Climate Change is Strangely Shrinking Bumblee Tongues

Climate change is having a strange effect on bumblebees; their tongues are shrinking. Scientists have found that climate-related changes in flower diversity caused the length of the alpine bumble bees' tongues to shrink.

Many co-evolved species have precisely matched traits. For example, long-tongued bumblebees are well adapted for obtaining nectar from deep flowers with long corolla tubes. Recent studies, though, have suggested that these bees with longer tongues are declining in number. In order to better understand why, the researchers studied several high-altitude sites in Colorado.

Using bumble specimens from 1966 through 1980, and from 2012 through 2014, the researchers measured changes in tongue length, noticing a significant shortening.

Then, the researchers examined possible mechanisms for this change. It wasn't a result of decreasing body size, competition from invaders or even co-evolution with flowers in the area.

So what was the cause? In this case, the scientists found that it may be the result of warming summers, which reduced numbers of the deep flowers these species preferred. This, in turn, forced the insects to be general foragers, capable of feeding across the remaining flowers, including many shallow flowers.

The findings reveal how these bees react to climate change. Not only that, but the pattern seen in this particular study may predict future effects of climate change in other systems. The results also highlight how climate change can decouple well-established mutualisms between bees and plants.

The findings are published in the journal Science.

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