Data from: Parting ways: Parasite release in nature leads to sex-specific evolution of defense

We evaluate the extent to which males and females evolve along similar or different trajectories in response to the same environmental shift. Specifically, we use replicate experimental introductions in nature to consider how release from a key parasite (Gyrodactylus) generates similar or different defense evolution in male versus female guppies (Poecilia reticulata). After 8-12 generations of evolution, guppies were collected from the ancestral (parasite still present) and derived (parasite now absent) populations and bred for two generations in the laboratory to control for non-genetic effects. These F2 guppies were then individually infected with Gyrodactylus and infection dynamics were monitored on each fish. We found that parasite release in nature led to sex-specific evolutionary responses: males did not show much evolution of resistance, whereas females showed the evolution of increased resistance. Given that male guppies in the ancestral population had greater resistance to Gyrodactylus than did females, evolution in the derived populations led to reduction of sexual dimorphism in resistance. We argue that previous selection for high resistance in males constrained (relative to females) further evolution of the trait. We advocate more experiments considering sex-specific evolutionary responses to environmental change.

本研究旨在评估雌雄个体在响应同一环境变化时，其演化轨迹的趋同与分化程度。具体而言，本研究通过重复野外引种实验，探究解除关键寄生虫三代虫（Gyrodactylus）的寄生压力后，雌雄孔雀鱼（Poecilia reticulata）的防御演化是否存在趋异或趋同模式。在经历8至12代野外演化后，研究人员分别从祖先种群（仍存在该寄生虫）和衍生种群（寄生虫已被清除）采集孔雀鱼，并在实验室中繁育两代以控制非遗传效应的干扰。随后对这些F2代孔雀鱼进行单头三代虫感染实验，并监测每尾鱼的感染动态。研究结果显示，野外解除寄生虫压力后，雌雄个体产生了性别特异性的演化响应：雄性的抗寄生虫抗性未出现显著演化，而雌性的抗性则显著提升。由于祖先种群中的雄性孔雀鱼对三代虫的抗性本就高于雌性，衍生种群的演化最终使得抗性相关的性别二态性得以降低。本研究认为，祖先种群中针对雄性高抗性的定向选择，相较于雌性，限制了该性状的进一步演化。我们呼吁未来开展更多针对环境变化下性别特异性演化响应的相关实验。