hardy-weinberg genetic equilibrium hardy-weinberg equilibrium describes populations that are not...
TRANSCRIPT
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
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
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 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 Affects small populations mostly Lose alleles if not enough to mate or a catastrophe
occurs EX: tornado, disease, hurricane etc.
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
IV. Natural Selection (3 Types) Organisms best suited to their
environment live to reproduce and pass on their genes
Acts on a phenotype
IV. Natural Selection (3 Types) Organisms best suited to their
environment live to reproduce and pass on their genes
Acts on a phenotype Varying types of selection
1. Directional Selection
Individuals with a more extreme form of trait have higher fitness
Normal DistributionDistribution after Selection
Suppose termites in an area begin to build deeper nests. Anteaters with long tongues could more effectively prey on termites than those with short or average tongue length
2. Stabilizing Selection
Having average form of trait has highest fitness
Normal DistributionDistribution after Selection
Blue curve shoes variation after a new predator is introduced. Predator can easilty capture the large, visible lizards and the small slower lizards. Thus, selection against these extremes body types reduces the size range in lizards
3. Disruptive Selection
Individuals with any extreme trait has a higher fitness and most likely results in two new species
Normal DistributionDistribution after Selection
The white limpets blend in with barnacles on rocks. On bare rocks, dark-shelled limpets blend in. However, the tan colored limpets are easy to spot by birds.
Can amplify certain traits and reduce others through sexual selection
V. Non-random mating
Can amplify certain traits and reduce others through sexual selection
Sexual Selection - Choose mates based on specific traits and those traits increase in the population
V. Non-random mating
Class work Create 4-squares for the following words Use page 325
Directional Selection Stabilizing Selection Disruptive Selection
def Graph
Example 2 associated phrases (description)
Word
Homework
WS #2