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Dryad

Do animal personality components independently evolve and develop in response to environmental complexity?

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Jan 28, 2025 version files 587.04 KB

Abstract

Widespread existence of consistent differences in behaviour among individuals even within species and populations, i.e., animal personality, has been established since the last decades in a wide array of taxa. However, little is known about personality traits' ontogeny and evolution. This study aimed at exploring eco-evolutionary mechanisms driving the emergence and development of animal personality. Focusing on boldness as a personality trait, we assessed how personality components (mean, among- and within-individual variabilities, repeatability, and plasticity in response to environmental complexity) develop at early age. Investigating developmental trajectories of all personality components, rather than averages only, offers a more exhaustive and comprehensive picture of how personality emerges, develops, and evolves. We compared personality components between juveniles of five morphs of Arctic charr (Salvelinus alpinus) ranging along gradients of ecological and genetic divergence from a common ancestor, raised from hatching in plain vs. structurally complex treatments. On the one hand, we show that some of these personality components evolve and develop independently from the others: mean boldness, which increases with divergence from the ancestor, was predominantly genotype-dependent and suspectedly a highly heritable trait with strong and stable selective pressures acting on it in the wild, while boldness repeatability might rather depend on the ecology of each morph. These two components were not affected by environmental complexity. On the other hand, variability-related components of personality, including their plasticity in response to environmental complexity, were rather dependent on genotype-by-environment effects and seemingly evolve and develop jointly. Boldness tended to be more consistent within the treatment mimicking the structural complexity of a given morph’s natural habitat, hinting that personality emergence might be favoured for individuals experiencing conditions to which they have been adapted. These findings suggest mechanisms by which personality components could be implicated in adaptability to environmental changes or even sympatric diversification and biodiversity.