Smithsonian Science » Tropical Research Institute

New frog species pose challenge for conservation project in Panama

John Barrat — Thu, 29 Jul 2010 12:06:04 +0000

The recent discovery of what may be three new frog species by researchers in Panama illustrates the hope and fear encountered daily by the Panama Amphibian Rescue and Conservation Project. The discoveries lead to hope that project researchers can save these animals from a deadly fungus killing frogs worldwide and the fear that many species will go extinct before scientists even know they exist.

Photo right: One of the three potentially new species appears to be a robber frog, genus Craugastor, shown here. The unique skin folds on its arms and feet distinguish it from other closely related species. Robber frogs are especially susceptible to chytrid. (Photos by Brian Gratwicke, Smithsonian Conservation Biology Institute)

“It is disturbing to witness the disappearance of species that some of us only recently described and even more devastating to lose those we know are probably new species,” said Roberto Ibáñez, local director of the project and a scientist at the Smithsonian Tropical Research Institute, one of nine project partners, including the Smithsonian’s National Zoo. “Scientists are just starting to investigate the ecological impact of the loss of amphibians, and while we’re aiming to preserve some of these species, we already know it will be impossible to save them all.”

Nearly one-third of all amphibian species globally are at the risk of going extinct. The rescue project aims to save more than 20 species of frogs in Panama, which is one of the world’s last strongholds for amphibian biodiversity. While the global amphibian crisis is the result of habitat loss, climate change and pollution, the deadly amphibian chytrid fungus is likely at least partly responsible for the disappearances of 94 of the 120 frog species that are thought to have gone extinct since 1980.

Photo left: Two of the three potentially new species is a rain frog from the genus Pristimantis. The species pictured here has a bright red stomach that is uncharacteristic for rain frogs, earning it the nickname “red tomato.”

Although it can take years to determine that a species is new to science, project researchers have identified some telltale signs indicating that the three species found in eastern Panama are, indeed, new. The first two are rain frogs from the genus Pristimantis. One of these species has a bright red stomach that is uncharacteristic for rain frogs, earning it the nickname “red tomato.” The second species is much larger than any known Pristimantis in the region. The third frog species appears to be a robber frog, genus Craugastor, but unique skin folds on its arms and feet distinguish it from other closely related species. Robber frogs are especially susceptible to chytrid.

A new study by Andrew Crawford, a STRI research associate, and colleagues reveals that many frog species at a site in western Panama have gone extinct before researchers knew they existed. The project’s three potentially new species are evidence of the same story playing out right now in the mountains of eastern Panama. Researchers have brought a handful of animals of each species back to the Summit Municipal Park in Panama City, Panama, where the project has turned used shipping containers into amphibian rescue pods.

“We are doing our best to salvage what we can, but we are in urgent need of funding to build capacity in Panama to house all of these chytrid refugees,” said Brian Gratwicke, a National Zoo research biologist and the international coordinator for the Panama Amphibian Rescue and Conservation Project. “The species is the basic unit of conservation, so these discoveries are rewarding, but that comes with the daunting responsibility of deciding how we look after them. We already have a huge job, and it just gets bigger with every discovery.”

Now project scientists will use collections of frogs from the same region at the Smithsonian’s Natural History Museum and elsewhere to determine if these species are genuinely new or if they have already been discovered (or “described”) elsewhere. The project has also collected tissue sample to use DNA testing to map out the animals’ closest genetic relatives.

“Finding a new species is like discovering a new Pablo Picasso,” said Gratwicke. “Each species is a priceless creation painted with the brushstrokes of natural selection on the canvas of DNA and has something of value to offer. We might not know how they’re valuable to us right now, but if they go extinct, we lose the opportunity to learn what secrets they hold.”

The mission of the Panama Amphibian Rescue and Conservation Project is to rescue amphibian species that are in extreme danger of extinction throughout Panama. The project’s efforts and expertise are focused on establishing assurance colonies and developing methodologies to reduce the impact of the amphibian chytrid fungus so that one day captive amphibians may be re-introduced to the wild. Project participants include Africam Safari, Autoridad Nacional del Ambiente, Cheyenne Mountain Zoo, Defenders of Wildlife, El Valle Amphibian Conservation Center, Houston Zoo, Smithsonian’s National Zoological Park, Smithsonian Tropical Research Institute, Summit Municipal Park and Zoo New England.

Tropical tree study shows interactions with neighbors plays an important role in tree survival

John Barrat — Thu, 08 Jul 2010 11:29:16 +0000

Home to jaguars, harpy eagles and red-eyed tree frogs, tropical forests support some of the rarest species on the planet and are the most biodiverse ecosystems on land. Understanding why some species are common while others are exceedingly rare has been a challenge in these mega-diverse forests. New results from a massive study at the Smithsonian Tropical Research Institute show that interactions among community members play an important role in determining which organisms thrive.

“Based on information about the survival of more than 30,000 seedlings of 180 species of tropical trees, we found that seedlings of rare species are much more sensitive to the presence of neighbors of their own species than seedlings of common species are,” said Liza Comita, the primary author on the study and now a postdoctoral fellow at the U.S. National Center for Ecological Analysis and Synthesis. “Not only does this tell us where to look for the mechanisms that explain why certain species are rare, but it also provides potential clues about how to conserve rare species that are most vulnerable to extinction.”

Photo left: Botanist Liza Comita measures the stem diameter of a seedling on the Smithsonian Tropical Research Institute’s Barro Colorado Island in the Panama Canal. (Christian Zieglar photo)

The lowland tropical forest on Panama’s Barro Colorado Island is the site of a huge long-term study focusing on plant diversity: more than 400,000 individual trees and shrubs of more than 300 species have been marked, mapped and measured every five years for the past 30 years. A unique window on climate change and other large-scale processes, the experiment was originally set up because two ecologists, Robin Foster, now at Chicago’s Field Museum, and Stephen Hubbell at UCLA, a co-author on this paper, had an argument about how life organizes itself.

What determines the members of a community? The study site—a patch of forest the size of nearly 100 football fields—is large enough to include individuals of many rare species that would not be present in smaller studies. After realizing that many of the processes that shape diversity happen early in a tree’s life, researchers decided to expand the study to include an annual survey of seedlings growing in the forest understory. This study of seedlings, led by Comita, Hubbell and Panamanian botanist and co-author Salomón Aguilar, has now been going for nearly a decade and has yielded new insights into this diverse forest.

For years, researchers have noticed that individual plants surrounded by neighbors of the same species do not grow and survive as well as individual plants surrounded by other species. Some evidence suggests that this is either because pests and pathogens move more readily among individuals of the same species or because they are competing with each other for the same resources.

“It became clear with this seedling survival survey that even though neighbors can be shaded out by individuals of the same or of other species, there are real differences in the survival of different species depending on how many of their neighbors are the same species,” said Helene Muller-Landau, staff scientist at the Smithsonian and adjunct professor at the University of Minnesota. “Some of our colleagues are working on the specific mechanisms that explain these differences, and we look forward to seeing their results, which will be published soon.” –Beth King

Scientists find ultrasonic calls of bats also serve a social function

John Barrat — Thu, 17 Jun 2010 18:10:20 +0000

To find flying insects and navigate in the dark, bats emit ultrasonic cries and then listen to the echoes that are reflected back to them. Now, a new study by scientists from the Smithsonian Tropical Research Institute, the Leibniz Institute for Zoo and Wildlife Research, and other research organizations suggest that echolocation calls also serve a social function for bats. Namely, bats listen to the ultrasonic calls of other bats to identify roost mates, bats of the same species, members of the opposite sex and intruders to their territory.

