Lecture 14: Kin selection

Question 1

4 examples of social interactions within group living

Answer 1

• ccoperation
• altriusim
• selfishness
• spiteful
• -conflict may be involved in any

Question 2

how can altruism evolve? what u would probs predict?

Answer 2

• 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?

Question 3

why don’t altruistic behaviours go extinct? group selection?

Answer 3

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!

Question 4

so how have altruistic behaviours evolved?!

Answer 4

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

Question 5

e.g. kin selection

Answer 5

• 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)

Question 6

kin selection was put forward by

Answer 6

Bill Hamilton

–incorporates idea of inclusive fitness

Question 7

inclusive fitness =

Answer 7

direct fitness (personal fitness gains) + indirect fitness (additional fitness gained from relatives made possible by individual actions)

Question 8

kin selection: amount of indirect fitness depends on

Answer 8

how relate individuals r

Question 9

Hamiltons rule:

Answer 9

rB>C –> for altruism to occur

(rB–C>0)

B = benefit to recipient 
r = relatedness 
C = cost to actor

Question 10

Eusociality:

Answer 10

ultimate example of altruism

• -individuals give up their reproductive potential completely to assist another in producing offspring
• insects (bees,wasps,ants) –> Hymenoptera

Question 11

Characteristics of eusociality:

Answer 11

• overlap in generations between parents and offspring
• cooperative brood care
• specialised castes of non-repordictive individuals

Question 12

why does eusociality occur in hymenoptera:

Answer 12

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

Question 13

is haplodiploidy the explanation of eusociality in hymenoptera:

Answer 13

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

Question 14

haplodiploid may _____ the evolution of eusociality but a more important factor may be the ___

Answer 14

facilitate

-the need for help in rearing young

Question 15

how many independent origins of eusociality are there in hymenoptera?

Answer 15

3! all associated with nest building and larval care

Question 16

Eusociality ONLY occurs in species with

Answer 16

1) complex nests
2) extensive larval care
- -females unlikely to be able to breed alone –» ECOLOGICAL NOT GENETIC?

Question 17

example of kin selection in non help situation

Answer 17

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

Question 18

are sperm altruistic?

Answer 18

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

Question 19

sperm cooperation?

Answer 19

sperm can hook onto others from the same male, they don’t hook to other males or even other siblings

Question 20

active kin-directed bevaiour requires what?

Answer 20

KIN RECOGNITION

• smells
• song
• learned familiarity
• visual similarity
• -kin recognition is NOT necessary for kin selection to operate

Question 21

kin selection operates as long as altruists are ____ towards kin, for whatever reason (bcos selection will favour this behaviour)

Answer 21

biased

Question 22

kin selection uses idea of ____ to explain realist that are antagonistic to NS

Answer 22

inclusive fitness