Login
Copyright

The Causes of Species Extinction

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: The Defining Characteristics of Living Organisms

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
 Replay
Your next lesson will play in 10 seconds
  • 0:03 Past Extinctions
  • 1:26 Catastrophic Events
  • 2:30 Disease & Predators
  • 3:58 Competition & Climate Change
  • 5:45 Lesson Summary
Add to Add to Add to

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Login or Sign up

Timeline
Autoplay
Autoplay
Create an account to start this course today
Try it free for 5 days!
Create An Account

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Julie Zundel

Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.

What do dinosaurs, passenger pigeons, and a species of Australian rat all have in common? They have all gone extinct. This lesson will examine the causes of species extinction from mass extinctions in the past to human-caused extinctions today.

Past Extinctions

Scientists believe that over 99% of all species that have ever existed on Earth have gone extinct, meaning all members of a species have died and the species ceases to exist. Yep, from dinosaurs to saber tooth cats, Earth has seen many species come and go.

So far on Earth, there have been five mass extinctions, meaning a large percentage of the species on earth go extinct. The most recent occurred 65 million years ago, where 85% of species died off. You may know this as the dinosaur extinction, but other species went extinct too. However, that wasn't the most severe extinction - that belongs to the Permian extinction, which occurred 250 million years ago and some estimates suggest 96% of organisms died. Pictured here are fossils of trilobites. All species of trilobites went extinct during the Permian extinction.

trilobite

Some of these mass extinctions are believed to be caused by a catastrophic event, like an asteroid or increased volcanic activity. But extinctions are occurring all of the time, even if they are not part of a mass extinction. And catastrophic events are not the only culprits. Disease, competition, new predators and climate change can also cause species to go extinct. Let's examine each of these causes of species extinction.

Catastrophe Events

When you hear 'extinction,' a major catastrophic event probably pops into your mind, so let's start there. An asteroid likely caused the extinction that wiped out the dinosaurs 65 million years ago. Of course there's debate among the scientific community, but many believe the asteroid impact caused dust to block out the sun, which reduced Earth's temperature.

But is it just asteroids that cause mass extinctions? Again, there's debate within the scientific community, but the mass extinction that occurred at the end of the Triassic period has been attributed to lowering sea levels, which were caused by the volcanic rift that formed in the present day Atlantic Ocean. The lowering sea level killed off many marine species.

The largest mass extinction that occurred at the end of the Permian period is believed to be caused by increased global temperatures coupled with volcanic eruptions, which caused the temperature to increase even more. It's important to remember that, even in catastrophic events, extinctions don't happen over night, but over a period of a few hundred years to thousands of years.

Disease & Predators

Okay, enough about catastrophic events, let's look at some examples of species that have gone extinct from disease and predators.

Of course diseases can kill off some members within a species, but can disease really kill off an entire species? Yes, believe it or not, it can! Yikes! Case in point: the rat species Rattus nativitatis inhabited Australia but went extinct in 1908. Scientists believe the black rat, which was an invasive species, or a species that is nonnative to a region, was to blame. The black rat reached Australia via a ship and transmitted disease through fleas to Rattus nativitatis, which may have caused them to go extinct. Island populations, like Rattus nativictatis, are especially susceptible because they are not exposed to the same diseases as mainland critters.

Another cause of extinction is the introduction of predators. The dodo was a flightless bird that once thrived on the island of Mauritius, which is located in the Indian Ocean. Prior to human inhabitation of the island in 1505, the dodo had no predators. But once humans inhabited the region, they became the dodo's first predator, killing the flightless bird for food. Later, invasive species that were introduced by humans came to the island. Between humans and the introduced rats, pigs, and monkeys, the once predator-free dodo bird became a popular food source for several species, and by 1681, the dodo was extinct.

Competition & Climate Change

You're probably gathering that humans may be having an adverse effect on some of Earth's species. Yep, humans are to blame for many of the extinctions currently occurring. In fact, scientists believe we are entering the sixth mass extinction, and the changes to Earth due to humans are to blame. Scientists believe species are going extinct at 114 times the normal rate of extinction.

Not only do humans introduce invasive species, but we also compete with other species for habitat and food. Habitat loss due to deforestation has caused numerous extinctions. For example, the passenger pigeon once inhabited much of the United States, but as forests were cleared in the Eastern United States, populations moved to farming fields where they damaged crops, so they were hunted and became extinct.

To unlock this lesson you must be a Study.com Member.
Create your account

Register for a free trial

Are you a student or a teacher?
I am a teacher

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back

Earning College Credit

Did you know… We have over 95 college courses that prepare you to earn credit by exam that is accepted by over 2,000 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it free for 5 days!
Create An Account
Support