Natural Selection
Andrea and Kayla
Instructional Notes
Earth is home to millions of species, most yet undiscovered. Still, with the
diversity on earth that abounds, scientific evidence points to one common ancestor.
Evolution is the driving force behind this widely accepted scientific theory, and Charles
Darwin is a well known name amongst scientists and non-scientists alike. His voyage
aboard the Beagle allowed him to conduct scientific observations that have paved the
way for scientists to follow. Yet, before him, there were other great scientists whose
work paved the way for Darwin to complete his findings. Among those are, Carolus
Linnaeus, who in the 1700s developed the classification system for all organisms, and
later in his career proposed that species diversity may have arisen through
hybridization. Georges Louis Leclerc de Buffon, who in the 1700s proposed that species
share a common ancestor. Erasmus Darwin, Charles Darwins’ grandfather, who
proposed that all living things descended from a common ancestor and that more
complex organisms arise from simpler organisms. Finally, Jean-Baptiste Lamarck, who
in 1809, proposed that changes in an environment caused behavior to change, which
led to change that was then passed on to offspring. While none of these scientists had it
absolutely correct, their work has proved beneficial to scientists after them, and their
work continues to be a driving force of scientific explanation. These scientific works and
ideas contributed greatly to the well-known Darwin’s theory of evolution, and in this
lesson specifically, natural selection.
In 1831, the HMS Beagle set sail on a voyage that would take Charles Darwin
from England to South America to the Pacific Islands and back. During this voyage,
Darwin observed difference among island species, variation; and he observed fossil and
geologic evidence supporting an ancient Earth.
The variation in species was especially observable in the Galapagos Islands.
Here, Darwin noticed that certain variations of the same species proved to be beneficial
for different environments and diets. These adaptations made it easier for the organism
to survive. Darwin combined his observations of domesticated plants and animals, and
coupled his understanding of artificial selection with his observations in nature. Doing
this, he developed his theory of natural selection, a mechanism by which individuals that
have inherited beneficial adaptations produce more offspring on average than do other
individuals. In nature, the environment is the natural ‘selective’ agent.
Darwin was not the only individual to explain how evolution can occur. Alfred
Russel Wallace, independently developed a theory similar to Darwin’s. Both ideas were
presented to a group of scientists in 1858, and the next year, Darwin published his wellknown publication, On the Origins of Species by Means of Natural Selection.
The nature of science, the historical importance of previous scientific work,
communication in the science community, the evidence behind scientific theories, and
the way that scientific knowledge builds upon itself is highly observable in Darwin’s
contributions to science. This lesson will focus primarily on the theory of natural
selection. The teacher should also discuss these other important aspects of science
when appropriate, to reiterate their importance.
Intended Learning Outcomes


SC-HS-3.5.1a.4 – Students will predict the impact on species of changes to
natural selection.
o
Objective 1: Recognize and explain the driving force behind natural
selection (survival of the fittest).
o
Objective 2: Gather statistical data using Microsoft Excel.
o
Objective 3: Develop an explanation of data towards a conceptual model
of natural selection.
SC-H-BC-S-2 – Students will explain the role of natural selection in speciation,
adaptation, diversity and phylogeny.
o
Objective 3: Predict the fate of a chosen species (plant or animal).

Students will compile all their data and conceptual understandings
of natural selection and what role the nitrogen cycle play in
environmental change, and couple it with new data to predict what
will happen to a pond environment that is subject to increased
nitrogen levels.

SC-H-BC-S-1 – Students will identify evidence of change in species using fossils,
DNA sequences, anatomical similarities, physiological similarities and
embryology.

SC-H-BC-U-3 – Students will understand that some organisms have greater
adaptive capabilities than others, giving them a greater chance of survival under
changing environmental conditions. These adaptations may be patterns of
behavior as well as physical characteristics.
o

Objective 4: Students will describe how Darwin developed his theory of
natural selection.

Students will experience a virtual field trip of Darwin’s expedition
that will lead to the understanding that Darwins voyage provided
insights into evolution.

Students will realize that Darwin observed differences among island
species.
Students will revise conceptual models of natural selection when presented with
new data and new vocabulary and definitions

Students will apply their chemical knowledge of nitrogen to natural selection.

Students will utilize Microsoft Excel to prepare graphs to study trends among
data.

Students will become familiar with Wikispaces as a means to blog data and
information and share their knowledge with others.

Students will explore a virtual field trip to shape and frame their knowledge of
natural selection.

