Allopatric Speciation

Question 1

State first stage in allopatric speciation

Parent population

Answer 1

• Parent population is able to increase its geographical range (move and spread out across the ladscape).
• Gene flow is regular

Question 2

State second stage in allopatric speciation

Formation of barriers

Answer 2

• Over time physical geographical barriers form which begin to isolate the populations from each other.
• Gene flow is less regular since organisms struggle to cross these barriers.

Question 3

What are examples of physical geographical barriers?

Answer 3

• Continental drift
• Climate change
• Changes in sea level
• Mountain range formation

Question 4

State third

Isolation and mutations

Answer 4

• The physical geographical barriers then isolate the population and so gene flow stops.
• Any mutations that are beneficial to a population are not shared to other populations.
• If environments have different selection pressures then different mutations will be beneficial.

eg: snow means white coat is beneficial for species A

Question 5

State fourth stage in allopatric speciation

Answer 5

• As the mutations increase in each population, they become more and more different to each other.
• If they are brought back together, they cannot interbreed to produce fertile viable offspring.
• They are now a different species.