Carley Lauren N, Mitchell-Olds Tom, Morris William F
University Program in Ecology, Duke University, Durham, North Carolina, USA.
Department of Biology, Duke University, Durham, North Carolina, USA.
Ecol Lett. 2025 Jan;28(1):e70039. doi: 10.1111/ele.70039.
It is unclear how environmental change influences standing genetic variation in wild populations. Here, we characterised environmental conditions that protect versus erode polymorphic chemical defences in Boechera stricta (Brassicaceae), a short-lived perennial wildflower. By manipulating drought and herbivory in a 4-year field experiment, we measured the effects of driver variation on vital rates of genotypes varying in defence chemistry and then assessed interacting driver effects on total fitness (estimated as each genotype's lineage growth rate, λ) using demographic models. Drought and herbivory interacted to shape vital rates, but contrasting defence genotypes had equivalent total fitness in many environments. Defence polymorphism thus may persist under a range of conditions; however, ambient field conditions fall close to the boundary of putatively polymorphic environment space, and increasing aridity may drive populations to monomorphism. Consequently, elevated intensity and/or frequency of drought under climate change may erode genetic variation for defence chemistry in B. stricta.
目前尚不清楚环境变化如何影响野生种群中的现存遗传变异。在此，我们描述了保护与侵蚀短寿命多年生野花岩生庭荠（十字花科）中多态性化学防御的环境条件。通过在一项为期4年的田间实验中操纵干旱和食草作用，我们测量了驱动因素变化对防御化学不同的基因型的生命率的影响，然后使用种群统计学模型评估了驱动因素对总适合度（估计为每个基因型的谱系增长率，λ）的相互作用效应。干旱和食草作用相互作用以塑造生命率，但在许多环境中，具有不同防御能力的基因型具有相当的总适合度。因此，防御多态性可能在一系列条件下持续存在；然而，田间环境条件接近假定的多态环境空间的边界，而干旱加剧可能会使种群变为单态性。因此，气候变化下干旱强度和/或频率的增加可能会侵蚀岩生庭荠中防御化学的遗传变异。
