Genes, Traits and Individuals Background t h e

t h e e f f e c t o f n at u r a l s e l e c t i o n o n
Genes, Traits and Individuals
Background
Evolution is the process by which living things change over many generations. Evolution requires only three simple
things in order to occur. First, individuals of a species must have variation, which means they are different from one
another. Second, these differences must be heritable (inherited by offspring from their parents). Third, some of these
differences must make certain individuals more likely than others to survive and reproduce (the ability to survive well
enough to reproduce is called fitness). When individuals with greater fitness have more offspring than those with
lower fitness, natural selection has occurred.
That’s it! As long as there are heritable differences among individuals, and these differences make some individuals
more successful at survival and reproduction than others, evolution by natural selection will occur.
Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient
life forms, as well as the striking molecular similarities observed among the diverse species of living organisms.
Kacy Gordon, a Ph.D. candidate at the University of Chicago, is interested in evo-devo (evolutionary development)
and how gene regulatory networks evolve. She studies the microscopic worm C. elegans and its relatives, with whom
she proudly shares evolutionary ancestors that lived over half a billion years ago. For more information on Kacy
Gordon and her research, visit: ruvinskylab.uchicago.edu/people.html.
Lesson Overview
In this project, students will engage in the scientific process to answer the research question: how might biological
change have occurred and been reinforced over time? The project involves multiple activities including collaborative
group work, learning stations, computer data collection and analysis, and large and/or small group discussion.
The learning stations focus on different topics relevant to understanding evolutionary change and natural selection,
and ultimately determining how changes in DNA and genomes are the driving force behind evolution of life on
Earth. After completing all stations, students will form a conclusion answering the question: how might biological
change have occurred and been reinforced over time? Moreover, students will make the connection between this
project and systems biology: looking at the molecular level (DNA/genomes) in order to understand survival success
of individual organisms, and understand population dynamics that allows for survival of species.
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Essential Questions
• How do random changes in DNA result in random variations in organisms?
• How does natural selection on these random variations change the traits of a species over time?
• How is this project an example of systems biology?
Objectives
Students will…
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Explain how genetic traits and variations are passed on from one generation to another.
Explain why some traits are beneficial to an organism and help it survive.
Correlate changes in genetic information with evolutionary change among organisms.
Identify analogous and homologous structures in organisms.
Explain how “form fits function” and how this can provide evolutionary advantages for species.
Make the connection between this project and systems biology.
Next Generation Science Standards
HS-LS3-3. A
pply concepts of statistics and probability to explain the variation and distribution of expressed traits
in a population. (if completing Station 3 G-Test.)
HS-LS4-4. Construct an explanation based on evidence for how natural selection leads to adaptation of populations.
HS-LS4-5. Evaluate the evidence supporting claims that changes in environmental conditions may result in:
(1) increases in the number of individuals of some species, (2) the emergence of new species over time,
and (3) the extinction of other species.
Common Core State Standards
CCSS.ELA-Literacy.WHST.9-10.1a Introduce precise claim(s), distinguish the claim(s) from alternate or opposing claims,
and create an organization that establishes clear relationships among the claim(s), counterclaims, reasons,
and evidence.
Prerequisite Knowledge
• Understand the differences between analogous and homologous structures
• Understand mutation and adaptation
• Understand natural selection
•Understand the mechanism for traits/adaptations (changes in DNA and the passing down of this DNA from
one generation to another)
Materials
Introduction
• Assorted images and/or specimens of diverse organisms
Station 1
• Station Card 1
• White paper
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• Colored pencils
• Large poster paper
• Tape
Station 2
• Station Card 2
• Specimens and/or images of animal skulls (some images provided)
Station 3
• Station Card 3
•DNA of Adh gene from two species of Drosophila—one individual of Drosophila simulans (DsimC) and
5 individuals of Drosophila yakuba (DyakL, J, I, G, A)
Station 4
• Station Card 4
• Assorted skeletal specimens such as a lion, hawk, horse, wolf, frog and mole, models and/or images
• Bat, bird, and insect skeletal specimens, models and/or images (images provided)
Station 5
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Station Card 5
Coin
Two different colored chips, blocks, cards, etc. (~50 per team)
1 small box
Time Frame
The time frame for the entire project is subjective. A total estimated time of 150-190 minutes is suggested.
Teachers can lengthen or shorten the time spent on each part of the project. An approximate time frame for
each part is provided within the lesson procedure.
Assessment
• Informal assessment through discussion
• Lab journal or team write up including data collected during the project
• Team presentations
Additional Resources
The Field Museum’s Evolving Planet exhibition videos and resources can help you review key topics with students:
• Natural Selection: archive.fieldmuseum.org/evolvingplanet/precambrian_14.asp
• Fossilization: archive.fieldmuseum.org/evolvingplanet/cambrian_14.asp
• Phylogeny: archive.fieldmuseum.org/evolvingplanet/mesozoic_21.asp
• Coevolution: archive.fieldmuseum.org/evolvingplanet/mesozoic_23.asp
• Convergent Evolution: archive.fieldmuseum.org/evolvingplanet/tertiary_16.asp
• Biogeography: archive.fieldmuseum.org/evolvingplanet/quater_10.asp
• Key Terms: archive.fieldmuseum.org/evolvingplanet/educational_17.asp
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Procedure
Part 1: Biodiversity Introduction (30–40 minutes)
• Display examples of different organisms.
•Have student teams observe the specimens and list of as many differences among the organisms as possible.
Then, create a list of as many similarities as possible.
•At this time the teacher should review important terms relating to evolutionary biology (variation, traits/adaptations,
natural selection, genetic basis for traits, etc).
Part 2: Research Stations (90–120 minutes)
• Introduce each station and procedures using the Station Cards.
• Note that students should record all data and responses per station. A recorder may be assigned per group.
Part 3: Final Discussion (30 minutes)
•Have teams develop a conclusion addressing the research question: How might biological change have occurred
and been reinforced over time? Students should write their conclusions and rationale in their lab notebooks,
using examples from the stations to support their conclusion.
•Then, have teams present their conclusions and rationale. Explanations should include changes in genomes over
time and the mechanism for these changes. If necessary, prompt students to address these points.
•Discuss how this project ties in with systems biology: looking at molecular level (DNA and genomes) in order to
understand the whole organism, natural selection, and evolutionary change.
Optional Field Trip
The Field Museum of Natural History, Chicago, Illinois
World of Mammals exhibition
•At least two weeks before your field trip, visit fieldmuseum.org/schools to access planning resources and place a
reservation for your visit.
• In the World of Mammals exhibition, have students observe various skeletal specimens.
•Select one skeletal specimen to use in explaining the statement “form fits function.” Respond to the question:
How does an animal’s “form” help it to perform different “functions” (e.g. running, climbing, chewing, hunting, etc.)?
•Select one order of mammals (e.g. primates, carnivores, marsupials). Explain which animals in that order seem
to be more closely related (name them, e.g. coyote, gray wolf, red fox) based upon the skeletal specimens.
Explain your reasoning.
•List and explain two adaptations possessed by the order of mammals you have selected to study. Respond to the
following questions: Do you think they would have similar genomes? Why/why not? Why do some animals have
similar structures?
Funding and support provided by NIH & CCSB. The project described was supported by award number P50GM081892 from the National Institute of
General Medical Sciences. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National
Institute of General Medical Sciences of the National Institutes of Health.
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