Kin selection theory explains the evolution of altruism. While altruism seems to go against individual survival and fitness, kin selection demonstrates that altruistic behavior can persist if the altruistic individual helps genetically similar relatives to survive and pass on shared genes. Key examples discussed are sterile worker ants helping their queen sister reproduce since they share three-quarters of their genes, and ground squirrels whose alarm calls risk individual safety but benefit genetically related neighbors. The theory was developed by W.D. Hamilton and others to explain how natural selection can favor altruism between kin.

1. The Evolution of Kin Selection By Aditya Kuroodi Period 5

2. Key Vocab Fitness of an Animal: How many offspring it has, which leads to number of genes present Individual Fitness: Number of own offspring and genes passed on Inclusive Fitness: Ind. Fit. + Number of identical offspring and genes passed on Altruism: Selfless concern for the welfare of others

3. Kin Selection Kin selection is a theory about the evolution(persistence) of altruism When animal risks itself to help relatives survive Since they’re related, some of that animal’s genes still get passed on Altruistic animals still persist because their genes are present in the relatives they save

4. Kin Selection Natural selection technically shouldn’t allow for evolution of altruistic animals But kin selection theory proved that it could Kin selection says that relatives also might contain the “altruistic gene” Thus, offspring still receive gene, and altruism continues Altruism is preferred on a group basis, not an individual one, unless it has to do with kin

5. Fire Ants All ants are Euosocial Have sterile workers and Queen to reproduce Because they are haplodiploid Normally, no one would be sterile Sisters share 75% genes w/ each other More effective to help Queen make sisters than have own offspring This is kin selection at its finest

6. Alarm Calls in Squirrels Many squirrels have alarm calls when they sense danger The squirrel that makes the call puts itself in risk, but saves others around it The closest animals around it are most probably kin The kin survive, and the ability to make an alarm call persists Also, scientists have discovered that some squirrels change the call if relatives aren’t around

7. Cool Squirrels

8. Cool Squirrels

9. Scientists The idea of kin selection was pondered at first by Darwin “a tribe including many members who...were always ready to give aid to each other and sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection” (p.166) Darwin thought altruism was caused by group selection

10. Evidence against Group Selection The idea of group selection was quickly discarded Idea of “free riders” cashing in on groups of altruists (Dawkins) They would have huge advantage and take over; altruism would be run over by selfishness This was from works of John Maynard Smith, Richard Dawkins, W.D. Hamilton and G.C. Williams

11. W.D. Hamilton Main man in the world of kin selection Used inclusive fitness to support theory Inspired by Haldane, and R.A. Fisher His rule RB>C explains when altruism would continue R is how related the animals is (brother vs cousin, etc) B is benefit to group(Inclusive fitness) C is cost to individual ( Loss of Individual Fitness)

12. Contribution of Kin Selection Theory Kin selection puts a new spin on the classic ideas of natural selection Darwin imposed It differs from the view that evolution and life is on a strict individual basis Relationships in animals plays a major role in evolution There could be an “Altruistic Gene” that is passed on or not

13. Timeline

14. Works Cited http://plato.stanford.edu/entries/altruism-biological/ http://taumoda.com/web/PD/library/kin.html http://es.rice.edu/projects/Bios321/eusocial.insect.html http://www.animalbehavioronline.com/haplodiploidy.html www.Wikipedia.com