Chap 24:
Evolution Mechanisms
Supplemental Instruction
Iowa State University / Leader: / Adam
Course: / Biology 211
Instructor: / Dr. Wilsey
Date:

1.  All of the alleles for every gene in a given population is called a?

2.  What two letters represent allele frequencies?

Two population genetics calculations:

1.  Allele frequency: The number of copies of a specific allele in a population / total number of all alleles for that gene in a population

2.  Genotype frequency: number of individuals with a particular genotype in a pop/ total number of individuals

Worked Problem:

You are a small organic farmer. You go out into your garden and picked 170 cucumbers. You notice some are smooth, some are rough, and some are indented on their skin. There are two alleles for cucumber skin: C^R and C^I. You look more closely and have 89 cucumbers that are rough (C^R,C^R), 66 cucumbers are smooth (C^R,C^I), and 15 that are indented (C^I,C^I). The organic cumbers are diploid.

a.  What is the allele frequency of C^R

b.  What is the allele frequency of C^I

c.  What is the genotype frequency of rough skin, smooth skin, and indented skin.

Hardy-Weinberg equation:

Describes a population that is not…..

Used to estimate the percentage of a ______carrying the ______for an inherited disease

States that the frequencies of alleles and genotypes in a population will remain ______from generation to generation provided that only ______segregation and recombination of alleles are at work.

The Hardy-Weinberg equation: p2 + 2pq+q2=1 describes a population that is not evolving

p2 & q2 represents:

2pq represents:

Genotype frequencies add to what sum?

Question: Using the Hardy-Weinberg equation with two alleles A and a, the frequency of the a allele is .2. What is the percentage of the population that is heterozygous for this allele? (show calculations)

Question: In a population in Hardy-Weinberg equilibrium, 55% of the individuals have a dominate allele for a particular gene and 45% have the recessive allele. The proportion of homozygous recessive individuals in the F1 generation will be what?

5 conditions are required to reach Hardy-Weinberg equilibrium:

1. 

2. 

3. 

4. 

5. 

Genetic Drift:

  1. Refers to changes in ______frequency due to ______.
  2. Has a great impact on what size of populations?
  3. Tends to reduce what?
  4. Can cause harmful alleles to become fixed

There are two types of genetic drift:

  1. -A sudden change in the environment may drastically reduce the size of the population

Occurs for two reasons

1.

2.

  1. -Occurs when a few individuals become isolated from a larger population, this new group establish a new population whose gene pool differs from the source population
  2. The founding populating is expected to have _____ genetic variation than the larger population.

6.  Migration

  1. Can alter allele frequencies between what?
  1. Tends to ______differences in allele frequencies between populations while ______genetic diversity within populations.

??Changes in allele frequencies indicates what??