________Minneapolis College | Principles of Biology | BIOL 2200 | Instructor: Mitch Albers

IX. Evolution is the core theme of biology

Evolution is the one unifying biological theme.

In 1859, Charles Darwin published On the Origin of Species in which he made two major points:

1. Species change, and contemporary species arose from a succession of ancestors through a process of "descent with modification."

2. A mechanism of evolutionary change is natural selection.

Darwin synthesized the concept of natural selection based upon the following observations:

Organisms' adaptations to their environments are the products of natural selection.

Darwin proposed that cumulative changes in a population over long time spans could produce a new species from an ancestral one.

Descent with modification accounts for both the unity and diversity of life: