paleontologists Scientists who study fossils to learn about life in the past.
radiometric dating A method to determine the age of rocks and fossils in each layer of
rock; measures the decay rate of radioactive materials in each rock layer.
vestigial structure Body part that has lost its use through evolution, such as a whale’s
pelvic bones.
Points to Consider
- How do you think new species evolve?
- How long do you think it takes for a new species to evolve?
7.3 Lesson 7.3: Macroevolution
Lesson Objectives
- Students will understand the differences between macroevolution and microevolution.
- Students will understand that speciation is the formation of new species.
- Students will understand the mechanisms of speciation.
Check Your Understanding
- Why can’t an individual person evolve? Why can only groups evolve over many gen-
erations? - What causes a species or a population to evolve?
Introduction
Small changes or large changes, how does evolution occur? It is easy to think that many
small changes, as they accumulate over time, may gradually lead to a new species. Or is it
possible that due to severe changes in the environment, large changes are needed to allow
species to adapt to the new surroundings? Or are both probable methods of evolution?