evolution - genetic change in populations  

• mutation - changes in genetic message of cell
• fitness - organism’s tendency to produce more offspring
  • individuals w/ better genes more able to survive, pass down genes
• natural selection - environmental conditions determine the characteristics of a population
• major force that guides formation of new species, genetic change
• frequency - proportion of individuals w/ a certain trait relative to total number of individuals

Hardy-Weinberg principle - used to calculate/predict allelic frequencies

• based on data for 1 or 2 frequencies
• p = frequency of dominant allele
• q = frequency of recessive allele
• p + q = 1
• p2 + 2 pq + q2 = 1
• assumptions - large population, random mating, no mutations, no migration, no selection pressure

selection pressures - factors that affect organisms, lead to selective reproduction 

• selection - differential reproduction of phenotypes
  • certain phenotypes passed down more often than others
  • positive selection - genotypes for adaptive traits increase in frequency
  • negative selection - genotypes for nonadaptive traits decrease in frequency
• can totally eliminate a certain trait from the entire population