Natural Selection and Evolution Notes
Name:
Chapter 16
Date:
Period:
Activating Prior Knowledge:
1. List the eight characteristics of living things.
2. Describe the relationship between a hypothesis, an inference and a theory.
3. Identify an advantage and a disadvantage for sexual and asexual reproduction.
4. What is an allele? Distinguish between a dominant and a recessive allele.
5. Distinguish between the terms genotype and phenotype and give an example of each.
6. Distinguish between the terms homozygous and heterozygous and give an example of each.
7. Distinguish between a germ mutation and a somatic mutation.
8. What do we call traits controlled by two or more genes? Give an example of a trait inherited in this way.
9. What is segregation? When does it occur during meiosis?
10. What process can happen during Prophase I of meiosis to separate genes found on the same chromosome?
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Darwin’s Epic Journey
Evolution:
 In 1831, Darwin was invited to sail on the
coastline of South America. Most famous for observations made at
5-year voyage mapping the
Darwin noticed three patterns of Biodiversity:
1. Species vary
a. Different, yet
similar
but ecologically
species inhabited separate,
around the globe
b. Examples:
2. Species vary
a. Different, yet
within a
species occupied different habitats
area
3. Species vary
a. Fossils =
b. Fossils of
animals were
to
species.
Lamarck’s Theory of Evolution:
Why was Lamarck wrong?
Selective Breeding:
Artificial Selection:
Natural Variation:
Population Growth:
 Malthus observed that babies were being born faster than people were dying.
 If population continued to grow there would be
 In plants or animals most of the offspring die
 Only those who survive can
What determines which ones will survive and reproduce?
Struggle for Existence:
Adaptation:
2
Three types of adaptations that involve body parts or structures:
1. Structural –
Ex:
Mimicry Camouflage 2. Behavioral –
Ex:
3. Physiological –
Ex:
Variations vs. Adaptations - How are they different?
Sources of Variation:
1.
2.
3.
What is Fitness?
 Individuals with adaptations well-suited to their environment can survive and reproduce =
 Individuals with characteristics that are not well-suited to their environment either die without
reproducing or leave few offspring =
.
Survival of the Fittest:
Natural Selection:
3
Descent with Modification:
Darwin’s presents his case in his book:
Age of the Earth:
Evidence Supporting the Theory of Evolution
fossil, anatomical, physiological, embryological, biochemical and universal genetic code
Vocabulary
Description
Example(s)
Fossil
Evidence
Homologous
Structure
(Anatomical
Evidence)
Analogous
Structure
(Physiological
Evidence)
Vestigial
Structure
Embryological
Evidence
Biochemical
Evidence
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Evolution and Population Notes - Chapter 17
Evolution of Populations
Evolution
(In Genetic Terms)
 Natural selection acts directly on

a group of ______________________ of the
species that share a

__________________________________ in which evolution occurs

Combined _____________________ information of _______________________
__________________________________________________________________

Relative
Frequency
.
______________________ area, mate and produce ________________________.
Population
Gene Pool
, not
The number of times a particular
occurs in a gene pool,
compared with the
.
Example:
Allele
Frequency
(Equation)
Phenotype
Frequency
(Equation)
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Determining Phenotype and Allele Frequencies Using Japanese Four o’ Clock Flowers:
RR
RR
RW
Phenotype Frequency
RW
White =
RR
RW
RW
Allele Frequency
RR
R=
Pink =
W=
Red =
Predicting Genotypes and Phenotypes of Second Generation:
According to the laws of probability, the chance of an R gamete meeting with another R gamete is the
product of the allele frequencies in the gene pool.
Red (RR) = R
x
White (WW) =
W
R
x
=
W
RR
=
WW
The frequency of all types expected in the second generation must add up to 1.0
1.0 - RR - WW = RW
Single-Gene Trait

Controlled by only _________ gene.

Single-gene traits may have just _______ or
_______ distinct phenotypes.

Dominance of an allele for a single-gene trait does
not necessarily mean that the ________________
_________________________________________
Polygenic Trait
 Traits controlled by ______ or __________ genes.
 Each gene of a polygenic trait often has
________________________________________.
 A single polygenic trait often has many possible
________________________________________.
_________________________________________
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Evolution as Genetic Change in a Population
Natural Selection on Polygenic Traits
Type of
Selection
Description

Example
Individuals at one __________ of the curve
have higher _____________________ than
Directional
Selection
individuals in the ________________ or at
the other __________

Individuals near the _______________ of
the curve have higher
Stabilizing
Selection
______________________ than
individuals at either end.

___________________________________

Individuals at the _______________
and ___________________ ends of the
curve have higher fitness than
Disruptive
Selection
individuals near the middle.

Can create ________ distinct
_______________________.
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
Occurs in _________________ populations
when an ____________________________
Genetic
Drift
___________________________________.

Genetic drift is a ________________ change
in _________________________________.
What conditions are necessary to maintain genetic equilibrium? (Hardy-Weinberg Principle of Genetic
Equilibrium) Based on a set of assumptions about an ideal hypothetical population that is not evolving.
1. The population must
.
2. There can be
.
3. There must be
.
4. There can be
.
5. No
.
A population is in
if allele frequencies in the population
. If allele frequencies
not
, the population will
.
The Hardy-Weinberg principle predicts that 5 conditions can disturb genetic equilibrium and cause evolution to
occur:
1. ________________________________ – individuals select mates based on
2. ________________________________ – evolutionary change due to
happens more easily in
populations
3. ________________________________ – movement of individuals into (
out of (
) or
) may introduce new alleles or remove alleles from the gene pool
4. _________________________ – introduce
5. ________________________________ – different
alleles changing allele
have different
One or more of these conditions usually holds for real populations = evolutions happen most of the time
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The Process of Speciation
Speciation
Species
Occurs when a population _________________________________________ and the
Reproductive
Isolation
two populations _______________________________________. When populations
become reproductively isolated, they can _____________________________________
______________________________.
Types of Reproductive Isolation:
Behavioral
Isolation
Geographic
Isolation
Temporal
Isolation
Occurs when
develop
Occurs when
that are capable of interbreeding
in courtship rituals or other behaviors
are separated by
______________________________ such as rivers, mountains, or bodies of water.
Happens when two or more species ___________________________ at different times
Gradualism
Patterns and Processes of Evolution
Punctuated Equilibrium
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Rapid Evolution After Equilibrium

Rapid evolution may occur after a
population becomes
from
the main population.
o This small population can evolve
than the larger one because genetic
changes spread more

among
Rapid evolution may also occur when a
to a
individuals.
group of organisms
.
o That’s what happened with the
Genetic Drift  A change in
frequencies that occurs due to
.
events rather than
in

Genetic drift can cause big losses of
for
populations.
o Population Bottlenecks occur when
o Founder Effect occurs when a

This small population size means that the colony may have:

_____________________________________________from the original population.

a ______________________________________________ in the original population.
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