自然选择倾向于最小化此类代价的结果。