Earth Science

Life on Earth

Extinction and Radiation of Life

Study Tip
The growth of the human population is threatening other species. Some endangered animals include: African and Asian elephants, West Indian manatees, American alligators, Western gorillas, grizzly bears, Florida cougars, jaguars, tigers, black rhinos, humpback whales, sperm whales, green sea turtles, Atlantic salmon, and red wolves.

Extinction

  • Extinction is the complete termination of a species. There are two ways for a species to go extinct:
  • Dying out completely
  • The species evolves into another species
  • When a species goes extinct, they leave niches for other species to fill.
  • Extinction is a natural process on earth, and most species that have lived on earth have also gone extinct.
  • A mass extinction is an extinction that has been accelerated by factors such as:
  • The earth colliding with comets or asteroids
  • Volcanic eruptions
  • Rapidly changing climate
Study Tip
The growth of the human population is threatening other species. Some endangered animals include: African and Asian elephants, West Indian manatees, American alligators, Western gorillas, grizzly bears, Florida cougars, jaguars, tigers, black rhinos, humpback whales, sperm whales, green sea turtles, Atlantic salmon, and red wolves.

Adaptive Radiation

  • Adaptive radiation is when after a mass extinction occurs and there are many new available habitats, species adapt in order to fill the habitats.
  • Mammals underwent adaptive radiation to become the dominant life form after the extinction of dinosaurs.
Concept Check
  • How do species usually go extinct? Is this normal?
  • What are some causes of mass extinctions?
  • What is adaptive radiation?