Download Genetics and Evolution

The Genetics of Evolution
What is the relationship between
the genes of a population and
evolution?
Standards:
 BI7. a. Students know why natural selection acts
on the phenotype rather than the genotype
 of an organism.
 BI7. c. Students know new mutations are
constantly being generated in a gene pool.
 BI8. c. Students know the effects of genetic drift
on the diversity of organisms in a population.
Objectives:
SWBAT…
 Explain that new mutations are constantly
being generated in a gene pool, and this can
cause evolution.
 Understand the decrease in genetic diversity
in a population caused by genetic drift.
Where does the genetic variation
come from for evolution?
 Gene pool-combined alleles for all the
individuals in a population
 Genetic variation is stored in the gene pool
 Alleles-different forms of trait (eye color)
 Allele frequency-measure of how common
an allele is in a population
What are the five factors that can
cause evolution?
 Genetic drift-allele frequencies can change due to
chance alone
 Gene flow-the movement of alleles from one
population to another, changes allele frequencies
in each pop.
 Mutation-can form new alleles, creates genetic
variation needed for evolution
 Sexual selection-certain traits may improve mating
success
 Natural selection-certain traits can help survival,
these traits increase in frequency
What is gene flow?
 Gene flow-movement of alleles from one
population to another
 Occurs when individuals of species move
between populations
 Increases genetic variation
What processes allow genetic drift to
take place?
 Genetic drift-changes in allele frequency
due to chance, decreases genetic diversity
 Bottleneck effect-GD that occurs after an
event greatly reduces the size of the
population. (overhunting)
 Founder effect-GD that occurs after a small
number of individuals colonize a new area.
(islands)
Genetic Drift
Bottleneck Effect
Polydactyl (Amish)
Summary Questions
 What is the gene pool of a population?
 Name two genetic factors that can cause
evolution.
 Does genetic drift decrease or increase
genetic diversity?
 What is the relationship between the genes
of a population and evolution?