Collaborate and share models and information using Wikispaces.
Necessary Student Background Knowledge
o
o
o
This is intended for a first level high school/advanced middle school biology or
life science class. Students should have a basic understanding of genetic
diversity on our planet.
Students will have learned various cycles (the nitrogen cycle, the carbon cycle) in
their biochemistry unit, but could use some refreshing when we revisit the
nitrogen cycle in this lesson.
Students should have basic computer skills in which they can apply to learning
Microsoft Excel and the internet (Wikispaces and Virtual Fieldtrips).
Pre-existing student conceptions
o Students understand evolution as a process in which species respond to
environmental conditions by making a conscious decision to change gradually
over time.
Bishop, B. A. and Anderson, C. W. (1990), Student conceptions of natural selection
and its role in evolution. Journal of Research in Science Teaching, 27: 415–427.
doi: 10.1002/tea.3660270503
“Survival of the fittest” means survival of the physically fittest species instead of
survival of the “fittest” genes in a given environment.
o “Fit” means dominant and “unfit” recessive, in the allelic sense as opposed to the
expressed trait being “fit”, regardless of whether it is dominant or recessive.
o “Genetic drift” is gene flow between different species, as opposed to change in a
particular species over time.
o Drastic climate change is required for evolution to occur, instead of gradual
change over time as a result of the ability to reproduce and pass on certain traits.
o Heritable “compensation” of one trait occurs when another faculty is lost (e.g.,
“super” hearing or smell was attributed to suddenly blind salamanders), instead
o
of the fact that the mutations that lead to “super” hearing enabled certain
individuals to survive and reproduce because they had a greater advantage.
(NEHM, R.H., REILLY, L. (2007). Biology Majors’ Knowledge and Misconceptions
about Natural Selection. BioScience. 57 (3) 263-272.
http://ehe.osu.edu/edtl/research/nehm-laboratory/downloads/Nehm-Reilly-2007.pdf
Supplies
o
o
o
o
o
o
o
Natural Selection Pre-test
50 each (red, yellow, blue and green toothpicks) * Teacher may also use hole
punch pieces or any other colored objects. The key is to have some objects
“stand out” and some object “blend in” with the environments.
Data Collection Sheets
Computers with Microsoft Excel and internet access for the virtual field trip.
Virtual Field Trip: http://www.nhm.ac.uk/nature-online/science-of-naturalhistory/expeditions-collecting/beagle-voyage/
Handouts (1-12)
Website to review nitrogen cycle:
http://www.thenakedscientists.com/HTML/articles/article/nitrogenthebadguyofglo
balwarming1160583306/).
Teaching and Learning Activities
This is an integrated lesson that incorporates biological concepts, as well as
chemistry and technology. This material will take about 3 days to complete. It starts with
a review of students’ prior knowledge of Natural Selection and continues as students
build upon and revise their explanations of natural selection (in their own words) and
apply their knowledge of natural selection to predict what effects humans have on the
natural selection process. Students will be presented with data that (1) they collect
through an inquiry type investigation activity, (2) through virtual field trips, and (3)
through guided teacher discussions and data.
On Day 1, students will be given a pretest that allows them to confront the
common misconception that Lamarck proposed, and also helps students build their
explanatory power, by explaining a concept in their own words. Day 1 also includes an
activity in which students will gather data from an activity that will provide them with
information in which they can apply the conceptual process of natural selection.
Students will work in groups and share their group information on the class Wikispace
after teacher instruction. For homework, students will analyze the data collected from
the class Wikispace and create a graph (by drawing one on graph paper), and interpret
the graph – explaining the data in their own words.
The focus of Day 2 will be learning how to graph data in Excel and learning about
the Nitrogen Cycle and effects it has on various species. The teacher will instruct
students on how to use Microsoft Excel using Day 2 EXCEL Handout. Students will then
be presented with a lecture on the nitrogen cycle and what it does in order to refresh
their memory from their Biochemistry unit. Student will use teacher provided data to
graph information regarding where nitrogen comes from, in order to practice their excel
skills and learn more about the role of nitrogen in the environment and the effect it has
on the balance of various ecosystems and species populations. Students will end the
day, by compiling and graphing the classroom data from Day 1 activity (that they should
have gathered for homework), that they derive from Wikispaces. This end activity will
serve as an assessment.
On Day 3, students will experience a virtual field trip, Beagle Voyage from the
Natural History Museum. Using this research and the conceptual models they have
created and data they have explained from days 1 and 2, students will explain new data
the teacher presents them (finch data). Students will be introduced to key terms this
day, and revise their explanations to include these key terms. After their concrete
understanding of natural selection is developed and confirmed by the teacher, students
will then apply their understanding to predict the consequence of increased nitrogen in a
pond environment. Students will be given a couple of articles that contain data to
answer the question, but students will have to elaborate on the explanations. For
homework, students will take the pretest home, reflect upon their progression of
knowledge and understanding, and revise their pretest answers.
Day 1 – Students’ Prior Knowledge and Activity
Step 1- Pretest (Handout #1)
Students should take the Natural Selection Pre-test at the beginning of this unit. This
will allow an opportunity for the teacher to address and become aware of any barriers
and misconceptions the students may have. This will also serve as a tool in students’
self assessment when the unit is complete. Students will be presented with historical
evolutional data regarding the giraffe’s long neck, through various images. The students
will be instructed to explain what has happened to the giraffe’s neck over time, and what
has caused these changes. This will allow the teacher to address the misconception
that acquired changes at the individual level arise from need. However, at this point, the
teacher is simply going to administer the pretest, and proceed throughout the lesson.
This will be revisited at the end. The teacher does not want to give all the answers at
this point, because students will be building their conceptual knowledge of natural
selection and their explanatory power as this lesson progresses.
Step 2 – Woodworms (Handout #2) (or another similar activity- see list of alternative
activities)
The purpose of this activity is to “show” students how certain characteristics make an
individual or species more or less susceptible to predation. This allows the students to
collect data and recognize that the vibrant organisms, or the ones that ‘stand out’
visually, are the prey that is eaten. Students will collect data throughout an environment
(classroom or outdoor environment) and create a graph of compiled classroom data,
using Microsoft excel. Students should be able to explain, using the graph and data
collected, what occurred. They may not be using the term, natural selection, but they
should notice that certain colors were ‘eaten’, while others were left alone (or few were
eaten). * See Appendix for Woodworms Documents for Teacher notes and Handouts*
1. Outdoors is best for this activity. However, if unable to take the class outside, the
teacher can use various colors of paper to serve as the environmental
“background”. Teachers need to be sure that they have varying colors of
whatever you choose to use as your organisms (toothpicks, hole punch pieces,
etc), so that some stand out and some are camouflaged.
2. Teacher should create groups, or pairs, depending on how much data the
teacher wants the students to compile. The groups, or pairs, will be called flocks,
and will represent the predator species.
3. Each flock will have their own environmental setup, so that the flocks are not in
each others’ territories.
4. Distribute/Throw the “organisms” around randomly against the background for
EACH group, pair, or “flock”.
5. Each flock should have the same number of “organisms”. As well as the same
number of each color of organism.
6. Give students 1 minute to search and pick up as many of the organisms as
possible.
7. Flocks will then record the number of each color of organism that was collected
in a basic data table (you can provide one or you can have them make their
own).
8. Students will then share their data on the class WIKISPACE.
a. WikiSpace site (Username: Natural_Selection Password: darwin)
9. For homework, students will compile the data, draw (with pen and paper) an
appropriate graph and data table of classroom data, and answer the following
questions:
a. What type organism was the most successful?
b. Why?
c. What environmental factors affected the outcome?
d. Propose a situation in which the organisms that were “ate” the most would
survive.
e. What may the population of organisms look like over time, given the same
predator lurking about? Why?
f. Now, using this data, explain how you think species (like a group of these
organisms) change over time.
Day 2 – Microsoft EXCEL and Chemistry Day
The focus of day 3 will be learning Microsoft
Excel and revisiting the Nitrogen Cycle.
For homework, the students should have
compiled classroom data from the class activity
from day 1. This information will be used at the
end of Day 2 to assess Microsoft Excel skills,
and data representation and interpretation.
Step 1 – Microsoft Excel (Handout #3)
Day 3 will start off with a Microsoft Excel lesson.
See Day 2 EXCEL Handout.
Step 2 – Practicing Excel Skills and Revisiting the Nitrogen Cycle (Handout #4)
After students have grasped Microsoft Excel and how to use it, they will be required to
graph data from a teacher administered data table. This data table is derived from one
of the article the students will be presented with on Day 3 and outline the various
sources of biological nitrogen. Before these graphs are administered, the teacher will
revisit the Nitrogen cycle briefly, by directing students to the image obtained from,
http://www.thenakedscientists.com/HTML/articles/article/nitrogenthebadguyofglobalwar
ming1160583306/). This will remind students what the Nitrogen Cycle is, and what role
it plays in the overall scheme of the balance in nature.
Students will then graph the data from the articles, while the teacher addresses the fact
that humans can throw off the balance of the Nitrogen Cycle, which in turn has
consequences. The teacher will ask students if they realize that while Nitrogen serves a
role in maintaining balance, it also serves as a harmful greenhouse gas.
Step 3 – Applying and Assessing Excel Skills
After students have practiced graphing data given to them by the teacher, they will then
use the data they compiled from the class Wikispace and create a table and graph in
Excel. This will serve as an assessment tool for the teacher. And this will wrap up Day 2
agenda.
DAY 3 – Virtual Field Trip, Application, and Elaboration
This will be the final day in the natural selection lesson. Students will experience a
virtual field trip, explain phenomena that Darwin observed by using the knowledge they
have acquired thus far, and predict what role and increase in Nitrogen will have on a
pond environment by elaborating
on teacher provided articles.
Step 1 – Virtual Field Trip
(Handout #5 and #6)
Students will experience Darwin’s
Voyage aboard the HMS Beagle
through the virtual field trip Beagle
Voyage. After students experience
Darwin’s Voyage, they will be
asked to go back to the Galapagos
Island Stop, which details the
observations Darwin noticed, and
explain the reasons for the
difference that Darwin observed.
To answer this question, students will also have Darwin’s Finch data in front of them,
that will be provided by the teacher.
Step 2 – Applying Key Terms to Explanations (Handout #7)
Students will be given a list of key vocabulary terms to use to revise their explanations.
The teacher can go over these definitions if he/she sees fit, or the teacher can simply
allow the students to read the worksheet and assess the students understanding of key
terms in their explanations, and revisit if needed.
Step 3 – Part 1 Take Home Assessments - Elaborating using Scientific Terms and
Conceptual Explanations (Handouts #s9, 10, 11)
Students will be provided with the following articles that address the impact of human
activity on the nitrogen cycle. Students will explain what happens to a pond environment
when faced with an increase of nitrogen, where the increase in nitrogen comes from,
and predict what consequence the increase will have on other pond species. Students
will be required to elaborate on the highlighted statements in the articles.
Articles:

