Genetic accommodation and behavioural evolution: insights from genomic studies

Many behaviours vary in response to the environment (biotic or abiotic) and therefore represent an interesting form of phenotypic plasticity. Behavioural plasticity, like other plastic traits, can evolve through genetic assimilation or accommodation. However, little is known about the nature of changes in gene expression plasticity that accompanies these evolutionary changes in phenotypic plasticity. We know that variation in gene expression level, a first-order phenotype, underlies much behavioural variation. Several studies have begun to document which genes show expression-level variation related to plastic changes in behaviour as well as evolved changes in behaviour. Advances in sequencing technology allow us to address these questions on a genomic scale. By characterizing changes in gene expression according to the concept of a norm of reaction one can describe the evolved patterns of gene expression that accompany the evolution of behavioural plasticity. Here, we describe how genomic approaches can help us understand changes in gene expression that accompany or underlie the evolution of behavioural plasticity. To do this, we provide a framework of classification for the evolved patterns of gene expression plasticity that could underlie genetic assimilation or accommodation of behaviour. We provide examples of genetic assimilation from the animal behaviour and animal physiology literature that have been, or can be, studied at a genomic level. We then describe the characteristics of an appropriate study system and briefly address experimental design using the available genomic tools in a comparative context. Studying the patterns of gene expression associated with genetic assimilation will elucidate processes by which behavioural plasticity has evolved.

► Behavioural plasticity is an important form of adaptive phenotypic plasticity.
► As a concept ‘genetic assimilation’ can describe the evolution of behavioural phenotypes.
► Advances in modern genomics can be applied to the evolution of behavioural plasticity.
►  Several patterns of evolved gene expression plasticity can underlie behavioural plasticity.
► The appropriate study system allows comparison between species and environments.