Evolution and the tree of life

Discover the diversity of life on Earth and the forces that shape it! In this section, you can learn about evolution, natural selection, and the tree of life, as well as basic population genetics. Special bonus: take a peek into the amazing worlds of bacteria and viruses.
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Learn about evolution, the process in which groups of organisms change in their genetic makeup and heritable features over time. Natural selection is an important mechanism of evolution, one that can cause groups to become better suited to their environments over generations.

At its core, evolution is a change in the allele frequencies in a population over time. But how does this change happen, and how can it be measured? Here, we'll address these questions at both the conceptual and mathematical levels.

A family tree can tell you how you are related to your close relatives...but an evolutionary tree can tell us how all living things on Earth are related! Learn about what makes something a species, where new species come from, and how living organisms can be classified into groups (on the basis of either evolutionary relatedness or other features).