Lec9 Adaptation
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Lec9 Adaptation

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    Lec9 Adaptation Lec9 Adaptation Presentation Transcript

    • Animal Behavior: Adaptation ANIMALEHAVIOR LEC 3 ANIMAL BE ANIM Animal Behavior, Lec. 9, BIOL 4518
      • Chapters 6 and 9
        • Homework in quiz on Blackboard
        • Due Thursday
      • Midterms
    • Expectations
    • So far...
        • First part of course
          • tools to ask evolutionary questions:
            • mechanisms of speciation,
            • history of ethology and animal behavior,
            • two ways of looking at animal behavior (proximate and ultimate)
            • hypothesis development (e.g., “if, then” statements) to test explanations for behavior,
            • how to collect data to test hypotheses (lab)
          • basics of animal behavior:
            • relative magnitude of influence of genes and environment
            • introduction to social insects
            • physics of communication, orientation/navigation etc.
    • 2 nd half
      • Second half of the quarter
        • Examine ULTIMATE questions more deeply
          • The sorts of questions we will ask include:
            • Is that an adaptation?
          • Current theories
            • Attempt to explain broad classes of behaviors across many species
            • Examine data that do/do not support
        • Discuss cases of observations of animal behavior in more detail.
    • 2 nd half – Evaluation
      • Tests
        • Forming a detailed argument
        • nuances of the argument
        • Using detailed information to support/not support the hypothesis
      • Example test question:
        • Provide both sides of the argument of XY and Z topic, and defend your conclusion.
    • Concepts in 2 nd half of class
      • Key words
          • Fitness
          • Inclusive fitness
          • Cost benefit analysis
          • Altruism
          • Honest signals
        • Theories:
          • Optimality theory
          • Game theory
    • Outline
        • Adaptations (behavioral)
        • Phylogenies
        • Fitness
    • Phylogenies and adaptations
      • What is a phylogeny?
      • How is it constructed?
      • Is there only one phylogeny?
    • Phylogenies and adaptations
      • Does it matter which traits are used to make the phylogeny?
    • Phylogenies and adaptations
      • Weak phylogenetic relationship but the same characteristic!
      • Convergent Evolution
        • Similar selection pressure
        • Examples
          • Quoll (marsupial) and human cat (placental)
          • Saber toothed tiger marsupial!!!
      • Doesn't require animals being in the same habitat
    • Phylogenies and adaptations
      • Strong phylogenetic relationship but different characteristics
        • Divergent evolution
        • Shared ancestry but different behavior
      • Doesn't require animals being in the same habitat
    • What is fitness?
      • Fitness is the reproductive success. Several ways to measure it, but the best is to measure the number of offspring (F1) that produce viable offspring (F2).
    • What is fitness?
      • What can reduce your fitness?
    • How measure fitness?
      • Fitness can be less precisely measured as the
        • number of offspring produced, or the
        • number of copulations, or the
        • number of surviving offspring
        • None of these measurements measure the full chain required for fitness
    • How measure fitness?
      • Relative fitness
          • Fitness of individual with one trait vs fitness of an individual with another trait
    • What is an adaptation?
      • Definition: trait which has been positively selected for and increases the relative fitness of an individual
    • What is an exaptation?
      • Human hand vs. bat wing?
      • Exaptation: trait originally selected for one purpose and different selection pressures resulted in the current use. Potential explanation for why something may not be the best design if you were starting from scratch
      • e.g. human knees – not necessarily the best design for extensive bipedal walking; joint wears out, highly susceptible to damage, etc.
    • How do you determine just so vs. adaptation?
      • Is that an adaptation?
        • To find out you construct a hypothesis and test
      • The test design is important, however!
      • When does the trait increase fitness?
        • In rare extreme environment/events
        • In a typical environment/event?
      • For example:
        • a trait which does not appear to confer a fitness advantage in typical environment, may confer high advantage in a rare event.
        • Rocky intertidal example
      • Context is crucial to correct determination of whether the trait is selected for/is an adaptation
    • Example of testing whether behavior is adaptive
      • Projectile caterpillar poop!
    • Example of testing whether behavior is adaptive
      • Gazelles
      • Stotting behavior
        • Leap into air and show white rump?
      • Is this adaptive?
    • Example of testing whether behavior is adaptive
      • Hypotheses:
        • Alarm signal:
        • Social cohesion:
        • Confusion effect:
        • Pursuit deterrence:
    • Example of testing whether behavior is adaptive
      • Solitary gazelle stots
      • Grouped gazelles stot
      • Stotters show rump to predator
      • Stotters show rump to gazelles
    • Example of testing whether behavior is adaptive
      • Data
        • Lone gazelle stots when approached by cheetah
        • Stotting gazelles orient rump to predator and not to gazelles
    • Example of testing whether behavior is adaptive
      • Conclusion
        • Pursuit deterrence
    • Example of Darwinian puzzle
      • Traits whose benefits are unlikely to be balances by the negatives
      • Bright coloration by insects
      • Monarch
        • Milkweed toxins
        • Butterflies regurgitate
        • Wings rejected
      • Mimics
    • Optimality
      • Behavioral decisions (strategies) are chosen to maximize reproductive success
      • Examples of fitness measurements proxies:
        • Energy gain per time
        • Energy loss per time
        • Being predated
      • Used as a test to see whether you have accurately assessed the selection pressures
    • Optimal foraging theory
      • Behavioral decisions of foraging:
        • Where should I search?
        • For what prey?
        • For how long?
        • At what time of day?
    • What is being optimized?
      • Caloric intake per time
      • Others?
    • Does a behavior have to be optimal to be adaptive?
      • Is efficiency required?
    • Game Theory
      • Unconscious maximization of reproductive success
      • Behavioral decisions (strategies) are chosen to maximize reproductive success
      • Costs and benefits are weighed
      • Social context – each individual is maximizing its own success (or genes)
    • Example of Game Theory
      • Assume most individuals are solitary
      • Selfish herd (Hamilton)
        • Individuals try to get into the center of the group
        • Use other individuals as “shields”
      • What would happen over evolutionary time?
      • Would this be selected for over other traits?
      • Does it still work if everyone uses it?
    • Game theory: 2 different strategies in a species
      • Individuals in the same species are known to specialize on different prey items
      • Why hasn't the behavior with the higher fitness replaced the other over evolutionary time?
        • Small differences can have big impacts
      • Behavior exhibited depends on context
    • Game theory: 2 different strategies in a species
      • How can two strategies coexist in a population?
      • Frequency dependent selection
        • The fitness of one genotype depends on the frequency of other genotypes in the
    • Frequency of fish-stealing genotype in the population 0.25 0.5 0.75 1.0 0 Game theory: 2 different strategies in a species Fitness of phenotypes high low medium Fish stealer Fish hunters 4 8 12 4 12 4 4 12 0 16 8 8 16 12 4 0
    • Frequency of fish-stealing genotype in the population 0.25 0.5 0.75 1.0 0 Game theory: 2 different strategies in a species Fitness of phenotypes high low medium Fish stealer
    • Frequency of fish-stealing genotype in the population 0.25 0.5 0.75 1.0 0 Game theory: 2 different strategies in a species Fitness of phenotypes high low medium Fish hunter Fish stealer
    • Frequency of fish-stealing genotype in the population 0.25 0.5 0.75 1.0 0 Game theory: 2 different strategies in a species Fitness of phenotypes high low medium Fish hunter Fish stealer Equilibrium point