Transcript The Theory of Evolution on Natural Selection

The Theory of Evolution on
Natural Selection
Luis Mayo
EDT 610
June 24, 2009
Bellringer Exercise

Explain the following statements in
your own words:
Long Life Span;
Short Life Span

Write a paragraph relating an
organism’s life span to the potential
rate of evolution of a species.
Bellringer Exercise
 Once
all students have completed writing the
paragraph, the class will discuss their answers.
 Additionally,
a discussion on the topic of evolution
will take place.
 Make
sure that you respect your classmates when
they are discussing the topic!
The Main Ideas

What is natural selection?

What are the observations that led Darwin to conclude that
species evolve?

What are the main points of the Theory of Evolution on
Natural Selection?

What is the effect of natural selection in a population?
Review of the Principles of Evolution
Evolution is a gradual
change over a period of
time.
 It deals with the orderly
changes that have shaped
Earth.
 Additionally, it has
modified the living species
that inhabit Earth.

Review of the Principles of Evolution

Evidence of evolution comes from each of the following:
A) the geologic record
B) fossil evidence
C) cell studies
D) genetics
E) comparative anatomy
F) comparative embryology
Review of the Principles of Evolution

The Geologic Record
Review of the Principles of Evolution

Fossils
Review of the Principles of Evolution

Cell Studies

Genetics
Review of the Principles of Evolution

Comparative Anatomy

Comparative Embryology
What is Natural Selection?
 In
your own words, write down what do you think
is natural selection?
 Construction
paper and markers will be handed out
so that you can create your definition.
 Pictures
may also be drawn to depict the
terminology of natural selection.
What is Natural Selection?
 Definition:
individuals that have physical or
behavioral traits that better suit their environment
are more likely to survive and will reproduce more
successfully than those that do not have such traits
 Natural
selection can also be described as
“survival of the fittest”!
Evolution by Natural Selection

A.
Theories:
Jean Baptiste Lamarck:
1. Proposed that differences
among animals and plants
were due to changes that
caused significant
variations among species.
2. Lamarck believed that
changes are going on all
of the time because
evolution is a continuous
process.
Evolution by Natural Selection
3. He believed that systems & body structures
developed in response to “use”, and those
structures in “disuse” eventually disappeared.
4. He believed that acquired characteristics could be
passed on from parent to offspring.
Evolution by Natural Selection
B.
Charles Darwin
1. British naturalist who
became famous for his
theories of evolution &
natural selection.
2. He believed that all life on
earth evolved (developed
gradually) over millions of
years from a few common
ancestors.
Evolution by Natural Selection
3. From 1831 – 1836, Darwin served as a naturalist
aboard the H.M.S. Beagle on a British science
expedition around the world.
4. In South America, Darwin found fossils of extinct
animals that were similar to modern species.
Evolution by Natural Selection
5. On the Galapagos Islands in the Pacific Ocean, he
noticed many variations among plants and animals
of the same general types as those in South
America.
6. Upon his return to London, Darwin conducted
thorough research of his notes & specimens.
Darwin’s Voyage
An Example of
Darwin’s Observations
Evolution by Natural Selection

1.
Out of this study grew several related theories:
Evolution did occur
2. Evolutionary change was gradual, requiring thousands to millions of
years
3.
The primary mechanism for evolution was a process called natural
selection
4. Millions of species alive today arose from a single original life form
through a branching process called “specialization”
Evolution by Natural Selection

Charles Darwin’s Theory
of Evolution on Natural
Selection holds that
variation within species
occurs randomly & that
the survival or extinction
of each organism is
determined by that
organism’s ability to adapt
to its environment.
Evolution by Natural Selection
1.
Darwin concluded the following:
The best adapted individuals in a population survive &
produce offspring that are likewise well adapted
2.
The least adapted individuals produce fewer offspring
3.
Suitable variations are passed on from one generation to
the next
4.
Other variations are lost

Evolution by Natural Selection
 Variation:
marked difference or deviation from
the normal or recognized form, function, or
structure
 Also,
it refers to an organism or plant exhibiting
such difference or deviation.
Evolution by Natural Selection

1.
•
Three causes of
variation:
gene flow: the
movement of new
genes into a population
acts against the effects
of natural selection
Evolution by Natural Selection
2. genetic drift: a change in
a gene pool that takes
place in a population as a
result of chance
• If a mutation occurs in a
gene of one person, & that
person does not reproduce,
the gene is lost to the
population.
Evolution by Natural Selection
3. speciation: forming of
one or more new
species from a species
already in existence
• Occurs when a population
becomes divided & part of
the original species
continues life in a new
habitat.
Evolution by Natural Selection
 Darwin
further suggested that organisms are
different from place to place because their habitats
present different challenges to, and opportunities
for, survival and reproduction.
Evolution by Natural Selection
 Each
species has evolved and accumulated
adaptations in response to a particular
environment.
 adaptation:
an inherited trait that has become
common in a population because the trait provides
a selective advantage
Evolution by Natural Selection
 Another
factor affecting natural selection is time
frame.
 It
is believed that there is a time frame for
evolution.
 Gradualism
supports the idea that evolutionary
change is slow, gradual, & continuous.
Evolution by Natural Selection
 Punctuated
equilibrium states that species have
long periods of stability, lasting for 4 or 5 millions
years, & suddenly change as a result of some
geological or other environmental change.
Natural Selection Assignment

There will be ten questions pertaining to today’s lesson .

