Download Genetic Variations with Populations

Genetic Variations with
Populations
11.1 & 11.2
Genetic variation – the quantity of different genes
within a species. As a general rule, the more genetic
variation, the better…
Genetic variation is stored in a populations gene-pool
– the combined alleles (genes) of all individuals within
a population.
Allele frequency – a measure of how common an
allele is within a population.
Recall that an allele IS a gene; it is simply one of many
forms of THAT gene.
mutation– a random change in the DNA of a gene.
Recall that a gene is a specific sequence of DNA that
makes a protein.
If genes make proteins, and proteins determine traits,
what COULD possibly happen if a mutation occurs?
Normal distribution (bell-curve): type of distribution
in which the count is highest near the mean value and
lower at the extremes.
What the heck does that mean, Mr. Allen?!
Microevolution: the observable change in the allele
frequencies of a population over time.
Natural Selection can lead to microevolution.
Directional selection: a type of selection that favors
phenotypes at one extreme of a traits range. Example:
long necks become more common.
Natural selection can favor different alleles on the
bell-curve distribution.
Stabilizing selection: a type of selection that favors
the intermediate phenotype. Example: medium blue
becomes more common.
Natural selection can favor different alleles on the
bell-curve distribution.
Disruptive selection: a type of selection that favors
extreme phenotypes. Example: very tall and very
short people become more common.