Smithsonian Science » zoology

Heliconius butterfly genome explains wing pattern diversity

John Barrat — Thu, 17 May 2012 01:25:58 +0000

Pooling funds and putting their heads together, more than 70 scientists from 9 institutions including the Smithsonian Tropical Research Institute, sequenced the entire genome of the butterfly genus Heliconius, a brightly colored favorite of collectors and scientists since the Victorian era. Their results are published in the prestigious journal, Nature.

Image right: Based on the new sequence, scientists found that different species copy each other’s wing patterns by exchanging genes, a process thought to be very rare, especially in animals. (Photo by Mathieu Joron)

The genome of the Postman butterfly, Panama’s Heliconius melpomene, helps scientists understand how the stunning diversity of wing color patterns in tropical butterflies evolved. Heliconius species are highly distasteful. Their vivid wing patterns warn predators not to eat them. How have different butterfly species evolved similar wing patterns?

Based on the new sequence, scientists found that different species copy each other’s wing patterns by exchanging genes, a process thought to be very rare, especially in animals. Although many different species interbreed in the wild, their hybrid offspring often cannot reproduce successfully. But sometimes hybrids gain useful genes that help them adapt to changing conditions. Heliconius hybrids gain wing patterns that help them survive.

Kanchon Dasmahapatra, the a lead author of the study and a former Smithsonian fellow who worked with Jim Mallet at University College London notes: “What we discovered is that one butterfly species can gain its protective colour pattern genes ready-made from a different species by hybridizing with it–a much faster process than having to evolve one’s colour patterns from scratch.”

Some of the other genes in the sequence also surprised researchers. These butterflies, typically regarded as primarily visual insects, apparently have a rich array of genes for smelling and sensing chemicals in their environment, raising new questions about the links between perception and the origins of new species. Indeed, analysis carried out at the University of California by co-author Adriana Briscoe showed that butterflies have an even greater array of genes involved in chemical communication than moths, which depend on chemical signals for finding mates and host plants.

The study heralds a new era in genome biology and an important step in the Smithsonian’s goal to understand and sustain a biodiverse planet. Low-cost genetic sequencing opens doors to small research groups and individuals to sequence entire genomes, a technique formerly accessible only to labs with major government funding.

“Assembling a genome from scratch is still hard work: think Humpy-Dumpty,” said Owen McMillan, geneticist and Academic Dean at the Smithsonian Tropical Research Institute, “but it is getting easy, inexpensive, and is transforming how we do science. At the core, having a reference genome opens up new research possibilities and reveals previously unimagined connections.

Poachers at large in Thailand’s nature reserves despite ranger outposts

John Barrat — Fri, 11 May 2012 13:30:34 +0000

Khao Yai National Park in central Thailand covers some 1,357 square miles and, as Thailand’s oldest and most popular park, welcomes hundreds of thousands of visitors through its gates each year.

Recently, after examining hundreds of photos taken by camera traps set-up to monitor clouded leopards in the park, three Smithsonian researchers say Khao Yai also is quite popular with a different kind of visitor: poachers.

Next to the Eurasian wild pig, humans were the most common creature to show-up in the camera-trap photos, namely villagers, park staff, tourists and poachers, write Kate Jenks, JoGayle Howard and Peter Leimgruber of the Smithsonian Conservation Biology Institute in a recent issue of the journal Biotropica. Humans appeared in photos from 43 of the 217 different sites in the park where the camera traps were set, even though 78 percent of the park is zoned as a strict nature reserve/primitive area.

Images: Right, a clouded leopard in a camera trap photo. Above and below: poachers. (Photos courtesy of Kate Jenks)

Attached to trees in the forest, the camera traps use an infrared beam that can detect motion or a change in temperature to trip the camera’s shutter. The researchers considered humans in the snapshots to be “poachers” only if they were carrying a gun, a carcass or animal parts, a bag to carry forest products and animals; or if they were accompanied by a dog, Jenks explains.

Surprisingly, close analysis of the project’s some 650 photos revealed the presence of poachers very close to Khao Yai’s 21 ranger stations. Few carnivores, such as clouded leopards, were photographed near the stations.

“We expected to find higher carnivore biodiversity near the ranger outposts because those areas should be really well protected,” Leimgruber says. They are not.