Images: Lesser bulldog bats from Panama that were used in this study. (Photos courtesy Silke Voigt-Heucke)

To test the idea that echolocation calls can communicate social information for bats, the scientists recorded the ultrasonic echolocation calls emitted by lesser bulldog bats (Noctilio albiventris) and bats of other species, and then played them back to bulldog bats held in temporary captivity. They observed that captive bats reacted differently to calls made by bats of their same species than they did to calls by bats of another species. They also observed the bats respond differently to calls from bats which shared their roosts and to the calls of unfamiliar bats. The experiments were conducted in Panama. Ultrasonic white noise was used as a control in the experiment.

This video shows a lesser bulldog bat in a holding container responding to the ultrasonic calls of one of its roost mates. The audible chirps heard in this video is the bat’s non-ultrasonic voice. (Video courtesy Silke Voigt-Heucke)

“We were able to show that bats respond with a set of social behaviors [crawling, nodding, wing stretching, etc.] to the playback of echolocation calls,” the scientists write in a recent article in the journal “Animal Behaviour.” They conclude that N. albiventris can indeed distinguish between the ultrasonic calls of bats of their same species and bats of a different species, and between the calls of familiar and unfamiliar bats.

Our results demonstrate that echolocation calls are not only “perceived and processed by the individual producing the sound,” the scientists write, but that “other individuals may obtain information about species identity and group affiliation by listening to echolocation calls.” Authors of the paper are Silke L. Voigt-Heucke of the Leibniz Institute for Zoo and Wildlife Research; Michael Taborsky of the University of Bern, Switzerland, and Dina K.N. Denchmann, a research associate at the Smithsonian Tropical Research Institute in Panama.

Tiny, new brains prove just as adept as large, mature brains among tropical orb-web spiders

John Barrat — Wed, 02 Jun 2010 19:18:24 +0000

When it comes to brains, is bigger better? For instance, can the tiny brain of a newly hatched spiderling handle problems as adeptly as the brain of a larger adult spider? One theory, known as the size limitation hypothesis, predicts that the miniscule brains of tiny creatures contain fewer neurons and thus have less capacity, making these creatures more prone to mistakes.

Photo right: An adult Nephila clavipes on its web with an insect it has captured.

To test this theory, Thomas Hesselberg of the Smithsonian Tropical Research Institute in Panama, recently examined and compared the designs of webs woven by newly hatched, mid-size and adult orb-web spiders of the species Nephila clavipes and Eustala illicita. (Nephila grow explosively and an adult can weigh up to 500 times more than it did when newly hatched.) He collected a number of spiders from each age group, induced them to weave webs on square frames in a laboratory and then took careful measurements of each web. He also conducted observations of the webs of both species in the wild. A paper on Hesselberg’s work was published recently in the scientific journal “Ethology.”

Photo left: An N. clavipes resting at the hub of its laboratory web.

Orb-web spiders have a fixed reserve of sticky capture spiral silk inside their bodies prior to web building. This reserve is thought to be entirely used up as the web is completed. “As orb spiders build the capture spiral from the outer periphery towards the hub [or center of the web], they need to match web size to silk reserves,” Hesselberg writes. Younger spiders that haven’t mastered this behavior, he reasoned, should have a larger area free of silk at their web’s center hub. Or, to cover for a miscalculation, a young spider may increase the distance between the spirals of its capture silk spun out nearer to the web’s hub.

In his observations of the different webs, he found no evidence that adult Nephila or Eustala spiders have any more brain power or build webs any more effectively than newly-hatched spiderlings. “Neither species showed clear signs of being behaviorally limited or more prone to committing errors as spiderlings than were older juveniles or adults,” Hesselberg concluded.

Photo right: The web of an E. illicita spider in the wild. (Photos by Thomas Hesselberg).

One miscalculation may lie, Hesselberg adds, in the human assumption that “the orb web is the result of a demanding computational behavioral process. Theoretical models suggest that the construction of the orb web might be achieved by following a few simple rules of thumb and thus not pose any significant computational challenge for the spider.”

