Quiz 2

• Natural Selection


  produces organisms with improved body structures and habitats
• Directional selection 


  change in the environment causes a change
• Stabilizing selection


  intermediate phenotypes are more likely to survive
• DISRUPTIVE or DIVERSIFYING SELECTION


  extreme phenotypes are more likely to adapt
• Artificial selection 


  selective breeding. Humans select the variations that are useful to them.
• Recombination


  crossing-over of chromosomes during meiosis
• Non-random mating


  selected probability of mating

  • Inbreeding
  • Outbreeding
• Inbreeding


  mate with their close relatives, inbreeding depression
• Outbreeding or assortative mating


  individuals select distant relatives. similar phenotype are most likely to mate
• Mutation


  change in the structure of a gene
• SUBSTITUTION


  Has one altered nitrogenous base
• Insertion 


  addition of an extra set of base pairs
• Deletion


  set of base pairs in the genetic material is omitted
• Genetic drift 


  a change to a population's gene by chance
• Population bottleneck


  A sudden sharp decline in the population from natural selection
• Founder effect 


  A small group of individuals breaks off from a larger population
• Gene flow


  known as migration and happens when new alleles are introduced from one population to another
• EMIGRATION happens when organisms leave their habitat
• IMMIGRATION happens when organisms enter another habitat and live in it
• Hardy Weinberg Equilibrium


  It states that a population’s allele and genotype frequencies are constant, unless there is some type of evolutionary force acting upon them
• Assumptions of Hardy-Weinberg Equilibrium


  • No natural selection • No mutation • No migration • Large population • Random mating
• Godfrey harold hardy
• Wilhelm Weinberg
• role of gene flow in evolution


  It introduces new alleles into a population.
• Antibiotics kill susceptible bacteria, and those that survive possess a genetic mutation that renders them impervious to the drug. The survivors reproduce and pass on the beneficial mutation to the next generation.

  Disruptive selection
• Gene flow


  mechanism that directly introducing or transferring new alleles from one population to another