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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?
Population is in
equilibrium
5 Factors
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 WORK
Hardy Weinberg Scenarios and Chart