Leaf colour in autumn

[Jon Monroe]

Gunnar Fridborg recently raised an interesting question concerning why
leaves of some species turn red.  HOW they do it and WHAT the red pigments
are (anthocyanins) is well known but I have never heard a testable
evolutionary reason for WHY certain leaves turn red.  I'm scheduled to do a
spot on the local TV news tonight on "why leaves turn colors" and, while I
feel that I understand what is known and what isn't fairly well, I would
feel happier if I could confirm the latter!  Is it still true that nobody
knows?

Thanks!

Jon

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