Nitrogen, The Other Greenhouse Gas http://www.mnn.com/earth-matters/climateweather/stories/nitrogen-the-other-greenhouse-gas

NUTRIENT OVERLOAD: UNBALANCING THE GLOBAL NITROGEN CYCLE
http://earthtrends.wri.org/features/view_feature.php?fid=1&theme=2

Warming to Evolution http://evolution.berkeley.edu/evolibrary/article/060701_warming
Part 2 and 3 Take Home Assessment for Homework (Handout #12) – Students will be
given back their pretests and instructed to assess their knowledge over the course of
this lesson. Students will have to compare and contrast the Lamarckian and Darwinian
explanations of changes and revise their pretest answers. Students will also have
additional questions to answer on the take-home test, or the teacher can opt to use the
assessment as a bell-ringer for the next day.
Teacher Resources, Handouts, Answer Keys (on the following pages)
(Teacher Keys follow each handout and answers are highlighted in blue)
Handout #1: Natural Selection Pretest
Handout #2: Woodworms Activity
Handout #3: EXCEL Handout
Handout #4: Nitrogen Cycle and Data Tables
Handout #5: Virtual Field Trip
Handout #6: Virtual Field Trip – Darwin’s Finches
Handout #7: Key Terms
Handout #8: Final Assessment – Part 1: Human Impact on Natural Selection
Handout #9: Article 1, Nitrogen the Other Greenhouse Gas
Handout #10: Article 2, NUTRIENT OVERLOAD…
Handout #11: Article 3, Warming to Evolution
Handout #12: Final Assessment – Part 2: Article Questions and Part 3: Revision and
Reflection
Handout
1
Day 1: Natural Selection Pretest
Name:
Date:
Period:
SOURCE: http://scienceblogs.com/clock/2006/12/how_the_giraffe_got_its_neck.php
The image below depicts the change in the giraffes neck over time.
1. Explain how the giraffe
got its long neck, using
the images to the right to
form your explanation.
Day 1: Natural Selection Pretest
TEACHER ANSWER KEY
SOURCE: http://scienceblogs.com/clock/2006/12/how_the_giraffe_got_its_neck.php
Handout
2
Day 1: WoodWorms
A Lab of Natural Selection
Name:
Date:
Period:
Procedure:
You are a worm eating predator on the hunt. Your favorite food, the woodworm, is very
active today. There are five sub-species of the woodworm, and you like all five. During
this class, you will hunt for 1 minute, during which you will “eat” as many woodworms as
you can (this means collect in your hands). After the hunt, we will record our group data
in WIKISPACES: (Username: Natural_Selection Password: darwin)
Results:
Subspecies
Flock
1
Flock
2
Number Eaten
Flock
Flock
3
4
Flock
5
Flock
6
Total #
Eaten
Total
%
Eaten
Red
Blue
Green
Yellow
HOMEWORK: TO BE COMPLETED AFTER CLASS DATA IS COMPILED USING
WIKISPACE.
 What type organism was the most successful?
 Why?
 What environmental factors affected the outcome?
 Propose a situation in which the organisms that were “ate” the most would survive.
 What may the population of organisms look like over time, given the same predator
lurking about? Why?
 Now, using this data, explain how you think species (like a group of these organisms)
change over time.
Day 1: WoodWorms and WIKISPACES
1.
2.
3.
4.
5.
6.
7.
8.
9.
Outdoors is best for this activity. However, if unable to take the class outside, the teacher can use various colors of paper
to serve as the environmental “background”. Teachers need to be sure that they have varying colors of whatever you
choose to use as your organisms (toothpicks, hole punch pieces, etc), so that some stand out and some are camouflaged.
Teacher should create groups, or pairs, depending on how much data the teacher wants the students to compile. The
groups, or pairs, will be called flocks, and will represent the predator species.
Each flock will have their own environmental setup, so that the flocks are not in each others’ territories.
Distribute/Throw the “organisms” around randomly against the background for EACH group, pair, or “flock”.
Each flock should have the same number of “organisms”. As well as the same number of each color of organism.
Give students 1 minute to search and pick up as many of the organisms as possible.
Flocks will then record the number of each color of organism that was collected in a basic data table (you can provide one
or you can have them make their own).
Students will then share their data on the class WIKISPACE.
a. WikiSpace site (Username: Natural_Selection Password: darwin)
For homework, students will compile the data, draw (with pen and paper) an appropriate graph and data table of
classroom data, and answer the following questions:
a. What type organism was the most successful?
b. Why?
c. What environmental factors affected the outcome?
d. Propose a situation in which the organisms that were “ate” the most would survive.
e. What may the population of organisms look like over time, given the same predator lurking about? Why?
f.
Now, using this data, explain how you think species (like a group of these organisms) change over time.
 Teacher should expect students to “eat”, or collect a greater number of the
“organisms” that stand out against the background. It is very important to have
organisms that are camouflaged.
WIKISPACES – The teacher should go step by step through WIKISPACE website.
WIKISPACE serves as a tool for collaboration and data sharing.
Step 1: go to www.wikispaces.com and click on “sign in”.
Step 2: enter username: Natural_Selection
And password: Darwin
Step 3: Click on “Natural Selection” wiki.
Step 4: Click on Discussion tab.
Step 5: Student can then click on “New Post”. Instruct Students to Use their group,
or pair names as the Subject. Also, students should just enter their information in the
following format: Color 1 = # of organisms caught, Color 2= # of organisms caught…
and so on.
For homework, students are to gather the classroom data off the wikispace, compile
results and draw a graph (pen and paper), representing the data, and then answer the
questions on their worksheets.
Day 1: A List of Alternative Activities
Teachers can use candy dishes instead, providing good and “bad” (or not so popular)
candy. Teachers can offer the candy to the students without telling them that they have
the fate of the natural selection outcome in their hands. The teacher can then discuss
natural selection after candy has been chosen.
If the teacher is unable to go outside, he/she can set up different “environments” in the
classroom (ie, different colored paper), and use colored paperclips, hole punch pieces,
etc. The teacher can assign groups to each environment. The key is having colored
“organisms” that stands out, and some that blend in.
Bird Beak Buffet Lab: www.mysciencebox.org/files/bird_beak_student.doc, in which
students use different tools to represent different beaks, and collect data on which beak
works best to eat the beans.
Day 2: EXCEL HANDOUT
Handout
3
QUICK TIPS TO GENERATE GRAPHS IN EXCEL
Pull up (or enter) your data sheet in excel.
Click the “Insert” tab.
For the purpose of this exercise click “Column” then “2D Cluster Column”.
Choose “Select Data”
Remove any data that is already in the chart.
Where Legend Entries (Series) is, click Add.
In the series name box, type the title of your graph.
Series X: values click the qualitative column. (Hint, you should click the column
for the anthropogenic source.)
Series Y values: Click the quantitative column. (Hint, you should click your
annual fixed rate of nitrogen column.)
Now play with your graph until you make it look visibly appealing.
I know excel can be confusing and hard to navigate at first. Trust me, I was in
your shoes at one point! So if you ever get confused, or have questions, or just
want me to check and make sure you are doing it right, just ask.
Handout
4
Day 2: Nitrogen Cycle Re-visitation and Data Tables to Graph
NAME:
DATE:
Period:
Source: http://www.thenakedscientists.com/HTML/articles/article/nitrogenthebadguyofglobalwarming1160583306/).
STEP 1: Recall the Nitrogen Cycle from our
Biochemistry unit and study the image to the
right to jog your memory.
Question 1:
What role do bacteria serve in the nitrogen
cycle process?
(You may have to research this answer on
your own, or revisit your notes from
Biochemistry)
Question 2:
What would happen if there were no bacteria to perform this role?
STEP 2:
Make a graph, using Microsoft
Excel, using the data table to the
right. Answer the following
question.
Anthropogenic – “man-made”
Question 3:
Draw a conclusion from the data
table and the graph that you
create, and write a statement.
Write a question that comes to
mind when considering this data.
Day 2: Nitrogen Cycle Revisitation and Data Tables to Graph
TEACHER KEY
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/NitrogenCycle.html
To read more on nitrification and denitrification, visit,
http://www.thewaterplanetcompany.com/docs/WPC_Nitrification%20&%20Denitrification%20.pdf
Question 1:
What role do bacteria serve in the nitrogen cycle process?
Denitrification
The three processes above remove nitrogen from the atmosphere and pass it through ecosystems.
Denitrification reduces nitrates to nitrogen gas, thus replenishing the atmosphere.
Once again, bacteria are the agents. They live deep in soil and in aquatic sediments where conditions are anaerobic.
They use nitrates as an alternative to oxygen for the final electron acceptor in their respiration.
Thus they close the nitrogen cycle.
Question 2:
What would happen if there were no bacteria to perform this role?
Agriculture may now be responsible for one-half of the nitrogen fixation on earth through


