Genetic Equilibrium Population genetics looks at evolution at the genetic level Types of Evolution: Convergent Evolution Different species evolve similar traits Analogous structures – same function, look different Divergent Evolution - 1 species changes into 2 different species, each fitting into different niches of the environment - Causes adaptive radiation – filling a void in an environment… usually food Coevolution - Two unrelated species evolve adaptations to each other’s influences

Genetic Equilibrium In a population, there are different variations for genes, which is called the gene pool The allele frequency is how often a dominant or recessive allele shows up in an organism’s genotype The phenotype frequency is how often a trait is expressed Hardy-Weinberg Equilibrium Genotype frequencies tend to remain the same through generations, unless it is changing through evolution Shows that populations are at equilibrium most of the time

Disruptions to Genetic Equilibrium Any change to the genetic equilibrium of a population results in evolution Disruption to Genetic Equilibrium: Mutations Radiation or chemicals can cause changes in the DNA sequence, causing new alleles to be created Beneficial mutations are a vital part of evolution Gene Flow Genes move from one population to another Ex: Immigration & emigration; seed dispersal New alleles are introduced into populations

Disruptions to Genetic Equilibrium Genetic Drift Allele frequencies change randomly or as a result of chance Founder effect: newly populated areas have less diversity Non-random mating Mating is often influenced by location; related individuals can mate Also caused by organisms selecting traits similar to theirs Traits can become amplified in populations Natural Selection Favorable traits are selected for and persist in a population