Biology Week 7: Evolution of Living
Things - 
Day 3
Misconceptions about evolution:
find out if you have any misconceptions about evolution.
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To understand evolution, you must be
familiar with many different terms and theories. Any discussion of the topic is
useless without an agreement on these terms. Even the definition of
evolution can be debated.
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*Evolution
Video* : Gene frequency, natural selection and speciation
Fossils
Most living things change very slowly. While
some changes can be observed directly, much what we know about the history of
life on earth comes from the fossil record. A fossil is any trace
of a long-dead organism. Most fossils are formed when sediment is deposited by
wind or water. These sedimentary fossils usually develop only from hard body
parts. The soft body parts decompose before they can be replaced by hard
minerals. The special conditions needed for the formation of fossils cause the
fossil record to be less than complete. Because of this, the fossil record is
open to interpretation. Different scientists can look at the same fossil and
reach different conclusions about its place in the history of life.
Burgess Shale Fossils: See
some of the very interesting organisms found in Canada.
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Fossil imprint of an organism.
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Fossil track of an
organism.
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Organism preserved
in amber (fossilized tree sap).
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In 1669, Nicolaus Steno proposed the Law
of Superposition stating that successive layers of rock or soil were
deposited on top of one another by wind or water. This means that the lowest
layers are the oldest, while the top layers are the most recent. This law is
still accepted today and allows scientists to give fossils a relative age.
Carbon dating
can be used
to determine the actual age of an object. The only requirement is that the
object must have carbon in its structure.
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Paleontologist
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Species:
A group of organisms that mate
and produce fertile offspring.
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The morphological concept of species uses the
internal and external structure and appearance of organisms to determine a
species. These characteristics are easy to observe, making species
identification relatively convenient. The morphological concept of species
has limitations. All individuals within a morphological species do not look
alike. Humans, for example, do not all look alike. We are, however, all Homo
sapiens.
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The biological
concept of species states that a species is a population of organisms
that can successfully interbreed but cannot breed with other groups.
Scientists who study evolution today do not like this definition because
the reproductive compatibility of extinct organisms cannot be tested and
the definition is unsatisfactory for organisms that reproduce asexually.
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 Important terms
related to evolution theory:
 (bio lab 115)
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Natural
selection: organisms with favorable variations survive and reproduce
at a higher rate. These favorable characteristics are then passed on to
their offspring.
- Stabilizing
selection: individuals with the average form of a trait have the
highest fitness.
- Directional
selection: individuals with an extreme form of a trait have a
greater fitness. (see picture
 )
- Disruptive
selection: individuals with extremes on either side of the average
trait have a greater fitness than individuals with the average trait.
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Phylogeny:
inferred evolutionary relationships among organisms.
- Morphology:
a comparison of internal and external structures of organisms.
- Speciation:
the formation of a new species from an existing one.
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Adaptive
radiation: many species appear to be related to a single ancestral
species.
- Convergent
evolution: unrelated species becoming more and more similar in
appearance because of a shared environment.
- Divergent
evolution: two or more similar species becoming more and more
dissimilar because of environmental adaptations.
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Coevolution:
two or more species changing because of changes in a species with which
they are interacting.
- Gene pool:
the collection of genes for all the traits in a population.
- Allele
frequency: the percentage of a specific allele of a gene in the gene
pool.
- Genetic
equilibrium: allele frequencies do not change from generation to
generation.
- Genetic
drift: allele frequencies in a population change as a result of
events or chance.
- Gene flow:
the process of genes moving from one population to another.
- Immigration:
the movement of individuals into a population.
- Emigration:
the movement of individuals out of a population.
The Hardy-Weinberg Principle:
A population
will remain in genetic equilibrium if, and only if, all of the following
conditions are met.
- No mutations
occur.
- Individuals
neither enter nor leave the population through migration.
- The population
is large.
- Individuals mate
randomly.
- Natural
selection does not occur.
Evolution Theory Basic Timeline:
1809 - Lamarck
1844 - Darwin
1858 - Wallace
1859 - "The
Origin of Species" by Charles Darwin
July 10-25, 1925 -
"Scopes Monkey Trial"
Day 3 Assignment - Evolution of Living Things
This assignment must be turned in by the beginning of class tomorrow
to receive credit.