the use of fertilizers produced by industrial fixation
the growing of legumes like soybeans and alfalfa.
This is a remarkable influence on a natural cycle.
Are the denitrifiers keeping up the nitrogen cycle in balance? Probably not. Certainly, there are examples of nitrogen
enrichment in ecosystems. One troubling example: the "blooms" of algae in lakes and rivers as nitrogen fertilizers
leach from the soil of adjacent farms (and lawns). The accumulation of dissolved nutrients in a body of water is called
eutrophication.
STEP 2:
Make a graph, using Microsoft Excel, using the data table to the right. Answer the
following question.
Anthropogenic – “man made”
Question 3:
Draw a conclusion from the data table and the graph that you create, and write a
statement.Man Made sources outweigh biological sources.
Handout
5
Day 3: Virtual Field Trip
NAME:
DATE:
Period:
You will be taking a Voyage aboard the HMS Beagle, following the footsteps of
Charles Darwin. Start in England, at the beginning of this voyage, and set sail
through the 5 year journey. Encounter sights and wonders he observed along
the way, and record your observations in your “observation log”(your notes).
Type in the following website to get started. Go all the way through the voyage
(taking notes along the way), then follow the steps below.
http://www.nhm.ac.uk/nature-online/science-of-natural-history/expeditionscollecting/beagle-voyage/
AFTER YOU
COMPLETE THE
VOYAGE
1. Return to the stop
at the Galapagos
Islands.
2. What
observations did
Darwin record?
3. What do you think accounts for these differences?
4. Answer the Questions on the next page, using the key terms provided in
the KEY TERMS handout.
Day 3: Virtual Field Trip
NAME:
DATE:
Handout
6
Period:
SOURCE:
2007, Biology - High School
Question 11: Open-Response
Reporting Category: Evolution and Biodiversity
Standard: Evolution and Biodiversity - B 5.1
http://www.doe.mass.edu/mcas/search/
The illustrations below show a South American finch and some of the species of finches
found on the Galápagos Islands. The map shows the relationship of the Galápagos
Islands to the west coast of South America.
There are 13 species of finches found on the Galápagos Islands. These finches have a wide variety of
food sources and beak shapes. There is one genetically similar species of finch found on the South
American mainland. This finch eats small seeds.
Use the map and the bird illustrations to identify and explain two ways that these finches provide
evidence that supports the theory of evolution.
Handout
7
Day 3: Key Terms
NAME:
Key Terms you need to know:
1. Evolution –
2. Species –
3. Variation –
4. Adaptation –
5. Heritability –
6. Population –
7. Fitness –
DATE:
Period:
Day 3: Key Terms
TEACHER KEY
Key Terms you need to know:
1. Evolution – The process of biological change by which descendants come to differ
from their ancestors.
2. Species – a group of organisms that can reproduce.
3. Variation – Difference in physical traits of an individual from those of other individuals
by which it belongs to.
4. Adaptation – A feature that allows an organism to better survive in its environment.
5. Heritability – Ability of a trait to be passed on to offspring.
6. Population – all the individuals of a species in a given area.
7. Fitness – measure of the ability to survive and produce more offspring relative to other
members of the population of a given environment.
Handout
8
Day 3: TAKE HOME ASSESSMENT
Part 1 of 3 - Human Impact on Natural Selection – Articles and Graphs
NAME:
Date:
Period:
This will serve as part of your assessment for this unit.
Use the following articles to explain what happens to a pond environment when nitrogen
levels are increased. In your explanation, be sure to include what sources of nitrogen
can increase the levels, what effect this has on the pond ecosystem, and what effect
this has on various species living in the pond.
In your explanations, ELABORATE on the highlighted statements (on a separate sheet
of paper), using the Key Terms required in this lesson.
ARTICLE 1
Handout
9
Nitrogen, the other greenhouse gas
This often-overlooked global warmer is worse than CO2, and the amount of it in
our waterways is increasing.
By Jessica A. KnoblauchThu, Jan 14 2010 at 5:22 PM EST 9 Comments
Photo:
Associated Press
Nitrogen has become a staple for farmers to grow bigger crops, but too much nitrogen is
wreaking havoc on the environment, which researchers say is awash in man-made
nitrogen, according to a recent article in the Christian Science Monitor.
Though farmers use nitrogen to boost crop yields, much of the fertilizer is wasted,
eventually making its way into nearby waterways, causing dead zones where algae
blooms choke off marine life.
The most well-known dead zone is at the mouth of the Mississippi River in the Gulf of
Mexico, where scores of fish and shrimp have been eliminated across an 8,000-squaremile area. More than 400 dead zones with a total area of 245,000 square kilometers
were identified worldwide last year, according to the Monitor.
U.S. farmers waste as much as 40 percent of the nitrogen that they apply to their crops.
In China, the rate is even worse, where about twice as much nitrogen fertilizer is used
as in the U.S. to yield about the same amount of crops. In fact, as much as three-fourths
of all nitrogen used to grow rice in China may be wasted, said Vaclav Smil, a nitrogen
expert at the University of Manitoba in Winnipeg.
“Nitrogen plays a tremendously important role in feeding the world’s peoples, so that’s a
very positive benefit for humanity,” said James Galloway, a professor of environmental
science at the University of Virginia, Charlottesville, and a leading nitrogen researcher.
“The problem is how to maximize nitrogen’s benefits while diminishing its negatives —
especially waste.”
But farmers aren’t the only culprits of nitrogen overload. Vehicle exhaust, power plant
exhaust, and large-animal feeding operations are all sources of nitrogen emissions,
according to the report. These increased nitrogen loads from power plants and other
sources are causing smog, acid rain and global warming.
Unlike carbon dioxide, nitrogen doesn’t stick in the atmosphere for long periods of time.
Instead, it precipitates out within a few days as ammonia-laden rain — a mixture of
hydrogen and nitrogen that fertilizes plants as it falls to the ground. Researchers have
found major growth in ammonium in air quality data across 15 U.S. national parks,
including Rocky Mountain, Yellowstone, Mount Rainier and Canyonlands parks,
according to a previous Associated Press report. In addition, invasive grasses in the
Mojave and Sonoran deserts are taking over native plants and fueling wildfires — all
because of an increase in nitrogen.
“The more nitrogen that we use in agriculture or that comes from various combustion
processes — cars or power plants — the more ends up in the world’s ecosystem,” says
Lester Brown, president of the Earth Policy Institute in Washington. “By altering
concentrations of this key nutrient in the system, we are altering that ecosystem
in many, many ways.”
Luckily, there are people working to reduce nitrogen in the environment. EPA’s recently
proposed clean air standards could cut 90 percent of nitrogen emissions that come from
stationary sources like power plants. In addition, some farmers are working hard to
decrease their nitrogen use by increasing efficiency.
“Getting nitrogen right is critical for getting climate change right, food security right, and
a lot of issues associated with poverty that have to do with nutrition depletion,” said Bill
