Myosotis is a genus of small flowering plants. Many different Myosotis species grow on the islands of New Zealand, which are an important site of Myosotis evolution. Lowland Myosotis species grow at low altitude while alpine Myosotis species grow at high altitude at the tops of mountains. [Figure 5.1]

1. (a)Scientists wanted to obtain molecular data to determine the evolutionary relationships of New Zealand's Myosotis species. They extracted DNA from individuals of Myosotis species collected from three different islands in New Zealand. To carry out a polymerase chain reaction before DNA sequencing, the DNA samples were mixed with primers, deoxynucleotides and Taq polymerase and put through 35 cycles of treatment. Each treatment cycle involved one minute at 95°C, followed by one minute at 50°C and then four minutes at 72°C. Describe what happened to the DNA at each temperature.[3]
2. (b)Fig. 5.1 shows the three largest New Zealand islands. North Island has mostly lowland habitat. South Island and Stewart Island have mountains with alpine habitats that are above the tree line. DNA sequence data for three Myosotis species were compared. The results are described in the bullet points. • In the alpine species M. pygmaea, individuals on South Island showed genetic differences from individuals of M. pygmaea on Stewart Island. • In the alpine species M. pulvinaris, individuals from different mountains on South Island showed genetic differences. • In the lowland species M. pottsiana, individuals from different areas of North Island showed overall genetic similarity. Discuss reasons for the results in the three species.[5]
3. (c)State two factors, other than natural selection, that could drive genetic changes in populations of Myosotis.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.