What is adaptive radiation? Explain it with Darwin's finches and Australian marsupials, and show how it leads to convergent evolution.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Define in one line. Adaptive radiation is the evolution of different species in a geographical area from one ancestor, radiating into different habitats.
2 · Explain Darwin's finches. Galapagos; seed-eating ancestor; beaks changed to give insect-eating and vegetarian finches.
3 · Explain Australian marsupials. One ancestral stock gave kangaroo, koala, wombat, Tasmanian wolf, marsupial mole and others.
4 · Link to convergence. Placental mammals in Australia also radiated; each resembles a marsupial with the same way of life, e.g. wolf and Tasmanian wolf.
5 · Close in one line. So one ancestor can give many forms, and unrelated forms can come to look alike.
Scoring tip: Give one named pair of placental and marsupial look-alikes; it earns the convergence mark.
