Data from: Female fecundity variation affects reproducibility of experiments on host plant preference and acceptance in a phytophagous insect

Reproducibility is a scientific cornerstone. Many recent studies, however, describe a reproducibility crisis and call for assessments of reproducibility across scientific domains. Here, we explore the reproducibility of a classic ecological experiment—that of assessing female host plant preference and acceptance in phytophagous insects, a group in which host specialization is a key driver of diversification. We exposed multiple cohorts of Pieris napi butterflies from the same population to traditional host acceptance and preference tests on three Brassicaceae host species. Whereas the host plant rank order was highly reproducible, the propensity to oviposit on low-ranked hosts varied significantly even among cohorts exposed to similar conditions. Much variation could be attributed to among-cohort variation in female fecundity, a trait strongly correlated both to female size and to the size of the nuptial gift a female receives during mating. Small males provide small spermatophores, and in our experiment small females that mated with small males had a disproportionally low propensity to oviposit on low-ranked hosts. Hence, our results provide empirical support to the theoretical prediction that female host utilization is strongly affected by non-genetic, environmental variation, and that such variation can affect the reproducibility of ecological experiments even under seemingly identical conditions.

可重复性是科学研究的基石。然而近年来诸多研究均指出了可重复性危机，并呼吁开展跨科学领域的可重复性评估。本研究聚焦一项经典生态学实验的可重复性——该实验用于评估植食性昆虫（phytophagous insects）的雌性寄主植物偏好与接受度，而在该类群中，寄主专化性是驱动物种分化的关键因素。我们将来自同一种群的多组云斑粉蝶（Pieris napi）置于三种十字花科（Brassicaceae）寄主植物上，开展传统的寄主接受度与偏好性测试。尽管寄主植物的偏好排序具有极高的可重复性，但即便在实验条件相似的组间，雌性对低优先级寄主的产卵倾向仍存在显著差异。此类差异很大程度上可归因于不同组间雌性繁殖力的异质性——该性状与雌性体型及交配时获得的婚赠体积均呈显著正相关。体型较小的雄性会提供体积更小的精荚，而在本实验中，与小型雄性交配的小型雌性个体，其在低优先级寄主上产卵的倾向显著偏低。综上，本研究结果为下述理论预测提供了实证支撑：雌性寄主利用行为受非遗传的环境变异强烈影响，且此类变异即便在看似一致的实验条件下，仍可干扰生态学实验的可重复性。