Lecture 11 Flashcards
What is a group of female pigs with their offspring called?
a sounder
What are the different forms of group living among domesticated species?
- Pigs: female group, male group or solitary
- Horses: harems, bachelor herds
- Sheep: ewe flocks, seasonal male flocks
What is the difference between wild and feral?
wild: never been domesticated
feral: been domesticated but let back into wild (pigs, horses)
What are the soay sheep on St.Kilda?
- island off the coast of Scotland
- 1,000 sheep
- most primitive form of domestic sheep, arrived around 4,000 years ago
- went feral 1,000 years ago
- Ewe flocks with infant and juvenile offspring, on home ranges, groups and range are consistant, form small sub-groups for grazing
- Rams disperse and form small groups, establish home range, disband during breeding (rut)
What is the usask feral horse research?
- Sable Island ponies - around 400 horses (herd size increasing) in Nova Scotia
- linked to growing grey seal population - hunting from humans decreased
- horses benefit because seals fertilize the grass
What are the differences and similarities between domestic and wild animals?
Domestication of farm species happened 10,000 to 15,000 years ago (short)
Differences: Domesticates have… smaller brains, less active, reduced alarm responses, more socially tolerant
Similarities: same basic social characteristics are found, threshold or frequency of behaviours may change
How does natural selection operate on genetic difference for behaviour to evolve?
- there must be behavioural variation within the population
- the differences must be heritable - some of the variation must be genetic in orgin
- some behavioural variations will confer greater reproductive success
- Behaviour patterns are seleceted that will increase an animals chances of survival and reproduction - “fitness”
highest benefit with the lowest cost
What determines success in evolutionary terms?
survival
reproduction
Differences between Suffolk and Blackface sheep for maternal behaviour?
Suffolk:
* required more assistance
* abandoned more lambs
* more aggressive
* withdrew more often from lambs
Blackface (wild type):
* shorter labour
* more grooming
* cooperated more during suckling attempts
* lower lamb mortality
How does evolutionary theory explain groups?
- groupos are facilitated by cooperation - but evolutionary theory is usually described in terms of competition among individuals (beneficial to both)
- theories about selfish traits
What are the theories explaining cooperation?
Kin selection
* inclusive fitness theory
Reciprocal altruism
* generosity - I give you something today, you give me something another day
Multi-level (group) Selection
* Some selection occurs at group level
* There is strength in diversity
What is kin selection?
- Individuals can reproduce directly, or indirectly by aiding relatives (still helping gene pool)
- group living is facilitated by cooperation between individuals - increase genetic contribution by assisting with the success of relatives
- ex. wolves: others in pack will help raise pups
- part of the ‘inclusive fitness’ theory
What is Hamilton’s Rule in relatedness?
b > c / r
* c = cost (actor)
* b = benefit (recipient)
* r = degree of relatedness
shows how much you’re willing to help someone based on how closely related you are
bigger r= smaller cost
Why would non-relatives cooperate?
Reciprocal altruism:
* alternating benefits - long term relationships (I help you, expect something in return) - vampire bats
Multi-level selection:
* groups that cooperate outcompete those that don’t - lions elephants
stable societies - cooperation has long-term benefits
What are the costs and benefits of social groups?
Benefits:
* thermal
* foraging
* predation
Costs:
* contamination
* competition
* conspicuous
