BIOE 109 Summer 2009 Lecture 9- Part II Kin selection

1. BIOE 109 Summer 2009 Lecture 9- Part II Kin selection

2. Types of social interactions “Actor”  “Recipient” outcome of interaction measured in terms of fitness i.e. units of surviving offspring Actor benefits Actor harmed Recipient benefits Recipient harmed

3. Types of social interactions “Actor”  “Recipient” outcome of interaction measured in terms of fitness i.e. units of surviving offspring Actor benefits Actor harmed Recipient Cooperative benefits Recipient harmed

4. Types of social interactions “Actor”  “Recipient” Actor benefits Actor harmed Recipient Cooperative Altruistic benefits Recipient harmed

5. Types of social interactions “Actor”  “Recipient” Actor benefits Actor harmed Recipient Cooperative Altruistic benefits Recipient Selfish harmed

6. Types of social interactions “Actor”  “Recipient” Actor benefits Actor harmed Recipient Cooperative Altruistic benefits Recipient Selfish Spiteful harmed

7. Types of social interactions “Actor”  “Recipient” Actor benefits Actor harmed Recipient Cooperative Altruistic benefits Recipient Selfish Spiteful harmed Rare -an allele that results in fitness losses for both R&A would be eliminated by Natural selection

8. Types of social interactions “Actor”  “Recipient” Actor benefits Actor harmed Recipient Cooperative Altruistic benefits Recipient Selfish Spiteful harmed

9. Co-operation and altruism

10. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor

11. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor • Why does altruism exist in nature? how can altruistic behaviors evolve?

12. Bill Hamilton (1936 – 2000) http://www.blackwellpublishing.com/ridley/video_gallery/WH_What_is_the_problem_of.asp

13. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor • Why does altruism exist in nature? how can altruistic behaviors evolve? Br – C > 0

14. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor • Why does altruism exist in nature? how can altruistic behaviors evolve? Br – C > 0 let B = benefit to recipient

15. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor • Why does altruism exist in nature? how can altruistic behaviors evolve? Br – C > 0 let B = benefit to recipient let C = cost to actor (Both B and C are measure in units of surviving offspring)

16. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor • Why does altruism exist in nature? Br – C > 0 how can altruistic behaviors evolve? let B = benefit to recipient let C = cost to actor let r = coefficient of relatedness between actor and recipient

17. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor • Why does altruism exist in nature?Br – C > 0 how can altruistic behaviors evolve? let B = benefit to recipient let C = cost to actor let r = coefficient of relatedness between actor and recipient An allele for an altruistic behavior will be favored if: Br – C > 0

18. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor • Why does altruism exist in nature? how can altruistic behaviors evolve? Br – C > 0 let B = benefit to recipient let C = cost to actor let r = coefficient of relatedness between actor and recipient An allele for an altruistic behavior will be favored if: Br – C > 0 or Br > C

19. The evolution of altruism • an altruistic act benefits a recipient at a cost to the actor • Why does altruism exist in nature? how can altruistic behaviors evolve? Br – C > 0 let B = benefit to recipient let C = cost to actor let r = coefficient of relatedness between actor and recipient An allele for an altruistic behavior will be favored if: Br – C > 0 or Br > C • this is called “Hamilton’s rule”

20. Hamilton’s rule and the concept of inclusive fitness

21. Hamilton’s rule and the concept of inclusive fitness • “inclusive fitness” is equivalent to an individual’s total fitness

22. Hamilton’s rule and the concept of inclusive fitness • “inclusive fitness” is equivalent to an individual’s total fitness Inclusive fitness

23. Hamilton’s rule and the concept of inclusive fitness • “inclusive fitness” is equivalent to an individual’s total fitness Inclusive fitness  “Direct” component (i.e., individual’s own reproduction)

24. Hamilton’s rule and the concept of inclusive fitness • “inclusive fitness” is equivalent to an individual’s total fitness Inclusive fitness  “Direct” component“Indirect” component (i.e., individual’s own (i.e., act of individual that reproduction)increases fitness of its relatives)

25. Hamilton’s rule and the concept of inclusive fitness • “inclusive fitness” is equivalent to an individual’s total fitness Inclusive fitness  “Direct” component“Indirect” component (i.e., individual’s own (i.e., act of individual that reproduction)increases fitness of its relatives) kin selection is a form of natural selection favoring the spread of alleles that increases the indirect component of fitness.

26. A deeper look into Hamilton's rule which is ……..

27. A deeper look into Hamilton's rule which is …….. Br > C

28. What is the coefficient of relatedness (r)?

29. What is the coefficient of relatedness? • r is the probability that homologous alleles present in different individuals are “identical by descent”.

30. What is the coefficient of relatedness? • r is the probability that homologous alleles present in different individuals are “identical by descent”. • the inbreeding coefficient, F, is the probability that two homologous alleles present in the same individual are identical by descent.

31. What is the coefficient of relatedness? • r is the probability that homologous alleles present in different individuals are “identical by descent”. • the inbreeding coefficient, F, is the probability that two homologous alleles present in the same individual are identical by descent. • r can be estimated from:

32. What is the coefficient of relatedness? • r is the probability that homologous alleles present in different individuals are “identical by descent”. • the inbreeding coefficient, F, is the probability that two homologous alleles present in the same individual are identical by descent. • r can be estimated from: 1. pedigrees

33. What is the coefficient of relatedness? • r is the probability that homologous alleles present in different individuals are “identical by descent”. • the inbreeding coefficient, F, is the probability that two homologous alleles present in the same individual are identical by descent. • r can be estimated from: 1. pedigrees 2. genetic estimates of relatedness

34. Estimating r from pedigrees

35. Estimating r from pedigrees Parents contribute ½ of their genes…. The prob that genes are IBD in each step= 1/2 (1/2 * 1/2 )= 1/4

36. Estimating r from pedigrees (1/2 * 1/2 )+(1/2 * 1/2 )= 1/2

37. Estimating r from pedigrees (1/2 * 1/2 * 1/2)= 1/8

38. Examples of Kin Selection Selfish or Altruistic? http://www.youtube.com/watch?v=T3BgJ_BPm-M&feature=related

39. Alarm calls are given to warn kin Hoogland 1983

40. Alarm calls are given to warn kin Hoogland 1983

41. Examples of Kin Selection : Helping at the nest in bee-eaters

42. Examples of Kin Selection : Helping at the nest in bee-eaters Daughter Daughter/ Helper Mother Each parent, unaided, is able to raise 0.51 offspring………… Each helper is responsible for an additional 0.47 offspring being raised!

43. Helping at the nest in bee-eaters, why? Mother-Daughter Actor 1/2 Recipient Sister Sister r = 1/2

44. Bee-eaters direct help to close relatives Emlen et al. 1995 *relatedness matters!

45. Helping at the nest in bee-eaters, why? • Hamilton’s rule

46. Helping at the nest in bee-eaters, why? • Hamilton’s rule • Breeding Conditions • nest sites difficult to obtain, create and maintain • finding a mate is difficult • scarcity of food • defense of nests

47. Helping at the nest in bee-eaters, why? • Hamilton’s rule (Genetic predisposition) • Breeding Conditions (Ecological Constraint)

48. Helping at the nest in bee-eaters, why? • Hamilton’s rule • Breeding Conditions • First time breeders pay a slight cost:

49. Helping at the nest in bee-eaters, why? • Hamilton’s rule • Breeding Conditions • First time breeders pay a slight cost -Each parent, unaided, is able to raise 0.51 offspring -Each helper is responsible for an additional 0.47 offspring being raised!

50. The evolution of eusociality