–John Barrat

Transmitters unveil long-distance movements of orchid bees

John Barrat — Thu, 27 May 2010 17:42:51 +0000

In their daily search for food, blue-green orchid bees zip through increasingly scarce patches of tropical forest pollinating rare flowers. Now, for the first time ever, researchers at the Smithsonian Tropical Research Institute are able to track the routes of these creatures by gluing tiny transmitters to the backs of individual bees. The data they are collecting is yielding new insight into the role bees play in tropical forest ecosystems.

“When people disturb and destroy tropical forest they disrupt pollination systems,” says entomologist David Roubik, senior staff scientist at the Tropical Research Institute. “Now we can track orchid bees to get at the distances and spatial patterns involved in pollination—vital details which have completely eluded us in the past.”

The team trapped 17 iridescent blue-green orchid bees called Exaerete frontalis –a species common in the rainforest. “These bees easily carry a 300-milligram radio transmitter glued onto their backs,” says Martin Wikelski, director of the Max Planck Institute of Ornithology and a research associate at the Smithsonian. “By following the radio signals with a hand-held antenna, we have discovered that male orchid bees spend most of their time in small core areas, but will take off and visit areas farther away.

One male even crossed over the shipping lanes in the Panama Canal, flew 5 kilometres, and returned to Barro Colorado Island a few days later. Such long distance flights, the researchers say, support the claim that bees are major agents of gene flow, connecting widely-dsipersed orchids or other plants which they alone pollinate, over fragmented landscapes and for an extended time. This study proves that “bees are key evolutionary players in allowing orchids and other tropical plants to evolve into diverse taxa that are each spatially rare and thus require long-distance pollination,” the researchers write.

In the past, researchers have struggled to determine the distances that bees travel by following individuals marked with paint, or using radar, which doesn’t work well when trees are in the way. “Carrying a transmitter may reduce the distance that the bees travel. But even if the flight distances we record are the minimum distances that these orchid bees can fly, they are impressive, long-distance movements,” said Roland Kays, curator of mammals at the New York State Museum and a STRI research associate. “These data help to explain how the orchids these bees pollinate can be so rare.”

The Smithsonian Tropical Research Institute, the U.S. Environmental Protection Agency, the New York State Museum and the National Geographic Society all provided support for this study. Its co-authors are affiliated with the University of Arizona, Tucson, Cornell University, EcolSciences, Inc. and the New York State Museum.

Census reveals 1,200 howler monkeys living on Barro Colorado Island

John Barrat — Tue, 04 May 2010 18:27:55 +0000

The fifth Howler Monkey census of the Smithsonian’s Barro Colorado Island research station in Panama, organized by Katie Milton, professor in the department of Environmental Science, Policy and Management at the University of California, Berkeley, has revealed that monkey numbers have not changed significantly for 33 years.

Photo left: A howler monkey eating Astrocaryum fruit.
(Photo by Greg Willis)

Long before dawn on March 19 and 20, Katie Milton and a group of stalwart volunteers, each armed with flashlight and compass, spread out into the jungle to take up positions at 35 listening stations marked on their maps of the island.

Just before sunrise, howler monkeys launch into a chorus of howls, roars and barks. From 5:15 a.s. until 6:30 a.m., each volunteer recorded the time and direction of these vocalizations and estimated the distance to each group that they could hear from their stations. As they walked back to the lab in the early morning light they noted locations of all monkey groups they saw.

“It amazes me that volunteers want to get up at 4 a.m. to walk through the dark forest alone for an hour or more. But it is a thrill when they hear that first howl and know the dawn chorus is beginning,” Milton says.

Photo right: Students from the University of Panama attend a pre-census workshop.

Lines drawn on a map from each station toward the compass angle of the observed sounds intersect, marking the estimated location of each group. Based on this technique called triangulation Milton estimated that there are 60-70 groups on the island. By multiplying the number of groups by the average number of individuals in a group—between 17 and 18 monkeys— she concluded that there are roughly 1200 individuals in fairly evenly spaced groups.

