Old and new species Flashcards
Fossils
The remains of organisms from many years ago which are found in rocks
Extinction
A species that once existed has completely died out
Predator
An animal which preys on other animals for food
Geographical isolation
When two populations become physically isolated by a geographic feature
Speciation
The formation of a new species (the two populations can no longer successfully interbreed)
How old is the earth?
4.5 billion years (4.5 x 10^9)
How old is life on earth?
3.5 billion years old (3.5 x 10^9)
How are fossils formed?
- from the hard parts of animals that do not decay easily
- when organisms are preserved in ice, so decay conditions are not present
- when parts of the organism are replaced by other minerals
- traces of organisms are preserved
How many species of living organisms have existed over the years?
4 billion
What organisms can cause extinction?
- new predators
- new diseases
- new competitors
How can predators cause extinction?
Their prey do not have adaptations to avoid them when they are introduced or evolve
How might microorganisms cause extinction?
They can bring diseases that could kill a population if it lives close together
How might a competitor cause extinction?
New mutations might give it an advantage, meaning they eat their food or inhabit their habitations
How does environmental change over long time scales affect living organisms?
A species that is well adapted to a hot climate could face insufficient food or find it too cold to breed
What events can cause a mass extinction?
- a catastrophic event such as a volcanic eruption
- a dramatic environmental change, such as that following a collision between Earth and a giant asteroid
