Download Enviro2Go: Natural Selection

Name: _________________________________
Date: _____________________
Natural Selection
Enviro 2 Go
6.2.4.2, 6.2.4.3, 6.2.4.4
Objective- You should be able to:




Explain how species change overtime
Define natural selection
Describe Charles Darwin’s observations
Describe the peppered moth case study
Important Vocabulary
 Variation
 Adaptation
 Traits
 Survival of the Fittest
 Evolution
 Natural Selection
Natural Selection
 An important ___________________ in explaining how ____________________
________________________________.
 Helps maintain ________________________________________________.
Charles Darwin’s Observations
1. Organisms have the ability to produce more ________________________ than can
usually _______________________.
2. Members of the ______________ species normally have slight _________________
called variations. (They are not all identical!)
3. Members of a species must ______________________ with each other and with
other species to survive. Some organisms cannot successfully compete for limited
resources.
4. Some members of a species have ________________ that are helpful for survival,
called ________________________. Other traits are not helpful for survival.
5. Those organisms ___________________________ that are ___________________
___________________________________ are more likely to _____________________
___________________________________ than those without these traits.
6. The ability to ___________________________________________ establishes the
population for the ___________ generation.
Survival of the Fittest
 Natural selection is sometimes referred to as “___________________________.”
 Being “fit” means that an organism has ______________________, __________
that help it to _________________________.
 More importantly, being “fit” means that the organisms are able to ___________
_________________________ onto the _____________ generation.
Examples:
Remember This!!!
 Natural Selection explains how a species may change over time.
 The change is created because of successful reproduction.
 The organism most “fit” for an environment is most likely to be the one to
successfully reproduce and have offspring that mature into adults and reproduce.
Interesting Science Fact
After talking to local farmers, Charles Darwin discovered that the farmers had been
using artificial selection for centuries. The farmers and ranchers never allowed their
stock to reproduce on their own. Instead the farmers and ranchers always allowed
their best plants and animals to reproduce, but did not allow the weak ones to
reproduce. This type of reproduction creates stronger, better produce and livestock.
The Process of Natural Selection
 ______________ are passed from ___________________ to _______________
 Those organisms that _____________________ pass on the _____________ for
those _______________ that helped them _____________________.
 Organisms ________________________ those traits helpful for survival are less
likely to ________________________, so their genes are __________ likely to
be passed on to the next generation.
 Organisms that can survive long enough to reproduce are able to determine the
____________________________ of the _______________________________.
Question 1: How does the successful reproduction of an organism affect the next
generation?
Question 2: How does the unsuccessful reproduction of an organism affect the next
generation?
Remember This!!!
 Only those organisms able to reproduce affect the next generation.
 Organisms that reproduce pass their unique traits in the form of genes on to the
next generation; therefore the next generation inherits genes that helped the
previous generation to survive.
Natural Selection and the Environment
 If the _____________________________ stays the same, then natural selection
favors organisms with certain _____________________________.
 Organisms with these adaptations (traits) _____________________ and
_____________________________.
 Organisms that do __________ possess these traits may ___________________
long enough to ____________________________.
 The population __________________ to the __________________________
over time through ___________________________ or the failure to reproduce.
What happens if the environment changes?
 When the _________________________ changes (which it almost always is),
then other ______________________ might be favored.
 The traits that helped an organism survive in one environment may not help in
another situation.
Example: Peppered Moth Study
 There are two types of peppered moths:


 Normally, they are found in ______________ amounts in forested
areas of England.
 During the Industrial Age, the _______________ variety almost
became extinct in areas around the factories because the factories
produced large amounts of black soot that covered everything for
miles.
 The ____________ moths were able to ____________ on trees and it
became hard for their predators to find them.
 The ________________ variety was very easy to see and the
_____________________ had no trouble finding and eating them.
 Therefore, only the ___________ moths ____________________ long
enough to _______________________.
 As the environment changed, it favored the dark color over the white
color.
 In areas where the environment had not changed, both moth
variations were found with the same population numbers.
 The ___________________________ determined which variation
would __________________ long enough to ____________________.
 The next ____________________________ were almost exclusively
dark colored peppered moths.
Question 3: Predict what might happen to the population of the white and dark
moths if the factories covered the landscape with a white soot instead of a black soot.
Question 4: Explain how a changing environment affects the population of the
organisms living in that area.
Question 5: Compare how a changing population and a non-changing population
affect the organisms that live in the area.
Evolution
There is much evidence that the Earth has changed greatly over the last 4.6 billion
years. _________________________________ has continually favored the
___________________ of organisms with ______________________ that make them
suited to their __________________________. However, since the environment has
changed, the species have changed. This is referred to as _______________________.
Test Yourself: Matching
________
________
________
________
________
1.
2.
3.
4.
5.
natural selection
variation
adaptations
fit
survival of the fittest
a. Traits that help an organism
survive
b. An organism that has adaptations
c. A phrase to describe natural
selection
d. The process that explains how
species change over time
e. Differences among individuals of
the same species
Test Yourself: True or False
_____ 1. In order to understand natural selection, several observations must be
understood together.
_____ 2. Organisms have the ability to produce very few offspring.
_____ 3. Organisms have the ability to produce more offspring than can usually
survive.
_____ 4. Variations are traits that help an organism survive.
_____ 5. Variations are traits that do not help an organism survive.
_____ 6. Variations are differences among members of the same species.
_____ 7. All members of the same species are identical.
_____ 8. Members of a species must compete only with organisms of other
species.
_____ 9. Members of a species must compete with members of their own species and
members of other species.
_____ 10. Adaptations are traits that do not help an organism survive.
_____ 11. Adaptations are differences among members of the same species.
_____ 12. Adaptations are traits that help an organism survive.
_____ 13. Organisms have an equal chance of surviving and reproducing.
_____ 14. Organisms with adaptations have a better chance of surviving and
reproducing than organisms without adaptations.
_____ 15. A fit organism is more likely to survive and reproduce than a less fit
organism.
_____ 16. Evolution is the changing of species over time.
_____ 17. Natural selection has little to do with evolution.
_____ 18. Natural selection explains how species can change over time.
Test Yourself: Fill in the Blank
Natural selection
Adaptation
Reproduction
evolution
variation
compete
fit
survive
1. ______________ is the process often describe as “survival of the fittest.”
2. _____________ is the changing of species over time.
3. Organisms must _______________ to survive.
4. Those organisms that are more ________ have more traits that help them
survive.
5. A trait that helps an organism survive is called an __________________.
6. Since there is ______________ in a population, not all organisms are identical.
7. Some organisms are more likely to ________ because of their adaptations.
8. Organisms that survive long enough to _______________ can pass on the genes for
their adaptations to their offspring.
Test Yourself: Short Answer
1. What is a variation?
2. What is an adaptation? Give an example.
3. What are the five observations that explain natural selection?
4. How does natural selection change a population?