13-Extinction and Evolutionary Trends

Extinction

The end of an organism or group of organisms, usually resulting in the disappearance of the species.

Background Extinction

The ongoing, gradual process of species becoming extinct at a relatively constant rate.

Mass Extinction

A rapid and significant loss of a large number of species in a relatively short period of geological time.

Predation

The preying of one animal on others, which can contribute to extinction when predatory pressure increases.

Competition

The struggle between organisms, particularly species, for the same resources in an ecosystem, leading to extinction of less adapted species.

Punctuated Equilibrium

The theory that species evolution is marked by isolated episodes of rapid speciation between long periods of little or no change.

Cope's Rule

The observation that over evolutionary time, lineages of mammals tend to increase in body size.

Pseudoextinction

A gradual change in a species that results in the end species being functionally different from the starting species.

Fossil Record

The collection of fossils that provides evidence of the history of life on Earth, although it is often incomplete.

Cambrian Explosion

A period of rapid diversification of life forms around 541 million years ago, resulting in a significant increase in the number of marine taxa.