Why individuals differ in behavioural responses has received intense research attention, and has typically focused on describing variation in boldness, activity, and exploration. Nevertheless, the mechanisms underlying this behavioural variation remain largely unknown. Variation in these behaviours is likely influenced by genetic differences between individuals, with genes in the monoaminergic systems commonly implicated.

Therefore, to both replicate the generally expected associations between monoaminergic systems and behaviours used to describe personality, and to expand upon previous work in terms of genes. I have investigated associations between genes of the serotonergic system (TPH, 5HT1B, 5HT2A, 5HT2B, 5HT2C) and dopaminergic system (DRD1, DRD2) with variation in boldness, activity, and exploration, in the red junglefowl (Gallus gallus).

Additionally, I aimed to further investigate the relationship between the serotonergic system and variation in the behaviours impulsivity, boldness activity and exploration, by experimentally altering levels of serotonin in red junglefowl chicks using the human pharmaceutical Fluoxetine.