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 FactorsPopulation 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

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

• Can amplify certain traits and reduce others through sexual selection

V. NON-RANDOM MATING• 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.

CLASS WORKHardy Weinberg Scenarios and Chart