These questions will be on a handout.

Answer each of the following questions pertaining to natural
selection in complete sentences. The lecture notes and textbook
may be used to help you answer each question.

Each response should be a short answer.

Once you have completed the assignment, hand it in to the teacher
for a grade.
Natural Selection Assignment Sample
Galapagos Islands Activity

Using the Internet in the
science computer lab, look
up pictures of animal and
plant species on the
Galapagos Island.

You should have 5
different animal species,
and 5 different plant
species.
Galapagos Islands Activity

Once you have found pictures of those species, make a comparison
of those organisms to those found on the nearby continent of South
America.

After analyzing and comparing those living beings, in small groups,
you will be asked to write down the similarities and differences of
those organisms.

Once all groups have completed this activity, a discussion will take
place in the classroom on what are the possible explanations of
those similar looking species for having different characteristics.
The Galapagos Islands

Charles Darwin found evidence that challenged the
traditional belief that species do not change over time.

Darwin visited the Galapagos Islands, which are located
620 miles off the coast of Ecuador.

Darwin was struck by the fact that many of the animal and
plant species found on the Galapagos Islands resembled
those found along the coast of South America.
Animals of the Galapagos Islands
Plants of the Galapagos Islands
Observations of the Galapagos Islands
Assignment

You will watch a documentary on the Galapagos Islands.

A worksheet will be given out where you must answer
questions while watching the film.

All of the questions are in order of the video.

Once the video has finished, the teacher will go over the
questions of the video worksheet.
Observations of the Galapagos Islands
Assignment

Video Worksheet Sample:
Observations of the Galapagos Islands
Assignment

After watching the video, you will discuss independently
on an essay why do you feel that species evolve over
time?

You must give examples in the essay proving the topic.

Also, the essay must be written using correct grammar and
sentence structure.
Natural Selection and Galapagos
Islands Review

The class will be divided into two
teams and will be asked questions on
the material taught thus far. There
will also be questions from the
“Galapagos” video.

The team with the most points will be
given a “Certificate of Excellence”
award that can be used as a credit on
a missing assignment that a student
may not have turned in to the teacher.
Question 1: What concept identified by Charles
Darwin can be describes as the “survival of the
fittest”?
A. microscopy
B. natural selection
C. relativity
D. specialization
Question 2: What continent is located near the
Galapagos Islands?
A. Asia
B. Europe
C. North America
D. South America
Question 3: Which of the following animals
refers to name “Galapagos”?
A. albatross
B. giant tortoise
C. marine iguana
D. sea lion
Publication of Darwin’s Work
 In
1844, Darwin finally wrote down his ideas
about evolution and natural selection.
 In
1858, he decided to publish his work after he
received a letter and essay from Alfred Russel
Wallace, an English naturalist.
Publication of Darwin’s Work

Alfred Wallace was in Malaysia and
also described a concept of
evolution via natural selection.

In the letter, he asked Darwin if he
would help him get the essay
published.

With help from friends, Darwin was
able to present his concept of natural
selection, along with Wallace’s
paper at a scientific meeting.
Darwin’s Theory

In 1859, Charles Darwin’s book,
“On the Origin of Species by
Means of Natural Selection” was
published.

Many people were disturbed by his
theory, especially when it discussed
the evolution of man.

Despite such controversy, Darwin’s
evidence and observations slowly
convinced biologists around the
world.
Darwin’s Theory

1.
2.
Four main points support Charles Darwin’s Theory of
Evolution on Natural Selection:
Inherited variation exists within the genes of every
population or species (the result of random mutation and
translation errors).
In a particular environment, some individuals of a
population or species are better suited to survive (as a
result of variation) and have more offspring (natural
selection).
Darwin’s Theory
3.
Over time, the traits that make certain individuals
of a population able to survive and reproduce
tend to spread in that population.
4.
There is overwhelming evidence from fossils and
many other sources that living species evolved
from organisms that are extinct.
Darwin’s Theory

Darwin’s based his theory on the idea that in any
population, individuals that are best suited to survive and
do well in their environment will produce the most
offspring.

Today, scientists know that genes are responsible for
inherited traits.

Therefore, certain variations of a trait become more
common in a population because more individuals in the
population carry the genes.
Darwin’s Theory and
Matching Assignment

In your own words, summarize the main points of the
Theory of Evolution on Natural Selection in terms of how
it is stated in modern times.

Matching Assignment Instructions:
Each of the examples listed on the worksheet depicts a
major point of natural selection. Match the example listed
on the worksheet with one of the four main points of
natural selection.
•
Darwin’s Theory and
Matching Assignment

There will be ten
examples that must
be matched up to one
of the four points of
natural selection.

