Ongoing changes in flower diversity, related to a shifting climate (amongst other things), are impacting the bodies of bumblebees, according to recent reports. These changes include a decrease in the length of bumble bee tongues — leaving the bees with less options as far as feeding goes — according to the work.
The cause of the change is related to a change in behavior — the one that one would expect, rather than being specialized for feeding in specific flowers, the bumble bees have become generalists.
That’s certainly not a new pattern to observe though — it’s long been noted that when highly specialized relationships collapse (or begin to diverge) that generalist traits tend to be selected for amongst one or all of the species involved.
A recent press release provides more:
To better understand why, Nicole Miller-Struthman et al. studied several high-altitude sites in Colorado where two species of long-tongued alpine bumble bee live. Using bumble bee specimens from 1966 through 1980, and from 2012 through 2014, the researchers measured changes in tongue length, noticing a significant shortening.
Next, using archived bee specimens and field surveys of bumble bees and host plants, they examined possible mechanisms for this change. It was not a result of decreasing body size, competition from invaders, or co-evolution with flowers in the area, they report. Instead, it is a result of warming summers, which reduced numbers of the deep flowers these species preferred, forcing the insects to be general foragers capable of feeding across remaining flowers, including many shallow flowers.
Regardless of these changes, though, bumble bees are in general facings a very uncertain future — pollution, widespread insecticide use, and habitat loss, are all having profoundly negative effects on bumblebee population numbers and species.