Herz, vice president of scientific programs for the Fertilizer Institute, a Washington trade
organization that represent North American fertilizer manufacturers.
Handout
10
ARTICLE 2
NUTRIENT OVERLOAD: UNBALANCING THE GLOBAL NITROGEN CYCLE
Source: World Resources 1998–99
Author: World Resources staff
As a basic building block of plant and animal proteins, nitrogen is a nutrient essential to all
forms of life. But it is possible to have too much of a good thing. Recent studies have
shown that excess nitrogen from human activities such as agriculture, energy production,
and transport has begun to overwhelm the natural nitrogen cycle with a range of ill
effects—from diminished soil fertility to toxic algal blooms (Vitousek et al. 1997:2; Jordan
et al. 1996:665; Asner et al. 1997:232).
Until recently, the supply of nitrogen available to plants—and ultimately to animals—has
been quite limited. Although it is the most abundant element in the atmosphere, nitrogen
from the air cannot be used by plants until it is chemically transformed, or fixed, into
ammonium or nitrate compounds that plants can metabolize. In nature, only certain
bacteria and algae (and, to a lesser extent, lightning) have this ability to fix atmospheric
nitrogen, and the amount that they make available to plants is comparatively small. Other
bacteria break down nitrogen compounds in dead matter and release it to the atmosphere
again. As a consequence, nitrogen is a precious commodity—a limiting nutrient—in most
undisturbed natural systems.
All that has changed in the past several decades. Driven by a massive increase in the use
of fertilizer, the burning of fossil fuels, and a surge in land clearing and deforestation, the
amount of nitrogen available for uptake at any given time has more than doubled since the
1940s. In other words, human activities now contribute more to the global supply of fixed
nitrogen each year than natural processes do, with human-generated nitrogen totaling
about 210 million metric tons per year, while natural processes contribute about 140
million metric tons (Vitousek et al. 1997:5–6). (See Figure 1: Global Sources of Biologically
Available (Fixed) Nitrogen.)
This influx of extra nitrogen has caused serious distortions of the natural nutrient
cycle, especially where intensive agriculture and high fossil fuel use coincide. In
some parts of northern Europe, for example, forests are receiving 10 times the natural
levels of nitrogen from airborne deposition (Pearce 1997:10), while coastal rivers in the
northeastern United States and northern Europe are receiving as much as 20 times the
natural amount from both agricultural and airborne sources (Vitousek et al. 1997:10).
Nitrate levels in many Norwegian lakes have doubled in less than a decade (Vitousek et
al. 1997:10). Although many of the nitrogen trouble spots tend to be in North America and
Europe, the threat of nitrogen overload is global in scope, as both fertilizer use and energy
use are growing quickly in the developing world. In fact, global nitrogen deposition may as
much as double in the next 25 years as agriculture and energy use continue to intensify
(Asner et al. 1997:228).
The effects of this surfeit of nutrients reach every environmental domain, threatening air
and water quality and disrupting the health of terrestrial and aquatic ecosystems. Natural
systems may be able to absorb a limited amount of additional nitrogen by producing more
plant mass, just as garden vegetables do when fertilized. Atmospheric deposition of
nitrogen emissions on some heavily cut forests in North America and Europe seems to
have spurred additional growth in this manner. But there is a limit to the amount of
nitrogen that natural systems can take up; beyond this level, serious harm can ensue. In
terrestrial ecosystems, nitrogen saturation can disrupt soil chemistry, leading to loss of
other soil nutrients such as calcium, magnesium, and potassium and ultimately to a
decline in fertility (Vitousek et al. 1997:7–9).
Excess nitrogen can also wreak havoc with the structure of ecosystems, affecting
the number and kind of species found. Researchers in the United Kingdom and the
United States have found that applying nitrogen fertilizer to grasslands enables a few
nitrogen-responsive grass species to dominate, while others disappear. In one British
experiment, this effect led to a fivefold reduction in the number of species in the most
heavily fertilized plots (Vitousek et al. 1997:9–10; Wedin et al. 1996:1720–1721). In the
Netherlands, where nitrogen deposition rates are among the highest in the world, whole
ecosystems have been altered because of this shift in dominant plants, with species-rich
heathlands being converted to species-poor forests and grasslands that better
accommodate the nitrogen load (Vitousek et al. 1997:9–10).
Although terrestrial ecosystems are vulnerable to the global nitrogen glut, aquatic
ecosystems in lakes, rivers, and coastal estuaries have probably suffered the most so far.
They are the ultimate receptacles of much of the nutrient overload, which tends to
accumulate in runoff or to be delivered directly in the form of raw or treated sewage.
(Sewage is very high in nitrogen from protein in the human diet.) In these aquatic systems,
excess nitrogen can often stimulate the growth of algae and other plants. When this extra
plant matter dies and decays, it can rob the water of its dissolved oxygen, suffocating
many aquatic organisms.
This overfertilization process, called eutrophication, is one of the most serious threats to
aquatic environments today, particularly in coastal estuaries and inshore waters where
most commercial fish and shellfish species breed (Vitousek et al. 1997:11; Diaz et al.
1995:245). Partially enclosed seas such as the Baltic Sea, the Black Sea, and even the
Mediterranean have also been hard hit by nitrogen-caused eutrophication, and an
extensive "dead zone" of diminished productivity has developed at the mouth of the
Mississippi River in the Gulf of Mexico because of the large influx of nitrogen from
agricultural runoff (Warrick 1997:A1). One of the more troubling aspects of this nutrient
assault on aquatic systems has been a steady rise in toxic algal blooms, which can take a
heavy toll on fish, seabirds, and marine mammals (Anderson 1994:62–68).
The nitrogen glut also impinges on the health of the atmosphere when the nitrogencontaining gases-—nitric oxide and nitrous oxide—are released into the air, either from
fossil fuel burning, land clearing, or agriculture-related activities. Nitric oxide, for example,
is a potent precursor of smog and acid rain, and nitrous oxide is a long-lived greenhouse
gas that traps some 200 times more heat than carbon dioxide. Nitrous oxide can also play
a role in depleting the stratospheric ozone layer; concentrations in the atmosphere are
rising rapidly—about 0.2 to 0.3 percent per year (Socci 1997; Vitousek et al. 1997:6-7).
Curbing the world's nitrogen overload will mean acting on several fronts. Making fertilizer
applications more efficient is one of the most promising options. Agriculture accounts for
by far the largest amount of human-generated nitrogen—some 86 percent (Jordan et al.
1996:655). Fertilizer use was scant until the 1950s but since then has increased
exponentially. (See Figure 2: Trends in Fertilizer Consumption, 1961–1997)
In fact, one half of all the commercial fertilizer ever produced has been applied since 1984
(Socci 1997). The problem is that about one half of every metric ton of fertilizer applied to
fields never even makes it into plant tissue but ends up evaporating or being washed into
