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Define the following vocabulary:
1. Charles Darwin
Developed the theory of evolution by the process of
natural selection
2. Mutation
Any change in DNA. May be positive (beneficial),
negative(harmful) or neutral (no impact)
3. Variation
4. Population
different traits of a population due to differences in the
genetic code. Differences occur through mutations or
meiosis (reproduction)
All of the individuals of the same species in a specific
area or location (population of turtles in the courtyard
at WMS)
5. Adaptation
Beneficial inheritable variation that helps an organism
survive in their environment and reproduce
6. Natural Selection
the survival and reproduction of the individuals in a
population that exhibit the traits that best enable
them to survive in their environment.
7. Galapagos Islands
8. (Genetic) Trait
Islands where Darwin noticed that finches and other
organisms were similar to mainland species but had
changed over time to better fit the island environments.
This was one of many observations that led him to the
theory of evolution.
Physical characteristic that is coded in the organism’s
DNA and can be passed down to their offspring
9. Extinction
10. Evolution
11. Fossil
12. Fossil Record
when a species is no longer living on the face of the
Earth
change in a population over time
Preserved remains or traces of organisms that lived in
the past.
The collection of the millions of fossils that scientists
have collected. Though it isn’t complete, it tells the
story of life on Earth and allows us to track the changes
in populations over time (evolution)
13. Relative Dating
Using the fossils location in the rock layers to determine
the relative age (estimated rather than measured)
Deeper in the rock=older the fossil
14. Radiometric (radioactive dating)
Dating fossils by measuring the amount of radioactive
(unstable) elements in the rocks where the fossils are
found.
15. Early development/Embryology as
evidence of evolution
16. Homologous Structures/anatomical
structures as evidence of evolution
17. Distribution of organisms as
evidence of evolution
The study of the similar early development of organisms
(the embryos) that in later development have very
different adult forms. Evidence of a common ancestor
since the organisms all start out as very similar
embryos.
Structures that are similar in form (1 bone-2 bone-wrist
bone-fingers) but may have a different function based
on the environment in which they live. Evidence of
common ancestor since the general form is the same,
but organisms changed over time to better fit their
environment. (Whales moving from land to water-still
have the same form as our arms but use them very
differently)
Organisms on an island are more related to the mainland species but
have changed over time to better fit their environment. Squirrels at
the grand canyon are another example. Tortoises on different islands
share common ancestor but evolved to better fit their island
environment.
18. Genetic information (DNA analysis)
as evidence for evolution
19. Isolation and its role in producing
new species
The closer two organisms are related then the more similar their DNA
sequences will be. It shows that they share a more recent common
ancestor.
When a population of a species is isolated, random mutations and
meiosis will create variations in that population. Natural selection will
cause the variations that best fit the environment to survive and
reproduce. If the isolated population is in a different environment, it
will change differently than the original population. If the two
populations ever come back together, the changes may be so large that
the two groups cannot mate and produce fertile offspring. They will be
two separate species. (Remember the salamanders in California, one
population adapted to the environment with different variations of
camouflage, the other population adapted to their environment with
the variation of mimicry-when they looked like the very poisonous
newt.)
Answer the following questions:
1. Identify the 6 lines of evidence for evolution and explain how they are evidence for evolution
1. Fossil Record-bones show the changes of life on earth and specific changes to species as they changed over
time.
2. Anatomy/homologous structures- Organisms that have the same forms of structure but use them in
different ways is evidence that they descended from a common ancestor. Over time, the bone pattern stayed
the same but the structures were slightly modified for different functions as each species adapted to a different
environment. We can use the fossil record to track many of these changes through time.
2. Distribution of Organisms- Island species are more closely related to the nearest mainland species but over
time, both populations have evolved to better fit their different environments.
4. Radiometric dating-using radioactive isotopes (unstable elements) to determine the age of the rocks in which
we find fossils. Also beneficial in determining the age of the Earth.
5. DNA/Molecular evidence-Scientists analyze DNA sequences to determine the relationships among different
species living today. The more similar the DNA, the more closely related the organisms (more recent common
ancestor)
6. Early Development/embryology-when organisms share a common ancestor, they begin life looking very
similar. In the earliest development, the form and the structures of the embryos are very similar indicating a
common ancestor but as they develop the organisms change into very different adult forms.
2. Identify two ways variations can be introduced into a population?
Meiosis (reproduction) and mutations
3. Explain how different factors in the environment can bring about changes in the population.
Predator-Prey relationship can be a pressure that can cause a variation to be beneficial so that it is naturally
selected leading to evolution of the population.
Changes in the environment: Examples: color of the bark of a tree (pepper moth); temperature of environment;
availability of food; etc. can cause a variation to be beneficial so that it is naturally selected. Organisms with the
variation (adaptation) are more likely to survive and reproduce to have offspring with the beneficial trait.
Over time, the population will change so that a beneficial variation is more common this is evolution.
4. Describe how mutations, variations, adaptations, natural selection (naturally selected) , and extinction (extinct)
cause evolution (evolve) to occur.
Mutations and meiosis (reproduction) can cause variations in the traits in a population. Depending on
the environment, these variations may be neutral, harmful (negative), or helpful (positive). If the variation is
helpful, it is considered an adaptation. Adaptations can be functional, structural, or behavioral. Because
organisms with the adaptation are more likely to survive and reproduce offspring with the beneficial trait, the
variation is naturally selected and over time, the population will evolve to have more individuals with the
beneficial variation/adaptation. If no individual in the population has a beneficial variation to meet the changes
in the environment, then the population will struggle to survive and will probably go extinct.
5. Explain why natural selection can only act on traits that can be inherited and NOT acquired traits.
Natural selection can only act on traits that can be inherited because evolution (the change in the population
over time), relies on the fact that the beneficial trait will be passed down to the offspring for generations to
come so that the population’s traits shift to the beneficial trait. If the trait cannot be passed down, it will benefit
the individual, but the population itself will still be at risk for extinction.
6. Identify examples of homologous structures and explain how they are evidence for evolution.
Arms (forelimbs) of bats, whales, cats, dogs, chickens, humans. Though they are all used for different functions,
they are all the basic same form of 1 bone (humerus) connected to two bones (ulna and radius) to the wrist
bone and fingers. Each bone has been modified over time to fit the needs of the different organisms evolving in
different environments. (Think about the whale evolution movie and the anatomical (homologous) structure
station. We can determine the ancestors of the whale by tracking the changes in the arms and legs of the
whale.)
Be Ready to:
7. Recognize the different types of evidence of evolution based on a description or an image.
8. Apply your understanding of evolution to examples
9. Analyze relationships using evidence (similar to cytochrome C class activity)
Resources:
Brain Pop videos: Natural selection, Charles Darwin
Stated Clearly: “Evolution”, “Natural Selection”, and “Evidence for Evolution”
Quizlet: Evolution