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.

参与配偶获取与受精成功过程的性选择性状通常存在代价，雄性往往会根据社会环境可塑性地调整自身繁殖投入。一般认为雄性性性状的表型可塑性（phenotypic plasticity）具有适应性，但其相关代价却鲜有研究。雄性孔雀鱼（Poecilia reticulata）会依据感知到的交配机会，调整其射精量与性行为。在自然种群中，交配机会会持续波动，而可塑性响应的反复激活可能会给雄性带来代价。为探究此类代价，我们通过将雄性分别暴露于固定数量雌性的环境，或是雌性数量每周波动的环境，实验操控了雄性的社会环境。我们在雄性整个生命周期内，测量了与其生理状态及繁殖成功相关的性状。结果显示，两组间上述性状的表达水平以及雄性寿命均无显著差异。我们的研究结果表明，雄性孔雀鱼为反复激活可塑性响应所付出的代价可忽略不计，这或许是自然选择促使其最小化此类代价的结果。