Aim: How does gradualism differ from punctuated
equilibrium?
I. Evolution – change over time. The question is… How
much time?
A. Two theories of Evolution
1. Gradualism – evolutionary change is slow,
gradual, and continuous.
In your notebook, draw what you think gradualism
would look like.
B. Punctuated Equilibrium – A theory of the time frame
required for evolution that assumes that evolutionary change
occurs in bursts with long periods of relative stability
intervening (in between these sudden bursts).
In your notebook, draw what you think punctuated
equilibrium would look like.
Why do organisms become extinct?
II. Extinction – occurs when the environment changes
and the adaptive characteristics of a species are
insufficient to allow its survival.
If our environment is constantly changing, why
doesn’t extinction occur more often?