Natural Selection

A Study of Changes in Populations

A finch perched diagonally on a thin wooden branch against a clear blue sky. The bird has a stocky build with light brownish-grey feathered underparts heavily streaked with darker brown, a conical yellowish-beige beak, and a dark eye.

Populations of organisms change over generational time (evolve) as a consequence of natural selection and adaptation due to the interaction of four factors: (1) the potential for a population (species) to increase in number, (2) variations in traits inherited from organisms’ parents, (3) competition for an environment’s limited supply of the resources that individuals need in order to survive and reproduce, and (4) the ensuing proliferation of those organisms that are better able to survive and reproduce in that environment.

Natural Selection Overview

Content Connections

Natural Selection Lessons & Video

This material is based upon work supported, in part, by the National Science Foundation under Grant DRL-1503280. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.