BIOL 108 Chp 9 - Evolution and Behavior


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BIOL 108 Chp 9 - Evolution and Behavior

  1. 1. Chapter 9 Evolution and BehaviorBIOL 108 Rob Swatski Assoc Prof BiologyIntro to Bio Sci HACC- HACC-York 1
  2. 2. Learning Goals Cooperation, Sexual conflict selfishness, and can result from altruism can be CommunicationBehaviors are disparities in better and the designtraits that can reproductive understood of signals evolve. investment by with an evolve males and evolutionary females approach. 2
  3. 3. 9.1–9.4Behaviors aretraits that canevolve.
  4. 4. 9.1 Behavior has adaptive value, just like other traits. What is the problem with “mudcakes” from an evolutionary perspective?
  5. 5. Animals should maximize energyconsumed and minimize energy used. 5
  6. 6. Humans like to eat foods high in fat and sugar. 6
  7. 7. 7
  8. 8. Why do species have taste preferences? Maximal Feeding extraction Natural Living and choices of energy selection reproducing directly and can shape requireinfluence acquisition feeding energy. fitness. of essential behavior. nutrients. 8
  9. 9. Behavior encompasses any and all of the actionsperformed by an organism, often in response to its environment or to the actions of another organism. 9
  10. 10. Scope of Animal Behavior Conflict, aggression, and territoriality Cooperation, alliance building, and sociality Competing for food and avoiding predation Migration and navigation Behavioral control of body temperature Courtship and mate choice Pair bonding and fidelity Breeding and parental behavior
  11. 11. Behaviors can be influenced by natural selection. Feeding Maternal Singing behavior care behavior Humans; starlings; shore Mice Songbirds crabs 11
  12. 12. Effects of evolutionby natural selection are all around. Peacock feathers Cryptic coloration Behavior is part of an organism’s phenotype 12
  13. 13. Take-Home Message 9.1 When a heritable trait increases an individual’s Behavior is any and all reproductive success relativeactions performed by an to that of other individuals, organism. that trait tends to increase in frequency in the population. Behavior is as much a part of an organism’s phenotype as is an anatomical structure, and as such it can be produced and shaped by natural selection. 13
  14. 14. 9.2 Some behaviors are innate. 14
  15. 15. Role of the Environment The degree to which a behavior depends upon the environment varies a great deal. Instincts or innate behaviors Fixed action pattern 15
  16. 16. Fixed Action Pattern Triggered under certain conditions Requires no learning Does not vary Once started, runs to completion 16
  17. 17. Take-Home Message 9.2 At one extreme are instincts, The degree to which a innate behaviors present in behavior depends on the all individuals in a populationenvironment varies a great that do not vary much one deal. individual to another or over an individual’s life span. Innate behaviors don’t require environmental input to develop. 17
  18. 18. 9.3 Some behaviors must belearned (and some are learned more easily than others). 18
  19. 19. Learning Involves behaviorsthat are altered and modified over time in response to past experiences Tremendous variation among behaviors that require learning • Some are easy to learn • Others are not 19
  20. 20. Production of Behaviors and the Role of the Environment Primates—fear of snakes Appears not innate, but learned 20
  21. 21. 21
  22. 22. Prepared Learning Behaviors that are learned easily and by all (or nearly all) individuals Snake-fearing behavior of monkeys Acquisition of language in humans 22
  23. 23. 23
  24. 24. Why is it so much easier for aninfant to learn a complex language than for a college student to learn biology? What is the evolutionary basis for the acquisition of certain behaviors? 24
  25. 25. Take-Home Message 9.3 These behaviors require In contrast to innate some learning and are oftenbehaviors are behaviors that altered and modified over are influenced more by the time in response to past environment. experiences. Organisms are well- Organisms are less preparedprepared to learn behaviors to learn behaviors irrelevantthat have been important to to their evolutionary the reproductive success of success. their ancestors. 25
  26. 26. 9.4 Complex-appearing behaviors Complex-don’t require complex thought in order to evolve. 26
  27. 27. “I must maximize my reproductive success!” Why do animals have sex? Why do people have sex? 27
  28. 28. Animals don’t consciously try tomaximize their reproductive success, yet they behave as if they do? How does this happen? 28
  29. 29. How do weknow?Trickinganimals 29
  30. 30. Take-Home Message 9.4 If an animal’s behavior in natural situations usually increases its relative reproductive success, the behavior will be favored by natural selection. The natural selection of behaviors does not require an organism to consciously try to maximize its reproductive success. 30
  31. 31. 9.5–9.9Cooperation,selfishness, andaltruism can bebetter understoodwith an evolutionaryapproach.
