The genetic basis of animal behavioural diversity in natural populations.

Individual differences in animal behaviour influence ecological and evolutionary processes. Much behavioural variation has a heritable component, suggesting that genetics may play a role in its development. Yet, the study of the mechanistic description linking genes to behaviour in nature remains in its infancy, and such research is considered a challenge in contemporary biology. Here, we performed a literature review and meta-analysis to assess trends in analytical approaches used to investigate the relationship between genes and behaviour in natural systems, specifically candidate gene approaches, quantitative trait locus (QTL) mapping, and genome-wide association studies (GWAS). We aimed to determine the efficacy and success of each approach, while also describing which behaviours and species were examined by researchers most often. We found that the majority of QTL mapping and GWAS results revealed a significant or suggestive effect (Zr = 0.3 [95% CI: 0.25:0.35] and Zr = 0.39 [0.33:0.46], respectively) between the trait of interest and genetic marker(s) tested, while over half of candidate gene accounts (Zr = 0.16 [0.11:0.21]) did not find a significant association. Approximately a third of all study estimates investigated animal personality traits; though, reproductive and migratory behaviours were also well-represented. Our findings show that despite widespread accessibility of molecular approaches given current sequencing technologies, efforts to elucidate the genetic basis of behaviour in free-ranging systems has been limited to relatively few species. We discuss challenges encountered by researchers, and recommend integration of novel genomic methods with longitudinal studies to usher in the next wave of behavioural genomic research.