What is Gene
Frequency?
Gene frequency is the frequency
of occurrence or proportions of
different alleles of a particular
gene in a given population. It is
usually expressed as a proportion
or a percentage, and describes
the amount of genetic diversity
at the individual, population, or
species level. (1)
What is Natural
Selection?
The process by which forms of life
having traits that better enable
them to adapt to specific
environmental pressures, as
predators, changes in climate, or
competition for food or mates, will
tend to survive and reproduce in
greater numbers than others of
their kind, thus ensuring the
perpetuation of those favorable
traits in succeeding generations.(1)
How can Natural Selection and
Allele Frequencies effect one
another?

Natural Selection can increase or decrease an alleles frequency. If
the allele produces a phenotype which is advantages then their
frequency will increase, however if it is not advantageous, the
frequency will decrease.

They both work together to accelerate evolution or against each
other to slow evolution.
Gene Frequency Methods
• Add all the beads in one cup and mixed
• Randomly pick two bead pairs to determine the phenotype and genotype and record the data
 Case1:
50 red beads, 50 white beads to create RR homozygous dominant, Rw heterozygous, ww
homozygous recessive
33% deduction of ww homozygous recessive per generation for 6 generations
 Case 2:
50 red beads, 50 white beads to create RR homozygous dominant, Rw heterozygous, ww
homozygous recessive
100% deduction of ww homozygous recessive per generation for 6 generation
 Case 3:
40 red, 40 white, 20 black beads to create RR homozygous dominant, Rw heterozygous, ww
homozygous recessive, RB heterozygous mutation, Bw heterozygous mutation and BB homozygous
mutation.
100% deduction of ww, 150% survival of RB, and 200% survival of BB homozygous for each
generation for 6 generations
 Case 4:
40 red, 40 white, 20 black beads to create RR homozygous dominant, Rw heterozygous, ww
homozygous recessive, RB heterozygous mutation, Bw heterozygous mutation and BB homozygous
mutation.
100% deduction for ww, 100% deduction of BB, and 50% deduction of RB
Natural Selection Methods

1) Choose 40 same colored dots

2) 20 of those dots will go onto a colored cloth mat symbolizing an environment and the
dots will symbolize species.

3) Predators: (only get 1 minute) Generation #1- one person, one hand
Generation #2- one person, two hands
Generation #3- two people, one hand
Generation #4- two people, two hands
* Environment is changed (new colored place mat)
Generation #5- two people, two hand (lights going on and off)
Generation #6- Natural Disaster(playing card)

4) Take count of dead for each generation and record data
* If any colors/generation die out then a new color/generation will be added.

5) Each time we enter our results for each generation, we would add back the offspring for
each back into the environment.
Gene Frequency Results
Case 1: -33% ww
Case 2: -100% ww
80.0%
100.0%
70.0%
80.0%
60.0%
RR-33%ww
40.0%
Rw-33% ww
ww-33% ww
30.0%
Percent of Popula on
Percent of Popula on
60.0%
50.0%
RR-100% ww
40.0%
Rw- 100% ww
ww-100% ww
20.0%
20.0%
0.0%
10.0%
Gen 1
0.0%
Gen 1
Gen 2
Gen 3
Gen 4
Gen 5
Gen 6
Gen 7
Gen 8
Gen 9
Gen 10
Gen 11
Gen 12
-20.0%
Gen 2
Gen 3
Gen 4
Gen 5
Gen 6
Gen 7
Gen 8
Gen 9
Gen 10
Gen 11
Gen 12
Genera on
Genera on
Figure1
Case#1 and Case#2 decrease in Rw and ww due to
the negative selection of the ww genotype.
Figure 2
Gene Frequency Results
Case 3: Posi ve Muta on
Case 4: Nega ve Muta on
80%
80%
70%
60%
60%
Percent of Popula on
RR Pos tve Muta on
40%
Rw Posi ve Muta on
ww Pos ve Muta on
30%
RB Posi ve Muta on
wB Posi ve Muta on
20%
Percent of Popula on
40%
50%
RR Nega ve Muta on
Rw Nega ve Muta on
20%
ww Nega ve Muta on
RB Negai ve Muta on
0%
BB Posi ve Muta on
wB Negai ve Muta on
Gen 1
Gen 2
Gen 3
Gen 4
Gen 5
Gen 6
Gen 7
Gen 8
Gen 9
Gen 10
Gen 11
Gen 12
BB Nega Muta on
10%
-20%
0%
Gen 1
Gen 2
Gen 3
Gen 4
Gen 5
Gen 6
Gen 7
Gen 8
Gen 9
Gen 10
Gen 11
Gen 12
-40%
-10%
-20%
Genera on
Figure 3
Case #3: Increase in both Homozygous
Dominant BB (200% survival) and Heterozygous
dominant RB (150% survival) due to the positive
mutation . Decrease in RR, Rw, ww, and wB due
to neutral/negative survival.
-60%
Genera on
Figure 4
Case #4: RR, Rw, wB show little to no growth due
to neutral survival. RB increased slightly due to
50% survival. BB and ww declined due to 0%
survival.
Figure 5
Natural Selection Results
Figure 6
• Through generations 1-5 we were able to see natural selection at work as the phenotypes were
not well suited for the environment and were consistently killed off. Generation 6 we witnessed the
bottle neck effect with the natural disaster.
Natural Selection vs Allele Frequency
Figure 8
Figure 7
As long as the Phenotype is beneficial then the
species will have a will have a positive compound
annual growth rate %.
Conclusion

Natural selection acts more on the phenotype than on the
genotype.(2)

Natural selection acts indirectly via how the genotype affects the
phenotype. (2)

Allele frequency can be changed by Natural Selection, gene flow,
and genetic drift, yet only Natural selection consistently improves
the match between organisms and their environment. (2)

Evolution is therefore achieved because of Natural Selection.
Citations
1)http://dictionary.reference.com/b
rowse/gene+frequency
2)Reece, Jane B. "22 Descent with
Modification: A Darwinian View of
Life." Campbell Biology. 9.th ed.
San Francisco: Pearson Benjamin
Cummings, 2011. 460. Print.
3)https://solano.instructure.com/co
urses “Hardy-Weinberg Law” lab
instructions