A review and meta‐analysis of intraspecific differences in phenotypic plasticity: Implications to forecast plant responses to climate change

Abstract

Aim Many studies use differences among plant populations to infer future plant responses, but these predictions will provide meaningful insights only if patterns of plasticity among populations are similar (i.e., in the absence of population‐by‐environment interaction, P × E). In this study, we tested whether P × E is considered in climate change studies. Specifically, we evaluated whether population differentiation varies across environments and whether P × E is determined by aspects of the study system and experimental design. Location Global. Methods We conducted a literature search in the Thomson Reuters Web of Science database to identify studies assessing population differentiation in a climate change context. We quantified the occurrence of P × E and performed a meta‐analysis to calculate the percentage of traits showing P × E in the study cases. Results We identified 309 study cases (from 237 published articles) assessing population differentiation in 172 plant species, of which 64% included more than one test environment and tested P × E. In 77% of these studies, P × E was significant for at least one functional trait. The overall proportion of traits showing P × E was 33.4% (95% confidence interval 27.7–39.3). These results were generally consistent across life‐forms, ecoregions and type of experiment. Furthermore, population differentiation varied across test environments in 76% of cases. The overall proportion of traits showing environment‐dependent population differentiation was 53.7% (95% confidence interval 37.9–69.3). Conclusions Our findings revealed that differences in phenotypic plasticity among populations are common but are usually neglected in order to forecast population responses to climate change. Future studies should assess population differentiation in many test environments (accounting for P × E) that realistically reflect future environmental conditions, assessing climate change drivers that are rarely considered (e.g., multifactor experiments incorporating higher CO2 levels). Our review also revealed the predominant focus of population studies on trees from temperate climates, identifying underexplored life‐forms (shrubs, annuals), phylogenetic groups (ferns, ancient gymnosperms) and ecoregions (tropical, arctic) that should receive more attention in future.

Species interactions and environmental context affect intraspecific behavioural trait variation and ecosystem function

“…The potential for intraspecific variation should not be overlooked, given that it can strongly determine the functional identity and context-dependent contributions of each species [14]. Context-dependent variation may have consequences for ecosystem functioning as it can change, expand or narrow the distribution of relevant traits expressed and so alter the assumed functional contributions of organisms [65]. Differences in sediment reworking between treatments mechanistically underpin the differences in dissolved nutrient release observed between the same conditions, demonstrating that change in behavioural trait expression influences biogeochemical processes and so mediates the functioning of benthic habitats [15,51].…”

“…Given that natural systems are increasingly subject to drivers of ecological change, we highlight the need to determine the contexts in which intraspecific variability arises [54,65]. Within this framework, we must isolate the circumstances where it contributes to the functional integrity of ecosystems [64,69].…”

On the use of the coefficient of variation to quantify and compare trait variation

“…To unravel the causes of such variation and predict the ability of organisms to adapt, many studies have compared phenotypic plasticity and evolvability across traits, organisms, and populations using different methods for standardizing variation (e.g., Daehler 2003; Davidson et al. 2011; Palacio‐López and Gianoli 2011; Matesanz and Ramírez‐Valiente 2019, for phenotypic plasticity, and Mousseau and Roff 1987; Houle 1992; Merilä and Sheldon 2000; Hansen et al. 2011, for evolvability).…”

Within-individual phenotypic plasticity in flowers fosters pollination niche shift

“…In these types of environments, M. arvensis faces two contrasting climatic conditions, mild and wet during spring but extremely dry and hot during summer (Supplementary Table 1). A general strategy to cope with stressful environmental conditions is to express plasticity in traits essential for physiological and ecological functions 4,17,18 . Accordingly, M. arvensis was plastic for functional traits associated with resource acquisition, producing denser and thicker leaves with more structural carbon and higher water use efficiency during summer than during spring (Fig.…”