Ch. 8: Survival of Species
Vocabulary:
species, extinct, fossil, reproduce,endangered species, habitat, pollutant
What Is a Species?
•A species is a group oforganisms that canreproduce with each otherand create offspring(babies.)
•Animals that are not part ofthe same species cannothave offspring.
•If I were to attempt to matea cat and a dog, they wouldnot produce kittens orpuppies.
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Reproduction
•Reproduction occurs whenplants or animals makemore of their own kind.
•Every plant and animal onEarth dies, but a species isconsidered successful if itsmembers are able toreproduce.
•If a species is having troublereproducing, or reproducesslowly that species isconsidered endangered.
Extinction
•In the last chapter we discussedadaptations.
•Sometimes an ecosystem willchange, because of climate or theintroduction or loss of a new plantor animal species.
•If the plants and animals in anecosystem cannot adapt to thenew temperatures, plants, oranimals they will die out.
•If all of a certain type of plant oranimal dies, that species becomesextinct.
•We know that species havebecome extinct before, becausepaleontologists have discoveredfossils of plants and animals thatdon’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 causeextinctions.
•Some human-made causes are:
1. Overhunting
2. Habitat Destruction
3. Pollution
Natural Extinction Events
•Climate Change:Where the temperaturechanges from warm tocold, or from cold towarm
•It doesn’t need tochange a lot, a fewdegrees is enough tochange the climate ofthe Earth entirely.
Natural Extinction Events
•Ecosystem Change:Jungles change intodeserts, or forests turninto grasslands.
•Natural forest fires, if theplants are not adapted tofire, can cause large tracksof forest to burn down andchange the ecosystemfrom a forest to agrassland for many years.
Natural Extinction Events
•Flooding: After landgets flooded, if it doesnot have any place todrain, the plants andanimals that used to livethere can’t anymore.
•In the case of a flashflood, a large amount ofwater can inundate anarea in a matter ofminutes.
Natural Extinction Events
•Predators: When a newspecies enters an area, it canthrow an entire ecosystemout of whack.
•Maybe the new animal eatsall the prey that the lives inthe area; the old predatorswill die out.
•Maybe someone plants aflower that takes over ameadow, choking out all thegrasses that used to livethere.
Natural Extinction Events
•Meteor, Asteroid, or CometStrike: It has been shown thatasteroids and meteors strikethe Earth very frequently withno ill effects.
•When a large enough asteroid,meteor, or comet strikes theEarth, though it can throw updust and dirt into theatmosphere causing climatechange.
•Paleontologists think this iswhat happened to thedinosaurs.
Most scientists agree that theYucatan Peninsula in Mexico wascaused by the asteroid strike thatkilled the dinosaurs.
Human-Made Extinction Events
•Overhunting: In the past,humans have huntedanimals to extinction.
•The Tasmanian tiger, thepassenger pigeon, and thedodo bird are threeexamples of species humanshave hunted to extinction.
•We try not to do thisanymore.
Human-Made Extinction Events
•Habitat Destruction:Humans have notalways been carefulabout the amount oftrees that they cut down,or where they buildtheir homes.
•When this happens,entire species of plantsand animals can bedestroyed.
Clearcut forest
Human-Made Extinction Events
•Pollution: We alsohaven’t always beencareful about where weare putting our trash andpoisons.
•If they are dumped inthe wrong stream orarea they can cause theextinction of plants andanimals.
Used oil being
dumped into a lake
Questions About Chapter 8
1.What happens when a living thingreproduces?
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 ofextinction?