KEY CONCEPT Hardy-Weinberg equilibrium provides a framework for understanding how populations evolve.

Hardy-Weinberg equilibrium: Equilibrium state in which genotype frequencies in a population stay the same from generation to generation Why is it important: Comparing real data with that predicted by the equilibrium model; framework for testing factors that can lead to evolution

Five Conditions Required to be in Equilibrium 1. very large population: no genetic drift 2. no emigration or immigration; no gene flow 3. no mutations; no new alleles added to gene pool 4. random mating; no sexual selection 5. no natural selection; all traits aid equally in survival

Hardy-Weinberg equilibrium describes populations that are not evolving Hardy-Weinberg equilibrium describes populations that are not evolving. (Nothing for notes here just a recap) Real populations rarely meet all five conditions. Real population data is compared to a model. Models are used to studying how populations evolve.

The Hardy-Weinberg equation is used to predict genotype frequencies in a population. Hardy-Weinberg equation: p2 + 2pq + q2 = 1 What it means: Frequency of dominant homozygotes + frequency of heterozygotes + frequency of recessive homozygous = 1 (or any reminder of meanings of variables or meaning of equations. How it is used: To predict genotype frequencies of populations in Hardy-Weinberg equilibrium for simple, dominant-recessive traits

The Hardy-Weinberg equation is used to predict genotype frequencies in a population. "The Hardy-Weinberg equation is based on Mendelian genetics. It is derived from a simple Punnett square in which p is the frequency of the dominant allele and q is the frequency of the recessive allele."

There are five factors that can lead to evolution. 1. Genetic drift changes allele frequencies due to chance alone.

There are five factors that can lead to evolution. 2. Gene flow moves alleles from one population to another.

There are five factors that can lead to evolution. 3. Mutations produce the genetic variation needed for evolution.

There are five factors that can lead to evolution. 4. Sexual selection selects for traits that improve mating success.

There are five factors that can lead to evolution. 5. Natural selection selects for traits advantageous for survival.

Let’s wrap this up… In nature, populations evolve. (Duh!) expected in all populations most of the time respond to changing environments