Ch 2: Methods for Studying Behavior

Cards (29)

  • Observational Method: involves observing and recording behavior without manipulating the environment or the animal. 
  • Experimental Method: involves manipulating an independent variable to examine how this affects a dependent variable.
  • Comparative Method: involves examining differences and similarities between species to understand the evolution of behavior. 
  • Phylogeny: a diagram showing evolutionary ancestor-descendant relationships among a set of organisms.
  • Sister Species: two species that are more closely related to one another than to any other species.
  • Parsimony: the simplest explanation of an event or observation is more likely to be correct, all other things are equal.
  • Convergent Evolution: distinct ancestry, shared behavior.
  • Divergent Evolution: shared ancestry, different behavior.
  • Describe a strength and a weakness of the observational approach?
    Strength: it costs less money
    Weakness: you don't have a control
  • Natural Selection: the differential survival and reproduction of individuals due to differences in heritable phenotypes.
  • Conditions for Natural Selection:
    1. Variation
    2. Differential Reproductive Success
    3. Heritability
  • Variation: members of a population differ in characteristics.
  • Differential reproductive success depends on that variation, some individuals with particular characteristics have more offspring than others.
  • Heritability: parents can pass on characteristics to their offspring.
  • How do we Know Variation is Heritable?
    1.Parents Offspring Regression
    2. Selection Experiments
  • Parent Offspring Regression: examines the similarity between parents and their offspring. If a trait is heritable, the trait values of offspring should be similar to the trait values of the parents.
  • Selection Experiments: individuals are subjected to differential selection of a trait. If this results in a change in average trait value in later generations, the trait is heritable.
  • Variability is due to differences in genetic composition and environmental conditions.
  • Variability shows up when traits:
    do not affect fitness
    are subjected to certain types of selection
    are influenced by learning
  • Adaptation: traits that result from natural selection and confer higher fitness than alternative traits.
  • How do we measure Fitness?
    Direct: the number of progeny that go on to reproduce
    Indirect: survivorship, number of maters, body size and growth, etc.
  • Eastern screech-owls show great variation in dispersal direction with no coincident differences in reproductive success, indicating fitness is not associated with dispersal's compass direction.
  • Honeybee foraging performance increases due to trial and error learning.
  • Directional Natural Selection:
    Individuals in a population with an extreme trait value at one end of the spectrum posses the highest fitness.
    Ex: Galapagos medium ground finches with the median beak size have the best chance of survival
  • Disruptive Natural Selection:
    Individuals with extreme trait values have the best chance of survival.
    In Spadefoot tadpoles, the detritus and carnivore morphs have the highest chance of survival bc they can feed efficiently.
  • Stabilizing Natural Selection:
    Individuals in a population with intermediate trait values have the highest fitness.
  • Cooperative Behavior: many social animals help others to survive and reproduce.
    only works when everyone gets involved
  • Group Selection: selection operates at the level of the group. Groups that contain too many individuals maximizing individual gain will have lower fitness, than groups that work together.
  • Natural Selection Types
    A) Disruptive
    B) Stabilizing
    C) Directional