  32. 32. 9.5 A general theory of “kindness”helps explain the evolution of apparent acts of altruism. Does unconditional love exist in the animal kingdom? Altruistic behaviors—behaviors that come at a cost to the individual doing the behavior while benefiting the recipient. 32
  33. 33. 33
  34. 34. Apparent Acts of Altruism Kindness toward close relatives: kin selection Kindnesstoward unrelated individuals: reciprocal altruism 34
  35. 35. Take-Home Message 9.5 In almost all cases, these are not really acts ofMany behaviors in the altruism and have evolvedanimal world appear as a consequence of either altruistic. kin selection or reciprocal altruism. These behaviors are beneficial to the individual engaging in the behavior. 35
  36. 36. 9.6 Apparent altruism towardrelatives can evolve through kin selection. 36
  37. 37. 37
  38. 38. Hamilton’s Rule Altruistic-appearing behavior will occur when the benefits to close relatives are greater than the cost to the individual performing the behavior. They are really acting in their own genes’ best interests. 38
  39. 39. 39
  40. 40. Who are people most likely tobequeath money to upon their death? 40
  41. 41. 41
  42. 42. Redefining an Individual’s Fitness Direct fitness • An individual’s total reproductive output Indirect fitness • The reproductive output brought about by altruistic behaviors toward close kin Inclusive fitness • The sum of an individual’s indirect and direct fitness 42
  43. 43. Conflicts Because different individuals do not share all of the same alleles, we should always expect some conflict. Example: gestational diabetes 43
  44. 44. Take-Home Message 9.6 Kin selection describes apparently altruistic behavior in which an individual that assists a genetic relative compensates for its owndecrease in direct fitness by helping increase the relative’s fitness and, consequently, its own inclusive fitness. 44
  45. 45. 9.7 Apparent altruism towardunrelated individuals can evolve through reciprocal altruism. 45
  46. 46. 46
  47. 47. Vampire Bats Inmany cases, individuals give blood to unrelated individuals. How might this behavior have arisen? 47
  48. 48. Are they repaid the favor? Reciprocal Altruism Storing goodwill 48
  49. 49. 49
  50. 50. Certain Conditions Must Be Met1) Repeated interactions among individuals2) The benefits to the recipient must be significantly greater than the costs to the donor.3) The ability to recognize and punish cheaters 50
  51. 51. Why are humans among the few species to have friendships? 51
  52. 52. Why is it easier to remembergossip than physics equations? 52
  53. 53. Take-Home Message 9.7In reciprocal altruism, an The actor only gives up individual engages in an something of value when altruistic-appearing act likely to get something of toward another value later. individual.Reciprocal altruism occursonly if: 1) individuals have These conditions arerepeated interactions & 2) satisfied in humans but in individuals can recognize few other species. and punish cheaters 53
  54. 54. 9.8 In an “alien” environment,behaviors produced by natural selection may no longer be adaptive. 54
  55. 55. Behaviors favored by natural selection over evolutionary time can cause individuals to behave in a way that reduces their fitness. Belding’sground squirrels Craving high-fat foods Donations to refugees 55
  56. 56. 56
  57. 57. Take-Home Message 9.8 When organisms are in environments that differ fromthe environment to which they are adapted, the behaviorsthey exhibit are not necessarily evolutionarily adaptive. 57
  58. 58. 9.9 Selfish genes win out over group selection.Does evolution ever lead to behaviors that are for the good of the species or population, while being detrimental to the individual? 58
  59. 59. 59
  60. 60. Take-Home Message 9.9Behaviors that are good for the species or population but detrimental to theindividual are not generally produced in a population under natural conditions. 60
  61. 61. 9.10–9.15Sexual conflictcan result fromdisparitiesin reproductiveinvestment bymales andfemales.
  62. 62. 9.10 There are big differences in how much males and females invest in reproduction. 62
  63. 63. Definition of “Male” and “Female” A female produces the larger gamete. A male produces the smaller gamete. Themother’s material contribution to the offspring exceeds the father’s. 63
  64. 64. Evolution of Differences in Male/Female Behaviors1) Extent of energetic differences in the reproductive investment. 64
  65. 65. Why do malesusually compete for femalesrather than the opposite? 65
  66. 66. Differences in Reproductive Investments Fertilization within the female (internal gestation) Lactation in female mammals 66
  67. 67. 67
  68. 68. Offsets and Reversals in Reproductive InvestmentExamples: Birds • Gestation external • No lactation 68
  69. 69. Offsets and Reversals in Reproductive InvestmentExamples: Fish and amphibians • External fertilization 69
  70. 70. Evolution of Differences in Male/Female Behaviors1) Extent of energetic differences in the reproductive investment2) Paternity uncertainty • also has profound influence on reproductive behavior 70
  71. 71. Take-Home Message 9.10 In mammals and many other types of animals, there are important Fertilization usually takesdifferences between males place in the female. and females relating to reproduction. In species where fertilization occurs insideLactation occurs only in the the female, males cannot be female. certain that offspring are their progeny. These physical differences have led to the evolution of differences in male and female reproductive behavior. 71
  72. 72. 9.11 Males and females arevulnerable at different stages of the reproductive exchange. 72
  73. 73. Predictions About Sex-Related Behavior Sex-1) The sex that invests more will be more discriminating.2) The sex that invests less will compete amongst themselves for access to the higher- investing sex. 73
