Patterns of Selection

• Fitness (Relative Fitness):


  Fitness is the contribution to the gene pool, how they are able to survive and reproduce (including how their offspring survive + reproduce), and can be compared between organisms
• Why is Fitness important?


  It leads to adaptation
• Describe Adaptation:


  Adaptations is when traits increase individual fitness in an environment
• There are different kinds of Natural Selection:

  1.) Direction Selection

  2.) Stabilizing Selection
• Direction Selection is when:


  One EXTREME phenotype is favored (Ex: Antibiotic resistance)
• Stabilizing Selection is when:


  An average(intermediate) phenotype is favored
• Genotype:


  A genetic trait that determines characteristics such as lactose intolerance or allergies, genotype gives rise to phenotype
• Phenotype:


  A physical trait that determines observable characteristics such as eye color or height
• Alleles can either be Dominant(R) or Recessive(r)
• There are Three possible genotypes with 2 alleles:


  1.) RR - Homozygous Dominant

  2.) Rr - Heterozygous

  3.) rr - Homozygous Recessive
• The Two Hardy-Weinberg equations:

  1.)$p+$$q=$$1$

  2.) $p^2+$$2\left(p\right)\left(q\right)+$$q^2=$$1$
• p+q=1 will be used for allele frequencies (p for Dom. allele and r for Rec. allele)
• $p^2+$$2(p)(q)+$$q^2=$$1$ will be used for genotypic frequencies


  1.) P2 - RR

  2.)2(p)(q) - Rr

  3.)q2 -rr
• What is Hardy-Weinberg Equilibrium?


  It is a principle stating that allele freq. will not change in a population if certain conditions are not met, describing the gene pool of a non-evolving population
• There are Five major assumptions that lead to Hardy-Weinberg Equilibrium:


  1.) Large Population - a very large one

  2.) Random Mating - individuals not looking for specific traits when mating

  3.) No Mutation

  4.) No Gene Flow

  5.) No Natural Selection