Solved by a verified expert:Evolution and Natural Selection Lab (50 points)
Type your results and responses to
questions in this report and submit. Please answer all questions in full
sentences.
Materials:
Bag of 15 bean soup (dry beans), cup,
2 Paper lunch bags, paper and pencil.
1. We shall simulate genetic
drift and effects of a bottleneck on genetic drift in this simulation. (15 points)
Review “Evolution
Occurs in Several Ways”, Chapter 11.6 in your textbook.
Instructions:
Count out 25 speckled beans, 25 black beans, 25 white
beans and 25 red beans (it is easiest if you choose beans of the same size and
put in container. The beans represent different alleles (Unit 3). This means
each type of bean makes up 25% of the total number of beans (or alleles)
(25/100 = 0.25).
Write two hypotheses answering the two questions
below (5 points):
a.
How would the ratio of bean
phenotypes change if you randomly pick 40 beans from the container? Will the ratio change significantly in each
repetition (generation)?
b.
How would the ratio of bean
phenotypes change if you only pick 10 beans from the container? Will the ratio change significantly in each
repetition (generation)?
Method:
Now take 40 beans from the counter and count the
different phenotypes black, white, red and speckled. Write the results in the data
chart, then return the beans to the container, shake to mix, and repeat the
experiment two more times. Next, take only 10 beans from the container. Count
the different beans and add the data to the chart. Return the beans to the
container and repeat three more times. Complete the data chart below.
Results (5
points):
Large Sample (40 beans):
Bean
(Phenotype)
Original Population
Exp #1
Exp #2
Exp #3
#
%
#
%
#
%
#
%
Small Sample (10
beans):
BLR
(Phenotype)
Original Population
Exp #1
Exp #2
Exp #3
#
%
#
%
#
%
#
%
Were your hypotheses correct?
Answer the following questions (5 points):
I.
What was the range of ratios of
bean phenotypes in the large sample? In the small sample?
II.
How would genetic drift affect
the gene pool in a genetic bottleneck?
III.
Could genetic drift lead to
evolution of new species? Consider ratios of phenotypes of each small sample. Under
which condition would this change lead to speciation?
2. Simulation of Hardy
Weinberg Equilibrium (20 points)
Review “Evolution is Inevitable in Real Populations ”,
Chapter 11. 3 in your textbook.
Also, web site: http://www.nfstc.org/pdi/Subject07/pdi_s07_m01_02.htm
(click the glasses for more help)
We shall
simulate the frequency of two alleles in a population in Hardy Weinberg Equilibrium
over several generations.
Instructions:
This time the
beans will represent alleles (remember we carry two alleles for each trait or
gene, one from the father and one from the mother)
The red bean
represents a dominant allele and the white bean represents a recessive allele. The
homozygous dominant individual is represented by 2 red beans, the homozygous
recessive individual is represented by 2 white beans, and heterozygous
individuals are represented by one red bean and one white bean.
Method
Count and set
aside 60 red beans and 40 white beans. Label
one paper bag male and the other paper bag female. Divide beans evenly into
bags (30 red beans and 20 white beans into each bag). You will grab one bean
from each bag for the allele combination in the F1 generation, for a total of 50 pairs (50 individuals) in the
F1 generation.
Preparation (5 points):
Calculate the frequency of p (dominant allele – red) and
q (recessive allele – white) in population (see textbook chapter 11. 3B).
p=red beans/total # beans
q=white beans/total # beans
p+q=?
2pq = ?
P2= ?
q2= ?
What does p2, q2 and 2pq represent?
Write a hypothesis answering the following question:
a.
If the population is in Hardy
Weinberg equilibrium, what would be the frequency of both alleles in the F1, F2
and F3 generations?
Experiment 1 (5
points)
Remove one bean from each bag blindly and set the pair
aside. Repeat until all beans are paired. This represents one generation.
1.1 Count:
Red pairs (dominant homozygous ) = p2
White pairs (recessive homozygous) =q2
Red-white pairs (heterozygous) = 2pq.
P2 + 2pq + q2= 1
Calculate p = (2x red pairs + red-white pairs)/ total
number of alleles (beans) = ?
q = (2x white pairs + red-white
pairs)/total number of alleles (beans) = ?
p+q= ?
