Genetic variance for behavioural ‘predictability’ of stress response

Abstract

Genetic factors underpinning phenotypic variation are required if natural selection is to result in adaptive evolution. However, evolutionary and behavioural ecologists typically focus on variation among individuals in their average trait values and seek to characterize genetic contributions to this. As a result, less attention has been paid to if and how genes could contribute towards within‐individual variance or trait ‘predictability’. In fact, phenotypic ‘predictability’ can vary among individuals, and emerging evidence from livestock genetics suggests this can be due to genetic factors. Here, we test this empirically using repeated measures of a behavioural stress response trait in a pedigreed population of wild‐type guppies. We ask (a) whether individuals differ in behavioural predictability and (b) whether this variation is heritable and so evolvable under selection. Using statistical methodology from the field of quantitative genetics, we find support for both hypotheses and also show evidence of a genetic correlation structure between the behavioural trait mean and individual predictability. We show that investigating sources of variability in trait predictability is statistically tractable and can yield useful biological interpretation. We conclude that, if widespread, genetic variance for ‘predictability’ will have major implications for the evolutionary causes and consequences of phenotypic variation.

Synaptic Pruning in Schizophrenia: Does Minocycline Modulate Psychosocial Brain Development?

“…The microglia‐complement system has likely evolved in humans to ensure an endless supply of heterogeneity in human aptitudes and personalities and the plastic ability to change roles or fill vacancies in the social structure, in line with other research focusing on the adaptive importance of stochastic phenotypic variation in ecology and evolution (e.g., see refs. [65–67]). This stochastic heterogeneity, presumably tuned and optimized by the social evolutionary process (see ref.…”

Plasticity of behavioural variability reflects conflicting selection in group-living and solitary desert locusts

“…In contrast to most previous related work (e.g. Prentice et al 2020 [15] ; Briffa, 2013 [8] ) our models 319 measured individual variances relative to their corresponding mean. This explicitly acknowledges the dis-320 tributional properties of the observed data, which are well approximated by a log-normal distribution, in 321 that they have a lower bound of 0 and, importantly, variances that scale with the mean.…”

“…The contrasting selection pressures of group-and lone-living are therefore expected to 14 lead to adaptive differences in the extent of behavioural variability [5] . 15 Reduction in either within-or between-individual variability of behaviour contributes to greater homo- 16 geneity of animal collectives [6] . Previous studies have largely focussed on changes in behavioural variability 17 as an instantaneously reactive process, when animals behave in one way when alone, but immediately adjust 18 their behaviour to be less variable when in the presence of conspecifics [2] .…”

“…This implies that the extent 28 of behavioural variability is regulated by intrinsic mechanisms and forms part of an animal's phenotype [14] . 29 Indeed, very recent studies report evidence for a genetic component to between-individual differences in 30 within-individual variability [15] . While such differences in intrinsic behavioural variability are predicted by 31 theory to be subject to selection, empirical evidence for adaptive changes is largely lacking [5] .…”

“…The underlying regulatory 281 mechanisms are therefore likely subject to selection, which, in more stable environments, would provide a 282 substrate for the subsequent evolution of genetically determined differences in behavioural variability. Recent 283 studies on yellow-bellied marmots and Trinidadian guppies provide evidence for genetic variance for behav-284 ioral predictability [15,30] . As pointed out in these studies, demonstrating genetic variance for predictability 285 in behaviours provides an important starting point for identifying both the environmental factors that geno-286 types respond to and the magnitude and direction of the evolutionary responses.…”