Census volunteers always include internationally known ecologists: Smithsonian staff scientists and visiting scientists, as well as current students and fellows. Barro Colorado’s game wardens and two Panamanian national forest police manned some of the most inaccessible listening stations. Eight highly-motivated students from the University of Panama arrived on the Island on March 18th to participate in a 2-day workshop on determining primate densities that included volunteering for the count.

Photo left: A baby howler monkey with a bot fly lesion on its neck. An ongoing study of the cause of death of howler monkeys on Barro Colorado has identified the howler monkey bot fly, Cuterebra baeri, as the single most important factor.

Milton organized the first island-wide group count 33-years ago in March, 1977. That census also revealed approximately 65 groups and thus, around 1200 monkeys.

“It doesn’t look like howlers on Barro Colorado have suffered from any devastating diseases or other catastrophic problems for the last three decades,” Milton says. “Groups are larger at some times of year and smaller at others, which seems to reflect births and the specific causes of death that affect different ages of monkeys at different times of the year.”–Beth King

To listen to audio Files of howler monkeys and interview with Katie Milton, visit this Web site:
http://biogeodb.stri.si.edu/bioinformatics/dfm/metas/search/stxt:howler/type:Audio

Shipping industry sends help as project in Panama tackles amphibian crisis

John Barrat — Fri, 23 Apr 2010 13:34:26 +0000

As a disease known as amphibian chytrid fungus continues to wipe out amphibian species worldwide, frogs in Panama are finding a safe haven in a seemingly unlikely spot—between the metal walls of shipping containers once used to transport ice cream, strawberries, coffee beans, flowers and pharmaceuticals. Two of six refrigerated containers to be donated by the shipping company Maersk Line arrived this week at Summit Municipal Park in Panama City, Panama, where the Smithsonian Institution and partners are working to save amphibians in imminent danger of extinction.

Photo right: The limosa harlequin frog (Atelopus limosus) is one of 54 species that Amphibian Ark has identified as a priority rescue species for the Panama Amphibian Rescue and Conservation Project. (Click to enlarge)

“Each container provides us with critical space to house animals that may represent the last chance for the survival of their species,” said Brian Gratwicke, a National Zoo research biologist and the international coordinator for the Panama Amphibian Rescue and Conservation Project. “The containers are now self-contained ‘amphibian rescue pods’ that have been specially modified to control the climate and keep diseases out.”

The rescue pods will be part of the project’s Amphibian Rescue Center at Summit Municipal Park, which will also include a lab with a quarantine facility. After frogs are collected in the field, they will be quarantined for 30 days before being moved to the rescue pods that will serve as their new home. In addition to the two containers that are now in Panama, Maersk Line has agreed to donate two containers per year for the next two years to the project, for a total of six. Shipping company APL has also donated one container this year. Each container offers 995 cubic feet of space to house these animals. The seven together will more than double the amount of captive space the project currently has in Panama to safeguard endangered amphibians.

Photo left: Shipping company Maersk Line has agreed to donate up to six used shipping containers similar to this one to the Panama Amphibian Rescue and Conservation Project. The containers will serve as rescue pods for endangered amphibians.

“Maersk Line’s support of the amphibian rescue project is aligned with our long-term focus on sustainability,” said Mike White, head of Maersk Line’s North American organization. “Although we are pleased to donate these containers, the more valuable contribution is our expertise and resources. Our team’s assistance with documentation and transportation allows Brian’s group to concentrate on the overall effort.”

Amphibian Ark, an organization that mobilizes support for ex-situ (“out-of-the-wild”) conservation, has identified 54 amphibian species as rescue species for the Panama Amphibian Rescue and Conservation Project. At least 198 amphibian species live in Panama, of which 70 are listed as “critically endangered,” “endangered” or “data deficient” by the International Union for Conservation of Nature. Amphibian Ark estimates that about 500 amphibian rescue pods are needed to save the world’s 500 critically endangered amphibian species. Buying, outfitting and installing a single container costs about $50,000.

