Fidler Andrew E, van Oers Kees, Drent Piet J, Kuhn Sylvia, Mueller Jakob C, Kempenaers Bart
Max-Planck Institute for Ornithology, PO Box 1564, 82319 Starnberg, Germany.
Proc Biol Sci. 2007 Jul 22;274(1619):1685-91. doi: 10.1098/rspb.2007.0337.
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, genotype-environment 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 15bp indel (ID15) located 5' 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.
多个与神经递质相关的基因中的多态性与人类人格特质的差异有关。在这些关联中，较有前景的是人类多巴胺受体D4基因（Drd4）变体与寻求新奇行为之间的关联。然而，基因上位性、基因型 - 环境相互作用以及混杂的环境因素都使得基因型与人格的关系变得模糊。通过在标准化条件下测量人格以及进行选择实验可以解决这些问题，但这两种方法仅适用于非人类动物。在自由生活的鸟类大山雀（Parus major）中寻找类似的Drd4基因型与人格的关联时，我们在大山雀Drd4直系同源基因中检测到73个多态性（66个单核苷酸多态性，7个插入缺失）。我们研究了大山雀Drd4基因的两个多态性，以寻找与寻求新奇行为相关的证据：一个编码区同义单核苷酸多态性（SNP830）和一个位于假定转录起始位点5'端的15bp插入缺失（ID15）。在经过四代选择以获得不同水平“早期探索行为”（EEB）的两个大山雀品系中，三种Drd4 SNP830基因型的频率存在显著差异，但ID15基因型的频率没有显著差异。对自由生活、未经选择的鸟类的分析为这一发现的重要性提供了有力的确证，我们发现SNP830基因型与不同的平均EEB水平之间存在显著关联。这些发现表明，Drd4基因多态性与动物人格差异之间的关联在鸟类和哺乳动物谱系分化之前就已存在。此外，这项工作预示着在自然选择对不同人格类型有不同作用的种群中，追踪行为相关的Drd4多态性频率的微进化变化的可能性。
