domestication

biological process

• form of genetic selection in that the parent animal (first one domesticated) becomes isolated from the wild animal

This results in “genetic drift” from its wild ancestors (active or passive)

cultural process

• involves changes in how the animal becomes included in the social structure of human societies

  • in other words, what role does it play in its interactions with humans?

domestication is really a form of…

symbiosis

how does symbiosis occur

guest/host interactions

• guest is subordinate

• host is dominant

perfect symbiosis

occurs when both partners derive equal benefits, without domination by one of the partners

• both are equal and there is no subordinate or dominant partner (very, very, very rare)

• cow & microbes in rumen is very close to perfect

main takeaways

• domestication is a process and is constantly underway

• domestication is symbiotic (humans: host, animals: guest)

• domestication includes biological and cultural aspects)

what hypothesis did dmitry belyaev propose?

the primary factor selected for during domestication was a behavioral trait called tamability

how did belyaev define tamability?

• believed it was an innate behavioral genetic trait that all animals possessed

  • variation in expression among populations, just like any other trait

believed you could select for it

belyaev called tamability a “___ order gene”

tamability is a high order gene

• genes that control other traits called “lower order genes”

he observed how it affects the phenotypes

belyaev’s PREDICTED phenotypic changes of domestication

• blazed foreheads

• curled tail

• floppy ears

• piebald coat

describe belyaev’s experiement

he wanted to devise a way to select for tamability

• wanted to prove that animals differ in tamability and selecting for tamability would cause a change in phenotype

used a wild population of foxes

tested the tamability of foxes and grouped them together (class III, II, or I)

• bred within the tamability groups

after 20 gen, he observed many of the phenotypic changes that he predicted

belyaev class III

• less domesticated

• fled or bit when stroked or handled

belyaev class II

allowed handling

but showed no emotionally “friendly” response

belyaev class I

“Domesticated elite”

eager to establish human contact

lick or sniff

friendly

wagged tails or whined for attention

belyaev’s OBSERVED phenotypic changes of domestication

• dwarf & giant breeds (body size variation)

• piebald coat

• blazed foreheads

• floppy ears

• curled tails

• wavy or curly hair

physiological changes from belyaev’s tamability experiment

• breeding season (became less seasonal w/ domestication)

• fertility (become more fertile w/ domestication)

• hearing and sight age increased