What is an Adaptation?

  • An adaptation has to be better than alternative traits, not perfect
  • Adaptations are traits that confer higher fitness
  • Traits have fitness costs, and fitness benefits, to be an adaptation, a trait has to be better than alternative traits, not perfect!
  • By using a cost-benefit approach, we can be used to identify current adaptations.
  • We can also analyze phenotypes in terms of their fitness costs vs. fitness benefits.

Novel Environment

Other Reasons for Maladaptions

  • Pleiotropy: One gene causes multiple phenotypic effects. (Net Benefit Theory)
  • Genetic Drift
  • Gene Flow

In Texas:

  • Desert Grassland Population: Harsh environment, low predators. More Aggressive.
  • Riparian Population: More favorable environment, high predators. More Cautious.

In Arizona:

  • The Riparian population is much more aggressive and less cautious than predicted.
  • Gene flow from desert population to riparian responsible.