A changing world: the role of phenotypic plasticity in host-parasitoid interactions facing extreme temperatures

Abstract

Climate change alters many environmental parameters, such as temperature or precipitation. The alterations of these environmental parameters have strong consequences for all levels of ecological interactions, from species interactions to community dynamics. Temperature is crucial in determining ecosystem dynamics, especially for ectothermic species such as plants or insects. Phenotypic plasticity, the capacity of one genotype to produce different phenotypes in response to environmental conditions is a common mechanism by which individuals adapt to changing environments and is observed in multiple traits. In response to temperature plasticity is thermodynamically constrained at the molecular level. The capacity of genotypes to adapt to novel environmental conditions plays a crucial role in structuring ecosystem dynamics and species persistence in adverse conditions. Many studies have assessed plant and insect phenotypic plasticity responses to changing thermal conditions, either alone or with their interactions. It is well recognised that temperature in natural ecosystems fluctuates over multiple time scales (e.g., hour, day, season, year). Moreover, these fluctuations can follow predictable or unpredictable patterns, which have different consequences for phenotypic plasticity and ecosystem dynamics. Understanding how and to what extent phenotypic plasticity can track continuously changing environments and its role in structuring species' ecological niches is of utmost importance in the context of rapid climate change. This review discusses the literature on the role of phenotypic plasticity in fluctuating environments, highlighting the role of temporal dynamics. We focus on host-parasitoid interactions because of their importance in driving herbivorous insect populations and their significant representation in ecosystems. Although we discuss literature on phenotypic plasticity at large, this review emphasises the fundamental effects of extreme temperatures in driving biochemical rates underlying phenotypic plasticity.