QUESTION 9 (2 marks)
Scientists analysed data on three populations (A, B and C) in a region affected by habitat fragmentation. The graphs show how the rate of gene flow and genetic differences between the populations changed over time.
Key rate of gene flow genetic difference
Infer which populations underwent allopatric speciation. Justify your response.
QCAA guide · typeset solution
QCAA sample response and mark allocation
9 | Populations A and B. Allopatric speciation occurs when populations become geographically isolated, preventing gene flow from occurring. The graph for populations A and B shows that gene flow stopped suddenly at ~20 million years. | • infers population A and B [1 mark] • provides appropriate justification [1 mark] |
QCAA sample response and marking criteria reproduced from the official guide.
Compare your working with the guide above.