local watercourses (Vitousek et al. 1997:13). A combination of better timing of fertilizer
applications, more exact calculation of doses, and more accurate delivery could cut this
waste substantially.
Cutting airborne nitrogen emissions from fossil fuels will also be important and will benefit
from many of the same strategies used to reduce carbon dioxide emissions, including a
greater emphasis on energy efficiency, a gradual shift toward alternative energy sources,
and the use of low-nitrogen technology in power plants and cars.
Other strategies make sense as well, such as restoration of wetlands, which are natural
nutrient traps that sponge up excess nitrogen before it can damage aquatic systems.
But none of these steps is easy or obvious, and there seems little likelihood of concerted
action until the nitrogen threat is elevated to a higher global profile. While the risks of
global warming from a buildup of greenhouse gases in the atmosphere are fairly common
knowledge today, the dangers of the world's heavy nitrogen habit have gone largely
unheralded so far, although this habit may be as pervasive and as hard to address as
cutting greenhouse gas emissions.
ARTICLE 3
Handout
11
Warming to evolution
July 2006, updated July 2008
Global warming is, quite literally, a hot topic. Though the mechanism of global
warming — temperature rise due to humans' production of heat-trapping
greenhouse gases — may not be big news, the projected impact of global
warming often makes headlines. Al Gore's recent documentary on the topic has
focused even more attention on the potentially disastrous effects of even a few
degree temperature rise. Whole island countries could disappear into the ocean
as polar ice melts and sea level rises. Hurricanes and tropical storms may
intensify. And ecological interactions could change in unpredictable ways. For
example, a recent news story reports that melting sea ice may be forcing some
polar bears into cannibalism now that fewer seal hunting opportunities are
available. Increasingly, it seems, global warming shows up on the front page of
the newspaper — but the evolutionary implications of global warming often remain
hidden.
Global warming is changing the world in startling ways. On the left is
a photo of Boulder Glacier in Glacier National Park, Montana, taken
in July of 1932. On the right is a photo taken at the same spot in July
of 1988. The glacier is gone.
Where's the evolution?
Global warming is certainly a climatic and environmental issue — but it is also an
evolutionary one. Over the past 20 years, biologists have uncovered several
cases of evolution right under our noses — evolution caused by global warming.
One of the key mechanisms of evolution, natural selection, causes organisms to
evolve in response to a changing environment. Imagine a population with several
different variants in it: some individuals happen to be better able to survive and
reproduce at higher temperatures than other individuals. Clearly, if the
temperature increases, those heat tolerant individuals will have an advantage and
will leave more offspring — and those offspring will also carry the genes for heat
tolerance. Over many generations, this process produces a population with
adaptations well-suited for the hotter environment. So long as the population has
different genetic variants in it, some better able to survive and reproduce in
particular situations than others, the population has the capacity to evolve when
faced with a changing environment.
Over the past 25 years, global surface temperatures have increased about ½°F.
That might not sound like much, but it turns out to be more than enough to change
the ecology and evolution of life on Earth. In many cases, these changes are
simply non-evolutionary examples of phenotypic plasticity, where an organism
expresses different traits depending on environmental conditions. For example,
many organisms respond to warmer weather by reproducing earlier and taking
advantage of an earlier spring — but this early reproduction is not caused by
genetic changes in the population and so is not an example of evolutionary
change. Similarly, many species have shifted their ranges in response to this tiny
temperature difference, spreading towards the poles, as those habitats warm —
but this change in range cannot be traced to a genetic shift in the population and
so is not an example of evolution. And still other species simply seem to be on the
path to endangerment or extinction as their habitats (like coral reefs) are degraded
and their population sizes drop.
However, in a few cases, we know that species have actually evolved —
experienced a change in gene frequency in the population — in response to global
warming. Interestingly, in those cases, the species are not necessarily becoming
more heat tolerant, but are adapting to changes in seasonal timing:
Canadian squirrels are evolving to take
advantage of an earlier spring and are breeding
sooner, which allows them to hoard more
pinecones for winter survival and next year's
reproduction. Squirrels with genes for earlier
breeding are more successful than squirrels with
genes for later breeding.
European great tits (a type of bird) are also
evolving different breeding times. Birds that are
able to adjust egg-laying to earlier in the spring
can time hatching so that it coincides with
greater food (caterpillar) abundance — and with
recent climatic changes, the caterpillars have
been maturing earlier in the spring. Birds with
genes for more flexible egg-laying times are
more successful than birds with less flexibility in
their egg-laying.
Another European bird, the blackcap, has been
evolving due to changes in its migration
patterns. Some blackcaps have begun to
overwinter in the now slightly warmer Britain
instead of in Spain, Portugal, and North Africa,
as they historically did. The British subpopulation has evolved genetic differences from
the other birds and is more successful at
reproducing since its members arrive at the
nesting grounds earlier and have first choice of
territories and mates.
One North American mosquito species has
evolved to take advantage of longer summers to
gather resources while the weather is good.
Mosquitoes with genes that allow them to wait
longer before going dormant for the winter are
more successful than mosquitoes that go
dormant earlier.
In a sense, these populations are the lucky ones. Small animals (like the birds,
squirrels and mosquitoes described above) tend to have large population sizes
and short generation times — and that bodes well for their ability to evolve along
with a changing environment. Large population size means that the species is
more likely to have the genetic variation necessary for evolution, and having a
short generation time means that their rate of evolutionary change may be able to
keep pace with environmental change. However, other species may not be so
lucky: larger animals tend to have longer generation times and so evolve more
slowly — and larger animals also tend to have smaller population sizes, which
means that their populations are simply less likely to contain the gene versions
that would allow the population to adapt to warmer climates. If global warming
continues, such species may come face to face with extinction, as the
environments to which they have been adapted over the course of thousands or
millions of years change right out from underneath them in the course of a few
decades.
News update, July 2008
Since we published this report in July 2006, we've been monitoring the
news for other examples of evolution in response to global warming and
have identified two to add to the list:

