Chapter 13 Opener: Weaver ants form superbly cooperative societies. Chapter 9. The Evolution of Social Behavior

Transcription

1 Chapter 13 Opener: Weaver ants form superbly cooperative societies Chapter 9. The Evolution of Social Behavior

2 Social living for gain benefits

3 Social living is not always beneficial

4 13.1 The energy budget of helpers in Neolamprologus pulcher (Part 1) The cost of social living: Energy consumption helper Tail quivering display to the dominant fish

5 13.2 Effect of removal of the top-ranked subordinate helper in a cooperatively breeding group Cichlid fish Remove helper 1

6 13.2 Effect of removal of the top-ranked subordinate helper in a cooperatively breeding group Cichlid fish What do helpers gain? Dilution of predation risks with other helpers The top helper can replace one of the dominant male and female sometime After being breeder, he or she can helps by helpers

7 13.3 Reproductive interference in a social animal The cost of social living: reproductive interference 3 females + 4 males live together in one nest Tossing eggs out Stop tossing females lay eggs on the same day Woodpecker removes An egg from a nest

8 13.4 Competition for food is a cost of sociality in the fieldfare The cost of social living: Food competition

9 13.5 Effect of parasites on cliff swallow nestlings The cost of social living: Infection Infected with swallow bugs Bug-free nest Host range of parasites and viruses

10 13.6 Social living with defensive benefits? The Benefits of social living: Defense A school of Catfish Dilution of predation Spotting danger sooner Ganging up on their enemy

11 13.7 Mutual defense in a society of bluegills Bass Bluegills (SOCIAL) Sunfish (SOLITARY) Catfish

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13 13.8 The different categories of helping behavior

14 13.9 Cooperation among competitors Mutualism: Sleeping with the enemy Dull brown intermediate Dominant

15 13.10 Cooperative courtship of the long-tailed manakin Mutualism: Interview with competitor

16 13.11 Cooperation with an eventual payoff When alpha male disappears, the beta male replace it

17 13.12 A meerkat sentinel on the alert for approaching predators The Reciprocity hypothesis A meerkat sentinel on the alert for approaching predator 1)Reciprocal altruism? 2)Personal safety? -The sentinel duty is not regular but haphazardly -Lookouts are close to escape burrow -Sated meerkat usually do sentinel duty -Solitary meerkat also spend about the same proportion of each day in sentinel behavior Anyway, the result of sentinel behavior with alarm will be helpful to others

18 13.13 Reciprocity in a social primate The Reciprocity hypothesis A vervet monkey grooms a companion If he defect, no benefit gain A problem. How they believe each other?

19 13.15 The prisoner s dilemma A crime has been committed by two persons who agreed not to squeal on each other if caught The cops have enough evidence to convict them both lesser charge (1-year sentence) but need to have the criminals in order to jail them for more serious crime (5-year sentence) They therefore offer each suspect freedom if he will squeal on his pal What do think they cooperate Or defect?

20 13.15 The prisoner s dilemma If I defect Freedom > 1 year sentence Reward 5 year > 10 year Punishment If I cooperate Cooperation never happens!

21 Rewarding system for reciprocal altruism - If altruistic events can happen many Cost to the altruist offset by likelihood of a return benefit Female vampire bats will share food Unrelated females are more likely to share food with those that had recently shared with them

22 13.14 Experimental demonstration of reciprocity in cotton-top tamarins (Part 1) Helper food

23 13.14 Experimental demonstration of reciprocity in cotton-top tamarins (Part 2) They don t help defector

24 Vampire bats Sharing blood (foods) behavior is beneficial since more than 3-days starvation leads to death

25 Altruism Altruism Behavior that appears to benefit others at a cost to oneself Most altruistic acts serve to benefit the individual s close relatives

26 13.17 A Belding s ground squirrel gives an alarm call after spotting a terrestrial predator Obligate altruism Alarm call of belding s ground squirrels High risk of predation Females usually give alarm call Males are exploratory

27 Kin selection An organism can not only pass on its genes by having offspring but also by ensuring that relatives survive Inclusive fitness designates the total number of copies of genes passed on through one s relatives or as one s own offspring Kin selection behavior that lowers an individual s own fitness but enhances the reproductive success of relatives

