Fossils are evidence of earlier life forms and can be created in a number of ways.

• The fossil record supports Darwin’s theory of evolution because it shows how life began with simpler life forms.
• Extinction is where a whole species is wiped out and can occur due to a number of reasons.
• Speciation is the process by which a new species is formed.
• Isolation is one way in which speciation can occur.

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Evolution and Speciation – Test it!

1. Leopards are carnivores and hunt other animals for their food. They can be found in sub-Saharan Africa.

a) A change in the distribution of leopards would probably be due to which of the following:

i. not enough prey

ii. not enough predators

iii. too little oxygen

b) A big increase in the number of leopards in a particular area would probably lead to which of the following:

i. female leopards having more offspring

ii. more competition for breeding sites

iii. a decrease in the number of people in the area

c) If humans increased the amount of agricultural land they used this could lead to which of the following:

i. the appearance of new predators

ii. the formation of new diseases

iii. the extinction of leopards

2. One organism at risk of extinction is the African elephant.

They’re the biggest land animal and tend to live up to 70 years.

They usually live in big herds and feed on a lot of leaves.

The adult has no natural predators but they’re killed by humans for their tusks.

Their land is also disappearing rapidly as it is used more by humans.

Using the information above, give three reasons why do you think that the African elephant is at such a high risk of extinction.

1.___________________________________________________________

2.___________________________________________________________

3.___________________________________________________________

3. Fossils are used to find out about the earliest forms of life on Earth.

a) Write three ways fossils can be formed.

i. ___________________________________________________________

ii. ___________________________________________________________

iii. ___________________________________________________________

b) How does the fossil record support Darwin’s theory of evolution?

c) Why are scientists still not certain how life began on Earth?

ANSWERS

a) i. not enough prey

b) ii. more competition for breeding sites

c) iii. the extinction of leopards

i. They are being overhunted by humans.

ii. Humans are taking over their natural habitat so they have less area in which to live.

iii. They have less access to food if trees are cut down for agricultural land.

a) Any of the possible answers:

• they could be formed from the hard parts of animals which don’t decay easily
• the organism could have been preserved intact in ice, a peat bog or amber
• as an organism decays these parts could be replaced by another material
• it could be in the form of a preserved trace like a footprint or a burrow

b) The earliest fossils are of simpler organisms while the later rocks show more complex organisms.

c) Scientists can only make educated guesses on the evidence available to them. There is no concrete way of knowing for certain how life evolved or began on Earth however Darwin’s theory in terms of evolution is the best available so far.