10/13 HOMEWORK
10/13 homework: Finish page 135136 in the blue workbook and on
page 32 in your notebook take
notes on Genetic drift and gene
flow. I will check tomorrow.
10/13 Daily Catalyst Pg. 31 Mutations
 1. In a population in HWE, 32% of the people have green
hair (recessive trait) and 68% of people have purple hair
(dominant trait). Over the next five years, how would you
expect the percentage of hair color to change?
 2. What three HWE conditions cannot be met? Why can
they not be met?
 3. What can you assume about analogous structures and
their DNA?
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10/13 Daily Catalyst Pg. 31 Mutations
 1. In a population in HWE, 32% of the people have green hair (recessive
trait) and 68% of people have purple hair (dominant trait). Over the
next five years, how would you expect the percentage of hair color to
change?
 The percentages will not change! HWE!
 2. What three HWE conditions cannot be met? Why can they not be
met?
 Mutations, Natural selection, and random mating
 3. What can you assume about analogous structures and their DNA?
 These organisms do not share a percentage of DNA. They JUST live in
the same environment
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10/13 Daily Catalyst Pg. 31 Mutations
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Daily catalyst
Class Business
Homework review
Mutation Notes
 HW Review
10/13 Daily Objective Pg. 31 Mutations
 We will be able to connect evolutionary changes in
populations over time to a change in the
environment.
Recap
When gene frequencies change, this is evolution occurring at the
smallest scale.
Key Point #1: A change in the gene pool is called microevolution.
Genetic Variation
 We have no problem picking
out our friends and family in
a crowd because of the
variation in traits.
 Not all variation is heritable.
 Provide an example of this:
 Muscle mass and tattoos
Key Point #2:
ONLY THE GENETIC COMPONENT OF
VARIATION IS RELEVANT TO NATURAL
SELECTION.
Darwin’s Observations
• There is variation within a given species and the majority of this variation is
inherited. This litter of kittens vary with respect to coat pattern and color.
• Any variation may, to some degree, affect the ability of an organism to
reproduce and contribute genes to the gene pool, thus affecting
evolutionary success.
• Species change over time. These changes are related to traits that are
inherited or arise from an alteration of the genetic code.
• Some inherited traits are beneficial and contribute to survival.
• Whether a trait is beneficial or not is a function of the environment in
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which it lives.
Adaptations and Fitness
 An adaptation is a genetically controlled trait
that is favored by natural selection and gives
the organism a reproductive advantage
ensuring the trait is passed on to its
descendants.
 This trait may also allow the individual to
survive longer thus increasing the
reproductive rate of that individual.
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Adaptations and Fitness
 The antelope hare lives in the desert, and the
snowshoe hare lives in the mountains.
 Explain how the differences in their traits
enhance their ability to survive in their
respective environments.
 Evolutionary success or fitness refers to the
contribution of genes to the gene pool and
NOT how long an organism lives.
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The Effect of Environmental Change
• Earth’s environment is NOT STATIC, but rather ever
changing.
• As a consequence, traits or adaptations that were
favorable may become unfavorable.
• The peppered moth, Biston betularia is native to
England and exists in two forms, one is dark and the
other light with a “peppered” appearance. Birds are its
main predator.
• Prior to the industrial revolution, only 2% of the moths
were dark.
• The industrial revolution produced vast amounts of
sulfur dioxide and soot from the burning of coal which
altered the environment.
• Fifty years later 95% of the moths were dark.
• Propose an explanation!
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Industrial Melanism
England has since
regulated the burning of
coal and as a result, the
trees are returning to
their original state (A).
Consequently, the
coloring among the
population of moths in
Britain has shifted back
so that the peppered
moths are once again
favored.
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Evolution Defined
 Evolution is defined as a change in the
inherited characteristics of biological
populations over successive generations.
 Evolutionary processes give rise to diversity
at every level of biological organization,
from the molecular to the macroscopic.
 As a result diversity is prevalent among
molecules such as DNA as well as individual
organisms and species of organisms.
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Microevolution
Microevolution is simply a change in gene frequency within a
population.
 Evolution at this scale can be observed over short periods of time
such as from one generation to the next.
 Example: The frequency of a gene for pesticide resistance in a
population of crop pests increases.
 Such a genetic change might come about because:
 natural selection favored the gene
 the population received new immigrants carrying the gene (gene flow)
 nonresistant genes mutated into a resistant version of the gene
 or random genetic drift from one16generation to the next
Microevolution
 A gene is a sequence of DNA nucleotides
that specify a particular trait.
 An allele is a different version of a gene
For example: black coat color or white coat color
 B represents the allele for
black coat color and b for white coat color.
 Key Point #3: Natural selection acts on individuals, but only
populations evolve.
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 Remember last week when I told you your DNA determines
your inward and outward appearance?
 Genotype: genetic make up (gene for type O blood)
 Phenotype: expression of traits (eye color)
 Selection acts on phenotype because differential
reproduction and survivorship depend on phenotype not
genotype. Do you have what it takes to survive?
Sources of Genetic Variation
How does variation in a population or gene pool
arise?
 MUTATIONS!
 The wisteria pictured
on the right has a
mutation causing it
to produce white
flowers instead of
purple flowers.
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Types of Mutations
 Key Point #4: Only mutations occurring
in gametes affect future generations.
 Gamete cell, what?!
 SEX CELLS (sperm and egg)
 Obviously, mutations occurring in
somatic cells do not affect future
generations.
 Somatic cells, what?!
 All the rest of your cells (bones and
skin)
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Mutations may cause a
sheep to have a 5th leg.
But this is not evolution!
 Mutations can occur at either the gene or
chromosomal level.
Point/Substitution Mutations
 Key Point #5: One nucleotide is substituted for another.
 If this mutation does not affect the function of the
protein, then this mutation is harmless.
 AKA silent mutations
 Some mutations may add or delete nucleotides
therefore affecting the protein that is coded for.
Frameshift Mutation
 Key Point #6: A frameshift mutation occurs as a result
of either an insertion or deletion of a nucleotide.
 AKA insertion mutation
 AKA deletion mutation
 This changes the amino acid sequence of the protein
from that point forward. This has a huge effect!
What are my chances?
 Mutation rates in eukaryotic cells average about one
in every 100,000 genes per generation.
 What else can alter a population’s genetic
composition?
 Genetic Drift:
 Bottleneck Effect
 Founder Effect:
 Gene Flow