Say whether each example is adaptive radiation or convergent evolution…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Say whether each example is adaptive radiation or convergent evolution.
- Darwin's finches on the Galapagos Islands.
- The Tasmanian wolf and the wolf of the northern continents.
- The many kinds of marsupials of Australia that came from one ancestral stock.
- The flying phalanger and the flying squirrel.
- In which cases are the similar structures analogous, and in which are the structures homologous?
Need a reminder? The key ideaShow
Natural selection acts on the variation that is already there. A group that survives better leaves more young, so its share grows. One ancestor with many forms is adaptive radiation. Different ancestors with similar forms is convergent evolution.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Adaptive radiation. One group of finches gave many forms with different beaks.
Step 2. (b) Convergent evolution. A marsupial and a placental mammal look alike, but they came from different ancestors.
Step 3. (c) Adaptive radiation. Many forms from one ancestral stock.
Step 4. (d) Convergent evolution. A marsupial and a placental mammal that both glide.
Step 5. (e) The similar structures of (b) and (d) are analogous. The structures of the forms in (a) and (c) share an origin, so they are homologous.
Answer: (a) adaptive radiation; (b) convergent; (c) adaptive radiation; (d) convergent; (e) analogous in (b) and (d), homologous in (a) and (c).
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