UNIT 4 EVOLUTION AND CHANGE
A challenge to Darwin’s theory
Darwin’s theory of evolution states
that changes occur gradually and
over many years.He used the
fossil record to support his ideas.
In the 1970s, American biologist
Stephen Jay Gould (1941–2002)
presented a challenge to Darwin’s
theory called punctuated
equilibrium. He argued that a
species can remain unchanged for
millions of years. If a dramatic
environmental event occurs, a
species can undergo rapid
changes in a short period of time.
He also found evidence in the
fossil record to support his idea.- What does Gould mean by a
dramatic environmental event?
List some of your ideas. - Do you agree or disagree with
Gould’s ideas? Explain your
position and justify it with your
knowledge about evolution. - Could Darwin’s model for
evolution and Gould’s model
both be correct? Explain your
reasoning.
11.2 Section Review
- On his journey, Darwin observed how different animal and
plant species had adapted to function in their environments.
Explain how each of the following items is best suited to its
unique function. - Why did Darwin use selective breeding as evidence for
evolution? - How did the work of geologists support Darwin’s theories
about evolution? - What is natural selection?
- How did the work of Malthus help Darwin reach his conclusion
about natural selection? - List three environmental variables that affect the size of a
population. - A population of beetles eats only red flowers. Most of the
beetles are red but a few of them are yellow. The red beetles
are hidden from hungry, beetle-eating birds. The beetles eat
up all of the red flowers and now there are only yellow flowers
left. What would you expect to happen to the traits of the
beetle population over time? What process would cause this
to happen?