Photo right: Each shipping container offers 995 cubic feet of space to safeguard endangered species. (Photos by Brian Gratwicke)

“This requires an amount of resources that is insurmountable for the amphibian rescue community,” said Kevin Zippel, Amphibian Ark’s program director. “With a relatively small investment, the shipping industry has made a huge impact on one of the greatest conservation challenges that humanity has ever faced. We are currently seeking additional contributions of this kind.”

The mission of the Amphibian Rescue and Conservation Project is to rescue amphibian species that are in extreme danger of extinction from amphibian chytrid disease sweeping through Panama. The project’s focus is on developing appropriate technologies to control the amphibian chytrid fungus, so that one day captive amphibians may be reintroduced to the wild. Project participants include Africam Safari, ANAM (Autoridad Nacional del Ambiente), Cheyenne Mountain Zoo, Defenders of Wildlife, Houston Zoo, Smithsonian’s National Zoological Park, Smithsonian Tropical Research Institute, Summit Municipal Park and Zoo New England.

Amazon farmers who vanished centuries ago were remarkably innovative

John Barrat — Mon, 19 Apr 2010 05:28:35 +0000

Little is known about the long-vanished Arauquinoid, an Indian culture that thrived centuries ago in French Guiana, other than they were innovative farmers. The Arauquinoid were gone long before Columbus landed in the new world, yet what archaeologists and other scientists have recently learned about their farming methods comes through the auspices of some unlikely collaborators—ants, termites and earthworms. In addition, what scientists are learning about Arauquinoid farming methods may have important implications for today’s sustainable farms.

Image right: A pre-Columbian raised field in French Guiana filled with small, round mounds for growing crops.

Centuries ago these natives grew maize, manioc and squash upon a matrix of raised beds in flat, regularly flooded coastal marshes. Scooping slices of topsoil from the marsh they flipped them together and upside down, creating mounds which they topped with soil from other areas. Crops were planted, tended and harvested on this matrix of small islands.

Using aerial photographs, researchers have recently located a number of long abandoned “fossil” agricultural fields used by the Arauquinoid in coastal French Guiana. Follow-up examination of the soil and associated fragments from cooking implements, done in part by scientists at the Smithsonian Tropical Research Institute in Panama, have revealed microscopic starch grains from corn and manioc. Squash phytoliths also were recovered from soil analysis.

Image left: The aerial photograph at top shows different types of raised fields in a complex in French Guiana. The bottom image is an interpretation of these earthworks based on stereoscopic ananlysis and field studies.

This new research has revealed that in areas considered unsuitable for farming today, “pre-Columbian farmers constructed thousands of raised fields in the seasonally flooded coastal savannas of the Guianas,” scientists write in a paper published recently in the Proceedings of the National Academy of Sciences. ”They built conspiciuous earthworks, including raised fields, canals and ponds, that enabled them to practice intensive permanent agriculture in this low-lying region with highly seasonal rainfall.” The study combined archeology, archeobotany, paleoecology, soil science, ecology and aerial imagery and was carried out by scientists from a number of organization, including the University of Bayreuth in Germany, the University of Montpellier II and Centre d’Ecologie Fonctionnelle et Evolutive in France, the University of Exeter, and the Smithsonian Tropical Research Institute in Panama.

Image right: A matrix of raised mounds in an abandon field in a part of French Guiana named Savane Grande Macoua. Only the mounds are above water level.

In a region that receives on average four meters of rain each year, scientists were puzzled why the mounds have not eroded into obscurity over the centuries. They discovered that ants and termites, living in the raised mounds since before they were abandoned by the Arauquinoid, have continually rebuilt them with large quantities of new organic matter. Earthworms, attracted to this rich soil, kept the mounds porous, allowing rain to percolate through without washing them away. Grasses and other plants keep the mounds stable. A survey of the ants and termites in these former agricultural swamps, revealed that their nests occur entirely on the mounds, with none in the low, often submerged, areas surround them.

