6.4 Isolation and the Evolution of New Species

Question 1

What is geographical isolation?

Answer 1

Where landforms separate a species so they become isolated

Question 2

Name 4 ways geographical isolation can separate species

Answer 2

• an island separates from the mainland
• a new river splits into 2 areas
• mountain ranges split into 2 areas
• old craters separate areas

Question 3

Name 3 reasons for new species

Answer 3

• genetic variation/natural selection
• after mass extinction
• population isolation

Question 4

How does population isolation work?

Answer 4

1. The species becomes isolated by geographical isolation
2. Natural selection causes the species to become evolved to that specific area as they may be exposed to different environmental conditions, food availability or predators.
3. Natural selection will happen in both areas but different characteristics will be beneficial in each area
4. Interbreeding between the old and new species is not possible because they are so varied

Question 5

What do natural cycles linked to environmental change result in?

Answer 5

New species forming and old species dying out

Question 6

What happens to populations in an isolated area?

Answer 6

Alleles are selected that increase the chance of survival in the new environment

Question 7

What is speciation?

Answer 7

When two geographically isolated species can no longer interbreed as they have become so different

Question 8

Explain speciation

Answer 8

1. Geographical isolation splits a population into 2
2. Each population has a wide range of alleles that control their characteristics, known as genetic variation
3. Natural selection occurs in both areas so adapt the animals to their habitats so their chances of survival are increased. The alleles that control the characteristic to help the animal survive are selected so the organisms with those alleles will survive and breed
4. If the environment, competitors, food supply and predators are different for each area they will evolve differently
5. Speciation has occurred when the organisms can no longer successfully inter breed

Question 9

Shorthand for speciation using the correct terms?

Answer 9

1. Isolation
2. Genetic variation
3. Alleles selected
4. Interbreeding no longer possible
5. Speciation

Question 10

Name an example of speciation

Answer 10

Darwins finches became isolated on different islands and evolved differently mainly due to different food supplies

Question 11

How can new species arise from existing species?

Answer 11

A group becomes isolated from the rest