Ch. 8: Survival of Species

Vocabulary:

species, extinct, fossil, reproduce, endangered species, habitat, pollutant

What Is a Species?

• A species is a group of organisms that can reproduce with each other and create offspring (babies.)

• Animals that are not part of the same species cannot have offspring.

• If I were to attempt to mate a cat and a dog, they would not produce kittens or puppies.

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Reproduction

• Reproduction occurs when plants or animals make more of their own kind.

• Every plant and animal on Earth dies, but a species is considered successful if its members are able to reproduce.

• If a species is having trouble reproducing, or reproduces slowly that species is considered endangered.

Extinction• In the last chapter we discussed

adaptations.• Sometimes an ecosystem will

change, because of climate or the introduction or loss of a new plant or animal species.

• If the plants and animals in an ecosystem cannot adapt to the new temperatures, plants, or animals they will die out.

• If all of a certain type of plant or animal dies, that species becomes extinct.

• We know that species have become extinct before, because paleontologists have discovered fossils of plants and animals that don’t exist anymore.

Extinction Events• Sometimes the balance of an ecosystem changes.• There are many natural causes for this to happen.• Some of the natural causes are:

1. Climate Change2. Ecosystem Change3. Flooding4. Predators5. Meteor, Asteroid, or Comet Strike

• Sometimes humans can change their environment and cause extinctions.• Some human-made causes are:

1. Overhunting2. Habitat Destruction3. Pollution

Natural Extinction Events

• Climate Change: Where the temperature changes from warm to cold, or from cold to warm

• It doesn’t need to change a lot, a few degrees is enough to change the climate of the Earth entirely.

Natural Extinction Events

• Ecosystem Change: Jungles change into deserts, or forests turn into grasslands.

• Natural forest fires, if the plants are not adapted to fire, can cause large tracks of forest to burn down and change the ecosystem from a forest to a grassland for many years.

Natural Extinction Events

• Flooding: After land gets flooded, if it does not have any place to drain, the plants and animals that used to live there can’t anymore.

• In the case of a flash flood, a large amount of water can inundate an area in a matter of minutes.

Natural Extinction Events

• Predators: When a new species enters an area, it can throw an entire ecosystem out of whack.

• Maybe the new animal eats all the prey that the lives in the area; the old predators will die out.

• Maybe someone plants a flower that takes over a meadow, choking out all the grasses that used to live there.

Natural Extinction Events

• Meteor, Asteroid, or Comet Strike: It has been shown that asteroids and meteors strike the Earth very frequently with no ill effects.

• When a large enough asteroid, meteor, or comet strikes the Earth, though it can throw up dust and dirt into the atmosphere causing climate change.

• Paleontologists think this is what happened to the dinosaurs.

Most scientists agree that the Yucatan Peninsula in Mexico was caused by the asteroid strike that killed the dinosaurs.

Human-Made Extinction Events

• Overhunting: In the past, humans have hunted animals to extinction.

• The Tasmanian tiger, the passenger pigeon, and the dodo bird are three examples of species humans have hunted to extinction.

• We try not to do this anymore.

Human-Made Extinction Events

• Habitat Destruction: Humans have not always been careful about the amount of trees that they cut down, or where they build their homes.

• When this happens, entire species of plants and animals can be destroyed.

Clearcut forest

Human-Made Extinction Events

• Pollution: We also haven’t always been careful about where we are putting our trash and poisons.

• If they are dumped in the wrong stream or area they can cause the extinction of plants and animals. Used oil being

dumped into a lake

Questions About Chapter 8

1. What happens when a living thing reproduces?

2. What is a habitat?

3. Give three examples of extinct animals.

4. How does extinction work?

5. Write down 2 natural causes of extinction

6. What are 2 human-made causes of extinction?