Speciation

Question 1

Define speciation

Answer 1

The evolution of a new species from an existing one

Question 2

How can you check whether speciation has occurred

Answer 2

Take one organism from each potential species and mate them together, if they cannot produce fertile offspring then speciation HAS occurred

Question 3

What is allopatric speciation

Answer 3

Where a geographical barrier creates reproductive isolation

Question 4

How does allopatric speciation work

Answer 4

Geographical barriers
Create reproductive isolation
Natural genetic variation will occur due to mutation
Different selectional pressures exist each side of the barrier
The better adapted organisms survive and reproduce
The advantageous alleles are passed on to offspring
Over time the frequency of alleles changes to such an extent that a new species evolves
We can check a new species has evolved if the 2 individuals mate and cannot produce fertile offspring

Question 5

What is sympatric speciation

Answer 5

Where there is no geographical barrier, however reproductive isolation still occurs

Question 6

What could sympatric speciation be due to

Answer 6

Different flowering times
Different courtship rituals
Etc

Question 7

How does sympatric speciation work

Answer 7

No geographical barriers
Still creates reproductive isolation
Natural genetic variation will occur due to mutation
Different selectional pressures exist each side of the barrier
The better adapted organisms survive and reproduce
The advantageous alleles are passed on to offspring
Over time the frequency of alleles changes to such an extent that a new species evolves
We can check a new species has evolved if the 2 individuals mate and cannot produce fertile offspring

Question 8

What is genetic drift

Answer 8

When allele frequency randomly changes, reducing genetic variation

Question 9

What does genetic drift affect

Answer 9

Genetic drift only affects small isolated populations

Question 10

Define allopatric speciation

Answer 10

Evolution of a new species from an existing species due to reproductive isolation as a result of a geographical barrier

Question 11

Define sympatric speciation

Answer 11

Evolution of a new species from an existing species due to reproductive isolation such as different mating times