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I HAVE spent my life working on slime moulds and they sent me a message that started me thinking. What puzzled me was that two different forms are found side-by-side in the soil everywhere from the tundra to the tropics. The obvious difference lies in the tiny stalks that disperse their spores. In one species this fruiting body is branched, in the other it is not.
I had assumed that the branched and the unbranched forms occupied separate ecological niches but I could not imagine what those niches might be. Perhaps there were none and neither shape had an advantage over the other, as far as natural selection was concerned.
I wrote this up and sent it to a wise and respected friend who responded with a furious letter saying that my conclusion was absurd: ...
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