Field mustard plants have evolved in
response to an extreme, four-year-long drought in southern
California, which some sources have linked to global warming.
These plants flower and produce seeds near the end of the rainy
season, but when the rainy season is cut short by a drought, late
blooming plants may wither and die before they can produce seeds.
This form of natural selection favors early bloomers. Is just four
years enough time to see the results of this evolutionary shift?
Researchers compared plants grown from wild seeds collected
before and after the drought and found that post-drought plants had
evolved to flower much earlier — sometimes by as much as 10
days!

Scientists have been studying fruit fly
genetics for a century. When they
began to examine the genes found in
whole populations of wild flies, they
noticed a curious pattern. Certain
chromosomal markers (inversions)
were common in populations living in
warmer climates near the equator,
and others were common in more polar, cool-weather populations.
It wasn't clear what the genes associated with these different
markers did exactly, but they seemed to help the flies cope with
their divergent climates. Now, scientists have gone back to many of
the fly populations first studied — and have found that as the global
climate has warmed, the warm-weather genetic markers are
becoming more and more common. Of the 22 fly populations on
three continents that experienced warming trends, 21 seem to have
already evolved in response to the climactic shift.
With rising temperatures and further climate fluctuations, we expect more
examples of evolution in response to global warming to come to light.
Such rapid evolutionary shifts are disturbing and suggest the gravity of this
global threat, but even more unsettling is the likely fate of many species
with long generation times and low levels of genetic variation: extinction.
For these organisms, climate change may simply outpace their ability to
evolve.

