Transcript Ch. 8: Survival of Species

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 Change
2. Ecosystem Change
3. Flooding
4. Predators
5. Meteor, Asteroid, or Comet Strike
• Sometimes humans can change their environment and cause
extinctions.
• Some human-made causes are:
1. Overhunting
2. Habitat Destruction
3. 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?