In fact, Jenks says, “the ranger stations seem to be having the opposite of their intended effect. Building and staffing the outposts required the construction of roads into the park, which has provided easier access for everyone into the forest.”

This video depicts camera traps being set up in Thailand’s Pang Sida National Park, which is located adjacent to Khao Yai National Park.

In Southeast Asia poaching is fueled by demand from the traditional Chinese medicine trade, trade in wild bush meat for human consumption and forest products the researchers say. In addition, Jenks says, there are villages right up on the boundary of the park with no transition and no buffer zone. It is very easy for villagers to wander into the park.

Jenks, Howard and Leimgruber recommend increased foot patrols by park staff through the forest and continued monitoring of the impact of these foot patrols using the camera traps. Unless the human presence in and impact on the park is reduced, wildlife populations “will only shrink progressively into smaller and smaller core areas of the park” the researchers write.

(JoGayle Howard, a prominent researcher at the National Zoo who had dedicated her life to the study and conservation of endangered species, passed away last year. She had been instrumental in developing this wildlife conservation project.) –John Barrat

Article link: “Do Ranger Stations Deter Poaching Activity in National Parks in Thailand?” by Kate Jenks, JoGayle Howard and Peter Leimgruber appeared in the scientific journal Biotropica.

Global forest science research center moves from Harvard to the National Museum of Natural History, Washington, D.C.

John Barrat — Wed, 02 May 2012 14:32:22 +0000

In May, the Center for Tropical Forest Science-Smithsonian Institution Global Earth Observatory is moving from its headquarters at Harvard University to the Smithsonian’s National Museum of Natural History in Washington, D.C. The move enhances coordination efforts for the 46-plot research network, which partners with more than 75 institutions in 21 countries, including the Smithsonian’s Natural History Museum, the Smithsonian Conservation Biology Institute and the Smithsonian Environmental Research Center.

CTFS-SIGEO is a global network of forest research plots committed to the study of tropical and temperate forest function and diversity. The multi-institutional network includes plots across the Americas, Africa, Asia, and Europe, with a strong focus on tropical regions. Ecologists at the Smithsonian Tropical Research Institute established the first forest dynamics plot on Barro Colorado Island in the Panama Canal in 1980.

Image left: Daniel Johnson, a biology graduate student at Indiana University, measures the diameter of a white ash tree in the University’s Lilly-Dickey Woods. The 550-acre woods were recently added to CTFS-SIGEO’s global network of forest research plots. (Photo by F. Collin Hobbs)

Stuart J. Davies, CTFS-SIGEO director and senior staff scientist at the Smithsonian Tropical Research Institute, will make the move along with David Kenfack, CTFS-SIGEO Africa Program coordinator. Davies sees the need for increased presence at the Smithsonian in Washington, D.C. as the network continues to build partnerships within different Smithsonian units.

The scale and intensity of the CTFS-SIGEO research program remains unprecedented in forest science. Scientists monitor the growth and survival of about 4.5 million trees of approximately 8,500 species in 21 different countries. The work aims to increase the scientific understanding of forest ecosystems, guide sustainable forest management and natural-resource policy, monitor the impacts of climate change, and build capacity in forest science. Most recently CTFS-SIGEO added the Lilly-Dickey Woods–a 550-acre forest in Brown County Indiana that is a research and teaching preserve for Indiana University–to its network of forest research plots.

Because of its extensive biological monitoring, unique databases, and the expertise of its partners, CTFS-SIGEO enhances society’s ability to evaluate and respond to the impacts of global climate change. Monitoring so many forest plots at once is providing a comprehensive, yet locally detailed perspective on how the world’s forests are being transformed by global change. Research on tropical forest dynamics continues, but is joined by new initiatives studying carbon fluxes, temperate forests, ecosystem services, and biodiversity. CTFS-SIGEO and its many institutional partners are leveraging huge intellectual horsepower to transform our understanding of forest-ecosystem structure and function. The network has been so successful that the Smithsonian is now planning to extend its system of earth observatories to the near shore marine realm. –Source: The Plant Press, newsletter of the Department of Botany, National Museum of Natural History.