Scoring criteria
- Find out if you
have any of the misconceptions about evolution as others have. Use the link
at the top of the page along with is handout .
word
version
web version
- View the online
Evolution video above (Gene frequency, natural selection and speciation) to find out about some very interesting fossils.
- In what time period is the Burgess Shale thought to have formed?
Why is it so important?
- What does the Hardy Weinberg principle say about evolution?
- What are the mechanisms for evolution stated in the video? Are
these the same or opposite of the Hardy Weinberg principe?
- What is the
main limitation of the morphological species concept?
- Describe what
happens during disruptive selection.
- Explain the
difference between Divergent and Convergent evolution?
- A species of
butterfly feeds on only one species of flower. Through many flower
generations, the location of the nectar moves deeper and deeper into
the flower. As this happens, butterflies evolve longer tongues to
reach the nectar. What type of evolution is this?
- Who is Lamarck
and how is he link to the theory of evolution?
- What is the
"Scopes Monkey Trial" ?
- How old is the
earth estimated to be?
Honors biology: Complete the above section (1-9)
along with this activity.
- Complete the
"to Do" activity below. If this is done as homework have your
parent or guardian sign your log for verification of completion. You will
not need a stamp or signature by the teacher.
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How important is your opposable thumb?
Individually, ask your teacher for tape for the following:
- Tape the thumb on
your dominant hand to the finger next to it.
- Obtain a stamp or
signature on your tape from the teacher.
- Leave the thumb
taped down for as long as you can.
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Record the start
time and the end time.
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Keep a record of
all the ways this changes things you do during the day.
- Record is due
tomorrow.
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Evolution of Living Things:
Day 4-5
What is the Evidence
supporting Evolution?
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What are homologous
structures?
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Before
you begin this assignment watch this
and
complete the quiz at the end.
·
Turn in the
answers to your teacher.
Evidence Supporting Biological Evolution
A long path leads from the origins of primitive
"life," which existed at least 3.5 billion years ago, to the
profusion and diversity of life that exists today. This path is best understood
as a product of evolution.
Contrary to popular opinion, neither the term nor
the idea of biological evolution began with Charles Darwin and his foremost
work, On the Origin of Species by Means of Natural Selection (1859). Many
scholars from the ancient Greek philosophers on had inferred that similar
species were descended from a common ancestor. The word "evolution"
first appeared in the English language in 1647 in a nonbiological connection,
and it became widely used in English for all sorts of progressions from simpler
beginnings. The term Darwin most
often used to refer to biological evolution was "descent with modification,"
which remains a good brief definition of the process today.
Darwin
proposed that evolution could be explained by the differential survival of
organisms following their naturally occurring variation--a process he termed
"natural selection." According to this view, the offspring of
organisms differ from one another and from their parents in ways that are
heritable--that is, they can pass on the differences genetically to their own
offspring. Furthermore, organisms in nature typically produce more offspring
than can survive and reproduce given the constraints of food, space, and other
environmental resources. If a particular off spring has traits that give it an
advantage in a particular environment, that organism will be more likely to
survive and pass on those traits. As differences accumulate over generations,
populations of organisms diverge from their ancestors.
Fields of science contributing evidence:
The Fossil Record - paleontology
Common Structures - comparative anatomy
The Distribution of Species - biogeography
Similarities
During Development - embryology
Evidence from Molecular Biology - molecular biologist
Day 4-5 Assignment - Evolution of Living things
This assignment will be presented in two days in order to receive
credit.
Scoring RubricHtmlWord Document
You are now part of a scientific team. The team consist of
people specializing in each of the following areas: Paleontology, Molecular
biology/Genetics, Anatomy/Physiology. Go to the following site Evidence for
Evolution WebQuest
and
complete the task.
- Read Activity 2, Complete
the task by following the process listed on the web site (Observations
Lead to a Theory).
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Discuss in your group who will represent each
area of specialization and how your group will present its findings.
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Provide a list of group members and their area
of specialty to the instructor
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Your group may change its visual presentation
(webpage, power point, poster, video, etc.)
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Print out and read Evidence for Evolution
rubric, bring to presentation.
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Remember read and follow the directions
carefully.
Research Links:
Earth's
Age:
Evolution Theory:
Human History:
Homologous
structures are similarities in the skeletal structures of different species.
