Download the alleles in a population

11.1 Genetic Variation within Populations
11.3 Other Mechanisms of Evolution
Gene pool: the alleles in a population (#)
Gene flow: Movement between populations, alleles
move from one population to another separate
population.
Allele frequency: Measure of how common
the allele is in a population (%)
Genetic Variation: difference in the
phenotypes of individuals
Caused by mutation (random
change in DNA) and recombination (during
meiosis and is caused when chromosomes
exchanged DNA segments).
Genetic drift: changes in allele frequency due to chance
NOT MOVEMENT, this also lowers genetic diversity
Bottleneck effect: A catastrophic effect kills off most of
the population and only a small number of the
population is left.
Founder effect: A small population goes to a new
unpopulated region and start their own population.
(Different than gene flow because these people are
creating a population not moving to a new one).
11.2 Natural Selection in Populations
Sexual selection: Certain traits increase mating success
Normal Distribution: NO NATURAL
SELECTION OCCURS! There is no change in
environment. Bell shaped curve
Intrasexual selection- MALES chose mates
through competition
Microevolution: change in a population over
time
Directional selection: NATURAL SELECTION
OCCURS. Goes to one homozygous
phenotype of another (not both).
Stabilizing selection: NATURAL SELECTION
OCCURS. Goes to the heterozygous
phenotype and the homozygous
phenotypes go down.
Disruptive selection: NATURAL SELECTION
OCCURS. Goes to BOTH the homozygous
phenotypes and the heterozygous
phenotype goes down.
Intersexual selection- FEMALES chose mates
due to appearance
11.5 Speciation through Isolation
Speciation: When two or more species come from one
existing species
Reproductive isolation: Two different population can no
longer mate causing them to become different species.
(Physically not able to mate, do not make viable
offspring).
Behavioral isolation: Difference in courtship and mating
behaviors causing different populations to not mate,
making them a different species.
Geographic isolation: Two populations are separated by
geographical barriers, causing the populations to no
longer get along and not mate. This makes them
different species
Temporal isolation: When reproduction (mating)
happens at different times of the year, or day. This does
not allow different populations to mate causing them to
be different species.