Bee Tongues And Flowers Reveal Evolution In Overdrive

Wired  By Gwen Pearson  September 24, 2015

Living on a mountain is hard for bees and flowers. It’s cold. There’s extreme weather. And new research has found it’s getting even harder for both flowers and bees to make a living in alpine evironments lately. Scientists compared over 40 years of mountain bumblebee and flower records on three Colorado mountains, and found major decreases in both bees and flowers. But they also found clear evidence of rapid evolution by the bees, suggesting it’s not time to give up on mountain bumble bees just yet.

Open-Source Bugs

Entomologists and botanists get teased about traveling the world, meeting interesting insects and plants, and then killing them. But it’s a morbid habit that pays off; it creates a long-term, stable record of the biological past. Museum collections may look like a creepy charnel house to outsiders, full of corpses, pins, and mothballs. Our libraries of dead things become a book of evolutionary change for future scientists to read.

Preserving organisms from taxonomic or ecological studies lets us travel back in time. “People are always interested in having their data looked at and reanalyzed in a different way, a way that they hadn’t thought about previously. That is one of the great things about having open access data,” said Dr. Nicole Miller-Struttmann, lead author on the new bumble bee study.

To investigate how flowers and bumble bees changed, a team of scientists dug through over 40 years of records. They tracked down thousands of bumble bee specimens collected on mountains in Colorado between 1966 and 1980, and compared them to bumblebees collected in the same areas between 2012 and 2014. They also used herbarium specimens of flowers collected during similar time frames, and surveyed flowers in the field.

Plants on mountains often have very narrow temperature tolerances; too much heat can reduce flowering. On one of the mountains in the study, between 1960 to 1985 only 12 percent of the years were hot enough to reduce flowering. Since 1985, 48 percent percent of years were too hot for flowers that bumblebees typically forage on.

Since 1970, the total number of flowers available for bees on the mountain study sites declined by 60 percent overall. What did that mean for bees?

flower measuring
Researchers Jessica Kettenbach and Elizabeth Hedrick monitor plant density on Niwot Ridge
Long Term Ecological Research Site, Colorado.  NICOLE MILLER-STRUTTMANN

If Gene Simmons Were a Bee

Over 95 percent of bees in the study regions between 1966 and 1980 were just two species of “long-tongued” bees. These bees specialize in flowers with a narrow, elongated tubular shape. Their long tongue means they are able to reach the nectar hidden at the bottom of a flower, and can muscle out their shorter-tongued relatives. This is an an example of coevolution, where two species reciprocally affect each other over evolutionary time.

Bees collected from 2012 to 2014 were different, though. The long-tongued species of bumble bees declined by 24 percent. At the same time, warming temperatures and changes in flowering plants allowed some lower altitude bees to live at higher mountain elevations. The entire community of bumble bees changed. Long-tongued bumble bees responded to the scarcity of flowers by becoming less selective; the range of plants they foraged on changed significantly, and included flowers with no long nectar tubes.

The scientists wondered if the bees physically changed too, and measured body length and tongue length on their historic and modern bee specimens. How do you measure a bee’s tongue? Miller-Struttmann explains: “They tuck their tongue back into their body, so they sort of fold it back up along their chin, I guess you could say. We had to rehydrate historic specimens, and then fold the tongue out, and then measure it under a microscope with calipers.”

What no one expected was that the tongues of long-tongued bees would get shorter. A lot shorter. “A 24 percent decrease in tongue length is really dramatic,” says Miller-Struttmann. “That was in 40 years, in 40 generations, I should say, because these bumblebees only have one generation a year. That’s a pretty short period of time to see such a dramatic shift.” Bumble bee bodies also got slightly smaller, but not as much as the tongues shrank. The research team did not find changes in the depth of the flowers bumble bees were visiting. The bees’ shape changed, but the flowers didn’t.

Building and maneuvering a big tongue takes energy, and bees with shorter tongues may have done better at diverting that energy into more babies. In the short term, the bumble bees seem to be hanging on. But what about longer term?