For an easy-to-understand summary of global warming's potential
impact on many species, check out this article from
Smithsonian.com.
Handout
12
Day 3: TAKE HOME ASSESSMENT
Name: _________________________________ Date: ________ Period:______
PART 2of 3
Discussion and extension questions
1. How could global warming affect the evolutionary paths of different
species?
2. The process of natural selection involves variation, inheritance, selection,
and time. According to the articles, which of these elements is affected by
global warming and how is it affected?
3. The article above describes genetic variation as being critical for organisms
to evolve in response to global warming. Why is this essential to evolution?
Part 3 of 3
Analyze your pretest answer. Reflect upon your learning during this lesson, what you
thought you knew before, what you did know before, what you learned throughout the
lesson, and how comfortable you feel with your current knowledge of natural selection.
Be sure to include any misconceptions, or what you had wrong, that you recorded on
your pretest.
Write your Reflection and Revision Below:
Day 3: Natural Selection - FINAL ASSESSMENT Take Home
TEACHER KEY
PART 1: Use the following articles to explain what happens to a pond environment when nitrogen levels are increased. In
your explanation, be sure to include what sources of nitrogen can increase the levels, what effect this has on the pond
ecosystem, and what effect this has on various species living in the pond. ( excess nitrogen promotes algae growth. Algae
take over (eutrophication) and the dead matter from the algae suffocates the rest of life that require oxygen.)
“By altering concentrations of this key nutrient in the system, we are altering that ecosystem in many, many
ways.” Altering key nutrients (through human activity), promotes growth of some species, while hinders growth of
others. This alteration effects the ecosystem in many ways. The algae is one example. Another example is the
takeover of some invasive species.
This influx of extra nitrogen has caused serious distortions of the natural nutrient cycle, especially where intensive
agriculture and high fossil fuel use coincide. Human activity has increase the nitrogen levels so much so that the
natural cycle cannot keep up. Basically, nitrogen is stockpiling.
Excess nitrogen can also wreak havoc with the structure of ecosystems, affecting the number and kind of species
found. Nitrogen will favor some species, while hinder others.
PART 2
Discussion and extension questions
4.
How could global warming affect the evolutionary paths of different species? Certain species could not have the
adaptation advantages to pass on to offspring that would maintain the species. Some species could develop
adaptation advantages through mutations that allow them to better survive, then those traits would be passed on
to offspring.
5.
The process of natural selection involves variation, inheritance, selection, and time. According to the articles,
which of these elements is affected by global warming and how is it affected? all
6.
The article above describes genetic variation as being critical for organisms to evolve in response to global
warming. Why is this essential to evolution?
Without variation, we would keep getting the same species. These species could not have the adaptations to
survivie in new environments. Evolution is essentially change.
Part 3 – Reflections will vary