National Park Service natural history collections transferred to care of the Smithsonian

John Barrat — Tue, 01 May 2012 11:34:22 +0000

The National Park Service and the Smithsonian Institution have announced a new partnership to share responsibility for selected National Park Service natural history collections, making them more readily available to researchers through the Smithsonian.

Collections will continue to be owned by the National Park Service but will be in the permanent custodial care of the Smithsonian Institution. The agreement formalizing the relationship was signed today by National Park Service Director Jonathan B. Jarvis and the Smithsonian’s Under Secretary for Science Eva J. Pell at the National Museum of Natural History.

Photo right: Jon Jarvis, Director of the National Park Service, and Eva Pell, Under Secretary for Science at the Smithsonian sign an MOU between the two organizations. The partnership gives broader access to National Park Service collections through the Smithsonian’s care and management of them. (Johnny Gibbons photo)

“This agreement benefits science, the American people, and the long-standing and historic relationship between our two organizations,” said Jarvis. “Together we are building a collection that will become an extraordinary tool for the scientific community to study biodiversity, evolution, and the distinctive character of national park ecosystems.”

The Smithsonian echoed the significance of the new agreement. “Two venerable institutions long known for protecting the nation’s heritage, are now working together to enhance care and access to specimens that document the natural environment of our national parks,” said Eva Pell, under secretary for science at the Smithsonian.

Examples of National Park Service collections that the Smithsonian could curate under the new agreement are:

138 holotypes – a specimen described in scientific literature to establish a new species – that researchers in Great Smoky Mountains National Park in Tennessee and North Carolina have discovered and described over the past 14 years.

From George Washington Memorial Parkway in Virginia, 3,000 vascular plant specimens representing 1,326 species, as well as a wide range of specimens from the Potomac River Gorge, including holotypes of shoreflies, caddisflies, and copepods (small crustaceans).

National Zoo gorillas participate in heart disease study

John Barrat — Thu, 26 Apr 2012 12:35:54 +0000

Not on a plane, but how did blind snakes ever get to the Pacific’s Caroline Islands?

John Barrat — Wed, 25 Apr 2012 14:01:52 +0000

Two new species of blind snakes found living on small, low-lying atolls in the Caroline Islands are an unexpected discovery that is quite difficult to explain, say scientists studying the reptiles. The new snakes were announced recently in a paper in the journal Zootaxa co-authored by Addison Wynn, a herpetologist at the Smithsonian’s National Museum of Natural History, and colleagues from the U.S. Geological Survey, the College of Micronesia and the Yap Institute of Natural Sciences. The Caroline Islands are located in Micronesia, an area north of the equator and far west of Hawaii.

Both snakes (newly named Ramphotyphlops hatmaliyeb and Ramphotyphlops adocetus) are believed to be indigenous to islands that only formed in the last 2,000-years. These islands are surrounded by water and have never had any connection to land.

“The question is,” Wynn says, “how did they get there?” The only other terrestrial snake found in the Caroline Islands east of Palau is a third blind snake species known to have been introduced by humans years ago.

“These new species extend the known range of blind snakes some 2,000 kilometers out into the Pacific Ocean, into areas where we didn’t know they occurred or could ever occur. We just didn’t expect to find blind snakes out there in the middle of the ocean,” Wynn says.

Image right: The new blind snake species “Ramphotyphlops hatmaliyeb.” (Photo courtesy Marjorie Falanruw)

Blind snakes live underground, are typically four or five inches long and easily mistaken for large worms. “They eat termites and small ants, and there are about 240 or so known species in the world,” Wynn says. “They spend their lives burrowing so their head is blunt and pointed to push their way through the soil. Their rudimentary eyes can only differentiate between light and dark and exist as pigment spots underneath scales on their head.”

When we first received a single specimen from the island of Ant Atoll, in the Carolines, Wynn explains, “we initially thought it must be a waif, brought by humans aboard a ship, because it was so unexpected.” As the scientists received additional specimens they were faced with the fact that the snakes are a species indigenous to the Caroline Islands. One hypothesis to their presence is that they are a relic population that somehow survived on temporary cays, reefs, platforms and other oceanic structures for thousands of years until the islands on which they now live were formed.

Image right: Top and side photographs of the head of the newly named blind snake species “R. adocetus” with accompanying illustration showing the unique scale pattern that scientists use to identify them as to species.

