Ant 15

  1. Misconception about NS
    • - NS favors the survival of the species
    • - behavior is based on either nature or nuture
    • - culture triumps biology (or vice versa)
    • - evolution is progressive
    • - a biological explanation for a behavior that implies that is is justified
  2. what is Evolution?
    • - change over time
    • - in allele frequencies of a population from one generation to the next

    • Evolution:
    • Evolution allows us to explain relationships between living things. These resemblances are due to common descent from a shared ancestor.
  3. Natural Selection
    • 1. Tendency to overpopulate
    • 2. Individuals vary
    • 3. Variation passed onto offspring
  4. Postulate #1 Overpopulation
    • The ability of a population to expand is infinite, but the ability of an environment to support a population is always finite
    • Environment Constraints Population Growth:
    • ex. The Galapagos drought of 78'.
    • The drought affected seed availability (large, tuff).
    • Birds with beaks large enough to eat the seeds were most likely to survive.
    • Variation:
    • Organism's within populations vary, and this variation effects ability of organisms to survive and reproduce.
  5. Postulate #2 Variation
    • Individuals vary in ability to survive and reproduce
    • -beak size varied
    • -small beak birds were less efficient at eating the seeds
    • -larger beak depth in birds were more likely to survive
  6. Postulate #3 Inheritance
    • Variations are transmitted from parents to offspring
    • (beak size too?)
    • characteristics of population changed over time
    • -large beaked adults survived better
    • -large beaked birds had large beaked offspring
    • -mean beak size increased in population
  7. More on NS
    • The three conditions (Darwins Postulates in conjunction with the Galapagos drought) produce competition between organism for sutvival.
    • Organisms with advantageous raits pass them on
    • -adaptations
    • Leads to changes in a population

    • NS acts on Variation
    • -frequency of an allele will become more or less prevelant relative to other forms of the gene (pepper moth).
Author
trainingliz89
ID
135476
Card Set
Ant 15
Description
Natural Selection
Updated