Unit 32 The Origin and Extinction of Species 3.pptx

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1. Extinction of Species

2. Adaptation occurs as a result of a genetic change or mutation. This genetic change can help an organism survive better in its environment compared to others without the mutation.

3. Extinctions Species that are poorly adapted to their environment have fewer chances for survival and reproduction. In some cases, all individuals of that species die out because of poor adaptations. This refers to a phenomenon known as extinction .

4. True Extinction True extinction is more commonly just called extinction . When an organism goes extinct, it means that all individuals of that species have disappeared on Earth. The dodo bird was over hunted to extinction by humans.

5. Functional Extinction Functional extinction occurs when some members of the species are still surviving, but they can no longer reproduce. As of the time of writing, there are only two living Northern white rhinos left on Earth.

6. Extinct in the Wild Species that are extinct in the wild have living specimens that are only found in captivity, either in zoos or in laboratories. Père David’s deer is extinct in the wild.

7. Extinct in the Wild If a species is locally extinct, that means that the species has died out within a certain area but can still be found in other places. Another term for local extinction is extirpation . The saltwater crocodile is locally extinct in some areas.

8. Causes of Extinction Change in climate The biodiversity of Earth has been disrupted by the rapid changes in temperature and climate. These changes can cause extinction. Changes in climate can potentially wipe out species.

9. Causes of Extinction Diseases and Epidemics Each species has its own immune system that fights disease. Some animals lose the ability to fight off disease. The outbreak of pathogens can cause extinctions.

10. Causes of Extinction Invasive species When invasive species spread in a location, they use resources that other species depend on. Local species can go extinct as a result. The cane toad is invasive in many areas.

11. Causes of Extinction Catastrophes Catastrophic events , such as massive volcanic eruptions or large bolide impacts (like meteors and asteroids), can cause mass extinctions. Scientists believe that an asteroid caused the extinction of dinosaurs.

12. Background Extinction and Mass Extinction The background extinction rate refers to the rate by which organisms become extinct as part of natural processes. Humans have sped up the background extinction rate. Mass extinctions are periods in the history of Earth wherein the rate of extinction has gone up in a quick and widespread manner.

13. Background Extinction and Mass Extinction There have been 6 major mass extinction events. The Ordovician-Silurian extinction event which killed off more than 80% of Earth’s species ~440 million years ago. The Late Devonian extinction which wiped out around 75% of Earth’s species nearly 370 million years ago.

14. Background Extinction and Mass Extinction There have been 6 major mass extinction events. The Permian-Triassic extinction which occurred around 250 million years ago, and considered to be the worst since it wiped out almost 96% of all life on Earth. The Triassic-Jurassic extinction which wiped out 80% of Earth’s species 200 million years ago.

15. Background Extinction and Mass Extinction There have been 6 major mass extinction events. The K-T extinction which happened 66 million years ago and caused the death of the dinosaurs. The current mass extinction is known as the Holocene extinction , and the only mass extinction caused by humans .

16. When an organism goes extinct, it means that all individuals of that species have disappeared on Earth. 1 Mass extinctions are periods in the history of Earth wherein the rate of extinction has gone up in a quick and widespread manner. 2 There are six significant mass extinctions in terms of scale and intensity. 3

17. This happens when a plant or an animal species has died out completely. This occurs when some species are still living on Earth, but they can no longer reproduce. These species have living specimens that are only found in captivity. This means that the species has died out within a certain geographic area but can still be found in other places. This refers to the rate by which organisms become extinct as part of these natural processes. Identify the terms being described by each of the statements below.

18. How do humans affect the background extinction rate?