You can only choose
one of the four main
points per example
listed on the handout.
Simulating Natural Selection

You will receive a laboratory
assignment on simulating natural
selection using teddy graham
cookies.

You are to read the “Introduction”
and answer the question listed on the
next page. Make sure to answer each
question in complete sentences. All
answers are to be written on the Data
Sheet on page 5.
Simulating Natural Selection

1.
2.
3.
4.
5.
6.
Pre-lab Questions:
Who wrote the Theory of Natural Selection?
If all organisms were identical, would natural selection happen?
Explain.
If organisms did not to compete for basic needs, how would
natural selection be affected?
What is another way of describing natural selection?
How is artificial selection different from natural selection?
What might happen to a species if we move an exotic species into
an area, which competes with it for basic needs and resources?
Simulating Natural Selection
Procedures:
1. Read the story below:
• You are a bear-eating monster. There are two kinds of bears: happy
bears and sad bears. You can tell the difference between them by
the way they hold their hands. Happy bears hold their hands high in
the air, and sad bears hold their hands down low. Happy bears taste
sweet and are easy to catch. On the other hand, sad bears taste
bitter, are sneaky, and hard to catch. Because of this, you only eat
happy bears. New bears are born every year during hibernation and
the birth rate is one new bear for every old bear left from last year.
The trait of being a “happy bear” is inherited genetically, and it is
dominant over the trait of being a “sad bear”.

Simulating Natural Selection
Simulating Natural Selection
2. Obtain a population of 15 bears. You must obey the following rules:
You must have a least 7 happy bears, and at least 3 sad bears, but
remember that your total must add up to 15 bears (i.e. you could
have 10 happy bears and 5 sad, or 8 happy, and 7 sad, etc.).

3. Record in Table 1 the following information: the total
population, the number of happy bears, and the number of sad bears.

4. Make a prediction on what do you think will happen to the happy
and sad bear populations over time. Write the prediction in the Data
Sheet on page 5.
Simulating Natural Selection
5. Now the monster (you) will catch bears. You will eat 3 happy bears
and 1 sad bear (I know that sad bears are bitter and hard to catch,
but sometimes you might catch one or one might die of natural
causes. This is why you will eat a sad bear to represent those sad
bears that get caught or die.).
6. Now all living bears reproduce (add 1 new happy bear for every
happy bear still remaining, and 1 sad bear for every sad bear still
remaining.).
7. Repeat this two more times for a total of 4 generations.
Simulating Natural Selection
8. Determine the percentage of happy bears and sad bears for each
generation and record these in Table 2. Calculate the percent using
this formula:
For Happy Bears:
# of Happy Bears x 100
total number of bears
For Sad Bears:
# of Sad Bears
x 100
total number of bears
Simulating Natural Selection
9. Using Microsoft Excel, make a graph of Table 1: Generations versus the Number
of Bears. The values for Generations will be on X-axis, while the values for the
Number of Bears will be on the y-axis.
10. Using Microsoft Excel, make a graph of Table 2: Generations versus the
Percentage of Bears. The values for Generations will be on X-axis, while the
values for the Percentage of Bears will be on the y-axis.
11. Before answering the Analysis questions, make sure to clean up your area.
Cleaning up is part of your lab grade.
12. Answer the Analysis questions located on pages 6-7 in complete sentences.
Simulating Natural Selection
Table 1
Generations
1
2
3
4
Number of
Happy Bears
Number of
Sad Bears
Total
Number of
Bears
Simulating Natural Selection
Table 2
Generations
1
2
3
4
Percentage of
Happy Bears
Percentage of
Sad Bears
Simulating Natural Selection

1.
2.
3.
4.
5.
Analysis Questions:
What happened to the number of happy bears over time?
What happened to the percentage of happy bears over time?
Were your predictions correct? Explain.
What do you think would have happened to the happy bear
population over time if you had started with only 5 happy bears?
Be specific! Work it out over a few generations to answer the
question.
In our scenario, all bears reproduced to make like them. In
actuality, this would not always by the case. Explain why (think
about the relationship between genotype and phenotype).
Simulating Natural Selection

•
Conclusion:
Instructions:
Based upon your knowledge of natural selection, as well
as what you have just learned in the experiment, discuss
the effect of a population of a particular species over a
period of time. Be sure to include information supporting
the topic. Also, include the main points of the lab and the
results of the experiment. The conclusion will be written
using correct grammar and sentence structure.
Simulating Natural Selection

Once you have answered
all questions (Pre-lab and
Analysis”), developed the
data tables and graphs on
Microsoft Excel, and
written the essay, hand in
the laboratory assignment
to the teacher for a grade.
Final Assessments

Complete the worksheet on Chapter
13, Section 1: Theory of Evolution
by Natural Selection Active and
Direct Reading.

Answer in complete sentences the
Chapter 13, Section 1 Review
Questions on Page 282 of the “Holt
Biology” textbook.

Study and review the material you
were taught for your test next class.
The test is made up of multiple
choice, true or false, and short answer
response questions.