Heritable trait or behavior that aids in survival and reproduction

Parallel structures that have a common ancestor. Example: wings of a bird and forelimbs of a cat.

Structures that have no apparent function, derived from a distant ancestor. Example: leg bones of snakes

The process by which individuals with favorable traits survive and reproduce, leading to evolutionary change.

Process by which groups of organisms independently evolve similar forms. Example: whales and sharks look similar.

When on individual species branches out into many different species: Example: Finches of the Galapagos

Speciation that occurs due to geographic isolation: Example: squirrels that are separated by a mountain range

Speciation that occurs in the same geographic space. Example: Fish that feed at the top of a lake and fish that feed at the bottom.

Groups of individuals that can interbreed and produce fertile offspring:

Reproductive isolation that prevents a zygote from being formed:

Differences in breeding schedules isolate one population from another:

A model for rapid speciation that can occur when an event causes a small portion of a population to be cut off from the rest of the population, or a rapid change in the environment

Area where two closely related species continue to interact and reproduce. Example: Wolves, coyotes, coy-wolf

Fossils or organisms that show the intermediate states between an ancestral form and a current form.

Refers to how a species is named using its genus and species: Example: Giraffa camelopardalis