Download NAME: 07/23 SSA Science NATURAL SELECTION VIRTUAL LAB

NAME: _______________________________________________ 07/23 SSA Science
NATURAL SELECTION VIRTUAL LAB
STEP 1: Go to the following website: http://www.mhhe.com/biosci/genbio/virtual_labs/BL_12/BL_12.html
HOW DOES NATURAL SELECTION AFFECT ALLELIC FREQUENCIES?
STEP 2: *Refer to the information on the left column to answer the questions below.
1. What evolutionary mechanism are you simulating in this online lab?
2. This simulation is investigating the effect of ___ on certain phenotypes.
3. By placing pressure on these specific phenotypes, what will change?
4. What can natural selection alter in a population’s gene pool over time?
5. So how can evolution be described when referring to changes in gene pools?
6. What can these changes of genes lead to the evolution of?
7. What alleles are we using in this simulation?
8. These alleles show INCOMPLETE DOMINANCE. Define incomplete dominance below:
9. List the phenotypes for the following alleles:
AA
Aa
aa
10. Each variation of a trait may increase or decrease the organism’s survival in an environment. However, are all
phenotypic traits visible? List an example.
STEP 2: *Refer to the procedure for instructions. Fill out the data tables below for each generation and for each
environment:
ROCKY ENVIRONMENT: MAKE SURE ALLELE FREQUENCIES ARE A = .5 AND a = .5
GENERATIONS:
NUMBER OF INDIVIDUALS BEFORE AND AFTER NATURAL SELECTION:
Genotype
AA
BEFORE
1
2
3
Genotype
AA
AFTER
Genotype
Aa
BEFORE
Genotype
Aa
AFTER
Genotype
aa
BEFORE
Genotype
aa
AFTER
2
4
5
DESERT ENVIRONMENT: MAKE SURE ALLELE FREQUENCIES ARE A = .5 AND a = .5
GENERATIONS:
NUMBER OF INDIVIDUALS BEFORE AND AFTER NATURAL SELECTION:
Genotype
AA
BEFORE
Genotype
AA
AFTER
Genotype
Aa
BEFORE
Genotype
Aa
AFTER
Genotype
aa
BEFORE
Genotype
aa
AFTER
1
2
3
4
5
GRASSLAND ENVIRONMENT: MAKE SURE ALLELE FREQUENCIES ARE A = .5 AND a = .5
GENERATIONS:
NUMBER OF INDIVIDUALS BEFORE AND AFTER NATURAL SELECTION:
Genotype
AA
BEFORE
Genotype
AA
AFTER
Genotype
Aa
BEFORE
Genotype
Aa
AFTER
Genotype
aa
BEFORE
Genotype
aa
AFTER
1
2
3
4
5
URBAN ENVIRONMENT: MAKE SURE ALLELE FREQUENCIES ARE A = .5 AND a = .5
GENERATIONS:
NUMBER OF INDIVIDUALS BEFORE AND AFTER NATURAL SELECTION:
Genotype
AA
BEFORE
1
2
3
4
5
Genotype
AA
AFTER
Genotype
Aa
BEFORE
Genotype
Aa
AFTER
Genotype
aa
BEFORE
Genotype
aa
AFTER
3
Step 3: ANSWER POST LAB QUESTIONS USING YOUR DATA:
1. Did either allele A or a disappear from the following populations you studied?
 Rocky Environment:
 Desert Environment:
 Grassland Environment:
 Urban Environment:
2. A population in which the frequency of alleles remains the same over generations is said to be in genetic
equilibrium. Describe one mechanism by which a populations' genetic equilibrium can be disrupted and result
in the process of evolution. *HINT: It is what this lab is simulating*.
3. In which of the simulated environments do individuals of the genotype Aa survive best?
4. In which of the simulated environments do individuals of the genotype aa survive best?
5. Which set of data represents a type of natural selection that stabilizes the allele frequencies of the
population?