Kin Selection

Question 1

Describe kin selection in a social behaviour

Answer 1

• An altruistic mutation can invade if altruism increases the fitness of other carriers of the mutation
• Hamilton’s rule:
Relatedness * benefit > cost
• E.g. slime mould (a social amoeba)
- good conditions cells feed individually, starvation release cAMP and form slug then multicellular fruiting body that releases spores. Stalk dies
- experimental evolution under low relatedness using transfer of spores
- mix evolved strain with ancestor (Fluorescently labelled) and look at % stalk and % spores
- ancestor was underrepresented in spores
—> Altruism is only maintained by inclusive fitness benefits

Question 2

Define inclusive fitness

Answer 2

Evolution of a trait depends on the effect on both the bearer’s fitness and the fitness of others (kin)

Question 3

Describe kin selection in a non-social behaviour

Answer 3

Dispersal
• cost- mortality, benefit- reduce kin competition
• E.g. common lizard (Lacerta viviparous)- saturated habitat, senescence, breeding territory competition
- the benefit of increased maternal reproduction is age dependent
- the dispersal rate is higher when the mother is young

Question 4

How can spite have evolved?

Answer 4

Relatedness and benefit can both be negative:
• Can act in way that negatively benefits you and target if they are negatively related to you- more genetically dissimilar than random individual
• Green beard gene- social behaviour and recognition
• E.g. social chromosome in Fire Ant (Solenopsis Invicta)- monogynous and polygynous
- genetic difference at Gp9- alleles B and b. BB monogynous, Bb queens, Bb,BB workers poly (bb lethal)
- BB queens eliminated in polygynous colonies more by Bb workers than chance would predict
(Keller and Ross, 1998)
- allele linked to selfish gene-> spiteful elimination of non b carriers. Part of large non-recombining block
(Pracana et al., 2017)