This problem goes beyond the NEET syllabus, but A-Level and IB ask it…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
This problem goes beyond the NEET syllabus, but A-Level and IB ask it. Two species differ by 6 per cent in a gene. In each line, the gene changes by 0.5 per cent in each million years.
- How many million years ago did the two species split?
- What difference would you expect between two species that split 15 million years ago?
- A third pair of species differ by 9 per cent. When did they split?
Need a reminder? The key ideaShow
UPGMA joins the closest pair at half their distance, and averages the distances to the new group. The molecular clock gives , because both lines change. Closer relatives share a more recent common ancestor.
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.
Given. per cent, per cent in each million years.
Plan. The difference grows at per cent in each million years.
Step 1. (a) million years.
Step 2. (b) per cent.
Step 3. (c) million years.
Answer: million years; per cent; million years.
Watch out. If you forget the factor , you get million years in (a). Both lines change after the split.
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