Component 2.6 - Isolation And Speciation

Question 1

What is a deme?

Answer 1

A sub-group within the population which may breed more often with each other than with the rest of the population.

Question 2

How can speciation occur?

Answer 2

1) Deme becomes isolates so gene flow is prevented
2) Genetic drift
3) Natural selection
4) Founder effect of disproportionate allelefrequecies

Question 3

What is pre-zygotic isolation?

Answer 3

Gametes are prevented from fusing and so a zygote is never formed

Question 4

Allopatric vs sympatric

Answer 4

Allopatric means in different locations whereas sympatric means in the same location

Question 5

What is post-zygotic reproductive isolation?

Answer 5

Gametes fuse and a zygote forms but even if the organism develops and grows it is sterile.

Question 6

Give an example of hybrid sterility

Answer 6

Mule: a horse has 32 chromosomes in gametes and a donkey has 31 in gametes so mules have 63 chromosomes. Unable to pair at prophase 1 of meiosis.

Sympatric

Question 7

Describe Darwin’s theory of natural selection

Answer 7

1) Variation caused by mutation
2) Individuals have advantageous alleles better at surviving
3) Reproduce and pass on alleles
4) Over many generations this allele becomes more common so average phenotype changes

Question 8

What types of isolation are there?

Answer 8

Geographical
Behavioural
Morphological
Seasonal