Bee tongues are getting shorter as temperatures warm Queen bumblebee, Bombus balteatus, foraging for nectar on the alpine wildflower Polemonium viscosum. (Candace Galen/AP Photo/Jens Meyer)
Bee tongues are getting shorter as temperatures warm
Lexile

Climate change is already wreaking havoc on wildlife in a number of ways, from destroying habitats to throwing off circadian schedules. Mutualism -- win-win ecological partnerships honed over evolutionary timescales -- is a lesser-known ecological relationship. It also is vulnerable to the effects of a rapidly changing planet.
 
Bees and flowers are prime examples of mutualism. Some bee tongues are perfectly evolved to tap into the nectar and pollen of certain flowers. Those are ones with elongated, tubular petals. By specializing in those plants, the longer-tongued bees reduce competition with generalist insects. The generalists can't access those sweet resources. The longer-tongued bees ensure that their plant species of choice get in on the pollination action.
 
Climate change, however, has thrown that mutualistic relationship out of whack in at least one population of bees and flowers. Certain flowers in Colorado have become scarcer due to warming temperatures. So the tongues of the alpine bumblebees that historically fed on them have become shorter. 
 
Like many of their pollen-gathering relatives, alpine bumblebees are on the decline. To find out what's going on, a team of American and Canadian researchers headed to Colorado. The team focused on the plight of two species. They are Bombus balteatus and Bombus sylvicola.
 
The researchers examined bumblebee specimens collected on three mountains from 1966 to 1980. The team also gathered a fresh set, which they collected in the same places from 2012 to 2014. Suspecting that the relationship between bees and their favorite flowers might be involved, they performed the meticulous task of measuring all the historic and recently caught bees' tongues.
 
As the team reports in Science, both of the species' tongues have declined in length over time. They shrank on average 0.61 percent each year. Cumulatively, the team found a nearly 25-percent decrease in tongue length between the bees collected decades ago and those living in the same region today.
 
The scientists also found that the bees are visiting more species of flowers. Those include ones with shorter petal tubes. The bees also are covering greater ground while foraging.
 
These findings naturally led to a second question. What is causing the tongues to shrink? The bees' overall body size did not change significantly over the years, the researchers found. That means it's just the tongues that have been affected.
 
Next they turned to the flowers. Looking at contemporary and historic botanical data, the scientists confirmed that the number of flowers with short petal tubes did not increase in abundance. It indicated that the bees were not simply ignoring their historically preferred flowers for a more readily available food source.
 
The team set up sampling plots along different mountain gradients. These were to estimate flower productivity. The team wanted to compare it to past values. The team found that in response to warmer temperatures, flowers -- particularly ones with deep petal tubes -- have been moving up the mountains. They are becoming scarcer at lower elevations. Because surface area decreases as mountains taper off toward their peaks, this altitude-climbing effect has ultimately resulted in an estimated loss of millions of flowers.
 
As the authors report, even with some flower gains near the summits, bumblebee food resources on Pennsylvania Mountain, for example, have fallen by 60 percent. This is since the 1970s.
 
The findings paint a telling picture. Hotter summers caused bumblebees' choice flower species to disappear. That forces the bumblebees to evolve shorter tongues to tap into the remaining food sources. Then, competition with generalist species, more time and energy needed to collect enough pollen and a forced reliance on suboptimal resources all likely contributed to the bees' overall decline.
 
Still, if bumblebees can manage to shift their foraging strategies as rapidly as they did their tongue length, then they might ultimately be able to cope with the ecological shakeup that's now underway. As the authors write, for now, at least, "evolution is helping wild bees keep pace with climate change."

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CRITICAL THINKING QUESTION
How would you measure a bumblebee’s tongue?
Write your answers in the comments section below


COMMENTS (13)
  • charliet-orv
    9/29/2016 - 10:54 a.m.

    Take a dead bumblebee's proboscis.

  • tyk1-har
    9/29/2016 - 02:02 p.m.

    I would measure a bees tongue by put flowers somewhere were there are a lot of bees. Then take a picture or a video. After that i do that each season all year then measure to see if the bees tongue shrinks during climate change.

  • karaj-ric
    10/06/2016 - 10:13 a.m.

    I would measure a bumblebee's tongue by experimenting and using the creature to see how short it has became and if it will get shorter in the next few weeks, or years. So let's say that the bumblebee's tongue was 6 centimeters long, then its tongue got 3 centimeters shorter, so then, it would be 3 centimeters and is that bad? Probably, since their tongues are getting shorter,and if their tongues got shorter, how will they get pollen? The bumblebee's tongue would too short to reach the pollen, which will make the flowers go dead.

  • jennac-ver
    10/07/2016 - 12:14 p.m.

    As tempitares get warmer 60% or bumble bees original choices of flowers start to decrease. So there tongs get shorter during warmer tempitares.

  • laurenp-ver
    10/07/2016 - 02:38 p.m.

    I would measure a bumble bees young by going to a public park or something where there are many flowers, and take a slow motion video. i would do this every mounts for the whole Sping into Summer and to the begging of fall. Then we could tell if it is true.

  • isabelg-lew
    10/11/2016 - 03:31 p.m.

    This is one of the strangest and most interesting ways of how climate change is affecting nature.

  • alannab1-sto
    10/18/2016 - 02:12 p.m.

    Long ago the bees tongue was longer than it was today.So scientist are taking a noticed and posting worldwide about this problem.

  • ybailey-dav
    10/20/2016 - 10:02 p.m.

    In response to "Bee tongues are getting shorter as temperatures warm," I agree that this is a issue. One reason I agree is that if bees are not pollinating as much insects and other biotic thing can not get the stuff they need. Another reason is that flower population will start to decrease. In the article it says "Certain flowers in Colorado have become scarcer." That statement shows that more populations of flowers could decrease which would not be good for the enviroment. A third reason is that the bee population will also decrease, because if they can not pollinate the flowers, the flowers will decrease, and the the bees will begin to decease. All of that can happen just because a bees tongue got shorter! Even though it isn't a large population being effected yet I still stand firm in my decision that bees tongues getting shorter is harmful to nature because of the insects, flowers and bee's.

  • jahma-wim
    10/21/2016 - 11:36 a.m.

    I think that it really matters that bees tongues are getting shorter because without tongues, they won't be able to pollinate the flowers and if flowers aren't pollinated, they won't be able to spread their seeds far away, which could also lead to the end of flowers. :(

  • larno-wim
    10/21/2016 - 11:47 a.m.

    I would measure a bees tongue by taking a video of a bee eating pollen from a flower and put it in slow- motion to see how longa bees tongue is. I would do that for like 6 mouths tom see if the bees tongue has been getting smaller, if so I would know that the bees tongues are getting smaller because of the weather.

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