Because different species of blind snakes look so similar in appearance, an expert is normally required to tell species apart. Physical characteristics used to distinguish them are counts of the number of scales found along the back of the animal or scale rows around the animal’s body, shape and position of scales on the head, and color pattern.

Article link: “The unexpected discovery of blind snakes (Serpentes: Typhlopidae) in Micronesia: two new species of Ramphotyphlops from the Caroline Islands,” by Addison Wynn, Robert Reynolds, Donald Buden, Marjorie Falanruw and Brian Lynch appeared in the journal Zootaxa.

For a dentist, the narwhal’s smile is a mystery of evolution

John Barrat — Wed, 18 Apr 2012 16:33:32 +0000

When a dentist says “open wide,” he or she knows pretty much what they’ll find inside a patient’s mouth. But when a dentist peers into the mouth of an Arctic narwhal, all bets are off.

“Nothing makes sense,” explains Martin Nweeia, a practicing New England dentist and member of the Smithsonian’s Department of Vertebrate Zoology and the Harvard School of Dental Medicine. For one, narwhals have no teeth. “They eat large fish, yet swallow them whole. If you look in its mouth there’s nothing. There are absolutely no teeth.”

Image right: The mouth of a narwhal has no teeth. (Photo by Martin Nweeia)

Incredibly, the narwhal’s only visible tooth is outside of its mouth. Its tusk, in fact, is a giant canine tooth—that can grow as long as 9 feet—with a distinct left-hand spiral, covered in a tissue called cementum, normally only found around the base of a tooth lodged in bone.

Nweeia and a team of dentists and zoologists from the Smithsonian’s National Museum of Natural History, Harvard and other research organizations recently took a very close look at the dentition of the narwhal’s mouth. They studied more than 130 skulls in museum collections and 21 skulls of narwhals killed by native hunters in Canada. In a new paper published in The Anatomical Record, the team determined:

The long spiral tusk of the male narwhal is one of a pair of canine teeth positioned horizontally in the animal’s skull. They determined it was a canine and not an incisor because the tusk originates in the narwhal’s maxillary bone, where canine teeth in mammals originate. This is the first study to confirm the tusk as a canine tooth. In most mammals, canines are vertical in the mouth and are used for holding food or as weapons.

It is the left tooth of the pair that grows into a long tusk that erupts through the narwhal’s upper lip. The right canine tooth is also a tusk but it remains embedded in the narwhal’s skull unerrupted. Only occasionally do both tusks erupt. Female narwhals have two embedded tusks that erupt only very rarely.

Image left: A rare double-tusked narwhal in the collection of the National Museum of Natural History is examined by Martin Nweeia, left, and Charles Potter, collections manager, Smithsonian Marine Mammal Program. (Photo by Joseph Meehan)

A second pair of tiny teeth is located in open tooth sockets in the narwhal’s snout alongside the tusks. These teeth are vestigial, meaning they have no function. Close inspection across many specimens reveal extreme variation in location, morphology and histology (tissue structure) of these teeth, all indications they “are following a pattern consistent with evolutionary obsolescence,” the scientists write.

“It is striking when you think that this animal decided to take all of its tooth-producing energy and put it into one thing [a tusk] that sticks out nine feet into the ocean. With the amount of energy that it takes to produce that one tusk it could easily have 30 to 40 teeth in its mouth doing other things,” Nweeia explains. “Evolutionary-wise something is saying don’t do this, instead it is better to grow this extraordinary tusk.” A pretty compelling reason must be behind such a decision.”

Image right: An array of vestigial teeth collected from narwhals. (Photo by Joseph Meehan)

Did the narwhal once have teeth oriented vertically in its mouth as do other mammals? “One might assume this animal once had more teeth positioned vertically in the mouth, but there is no evolutionary evidence to say that would be true,” Nweeia explains. “With whales the evolutionary pieces of the puzzle are scant and I prefer to leave speculation out of the equation.”

There are many kinds of curious expressions of teeth in whales, narwhals being the most extraordinary, Nweeia says. “The strap-toothed whale, for example, has two teeth that wrap over its upper jaw preventing the animal from opening its mouth.”