Researchers now speculate that as the fertility of the mounds decreased with continued crop growing, these ancient farmers may have let their mound-matrix fields lay fallow, allowing ants, termites and worms to replenish the soil’s nutrients. This largely forgotten practice of growing crops in marshes and allowing ecological engineers such as ants and termites to replenish nutrients is a technique that may have practical uses in modern sustainable farms, the researchers write.

Newly discovered prehistoric turtle co-existed with world’s biggest snake

John Barrat — Wed, 07 Apr 2010 13:51:43 +0000

The discovery of a new fossil turtle species in Colombia’s Cerrejón coal mine by researchers from the Smithsonian Tropical Research Institute in Panama and the Florida Museum of Natural History helps to explain the origin of one of the most biodiverse groups of turtles in South America.

Image right: The thick fossil carapace of a newly discovered prehistoric turtle.

Cerrejonemys wayuunaiki takes its genus name from Cerrejón, and emys—Greek for turtle. Its species name is the language spoken by the Wayuu people who live on the Guajira Peninsula in northeastern Colombia near the mine. About as thick as a standard dictionary, this turtle’s shell may have warded off attacks by the Titanoboa, thought to have been the world’s biggest snake, and by crocodile-like creatures living in its neighborhood 60 million years ago.

Image left: Carlos Jarmillo with turtle specimens in the Cerrejón coal mine.

“The fossils from Cerrejón provide a snapshot of the first modern rainforest in South America—after the big Cretaceous extinctions and before the Andes rose, modern river basins formed and the Panama land bridge connected North and South America,” explains Carlos Jarmillo, staff scientist at the Smithsonian who studies the plants from Cerrejón.

“We are still trying to understand why six of this turtle’s modern relatives live in the Amazon, Orinoco and Magdalena river basins of South America and one lives in Madagascar,” explains Edwin Cadena, first author of the study and a doctoral candidate at North Carolina State University. This discovery “closes an important gap in the fossil record and supports the idea that the group originated near the tip of South America before the continent separated from India and Madagascar more than 90 million years ago.”

Image right: An artist’s conception of the giant prehistoric snake Titanoboa. (Illustration by Jason Bourque)

Cadena will characterize two more new turtle species and analyze the histology of fossil turtle bones from the Cerrejón site. “I hope this will give us an even better understanding of turtle diversity in the region and some important clues about the environment where they lived.”

For sweat bees, being social builds a more developed brain

John Barrat — Thu, 25 Mar 2010 12:52:41 +0000

Females of the tropical sweat bee Megalopta genalisa exhibit a very primitive form of social behavior. Either a bee lives as a solitary queen, going out from her nest to forage for her own food, or she can be a social queen–a stay-at-home mom. In that case, one of her daughters goes out to forage for her. The daughter’s ovaries don’t develop, and she never leaves her mother to start her own colony.

Recently, scientists at the Smithsonian Tropical Research Institute in Panama discovered that the brain region responsible for learning and memory is larger in the social queens than in the solitary queens of this species. Their study is the first comparison of the brain sizes of social and non-social individuals of the same species.

Image right: A tropical sweat bee, Megalopta genalisa, in her nest.

“The idea is that to maintain power and control in groups you need more information, so the bigger the group, the bigger individuals’ brains need to be.” says William Wcislo, Smithsonian staff scientist.

“It was surprising to us that even though the social queens don’t have bigger brains overall, the fact that the area associated with learning and memory–the mushroom body–was more developed in the social queens than in the solitary bees suggesting that social interactions are cognitively challenging, as predicted by the social brain hypothesis,” said Adam Smith, postdoctoral fellow at STRI. “It’s interesting to see that a characteristic like brain development changes so immediately, even with this simple mother-daughter division of labor.”

This study was done in the Smithsonian Tropical Research Institute’s new insect neurobiology laboratory, built to take advantage of diverse tropical insect groups with a variety of brain sizes to understand how brain size and behavior are related

These results were published recently online in the journal Proceedings of the Royal Society B.