Component 2.6 - Isolation And Speciation Flashcards
What is a deme?
A sub-group within the population which may breed more often with each other than with the rest of the population.
How can speciation occur?
1) Deme becomes isolates so gene flow is prevented
2) Genetic drift
3) Natural selection
4) Founder effect of disproportionate allelefrequecies
What is pre-zygotic isolation?
Gametes are prevented from fusing and so a zygote is never formed
Allopatric vs sympatric
Allopatric means in different locations whereas sympatric means in the same location
What is post-zygotic reproductive isolation?
Gametes fuse and a zygote forms but even if the organism develops and grows it is sterile.
Give an example of hybrid sterility
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
Describe Darwin’s theory of natural selection
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
What types of isolation are there?
Geographical
Behavioural
Morphological
Seasonal