Right now bumblebees and plants they historically fed on are mismatched physiologically. The bees may not be as good a pollinator for those plants, which could cause further declines in flowers. In the long term, perhaps they will also evolve, but they’re much longer-lived species. Their generation time is decades, not yearly. Change will be slower—or may not happen at all.

Dr. David Inouye has researched flowers and alpine bees at the Rocky Mountain Biological Laboratory for decades. He said “this study is a great example of the value of archiving data… an example of a change in bumble bees that is unexpected, and would not have been discovered without access to historical data. We have evidence from elsewhere in the Rocky Mountains that bumble bee queens of eight species have moved up 230m in altitude over about the same time span, and these kinds of changes in bumble bee communities will have interesting consequences over both ecological and evolutionary time scales.”

This study also highlights a common problem for mountain or other remote refuges—as the climate warms, the places where plants and animals thrive move slowly away from the areas we’ve designated for their conservation. By increasing areas set aside for nature, or making sure we have connections between isolated nature refuges, we can try to help bees and plants adapt to our new warmer world.

Miller-Struttmann, et al. 2015. Functional mismatch in a bumble bee pollination mutualism under climate change.

Nicole E. Miller-Struttmann & Candace Galen. 2014. High-altitude multi-taskers: bumble bee food plant use broadens along an altitudinal productivity gradient, Oecologia: 176(4) 1033

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Bumble Bees and Spiders Don't Mix?

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey

Bumble bees and spiders don't mix, you say?

Well, they will at the Bohart Museum of Entomology's open house from 1 to 4 p.m., Saturday, July 26. The family-centered event, free and open to the public, takes place in Room 1124 of the Academic Surge building on Crocker Lane, UC Davis campus.

Actually the theme is about spiders: "Arachnids: Awesome or Awful?" There you'll see black widow spiders, jumping spiders, cellar spiders and the like. But you don't have to "like" them as...


Bees From The Inside Out

National Science Foundation    July 7, 2014

It is 1,825 miles from New Haven, Conn., to Austin, Tex., which typically means 30 hours of driving and three nights in motels, not an easy trip for anyone. But for researchers moving from Yale University to a new lab at the University of Texas last August, it proved especially challenging. They made the journey in a minivan with a pet cat and 100,000 bees.

"That was probably the most heroic event in our beekeeping saga to date," says evolutionary biologist Nancy Moran, a professor at the University of Texas at Austin, who studies symbiosis, particularly among multi-cellular hosts and microbes. "We didn't want to be without bees upon arrival in Texas, and...

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Fish More Inclined to Crash Into Each Other Than Bees

Science Daily    Source: Lund University   May 28, 2014

Swimming fish do not appear to use their collision warning system in the same way as flying insects, according to new research from Lund University in Sweden that has compared how zebra fish and bumblebees avoid collisions. The fish surprised the researchers.

All animals need some form of warning system that prevents them colliding with objects in their surroundings. The warning system helps them to continually regulate their speed and judge their distance from objects. For flying and swimming creatures this is an extra challenge because they also have to deal with winds and currents that affect their speed and direction.

"Bumblebees use what is known as an optic flow to help them avoid crashing into surrounding objects," said Christine Scholtyssek, Postdoc at the Department of Biology at Lund University.

The optic flow can be described as the sensation that surrounding objects move as the bumblebee flies past. To the bumblebee, reality is reversed -- it is as though the bee remains still while the objects speed past. Humans can have a similar experience when travelling by train, for example, when the surroundings race past the window. The closer the bee comes to an object, the faster the object appears to move, i.e. the optic flow in the bee's field of vision grows stronger. If the optic flow suddenly becomes stronger in the right eye than the left, the bumblebee will turn left to reduce the risk of a collision.

"The bumblebee has to constantly balance the optic flow between its two eyes," said Christine Scholtyssek.

The researchers at Lund University used specially constructed tunnels containing...


Making a Beeline For The Nectar: How Patterns on Flowers Help Bees Spot Their First Nectar-Rich Flower

Science Daily   6/20/13

Bumblebees searching for nectar go for signposts on flowers rather than the bull's eye. A new study, by Levente Orbán and Catherine Plowright from the University of Ottawa in Canada, shows that the markings at the center of a flower are not as important as the markings that will direct the bees to the center.

