>Puzzlingly, the study does not explain why a long tongue would be any
disadvantage in working "shallow" flowers that do not necessarily require
longer tongues.  One would think that a longer tongue would always be
useful.

" we show that reduced flower abundance in bumble bee host-plants at the
landscape scale has accompanied recent warming".

Reduced flower abundance forces the long-tongued specialist to compete with
the short-tongued generalist?  Perhaps the tongue length is not now the
advantage that it was when there were more flowers that only the
long-tongued species could work?

Best wishes

Peter 
52°14'44.44"N, 1°50'35"W

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