The Evolutionary Consequences of Disrupted Male Mating Signals: An Agent-Based Modelling Exploration of Endocrine Disrupting Chemicals in the Guppy

Females may select a mate based on signalling traits that are believed to accurately correlate with heritable aspects of male quality. Anthropogenic actions, in particular chemicals released into the environment, are now disrupting the accuracy of mating signals to convey information about male quality. The long-term prediction for disrupted mating signals is most commonly loss of female preference. Yet, this prediction has rarely been tested using quantitative models. We use agent-based models to explore the effects of rapid disruption of mating signals. In our model, a gene determines survival. Males signal their level of genetic quality via a signal trait, which females use to select a mate. We allowed this system of sexual selection to become established, before introducing a disruption between the male signal trait and quality, which was similar in nature to that induced by exogenous chemicals. Finally, we assessed the capacity of the system to recover from this disruption. We found that within a relatively short time frame, disruption of mating signals led to a lasting loss of female preference. Decreases in mean viability at the population-level were also observed, because sexual-selection acting against newly arising deleterious mutations was relaxed. The ability of the population to recover from disrupted mating signals was strongly influenced by the mechanisms that promoted or maintained genetic diversity in traits under sexual selection. Our simple model demonstrates that environmental perturbations to the accuracy of male mating signals can result in a long-term loss of female preference for those signals within a few generations. What is more, the loss of this preference can have knock-on consequences for mean population fitness.

雌性个体可基于信号性状选择配偶，这类性状被认为与雄性质量的可遗传特征精准相关。当前人类活动，尤其是释放至环境中的化学物质，正干扰交配信号传递雄性质量信息的准确性。针对交配信号受干扰后的长期预测通常为雌性偏好的丧失，但该预测极少通过定量模型开展验证。本研究采用基于智能体的模型（agent-based models）探究交配信号快速受干扰的影响。在本模型中，基因决定个体存活率；雄性通过信号性状展示其遗传质量水平，雌性则借此选择配偶。我们先使该性选择系统达到稳定状态，随后引入雄性信号性状与质量间的干扰机制，其本质与外源性化学物质诱导的干扰相似。最后，我们评估了该系统从干扰中恢复的能力。研究结果显示，在相对较短的时间范围内，交配信号受干扰会导致雌性偏好的持久性丧失。同时还观察到种群平均存活力下降，这是因为针对新出现有害突变的性选择作用被削弱了。种群从交配信号受干扰状态中恢复的能力，强烈受到性选择性状相关遗传多样性维持或促进机制的影响。本简易模型表明，环境扰动对雄性交配信号准确性的影响，可在数代之内导致雌性对该类信号偏好的长期丧失。此外，此类偏好的丧失还会对种群平均适合度产生连锁影响。