2.8 Speciation

Question 1

Where does evidence for early life forms come from?

Answer 1

Fossils

Question 2

What are fossils?

Answer 2

The remains of organisms from many years ago

Question 3

How can fossils be formed?

Answer 3

From the hard parts of animals that don’t decay easily
If one or more conditions needed for decay are absent
When parts of organisms are replaced by other materials when decaying
As preserved traces (footprints)

Question 4

Why is it difficult to know what early life forms were like?

Answer 4

They were soft bodied

So they left few traces often destroyed by geological activity

Question 5

What can extinction be caused by?

Answer 5

Changes in the environment
New predator
New disease
New/more successful competitor
Natural disaster

Question 6

What can a new species arise from?

Answer 6

Isolation: a population is separated eg geographically
Genetic variation
Natural selection: only some survive new conditions
Speciation: the new populations are so different they can’t successfully breed