Associations of genetic polymorphisms with boldness, stress response, and route efficiency in homing pigeons (Columba livia)

Animals vary consistently in traits such as boldness and stress reactivity, which influence fitness, movement, and social dynamics. Identifying genetic variants linked to these behaviours can clarify proximate mechanisms and evolutionary trade-offs. Dopaminergic (DRD4) and serotonergic (TPH2) pathways are known to modulate exploration and emotionality, while LDHA contributes to neuroenergetics and endurance, yet their combined role in shaping behavioural diversity remains unclear. Here we show, in 137 homing pigeons, that a SNP at position C382T in DRD4 and T185A in TPH2 are significantly associated with boldness. Birds with DRD4 T/T and TPH2 T/A genotypes emerged more quickly from the shelter. We also found that DRD4 C/C and TPH2 T/A genotypes were associated with slower recovery from acute social isolation stress, quantified by eye infrared thermography. In addition, a microsatellite polymorphism in LDHA intron 6 interacted with the presence of a mirror companion, suggesting a genotype-dependent effect of social buffering. These findings provide evidence that common genetic variants in neuromodulatory and metabolic genes contribute jointly to behavioural and physiological syndromes in birds, and social context can interact with genotype to influence stress resilience. We demonstrate how candidate markers are useful in exploring the ecological and evolutionary consequences of personality variation.