The work is published online in Springer's journal, Naturwissenschaften -- The Science of Nature.

The first time bees go out looking for nectar, which visual stimuli do they use to identify that first flower that will provide them with the reward they are looking for? Orbán and Plowright test the relative influence of the type of floral pattern versus pattern position in a group of bumblebees that have never searched for nectar before i.e. flower-naive bees.

In a series of two experiments using both radio-frequency identification technology and video recordings, the researchers exposed a total of over 500 flower-naive bees to two types of patterns on...


Going Native!

Bug Squad - Happenings in the Insect World   By Kathy Keatley Garvey   4/24/13

The first thing you notice when you walk up to the Harry H. Laidlaw Jr. Honey Bee Research Facility on Bee Biology Road, UC Davis, are the natives.

Native plants, that is.

California golden poppies and phacelia are among the plants sharing the "Pollination Habitat" bed. The golden poppies literally light up the landscape. The phacelia, not so much.

The next thing you notice are the bumble bees, carpenter bees, honey bees...


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Heavy Metal Bothers Bumblebees

(The following is brought to us by CATCH THE BUZZ (Kim Flottum) Bee Culture, The Magazine of American Beekeeping, published by A.I. Root Company.)  

PITTSBURGH—Beekeepers and researchers nationally are reporting growing evidence that a powerful new class of pesticides may be killing off bumblebees. Now, research at the University of Pittsburgh points toward another potential cause: metal pollution from aluminum and nickel.

Published in the journal Environmental Pollution, the Pitt study finds that bumblebees are at risk of ingesting toxic amounts of metals like aluminum and nickel found in flowers growing in soil that has been contaminated by exhaust from vehicles, industrial machinery, and farming equipment. The Pitt study finds that bumblebees have the ability to taste—and later ignore—certain metals such as nickel, but can do so only after they visit a contaminated flower. Therefore, the insects are exposed to toxins before they even sense the presence of metals.

"Although many metals are required by living organisms in small amounts, they can be toxic to both plants and animals when found in moderate to high concentrations," said Tia-Lynn Ashman, principal investigator of the study and professor and associate chair in Pitt's Department of Biological Sciences in the Kenneth P. Dietrich School of Arts and Sciences. "Beyond leading to mortality, these metals can interfere with insect taste perception, agility, and working memory—all necessary attributes for busy bumblebee workers."

Ashman and George Meindl, coauthor of the study and a PhD candidate in Ashman's lab, studied bumblebee behavior using the Impatiens capensis, a North American flower that blooms in summer. Its flowers are large, producing a high volume of sugar-rich nectar each day—an ideal place for bumblebees to forage. The blooms were collected from the field each morning of the two-week study and were of a similar age, color, and size.

To determine whether nickel and aluminum in the flowers' nectar influenced bumblebee behavior...


Plight of the American bumblebee: Disappearing?

ABC News/AP    By Seth Borenstein AP Science Writer   Washington March 1, 2013 

It's not just honey bees that are in trouble. The fuzzy American bumblebee seems to be disappearing in the Midwest.

Two new studies in Thursday's journal Science conclude that wild bees, like the American bumblebee, are increasingly important in pollinating flowers and crops that provide us with food. And, at least in the Midwest, they seem to be dwindling in an alarming manner, possibly from disease and parasites.

Wild bees are difficult to track so scientists have had a hard time knowing what's happening to them. But because of one man in a small town in Illinois in the 1890s, researchers now have a better clue.

Naturalist Charles Robertson went out daily in a horse-drawn buggy and meticulously collected and categorized insects in Carlinville in southern Illinois.

More than a century later, Laura Burkle of Montana State University went back to see what changed. Burkle and her colleagues reported that...



The Buzz About Pesticides - Nature Video

Published by Nature Video Channel  10/21/12

Bees, the most important pollinators of our crops, are in trouble. All over the world, their populations are decreasing and scientists want to know why. In this video, Nigel Raine and Richard Gill introduce us to the bumblebees they study at Royal Holloway near London. Their experiments show that two commonly used pesticides affect foraging behaviour and brood development, making bumblebee colonies more likely to fail.

Read the Nature paper here: