Geographic (Allopatric) Speciation

Question 1

When does geographic speciation occur?

Answer 1

• when a new species is formed as a result of the whole or part of a population becoming geographically isolated from the ancestral species

Question 2

How did populations become geographically isolated in the past?

Answer 2

• erosion
• earth quakes
• volcanoes
• continental drift

Question 3

How do populations become geographically isolated and start geographic speciation today?

Answer 3

• a lake dries, forming 2 separate smaller bodies of water
• a few seeds stuck on a bird’s feather fall onto a newly formed island
• sea currents wash a few lizards or insects onto an island with no such organisms

Question 4

How does geographical speciation occur?

Answer 4

• becomes separated by a geographical barrier then the population splits into 2 populations
• there is now no gene flow between the populations
• each population is exposed to different environmental conditions and natural selection occurs
• the individuals of the two populations become very different from each other genotypically and phenotypically
• even if the populations were to mix again they will not be able to reproduce with each other