Transcript natural selection and gene frequency

NATURAL SELECTION AND
GENE FREQUENCY
BY WOLFGANG
RUBI CATALAN, MARNELLE MAC DULA,
LIANNE UMALI, ERICA WILEY, & CHRIS YOUNG
Student ID #’s:
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
• 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
The Natural Selection
Experiment
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
The Hardy Weinberg
Experiment
Purpose:
To create a population and
demonstrate how consistent HardyWeinberg'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
SPECIMENS &
MATERIALS
The Natural Selection
The Hardy Weinberg
Experiment
Experiment
Specimens:
• 40 small colored paper
dots which represent the
prey
• One clawed and double
clawed predators that kill
Materials:
species.
• the
1 plastic
cup for the “dead”
dots
• 2 distinct fabric mats
which represented
different environments for
your dots
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.
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
NATURAL SELECTION
RESULTS
NATURAL SELECTION
ANALYSIS
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
• Predators play a role in enforcing evolution and natural selection
chance at survival.
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
HARDY WEINBERG
METHODS
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 you’re doing have a
team member calculate the amount of white beads
GENE FREQUENCY RESULTS:
Mutation Effects
GENE FREQUENCY RESULTS:
Population Percent
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
• In this population, the red allele is dominant while the white allele is
allele
favored
phenotypesby
of the
recessive. The dominant phenotype
of producing
red is selected
for, represented
black and dark
red. Rw. This favored trait
homozygous dominant RR and heterozygous
dominant
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
HOW ARE
THEYthe
• Natural selection
can increase
frequencies of
alleles if they are
RELATED?
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
WORKS CITED
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.
Photo Credits
Darwin’s 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