Key Concepts of Evolution and Natural Selection

Evolution

Any change in the inherited traits of a population that occurs from one generation to the next.

Natural Selection

The process where organisms adapted to their environment tend to survive and produce more offspring.

Alfred Wallace

Credited alongside Darwin with independently conceiving the theory of natural selection.

Heredity

A mechanism for traits to be inherited or passed down.

Homologous Structures

Structures that have similar structures but different functions.

Analogous Structures

Structures that have similar functions but different evolutionary origins.

Fitness

A relative concept where one organism can be fit in one environment but unfit in another.

Darwinian Fitness

Measure of reproductive success, defined as the mean fitness or average reproductive success of members in a population.

Mean Fitness

Average reproductive success of members in a population.

Descent with modification

Organisms related through descent from a common ancestor.

Phylogenetic tree

A pattern of descent generated by analysis of similarities and differences among organisms.