How do you explain that the variability in a domesticated species is greater than in the same species, or a similar one, in the wild? For example: dogs vs. wolves; chickens vs. red jungle fowl.

i believe it is because the domesticated breeds were bred specifically through generations in order to serve a specific purpose, for example dogs could be bred for hunting or herding, etc and chickens could be bred for eggs or meat, etc. but in the wild, their only job is to survive and reproduce.