Environmental effects on the covariation among pace-of-life traits

Abstract

A range of life-history strategies along a slow-fast continuum emerge due to trade-offs between allocation to current and future reproduction. Pace-of-life syndromes (POLS) are suites of correlated life-history, physiological and behavioral traits that arise due to these trade-offs. The notion that correlations among traits may vary between populations of the same species or along environmental gradients suggests an important role for the environment in shaping and maintaining POLS. Understanding how environmental conditions influence POLS is important for understanding evolutionary change as covariation between traits may constrain their independent evolution. Here, we formulate a series of hypotheses on how environmental conditions influence POLS, with specific focus on the integration of behavior with life-history traits. We make predictions on the interactions among defining features of the environment (harshness, predictability) and type of organism (taxonomy, endothermy, life stage). We review the empirical support for each hypothesis from studies that measured changes in the association between behavior and life-history traits as a function of environmental conditions. Environmental factors were frequently found to influence the covariance of behavioral traits with life history but the effects were not broadly generalizable across study systems. Evidence of environmental harshness and the significance of early life environment suggest these as important determinants of POLS, but environmental predictability and differences between taxa are, in essence, unstudied. We identify knowledge gaps and highlight promising directions arising from current studies.

Differences in resource acquisition, not allocation, mediate the relationship between behaviour and fitness: a systematic review and meta‐analysis

“…resource) dependent, this could generate positive within‐individual correlations between behaviour and both survival probability and reproduction, as observed here. Although two recent meta‐analyses have demonstrated that resource acquisition influences behavioural expression within individuals (Dougherty, 2021a, 2021b), empirical work estimating the relationships between behaviour, survival, and reproduction simultaneously across environmental gradients of resource availability are needed to test this idea explicitly (Montiglio et al ., 2018; Hämäläinen et al ., 2021). Our results nonetheless indicate that variation in resource acquisition may play a more important role in shaping behaviour–fitness co‐variances than currently captured by theory.…”

Seasonal time constraints shape life history, physiology and behaviour independently, and decouple a behavioural syndrome in a damselfly

“…Studies that integrate plastic (within population) and evolutionary (among populations) responses to time constraints are needed to clarify this intriguing, contrasting pattern. With time constraints being a ubiquitous stressor in natural populations, our work is among the few to address the recent call to test POLS across relevant ecological gradients (Dammhahn et al 2018, Hämäläinen et al 2020). Our results thereby add new insights and suggest that, besides the predicted plastic changes in life history means, also plastic changes in behavioural trait integration may be an important but overlooked adaptive aspect of responding to seasonal time constraints.…”

“…How environmental stressors shape the strength and consistency of trait integration and the repeatability of traits is highly debated (Killen et al 2013, Montiglio and Royauté 2014, Hämäläinen et al 2020). On the one hand, environmental stressors such as predation stress can establish new (or enhance already present) trait correlations, as shown among behavioural traits (Bell and Sih 2007, Adriaenssens and Johnsson 2013), possibly to achieve an optimal trait combination that would increase fitness under these new conditions (Sih et al 2004).…”

“…On the other hand, environmental stressors such as toxicants can uncouple previously integrated trait sets, possibly because of stress‐related disturbance in the neuroendocrine and developmental mechanisms (Royauté et al 2015a, Dzieweczynski et al 2016). Overall, moderate environmental stressors are predicted to strengthen trait integration (Killen et al 2013), yet the limited empirical evidence reveals no clear pattern how the trait integration of the POLS responds to stress (Hämäläinen et al 2020). Environmental stressors are also predicted to effect trait repeatabilities (Bell et al 2009, Killen et al 2016), yet the direction of change is often challenging to predict for many stressors (e.g.…”

Early life history variation in phenotypes and fitness of a coral reef fish, Thalassoma hardwicke

“…Much of the recent literature on these topics have evaluated relationships between traits and environments across species (e.g., Fulton et al 2001, Case et al 2004, Trebilco et al 2015, Hämäläinen et al 2020, Mortelliti and Brehm 2020; relatively few studies have examined variation in phenotype-environment covariance in detail, and within a single species (see Zamudio et al 2016 and references therein).…”