  74. 74. 74
  75. 75. Potential Exploitation at Different Stages of the Reproductive Process At the point of mating At the point of parental care to offspring 75
  76. 76. Take-Home Message 9.11 Differing patterns ofinvestment in reproduction This has contributed to the make males and females evolution of differences in vulnerable to exploitation sexual behavior. at different stages. The sex with the greater The sex with less investment is more investment competes for discriminating about access to the higher- mates. investing sex. 76
  77. 77. 9.12 Tactics for getting a mate: competition and courtship 77
  78. 78. 78
  79. 79. 79
  80. 80. 80
  81. 81. 81
  82. 82. Take-Home Message 9.12 Males tend to increase their reproductive success by mating with many females and have evolved to compete for the opportunity to mate. Females increase their reproductive success not through extra matings but rather by being choosy about selecting a mate and by caring for their offspring. 82
  83. 83. 9.13 Tactics for keeping a mate: mate guarding can protect a male’s reproductive investment When offspring survival can be enhanced with greater parental investment… there is an incentive for males to provide some parental care… …even though such behavior makes him vulnerable to paternity uncertainty. 83
  84. 84. Why do so few females guard their mates as aggressively as males do? Mate guarding in order to reduce vulnerability Attempt to reduce paternity uncertainty “Danger zone” for males 84
  85. 85. Mate Guarding:From Simple to Macabre 85
  86. 86. Copulatory Plugs Reptiles, insects, and many mammalian species Males block the passage of sperm into the female Coagulated sperm and mucus 86
  87. 87. 87
  88. 88. Take-Home Message 9.13 Mate guarding can, in general, increase reproductive success by reducing additional mating opportunities for a partner… …and can improve a male’s reproductive success by increasing his paternity certainty and thus reducing his vulnerability when he makes investment in offspring. 88
  89. 89. 9.14 Monogamy versus polygamy: mating patterns can vary across human and animal cultures. 89
  90. 90. 90
  91. 91. Mating Systems Polygamy • When some individuals attract multiple mates while other individuals attract none Monogamy • Most individuals mate and remain with just one other individual 91
  92. 92. Mating SystemsPolygamy subdivided into: Polygyny • individual males mate with multiple females Polyandry • individual females mate with multiple males 92
  93. 93. Mating Systems Are Not Easy to DefineThree issues complicate the task: 1) Differences between animals’ mating behavior and bonding behavior Pair bond—appears monogamous 93
  94. 94. Mating Systems Are Not Easy to DefineThree issues complicate the task: 2) Mating system variation within the species 94
  95. 95. Mating Systems Are Not Easy to DefineThree issues complicate the task: 3) Males and females vary in their mating behavior 95
  96. 96. Examination of Birds and Mammals Reveals One Sharp Split 96
  97. 97. Are humansmonogamous orpolygamous? 97
  98. 98. Take-Home Message 9.14 Mating systems— monogamy, polygyny, polyandry—describe the variance in mate number of males and females. They are influenced by the relative amounts of parental investment by males and females. 98
  99. 99. 9.15 Sexual dimorphism is anindicator of population mating behavior. 99
  100. 100. 100
  101. 101. 101
  102. 102. Body Size Is an Important Clue to Behavior Level ofcompetition among the individuals of each sex Selection forlarger and larger body size when competition is high 102
  103. 103. It’s almost impossible todistinguish males from females among most bird species. Why does that mean they are monogamous? 103
  104. 104. Men are bigger than women.What does that tell us about our evolutionary history of monogamy versus polygamy? 104
  105. 105. Take-Home Message 9.15 Differences in the level ofcompetition among individuals In polygynous species, this for mating opportunities can results in larger males that are lead to male-female easily distinguished from differences in body size and females visually. other aspects of appearance. In monogamous species, there are few such differences between males and females. 105
  106. 106. 9.16–9.17Communicationand the designof signalsevolve.
  107. 107. Chemical Communication in Animals 107
  108. 108. Communication An action orsignal on the part of one organism that alters the behavior of another organism. Whattypes of animal behavior require communication? What types of communication do animals use? 108
  109. 109. Types of Animal Communication 109
  110. 110. Complex Forms of Communication Honeybee waggle dance What is language? 110
  111. 111. How is language identified?  Vervet monkeys  American Sign Language taught to chimpanzees and gorillas  Human language 111
  112. 112. 112
  113. 113. Take-Home Message 9.16 Methods of communication have evolved among animal species, enabling them to convey information. These abilities influence fitness and the evolution of virtually all other behaviors. 113
  114. 114. 9.17 Honest signals reduce deception. Conveying accurate information 114
  115. 115. 115
  116. 116. Honest Signal Cannot be faked Given when both the individual making the signal and the individual responding to it have the same interests Carries the most accurate information about an individual or situation 116
  117. 117. Deception Evolves! “Begging” allele Evolutionary “arms race” • Unambiguous signals • Sophisticated patterns of deception An organism’s phenotype includes its behaviors 117
  118. 118. Take-Home Message 9.17 Animals have evolved torely primarily on signals that cannot easily be faked in order to gain the maximumamount of information from them. 118