Drd4 gene polymorphisms are associated with personality variation in a passerine bird

Abstract

Polymorphisms in several neurotransmitter-associated genes have been associated with variation in human personality traits. Among the more promising of such associations is that between the human dopamine receptor D4 gene (Drd4) variants and novelty-seeking behaviour. However, genetic epistasis, genotypeenvironment interactions and confounding environmental factors all act to obscure genotype-personality relationships. Such problems can be addressed by measuring personality under standardized conditions and by selection experiments, with both approaches only feasible with non-human animals. Looking for similar Drd4 genotype-personality associations in a free-living bird, the great tit (Parus major), we detected 73 polymorphisms (66 SNPs, 7 indels) in the P. major Drd4 orthologue. Two of the P. major Drd4 gene polymorphisms were investigated for evidence of association with novelty-seeking behaviour: a coding region synonymous single nucleotide polymorphism (SNP830) and a 15 bp indel (ID15) located 5 0 to the putative transcription initiation site. Frequencies of the three Drd4 SNP830 genotypes, but not the ID15 genotypes, differed significantly between two P. major lines selected over four generations for divergent levels of 'early exploratory behaviour' (EEB). Strong corroborating evidence for the significance of this finding comes from the analysis of free-living, unselected birds where we found a significant association between SNP830 genotypes and differing mean EEB levels. These findings suggest that an association between Drd4 gene polymorphisms and animal personality variation predates the divergence of the avian and mammalian lineages. Furthermore, this work heralds the possibility of following microevolutionary changes in frequencies of behaviourally relevant Drd4 polymorphisms within populations where natural selection acts differentially on different personality types.

Individual behavioral phenotypes: An integrative meta‐theoretical framework. Why “behavioral syndromes” are not analogs of “personality”

“…The four key questions on the causation, ontogeny, adaptivity, and phylogeny that Tinbergen (1963) originally formulated to study behavior at the species level are increasingly refined to the individual level. Animal researchers study genetic variation (Fidler, van Oers, Drent, Kuhn, Mueller, & Kempenaers, 2007), epigenetic influences , psychobiological parameters (Kinnally, Lyons, Abel, Mendoza, & Capitanio, 2008;Schneider & Suomi, 1992), and developmental conditions (Fairbanks & McGuire, 1993) associated with behavioral differences among individuals. Assuming that "nothing in biology makes sense except in the light of evolution" (Dobzhansky, 1973), sophisticated models are developed to explain their emergence from evolutionary viewpoints (Dall, Houston, & McNamara, 2004;Wolf, van Doorn, Leimar, & Weissing, 2007).…”

A chromosome-wide QTL study on BTA29 affecting temperament traits in German Angus beef cattle and mapping of DRD4

“…The dopamine receptor D4 gene (DRD4) is involved in curiosity behaviour and novelty seeking in different mammals such as mice (Rubinstein et al, 1997), dogs (Niimi et al, 1999), horses (Momozawa et al, 2005) and birds (Fidler et al, 2007). In humans, DRD4 is also associated with novelty seeking, an aspect of human temperament (Keltikangas-Jarvinen et al, 2003).…”

What can whole genome expression data tell us about the ecology and evolution of personality?

“…For example, genetic variation in a candidate gene, the D4 dopamine receptor, DRD4, has been related to consistent individual differences in exploratory behaviour in a wild bird, the great tit (Fidler et al 2007), selected lines of a domesticated bird, laying hens (Flisikowski et al 2009), horses (Momozawa et al 2005) and humans (Munafo et al 2008), suggesting that exploratory behaviour in this diverse array of vertebrate species shares a common molecular basis (but see Korsten et al 2010). It is important to stress that in these cases, a polymorphism has been found in this receptor, but the functional significance of this polymorphism has not been tested in all species.…”

“…Although traditional quantitative genetic approaches have helped us to understand the genetic architecture underlying natural variation in personality traits (Dingemanse et al 2002;Drent et al 2003;Réale & Festa-Bianchet 2003;Bell 2005;Dochtermann & Roff 2010), such approaches necessarily measure phenotypes, rather than the genes that underlie behavioural variation, and therefore have limited use for understanding specific molecular and genetic mechanisms. When studies have tried to relate specific individual genes to personality traits in humans, model laboratory animals or domesticated animals (Champoux et al 2002;Geller et al 2002;Adamec et al 2006;Fidler et al 2007), they have found that specific candidate genes, such as the dopamine receptor 4 (DRD4), the serotonin transporter (SERT) and monoamine oxidase (MAO), only explain a small fraction of the total genetic variation (reviewed in Reif & Lesch 2003), indicating that we are yet to learn the identity of most of the important genes (or that all of the genes are of very small effect). Moreover, epistatic interactions between loci make it difficult to study the effects of single genes one-at-a-time (Mackay 2009).…”