Chapter 50

• Behavior


  Action in response to stimulus
• Behavior


  • Innate/learned
  • Honest/deceitful
  • Adaptive?
• Behavioral biology


  Ethology - study of how organisms respond to stimuli
• Proximate causation


  Explains how actions occur (neurological, hormonal, skeletal-muscular mechanisms)
• Ultimate causation


  Explains why actions occur (evolutionary consequences, fitness)
• Spiny lobsters finding way back to coral reef dens

  • Ultimate level - search for food during darkness to avoid predators
  • Proximate level - use receptors in brain that detect Earth's magnetic field

  
• Fixed action patterns


  Animals respond to change in environment in predictable, inflexible, stereotypical way (innate behavior)
• Most behavior


  • Flexible, learned, correlates with environment
• Cost-benefit analysis


  Animals appear to weigh costs & benefits of responses - measured by impact on fitness
• 5 questions in behavioral ecology

  • What should I eat?
  • Who should I mate with?
  • Where should I live?
  • How should I communicate?
  • When should I cooperate?

  
• Optimal foraging


  Organisms make decisions that maximize food found, given the cost/risk of finding it
• Optimal foraging


  • Flexible & condition-dependent
• Sexual dimorphism


  Differences in appearance between males and females of the same species
• Females Barn Swallows choose males


  With good alleles & resources
• Communication


  Any info-containing behavior from 1 individual that modifies behavior of another
• Honeybee language


  • Tactile, olfactory, acoustic, visual - correlates with habitat
• Round dance


  Communicates food within 80-100m of hive

  
• Waggle dance


  Indicates direction & distance to food > 100m away

  
• Deceitful communication


  • Hognose snakes playing dead
  • Female Photuris fireflies flashing courtship signal of another species and then eating males that respond
• Deceiving individuals of same species

  • Bluegill Sunfish - mimic releases sperm & fertilizes eggs, fathers offspring but doesn't help care for them
• Deceit works only when relatively rare - natural selection
• Kin selection


  Natural selection that acts through benefits to relatives & results in increased indirect fitness
• Hamilton's rule


  Altruistic allele spreads if Br > C (B = fitness benefit to beneficiary, C = fitness cost to actor, r = coefficient of relatedness)
• Altruistic behavior is most likely if 3 conditions are met: 1) Fitness benefit is high for recipient, 2) Fitness costs to altruist are low, 3) Altruist & recipient are close relatives (r high)
• Inclusive fitness


  Direct fitness (from individual's own offspring) + Indirect fitness (from helping relatives reproduce)
• Reciprocal altruism


  Exchange of altruistic acts over time