Natural Selection
What is natural selection?
A process where organisms with traits that help them survive and reproduce are more likely to pass those traits on.
What is artificial selection?
When humans select organisms with desired traits to reproduce.
What does the term adaptation mean?
A trait that helps an organism survive and reproduce.
A population of beetles has green and brown colors. Birds eat more green beetles. Which color becomes more common? Why?
Brown, because they are less visible and survive.
Why is variation important for survival of a species?
It increases the chance some individuals will survive changes.
Which two factors are required for natural selection to occur?
Genetic variation and environmental pressure.
Name one example of artificial selection.
Dog breeding, crops bred for size or taste.
Define variation.
Differences in traits among individuals in a population.
Farmers breed cows that produce more milk. Is this natural or artificial selection?
Artificial selection.
How could a lack of genetic variation lead to extinction?
No traits may exist that help survive new conditions.
How does competition for resources affect natural selection?
Organisms with helpful traits are more likely to survive when resources are limited.
How is artificial selection different from natural selection?
Humans choose the traits instead of the environment.
What is extinction?
When all members of a species die out.
A drought kills plants with shallow roots. What trait would be favored?
Deep roots.
Explain how natural selection can lead to biodiversity.
Different environments favor different traits.
Explain how a population changes over time through natural selection.
Helpful traits become more common over generations.
Why might artificial selection reduce genetic diversity?
Only selected traits are passed on repeatedly.
Define selective breeding.
Choosing organisms with desired traits to reproduce.
A species cannot survive a sudden climate change. Which standard does this relate to?
SC.7.L.15.3 (extinction due to lack of adaptation).
Compare long-term effects of natural vs. artificial selection.
Natural selection improves survival in nature; artificial selection meets human needs.
Why does natural selection act on populations rather than individual organisms?
Individuals do not evolve; populations evolve over time.
How can artificial selection negatively affect a species’ ability to survive in the wild?
Traits chosen by humans may not help survival in nature.
What does environmental pressure mean?
Factors in the environment that affect survival.
Over many generations, a fish population becomes smaller due to predators. What caused this change?
Natural selection based on environmental pressure.
Predict what might happen if environmental changes occur faster than a species can adapt.
The species may decline or become extinct.