Hardy-Weinberg Genetic Equilibrium Hardy-Weinberg equilibrium describes populations that are not evolving Genotype frequencies stay the same over time as long as certain conditions are met: Very large populations No emigration or immigration No mutations Random mating No natural selection

DISRUPTING GENETIC EQUILIBRIUM CH. 16-2 PP. 321-325

Definitions.. Evolution is the change in a population’s genetic material (alleles) over generations.

Definitions.. Evolution is the change in a population’s genetic material (alleles) over generations. A population is in genetic equilibrium if it’s not evolving

WHAT PUSHES A POPULATION OUT OF EQUILIBRIUM? 5 Factors Population is in equilibrium

I. Mutation Produces and introduces new alleles in a population New allele can create beneficial trait

II. Migration/ Gene Flow Movement of individuals in or out of a population Immigration – In (Entering population) Emigration – Out (Leaving population)

III. Genetic Drift The amount of an allele changes due to random events EX: extreme weather, disease, habitat destruction, etc

III. Genetic Drift The amount of an allele changes due to random events EX: extreme weather, disease, habitat destruction, etc Affects small populations mostly! Case Study: Population of the nearly extinct northern Elephant Seal have lost genetic variability—individuals are homozygous for all their genes tested. This result of genetic drift makes the species vulnerable to extinction.

III. Genetic Drift The amount of an allele changes due to random events EX: extreme weather, disease, habitat destruction, etc Affects small populations mostly! Lose alleles if not enough to mate or a catastrophe occurs Population of the nearly extinct northern Elephant Seal have lost genetic variability—individuals are homozygous for all their genes tested. This result of genetic drift makes the species vulnerable to extinction.

IV. Natural Selection (3 Types) Organisms best suited to their environment live to reproduce and pass on their genes Acts on a phenotype

V. NON-RANDOM MATING Many organisms do not mate randomly. Some animals choose mates based on desirable traits This can amplify certain traits and reduce others

V. NON-RANDOM MATING a. Artificial Selection- Humans choose desirable traits in animals to cause changes.

V. NON-RANDOM MATING b. Sexual Selection - Choose mates based on specific traits and those traits increase in the population EX: Peacock tails Tails are bright and heavy. Only the males who are able to get away from predators and have enough energy to grow a tail must have the best traits.

https://www.youtube.com/watch?v=nS1tEnfkk6M

Class work Hardy Weinberg Scenarios and Chart