Table 4.

Effects of Domestication and Feralization on Behavior-Related Phenotypes^a

Behavioral trait	Δ Domestic (versus wild) phenotype		Δ Feral (versus domestic) phenotype
Brain volume	↓	Diverse mammals, birds, fish [86]	=	Diverse mammals [86], with exception of dingo [88]
Proportional size of brain regions	↕	Altered allometry of motor, limbic, and sensory regions in diverse taxa. Most pronounced regressions affect limbic regions [86]	↕	In exception to many examples of stasis [86], dingoes and pigs show partial ‘wild-type’ reversions 88, 89
Gene expression in brain	↕	Dogs [116], cows, horses, pigs, rabbits [90]	?
Aggression toward conspecifics	↕	Reduced agonism in many taxa, including fish and dogs. Increased agonism in some fighting breeds (e.g., bulls and cockerels [12])	↑	Roosters [92]
Predator avoidance	↓	Chickens, pheasants, rodents, fish 19, 86, 93, 117	↑	Chickens [92], guppies [93]
Habitat selectivity	↓	Deer mice [12]	?
Neophobia	↓	Mice, rats [19]	↑	Chickens [92]
Stress response	↓	Guinea pigs, foxes, mice [116]	?
Reproductive seasonality	↓	Foxes [116], chickens [118], dogs [19]	?
Diet selectivity	↓	Cats [86]	↓	Salmon parr [12]
Vocalization	↕	Higher rates in dogs, birds, guinea pigs [12], reduced diversity in birds [19]. Rates are also variable among breeds [117]	?

^a↑trait magnitude is higher; ↓trait magnitude is lower; ↕trait change varies by case (e.g. among previously-studied taxa, contexts, or populations).