Cooperation and Selfish genes

Co-operation and Selfish genes

Meerkats (Suricata suricatta)

• Small Mongoose
• Southern Africa
• Invertebrates, small vertebrates - immune to venom from scorpions??
• Dirunal
• Elaborate burrow system
• Social groups of up to 40 individuals
• Female-dominated society
• Rich repertoire of cooperative behaviours

Breeding

• Family groups 2-40 individuals
• Dominant females, up to 4 litters, each of 4 pups, per year
• Pups stay in natal burrow in month 1 then follow gorup on foraging trips
• Independent at 3 months
• Studied since 1993 by Clutton-Brock

Compare the Meerkat

Benefit to parent

• Help rearing offspring
• More protection
• Increased resources, therefore increased survival and ultimately results in direct fitness
• Increased survival of offspring
• Can raise more young

Cost to parent

• stressful retaining dominance
• risk of infanticide
• lack of experience (from helpers and parent herself)
• Decreased survival of the offspring
• Responsibility of stress for others

Benefit to helper

• increased indirect fitness
• Higher social standing
• Increase protection
• Act on their instincts even though it isnt there offspring
• Experience

Cost to helper

• Unable to pass on genes directly
• weight loss (11%)
• Survival, disperal, breeding

A potential problem for evolutionary theory?

• Before 1960, biologists regarded co-operation as a prime example of acting "for the good of the species"
• But group seleciton is less robust than individual selection
• How can we account for the evolution of cooperation that involves helping another at a cost to oneself?

Hamilton (1964)

• It is possible for altruism to evolve as a trait as long as the benefits of altruistic acts fall on individuals that are genetically related to the donor.
  • It is advantageous for an animal to give an alarm call, and thus place itself in danger, to warn a group of relatives, since its relatives also carry copies of its genes.

Kin Selection

• r B>C or r B-C>0
  • C = fitness cost suffered by the altruist
  • B = fitness benefit gained by the recipient
  • r  = coefficient of relatedness between altruist and beneficiary
• So, the relatedness of the individual that profits from the altruistic act must be higher than the cost/benefit ratio this act imposes.
• Shared genes will profit if the cost to the altruist is less than the benefit to the recipent multipled by the probability that the recipient shares genes with the donor.
• So, you are more likely to aid a close relative over a distant one.
• …