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BehavioralEcology
How evolutionshapes behavior
Optimality
Organisms behave tomaximize benefit and minimizecost
Optimal Foragingmaximize nutritional benefitsminimize energetic/survival costs
Zach, 1978
Crows generally fly5 meters highZach, 1978
Higher than 5 meters does not increasethe chance of the shell breakingBenefits < CostsZach, 1978
Territory
TerritoryBenefits: exclusive access to food,matesCosts: energy required to defend
ReproductiveBehavior
Optimized Reproductionmaximize offspringminimize energetic/survival costs
Energetic/survival costs are typicallyunequal between males and females   “Battle of the              vs    Sexes”
MateChoice
Parental Investment TheoryThe sex with the most energetic costs from parenting  will be more selective
Which sex hashigher parental costs?
Birdsfemale produce large eggsand may lay 50 to over 100%of their body weight eachseason
Mammalsonly females can becomepregnant and lactate
Generally, females invest morein eggs than males do in sperm
Females are usually more selective
Mate Choice causesSexual SelectionIntrasexual: traits that give a  competitive advantageIntersexual: traits that are prefe...
Intrasexual Selection
Intersexual Selection
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Number of mates               ...
Mating systems                              Jacana    Polyandry: multiple males    Polygyny: multiple females    Promiscuo...
Clumped food (fruit tree): Polygyny/PolyandryRandom/uniform food (insects): Monogamy
Socialbehavior
From simple social groups………
…. To complex societies
Altruism
Behavior that benefits othersat a cost to the individual
Cost may be minor…
…or extreme!
Optimalitymaximize benefitminimize costSo how could altruism evolve?
Reciprocity
“You scratch my back,I’ll scratch yours.”
Vampire bats
Benefit = survival (as a recipient)Cost = small amount of food loss(as a donor)Benefit > Cost in the long term
Kin Selection
Helping your relatives
"Would I lay down my lifeto save my brother?No, but I would to save twobrothers or eight cousins.”-J.B.S. HaldaneSiblings:...
Fig. 37.17                                      Copyright © The McGraw-Hill Companies, Inc. Permission required for reprod...
Belding’s ground squirrels
Benefit = protect relativeswho share genesCost = increased predation risk to selfBenefit > Cost if relatives near by
Communication
Fig. 37.15             Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.       ...
Behavior, part 2
Behavior, part 2
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Behavior, part 2

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Slides for discussion of The Living World, 7th edition chapter 37, adapted from a compilation by Amy.

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Transcript of "Behavior, part 2"

  1. 1. BehavioralEcology
  2. 2. How evolutionshapes behavior
  3. 3. Optimality
  4. 4. Organisms behave tomaximize benefit and minimizecost
  5. 5. Optimal Foragingmaximize nutritional benefitsminimize energetic/survival costs
  6. 6. Zach, 1978
  7. 7. Crows generally fly5 meters highZach, 1978
  8. 8. Higher than 5 meters does not increasethe chance of the shell breakingBenefits < CostsZach, 1978
  9. 9. Territory
  10. 10. TerritoryBenefits: exclusive access to food,matesCosts: energy required to defend
  11. 11. ReproductiveBehavior
  12. 12. Optimized Reproductionmaximize offspringminimize energetic/survival costs
  13. 13. Energetic/survival costs are typicallyunequal between males and females “Battle of the vs Sexes”
  14. 14. MateChoice
  15. 15. Parental Investment TheoryThe sex with the most energetic costs from parenting will be more selective
  16. 16. Which sex hashigher parental costs?
  17. 17. Birdsfemale produce large eggsand may lay 50 to over 100%of their body weight eachseason
  18. 18. Mammalsonly females can becomepregnant and lactate
  19. 19. Generally, females invest morein eggs than males do in sperm
  20. 20. Females are usually more selective
  21. 21. Mate Choice causesSexual SelectionIntrasexual: traits that give a competitive advantageIntersexual: traits that are preferred by the chooser sex
  22. 22. Intrasexual Selection
  23. 23. Intersexual Selection
  24. 24. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Number of mates Fig. 37.12 5 0 140 150 160 Number of eyespots in tail feathers
  25. 25. Mating systems Jacana Polyandry: multiple males Polygyny: multiple females Promiscuous: multiple males & females Monogamy: one male, one femaleElephant seal Dunnock Black vulture
  26. 26. Clumped food (fruit tree): Polygyny/PolyandryRandom/uniform food (insects): Monogamy
  27. 27. Socialbehavior
  28. 28. From simple social groups………
  29. 29. …. To complex societies
  30. 30. Altruism
  31. 31. Behavior that benefits othersat a cost to the individual
  32. 32. Cost may be minor…
  33. 33. …or extreme!
  34. 34. Optimalitymaximize benefitminimize costSo how could altruism evolve?
  35. 35. Reciprocity
  36. 36. “You scratch my back,I’ll scratch yours.”
  37. 37. Vampire bats
  38. 38. Benefit = survival (as a recipient)Cost = small amount of food loss(as a donor)Benefit > Cost in the long term
  39. 39. Kin Selection
  40. 40. Helping your relatives
  41. 41. "Would I lay down my lifeto save my brother?No, but I would to save twobrothers or eight cousins.”-J.B.S. HaldaneSiblings: share 1/2 of your genesCousins: share 1/8 of your genes
  42. 42. Fig. 37.17 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Probability of helping (percent) 100 80 60 40 20 0 0 1/8 1/4 1/2 (cousin) (half-sibling) (full-sibling) Degree of genetic relatedness
  43. 43. Belding’s ground squirrels
  44. 44. Benefit = protect relativeswho share genesCost = increased predation risk to selfBenefit > Cost if relatives near by
  45. 45. Communication
  46. 46. Fig. 37.15 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 8 8 7 7 Frequency (kilocycles Frequency (kilocycles 6 6 per second) per second) 5 5 4 4 3 3 2 2 1 1 0 0 0.5 seconds 0.5 seconds Eagle Leopard (a) (b) a: © S. Osolinski/OSF/Animals Animals-Earth Scenes
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