variation

adaptation

homologous structure

vestigial structure

physical or behavioral tendencies.

physical or behavioral characteristics that help an organisms survive and reproduce.

physical or behavioral characteristics that do not help the organism in any way.

genetic mutations that have gone wrong.

Adaptation

Evolution

Extinction

Environmental influences

Scientists use them as evidence that many species must have had a common ancestor.

Scientists use them as evidence that many species must have independently evolved and are not related to other species.

Scientists use them as evidence to show that all kinds of structures in our bodies work to help us survive.

They are useful in the organism and show natural selection at work.

They are not useful in the organism but they were probably useful in some ancestor of that species.

They show that these organs or behaviors help an organism adapt to new environments

Embryos of many species have a lot of similar characteristics when they are first forming showing different creatures must have a common ancestor

Embryos of many species have very little in common until they start developing for long periods of time

Features like gills and tails prove that all animals are really just fish

Ancestral traits

Embryonic Development

Homologous Structures

Vestigial Structures

Vestigial

Homologous

Analogous Structures

Embryonic