Return beans to bags and repeat the pairing two times, recording
p2, 2pq and q2each time.
1.2 Count:
Red pairs (dominant homozygous ) = p2
White pairs (recessive homozygous) =q2
Red-white pairs (heterozygous) = 2pq.
P2 + 2pq + q2= 1
Calculate p = (2x red pairs + red-white pairs)/ total
number of alleles (beans) = ?
q = (2x white pairs + red-white
pairs)/total number of alleles (beans) = ?
p+q= ?
1.3 Count:
Red pairs (dominant homozygous ) = p2
White pairs (recessive homozygous) =q2
Red-white pairs (heterozygous) = 2pq.
P2 + 2pq + q2= 1
Calculate p = (2x red pairs + red-white pairs)/ total
number of alleles (beans) = ?
q = (2x white pairs + red-white
pairs)/total number of alleles (beans) = ?
p+q= ?
Answer the
following questions:
I.
How much did your experimental
data differ from the calculated data?
II.
Do you accept or reject your
hypothesis?
Experiment 2 (5 points)
Remove one bean from each bag blindly and set the pair
aside. Repeat 10 times. This represents a loss of 10% of the population
(migration).
Now repeat steps of experiment 1.
2.1 Count:
Red pairs (dominant homozygous ) = p2
White pairs (recessive homozygous) = q2
Red-white pairs (heterozygous) = 2pq.
P2 + 2pq + q2= 1
Calculate p = (2x red pairs + red-white pairs)/ total number of
alleles (beans) = ?
q =
(2x white pairs + red-white pairs)/total number of alleles (beans) = ?
p+q=
?
Repeat three times, each time removing 10% of the pairs,
so remove 9 and 8 pairs respectively. Keep the changing total number of beans in
mind when calculating allele (bean) frequencies.
2.2
Count
Red pairs (dominant homozygous ) = p2
White pairs (recessive homozygous) = q2
Red-white pairs (heterozygous) = 2pq.
Calculate p = (2x red pairs + red-white pairs)/ total
number of alleles (beans) = ?
q = (2x white pairs + red-white
pairs)/total number of alleles (beans) =?
p+q= ?
2.3
Count
Red pairs (dominant homozygous ) = p2
White pairs (recessive homozygous) = q2
Red-white pairs (heterozygous) = 2pq.
Calculate, p and q.
p + q = ?
Calculate p = (2x red pairs + red-white pairs)/ total
number of alleles (beans) = ?
q = (2x white pairs + red-white
pairs)/total number of alleles (beans) =?
p+q= ?
Answer the
following questions:
I.
How much did your experimental
data differ from the calculated data?
II.
Do you accept or reject your
hypothesis?
III.
Under what conditions is an
allele within a population in Hardy Weinberg equilibrium?
Experiment 3 (5 points)
Remove one bean from each bag blindly and set the pair
aside. Repeat until all beans are paired.
Remove all white pairs (lost to predation) This represents natural
selection.
3.1 Count
Red pairs (dominant homozygous ) = p2
White pairs (recessive homozygous) = q2
Red-white pairs (heterozygous) = 2pq.
Calculate p = (2x red pairs + red-white pairs)/ total number of
alleles (beans) = ?
q =
(2x white pairs + red-white pairs)/total number of alleles (beans) =?
p+q=
?
Write a
hypothesis answering the following question:
What will happen to p and q if this selective pressure
repeats in the next generation?
Work through another generation. Divide remaining beans
equally and return to bags, and repeat the experiment.
3.2
Count
Red pairs (dominant homozygous ) = p2
White pairs (recessive homozygous) = q2
Red-white pairs (heterozygous) = 2pq.
Calculate p = (2x red pairs + red-white pairs)/ total number of
alleles (beans) = ?
q =
(2x white pairs + red-white pairs)/total number of alleles (beans) =?
p+q=
?
Answer the
following questions:
I.
How much did your experimental
data differ from the calculated data?
II.
Do you accept or reject your
hypothesis?
III.
How does natural selection
affect allele frequencies?
3. Summary (15 points)
Answer the following question in full sentences, at least 150 to 200
words.
What did you
learn in this lab about the effects of population size, migration and natural
selection on allele frequencies in populations? How do allele
frequencies relate to evolution of
species?
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