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核心基石。然而，近期诸多研究均提及可重复性危机，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问题——即评估植食性昆虫（phytophagous insects）的雌性寄主植物偏好与接受度，在该类群中，寄主特化是物种分化的关键驱动因素。我们将来自同一种群的多批菜粉蝶（Pieris napi）个体，置于三种十字花科（Brassicaceae）寄主植物上，开展标准的寄主接受度与偏好测试。尽管寄主植物的偏好排序具有高度可重复性，但即便在实验条件相似的同批次个体间，雌性在低排名寄主上的产卵倾向仍存在显著差异。多数差异可归因于雌性繁殖力的批次间变异——该性状与雌性体型以及交配时获得的交配赠礼（nuptial gift）大小均呈显著相关。体型较小的雄性会提供体积更小的精荚（spermatophore），本实验中，与小体型雄性交配的小体型雌性，在低排名寄主上的产卵倾向异常偏低。综上，本研究结果为相关理论预测提供了实证支持：雌性的寄主利用行为强烈受非遗传的环境变异影响，且此类变异即便在看似一致的实验条件下，也可能影响生态学实验的可重复性。