Individual variation in quantitative traits clearly influence many ecological and evolutionary processes. Moderate to high heritability estimates of personality and life-history traits suggest some level of genetic control over these traits. Yet, we know very little of the underlying genetic architecture of phenotypic variation in the wild. In this study, we used a candidate gene approach to investigate the association of genetic variants with repeated measures of boldness and maternal performance traits (weaning mass and lactation duration) collected over an 11- and 28-year period, respectively, in a free-ranging population of grey seals on Sable Island National Park Reserve, Canada. We isolated and re-sequenced five genes: dopamine receptor D4 (DRD4), serotonin transporter (SERT), oxytocin receptor (OXTR), and melanocortin receptors 1 (MC1R) and 5 (MC5R). We discovered single nucleotide polymorphisms (SNPs) in each gene; and, after accounting for loci in linkage disequilibrium and filtering due to missing data, we were able to test for genotype-phenotype relationships at seven loci in three genes (DRD4, SERT, and MC1R). We tested for association between these loci and traits of 180 females having extreme shy-bold phenotypes using mixed-effects models. One locus within SERT was significantly associated with boldness (effect size = 0.189) and a second locus within DRD4 with weaning mass (effect size = 0.232). Altogether, genotypes explained 6.52–13.66% of total trait variation. Our study substantiates SERT and DRD4 as important determinants of behaviour, and provides unique insight into the molecular mechanisms underlying maternal performance variation in a marine predator.

数量性状的个体差异明显影响许多生态和进化过程。对人格和生活史特征的中等至高遗传力估计表明对这些特征存在某种程度的遗传控制。然而，我们对野外表型变异的潜在遗传结构知之甚少。在这项研究中，我们使用候选基因方法来研究遗传变异与在 11 年和 28 年期间分别收集的大胆和母体性能特征（断奶质量和泌乳持续时间）的重复测量之间的关联，加拿大黑貂岛国家公园保护区的灰海豹种群。我们分离并重新测序了五个基因：多巴胺受体 D4 ( DRD4 )、血清素转运蛋白 ( SERT)、催产素受体 ( OXTR ) 和黑皮质素受体 1 ( MC1R)和 5 ( MC5R )。我们在每个基因中发现了单核苷酸多态性 (SNP)；并且，在考虑了连锁不平衡中的基因座并由于缺失数据进行过滤后，我们能够测试三个基因（DRD4、SERT和MC1R）中七个基因座的基因型-表型关系。我们使用混合效应模型测试了这些基因座与 180 名具有极端害羞表型的女性特征之间的关联。SERT中的一个基因座与粗度显着相关（效应大小 = 0.189）和DRD4中的第二个基因座断奶质量（效应大小 = 0.232）。总之，基因型解释了总性状变异的 6.52-13.66%。我们的研究证实SERT和DRD4是行为的重要决定因素，并为海洋捕食者中母体表现变化的分子机制提供了独特的见解。