28 13.16 The components of selection and fitness

29 Hamilton s rule Altruistic gene favored by natural selection when rbb>rcc r is the coefficient of relatedness of donor (altruist) to recipient B is benefit to recipient C is cost incurred by donor One your son vs. three nephews 0.5 x 1 = 0.5; 0.25 x3=

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31 Predator has to eat one to learn to avoid them Death of individual in group of related butterfly benefits siblings r =0.5, B=50, and C=1, then 25(0.5x50)>1 so genes will spread Even to non-relatives (r=0), giving benefits

32 13.18 Altruism and relatedness in pied kingfishers Son takes care mother s net As a son As a neighborhood

33 Primary helper getting inclusive fitness Secondary helper getting direct fitness

34 13.19 Cooperation among scrub jay relatives Facultative altruism: Jays Helper

35 13.20 Seasonal changes in prolactin concentrations in breeders and nonbreeding helpers (Part 1) Mexican Jay

36 13.20 Seasonal changes in prolactin concentrations in breeders and nonbreeding helpers (Part 2) Mexican Jay

37 13.21 Helpers at the nest help parents raise more siblings in the Florida scrub jay Experimental removal of helper

38 13.22 Conditional reproductive tactics of female white-fronted bee-eaters (Part 1)

39 13.22 Conditional reproductive tactics of female white-fronted bee-eaters (Part 2)

40 13.27 Eusocial insects have sterile castes Hymenoptera Most extreme form of altruism is sterile castes in social insects Eusociality workers (females) help queen raise offspring Haplodiploidy females are diploid, males are haploid, females are more related to their sisters (0.75) than they would be to their own offspring (0.5) Direct fitness < indirect fitness

41 13.23 Haplodiploid sex determination in Hymenoptera (Part 1) Male haploid Female Diploid

42 13.23 Haplodiploid sex determination in Hymenoptera (Part 2)

43 13.23 Haplodiploid sex determination in Hymenoptera (Part 3) Queen can control the sex of her chidren? Large cells Small cells

44 13.24 Conflict within ant colonies over reproduction Worker can lay eggs but Queen eats them Other worker prevent Female with ovary Queen 0.75 relatedness Own son 0.5

45 13.25 A test of a hypothesis based on transactional theory

46 13.27 Eusocial insects have sterile castes Large teeth Attack granule on the head Eusocial animals sacrifice direct fitness and pursue inclusive fitness

47 13.28 Suicidal sacrifice by a worker bee Stinger attached to her Intestine

48 13.29 Eusociality has an evolutionary history

49 13.30 Haplodiploidy and the evolution of eusociality in the Hymenoptera (Part 1)

50 13.30 Haplodiploidy and the evolution of eusociality in the Hymenoptera (Part 2) Brother Sister Only 25% Worker Son Only 50%

51 13.30 Haplodiploidy and the evolution of eusociality in the Hymenoptera (Part 2) What if the queen is polyandrous? Formica ants Worker s helps Monogamous nest Ploygynous nest ++++

52 13.34 A mammal with an effectively sterile caste Existence of eusocial mammals predicted based on lifestyle Naked mole rats have a queen who suppresses reproduction in other females Relatedness~ 0.2 rbb < rcc

53 13.35 Fortress living space may provide an incentive against dispersal in many eusocial insects

54 Lecture schedule 3/30 case-1 Natural selection of genes and behaviors 4/01 case-2 Mouse genetic approaches to behavior 4/06 case-3 Gene-knockout and Transgenic technology 4/08 case-4 Experimental methods for measuring behaviors 4/20 Chapter 9: The evolution of communication 4/22 Chapter 9: The evolution of communication 5/04 Chapter 13: The evolution of social behaviors 5/06 Chapter 13: The evolution of social behaviors 5/11 Final examination 5/13 Group presentation-i 5/17 Group presentation-ii

55 Summary of hypothesis Final exam. -11 th May 10:30 am -How to prepare? 1) Case 1-4: only definition 2) Chapter 9 and 13: similar pattern with miterm.