Lecture 14: Kin selection Flashcards
4 examples of social interactions within group living
- ccoperation
- altriusim
- selfishness
- spiteful
- -conflict may be involved in any
how can altruism evolve? what u would probs predict?
- recipient of altruistic behaviour gains benefits, leaves more offspring
- actor is NOT going to leave more offspring, may even be fewer
- so if altruism is heritable should die out over generations?
why don’t altruistic behaviours go extinct? group selection?
group selection?
- pops made up of selfish genes have a higher extinction rate (bcos of exhausted food supply) than altruistic ones?
- expect groups evolve altruism though greater survival of groups, even tho individual survival will be opposite
- -> William (1966) said adaptations to benefit group don’t exist!
so how have altruistic behaviours evolved?!
by KIN SELECTION, an allele for altruism can increase in frequency in a population if the recipients of the altruistic behaviour tend to be related to the individual performing it
e.g. kin selection
- Beldings ground squirrel
- –females call to alert their relatives of danger
- Helpers at the nest
- –helpers tend to be related to parents (often own offspring from the brood)
kin selection was put forward by
Bill Hamilton
–incorporates idea of inclusive fitness
inclusive fitness =
direct fitness (personal fitness gains) + indirect fitness (additional fitness gained from relatives made possible by individual actions)
kin selection: amount of indirect fitness depends on
how relate individuals r
Hamiltons rule:
rB>C –> for altruism to occur
(rB–C>0)
B = benefit to recipient r = relatedness C = cost to actor
Eusociality:
ultimate example of altruism
- -individuals give up their reproductive potential completely to assist another in producing offspring
- insects (bees,wasps,ants) –> Hymenoptera
Characteristics of eusociality:
- overlap in generations between parents and offspring
- cooperative brood care
- specialised castes of non-repordictive individuals
why does eusociality occur in hymenoptera:
due to HAPLOPLOIDY;
- females are diploid
- males are haploid (unfertilised egg)
=sisters share 1/2 genes from their mother, but ALL from their father. so sisters share 3/4 of their genes = more closely related to each other than their offspring –> so help sisters instead
is haplodiploidy the explanation of eusociality in hymenoptera:
PROBS NOT:
1) the previous analysis assumes only 1 male fertilisers a queen – not always true (honeybees)
2) in some species, colonies may be founded by >1 queen
- many eusocial non-hymenopteran are diploid (e.g. termites)
- many hymenoptera aren’t unsocial
haplodiploid may _____ the evolution of eusociality but a more important factor may be the ___
facilitate
-the need for help in rearing young
how many independent origins of eusociality are there in hymenoptera?
3! all associated with nest building and larval care
Eusociality ONLY occurs in species with
1) complex nests
2) extensive larval care
- -females unlikely to be able to breed alone –» ECOLOGICAL NOT GENETIC?
example of kin selection in non help situation
cannibalistic spadefoot toad, develop into 2 morphs: one eats decaying plant, other eats tadpoles
–but they are more likely to eat non-sibs than sibs when given choice
are sperm altruistic?
some species produce distinct morphologies of sperm (SPERM HETEROMORPHISM)
-one morph is fertile (eusperm), other sterile (parasperm)–> parasperm protect eusperm in hostile female tract? YES
sperm cooperation?
sperm can hook onto others from the same male, they don’t hook to other males or even other siblings
active kin-directed bevaiour requires what?
KIN RECOGNITION
- smells
- song
- learned familiarity
- visual similarity
- -kin recognition is NOT necessary for kin selection to operate
kin selection operates as long as altruists are ____ towards kin, for whatever reason (bcos selection will favour this behaviour)
biased
kin selection uses idea of ____ to explain realist that are antagonistic to NS
inclusive fitness
