NATURAL SELECTION AND GENE FREQUENCY BY WOLFGANG RUBI CATALAN,
MARNELLE MAC DULA, LIANNE UMALI, ERICA WILEY, & CHRIS YOUNG
Student ID #s:
Slide 2
WHAT IS THAT? Natural selection is a key mechanism of
evolution. It is the process in which individuals with certain
heritable traits survive and reproduce at higher rates than other
individuals without those traits. These traits allow them to adapt
to various environmental pressures, favoring their survival and
passing on of those suitable traits to succeeding generations,
thereby altering allele frequencies. Gene frequency demonstrates
the occurrence of an allele compared to other alleles of the same
gene in a population. The Hardy-Weinberg Principle states allele
frequencies will remain the same through generations in a
population: with extremely large in size, that randomly mates, and
with the absence of mutations, gene flow, and natural
selection.
Slide 3
Purpose: The natural selection lab aims to simulate the process
by which biological traits become more or less prevalent in a
population that has a changing environment. The natural selection
lab will also attempt to show the relationship between predators
and prey. Hypothesis: We predict that the predator will naturally
pick out the prey that is most contrasting in color to its
environment. The species that blends in the most to its environment
in color will thrive and reproduce to make more generations of
offspring. The Natural Selection Experiment The Hardy Weinberg
Experiment Purpose: To create a population and demonstrate how
consistent Hardy- Weinberg's principle really is. To observe the
survival rates in genotypes and phenotypes of a population over a
span of 6 generations. Hypothesis: Since there are mutations,
certain allele frequencies will decrease dramatically due to the
circumstances of the mutation standards. For other cases of
mutation, new species will emerge.
Slide 4
Specimens: 40 small colored paper dots which represent the prey
One clawed and double clawed predators that kill the species.
Specimens: Red, white, and black beads which represented alleles.
Materials: Red beads were used to represent red alleles. Black
beads were used to represent black alleles. White beads were used
to represent white alleles. 6 cups to place different allele
combination in. 1 petri dish lid used to place allele combinations
in. The Natural Selection Experiment The Hardy Weinberg Experiment
Materials: 1 plastic cup for the dead dots 2 distinct fabric mats
which represented different environments for your dots A computer
to record results on excel SPECIMENS & MATERIALS
Slide 5
NATURAL SELECTION METHODS 1.Provided by the instructor, obtain
one of the bottles of colored dots and gather 40 paper colored dots
of one color per each individual in your group. 2. The instructor
will then provide a fabric board that will serve as an environment
for your species. 3.Place your colored species around the board in
any order. Next, designate a predator for each group and send them
to another environment where they will simulate the killing of a
species by eating them for an allotted time set by the instructor.
4.After the event has occurred, calculate how many could survive,
and add in the offspring produced in that generation to the
population. 5.Repeat this process with multiple claws,
environments, and various conditions in order to simulate natural
selection.
Slide 6
NATURAL SELECTION RESULTS
Slide 7
The different colored dots represented the genetic variation
between species. We predicted that those species that stood out
from their environment were less likely to survive. Those species
that adapted to their environment over time had a better chance at
survival. Predators play a role in enforcing evolution and natural
selection because they choose which populations survive and which
do not. Those species newly introduced thrive because the predators
are not yet familiar with them as shown in the previous slide the
newly introduced dark green dots thrived more than any of the other
populations. When a population is brought into a new environment
their survival may be affected. Those that once were able to
successfully survive in the old environment may not be able to
adjust so quickly to the new environment because they have not yet
adapted. NATURAL SELECTION ANALYSIS
Slide 8
Case 1-2 1.Gather all materials and count out 50 white beads
and 50 red beads. 2.Put the red and white beads into a single cup
so that the beads will mix. 3.Have 3 separate cups available for
your RR, Rw, and ww bead combinations. 4.Have a member of the group
randomly grab two beads at a time and put the appropriate bead
combinations into its corresponding cup. 5.Once the team member has
randomly picked all the beads, have someone count and record on
your excel document how many of each combination was acquired.
6.Depending on which case youre doing have a team member calculate
the amount of white beads that should be eliminated from the next
generation. 7.Repeat steps 2-6 until you have reached generation 6.
8.For cases 3-4 repeat steps from case 1-2 but with different beads
and different mutation standards. HARDY WEINBERG METHODS
Slide 9
GENE FREQUENCY RESULTS: Mutation Effects
Slide 10
GENE FREQUENCY RESULTS: Population Percent
Slide 11
In this population, the red allele is dominant while the white
allele is recessive. The dominant phenotype of red is selected for,
represented by the homozygous dominant RR and heterozygous dominant
Rw. This favored trait is passed on to more offspring, increasing
its allele frequency. In both cases of 67% survival and 0% survival
of the white allele, its frequency decreased dramatically over
time. However, we see that it is almost impossible to eliminate the
recessive alleles because of the heterozygous Rw genotype that
codes for the favored phenotype. Unsuccessful genotypes leads to
unsuccessful phenotypes resulting in the decline of allele
frequency over time. And natural selection consistently increases
the allele frequencies of of favorable phenotypes over time,
leading to adaptive evolution. GENE FREQUENCY ANALYSIS Our
hypotheses were validated because the mutations affected allele
frequencies significantly. The positive mutations led to an
increase in population % whereas the negative mutations lead to a
decrease in population %. Also, new species emerged with the
introduction of the dominant black allele producing favored
phenotypes of black and dark red.
Slide 12
Natural selection can increase the frequencies of alleles if
they are advantageous to a species survival and reproductive
abilities. If they somehow produce a phenotype that is not a
selective advantage, their frequency will decrease. The change in
allele frequencies is one way of defining evolution. A population
evolves as better alleles increase in frequency in the gene pool.
This means that gene frequency and natural selection go hand in
hand. They affect one another directly because the frequency of a
gene makes it better suited for natural selection, while
simultaneously, natural selection chooses which genes are going to
be selected against. HOW ARE THEY RELATED?
Slide 13
Campbell, Neil A., and Jane B. Reece. Campbell Biology. San
Francisco, CA: Benjamin Cummings, 2011. Print. Darwin, Charles. "On
The Origin of Species." The Origin of Species by Charles Darwin.
Usenet Newsgroup, n.d. Web. 17 Feb. 2015. Darwins Finches:
http://www1.northbrook28.net/~pamendelson/Mrs._Mendelsons_Site/Natural_Selection_Classification_files/shapeimage_3.png
Colorful Chromosomes:
http://genetics.thetech.org/sites/default/files/KaryColor.gif
Natural Selection Banner:
http://i.ytimg.com/vi/aTftyFboC_M/maxresdefault.jpg Hardy Weinberg
Penguins: http://i.ytimg.com/vi/oG7ob-MtO8c/maxresdefault.jpg NS
Cartoon Fish:
http://media-cache-ak0.pinimg.com/736x/1d/d1/34/1dd13452486e4fd130930d50d2acbb53.jpg
Gene Frequency Goats:
http://farm7.staticflickr.com/6128/5916685986_f891ba6255.jpg
Natural Selection Birds and Beetles:
http://uedata.berkeley.edu//media/3/52571_evo_resources_resource_image_380_original.gif
All other photography were done by SCC Biology 3 Students WORKS
CITED Photo Credits