Effects of intrinsic environmental predictability on intra-individual and intra-population variability of plant reproductive traits and eco-evolutionary consequences

Abstract

Background and Aims It is widely accepted that changes in the environment affect mean trait expression, but little is known about how the environment shapes intra-individual and intra-population variance. Theory suggests that intra-individual variance might be plastic and under natural selection, rather than reflecting developmental noise, but evidence for this hypothesis is scarce. Here, we experimentally tested whether differences in intrinsic environmental predictability affect intra-individual and intra-population variability of different reproductive traits, and whether intra-individual variability is under selection. Methods Under field conditions, we subjected Onobrychis viciifolia to more and less predictable precipitation over 4 generations and 4 years. We analysed effects on the coefficient of intra-individual variation (CVi-i) and the coefficient of intra-population variation (CVi-p), assessed whether the coefficients of intra-individual variation (CsVi-i) are under natural selection and tested for transgenerational responses (ancestor environmental effects on offspring). Key Results Less predictable precipitation led to higher CsVi-i and CsVi-p, consistent with plastic responses. The CsVi-i of all studied traits were under consistent stabilizing selection, and precipitation predictability affected the strength of selection and the location of the optimal CVi-i of a single trait. All CsVi-i differed from the optimal CVi-i and the maternal and offspring CsVi-i were positively correlated, showing that there was scope for change. Nevertheless, no consistent transgenerational effects were found in any of the three descendant generations, which contrasts with recent studies that detected rapid transgenerational responses in the trait means of different plant species. This suggests that changes in intra-individual variability take longer to evolve than changes in trait means, which may explain why high intra-individual variability is maintained, despite the stabilizing selection. Conclusions The results indicate that plastic changes of intra-individual variability are an important determinant of whether plants will be able to cope with changes in environmental predictability induced by the currently observed climatic change.

Associations between leaf developmental stability, variability, canalization, and phenotypic plasticity inAbutilon theophrasti

“…They could be independent components on their own and potentially part of important evolutionary processes (Bradshaw, 1965 ; Herrera et al, 2015 ). Meanwhile, they are also under selection (Kawecki, 2000 ; March‐Salas et al, 2021 ; Møller & Swaddle, 1997 ; Pigliucci et al, 2006 ). The presence of correlative relationships among them might simply reflect their similar trends in response to environmental gradients as a coincidence, and they do not have any actual correlations, or otherwise, they can have some common mechanisms and explain each other (Del Giudice et al, 2018 ; McDonald et al, 2018 ).…”

“…However, we found nonsignificant correlations between CV intra and PI rel . Since increased intraindividual variation can either be beneficial for plastic response (March‐Salas et al, 2021 ) or reflect adverse environmental effects, both positive and negative correlations can occur between intraindividual variation and plasticity, with overall results being nonsignificant.…”

“…The controversies suggest these relationships are complex and depend on other factors such as specific traits, environmental contexts, and growth stages (Woods et al, 1999 ), and direct evidence is lacking. In addition, another related concept that has recently been given more attention is “intraindividual variability,” which is reported to play important roles in determining the ability of plants to deal with environmental changes (March‐Salas et al, 2021 ) and improving distribution of species and population stability and persistence (Herrera et al, 2015 ). Environmental effects can alter intraindividual variability without affecting plant average performance (Gonzalez‐Jimena & Fitze, 2012 ) or intrapopulation variability (Herrera et al, 2015 ).…”

Predictability of Biotic Stress Structures Plant Defence Evolution

“…We propose that, even if dynamics in stress for the greater part remain uncertain, predictable patterns are readily integrated in plant strategies. Hence, the predictability of (sequences of) stressors is likely to be a key component governing inter-and intraspecific variation in plant responses and strategies maximising life-time fitness [64]. While studying plant interactions with stressors in isolation provides fundamental insights in the mechanisms underlying plant responses to stress, integrating predictability to the framework of plant-stressor interactions will yield important new insights in the evolution of plant defence strategies.…”

“…Variation in predictability of herbivore assembly on individual plants is likely to drive the evolution of (herbivore-specific) induced defences. This may include maintenance of genetic variation in plant populations by frequencydependent selection in which genotypes are selected to optimise resistance strategies to subsets of the community consisting of strongly correlated antagonists [64]. An emerging evolutionary consequence may be that heritability of traits in resistance to different herbivores becomes linked.…”