Image left: The dissection team at the Osteo-Prep Lab of the Smithsonian’s National Museum of Natural History begins dissection on a male narwhal specimen. From left, James Mead, curator emeritus, Museum of Natural History; Ted Cranford, San Diego State University; and Martin Nweeia. (Photo by Chip Clark, Smithsonian Institution)

“The whole thing that is great about the teeth of the narwhal is that nothing makes sense,” Nweeia adds. “The tusks are an extreme example of dental asymmetry. They exhibit uncharacteristic dimorphic or sexual expressions since females do not exhibit erupted tusks as commonly as males. Also, the tusk has a straight axis and a spiraled morphology. Conventional mechanisms of evolution do not help explain these expressions of teeth.”–John Barrat

Article link: “Vestigial Tooth Anatomy and Tusk Nomenclature for Monodon monoceros,” The Anatomical Record, April 2012. Authored by Martin T. Nweeia, Frederick C. Eichmiller, Peter V. Hauschka, Ethan Tyler, James G. Mead, Charles W. Potter, David P. Angnatsiak, Pierre R. Richard, Jack R. Orr, and Sandie R. Black.

New ‘Bumblebee’ gecko discovered in Papua New Guinea

John Barrat — Wed, 18 Apr 2012 14:58:35 +0000

Biologists from the Papua New Guinea National Museum and the U.S. Geological Survey have discovered a new species of gecko, adorned like a bumblebee with black-and-gold bands and rows of skin nodules that enhance its camouflage on the tropical forest floor.

Specimens of the lizard, which measures about 5 inches from head to tail, were collected in May 2010 in Sohoniliu Village on Manus Island in Papua New Guinea. Herpetologists George Zug of the Smithsonian’s National Museum of Natural History and Rober Fisher of the USGS Western Ecological Research Center described the new species in a report published in “Zootaxa” this month.

“We’ve officially named it Nactus kunan for its striking color pattern — kunan means ‘bumblebee’ in the local Nali language,” Fisher says. “It belongs to a genus of slender-toed geckos, which means these guys don’t have the padded, wall-climbing toes like the common house gecko, or the day gecko in the car insurance commercials.”

Fisher found two individuals of the bumblebee gecko on Manus Island in 2010 and analyzed their genetics to show that the lizards were new and distinctive. Two additional species were found that trip, and the specimens await further analysis.

“This species was a striking surprise, as I’ve been working on the genus since the 1970s, and would not have predicted this discovery,” Zug says.

“Exploration of Manus Province is in its infancy, with many new species possible, and this joint expedition was our first to this region,” says Bulisa Iova, the reptile curator at the Papua New Guinea National Museum.

This research on Pacific lizard biodiversity was supported by the Smithsonian, U.S. Department of Defense and USGS. USGS regularly collaborates on biological surveys with partner nations, as part of its mission to provide scientific information that help government managers address critical natural resource issues.–Source: USGS

5 rabbit realities

John Barrat — Fri, 06 Apr 2012 12:06:24 +0000

In celebration of the annual spring appearance of the Easter bunny on Sunday, April 8, Smithsonian Science offers these facts from Rabbits: The Animal Answer Guide, a new book by John Seidensticker, conservation scientist at the Smithsonian’s National Zoo, and Susan Lumpkin, freelance writer.

1

Rabbits are not rodents, but lagomorphs (lag-uh-mawrf), a scientific term which means “hare-shaped.” Hares and pikas also are lagomorphs.

Image: A domestic rabbit, breed: Silver Fox (Photo by Mehgan Murphy)

2

Scientists studying the bones of an extinct giant rabbit found on the Mediterranean island of Minorca estimate this prehistoric animal weighed as much as 31 pounds! The largest rabbits alive today– domestic breeds such as the Flemish giant–weigh 22 pounds at most.

Image: A reconstruction of a giant Minorcan rabbit is shown next to a modern European rabbit. (Image by Meike Köhler)

3

Thanks to human introductions the European rabbit (Oryctolagus cuniculus) is found throughout Western Europe, Australia, parts of South America, North Africa and on more than 800 islands around the world. Today in Iberia, Spain, the European rabbit’s sole home for many thousands of years, it is threatened.

Image: A European rabbit. (Image courtesy Encyclopedia of Life)

4

Archaeologists have evidence of people hunting rabbits in the south of France some 120,000 years ago. Scientists suspect even Neanderthals lived on diets made up largely of rabbits.

Painting: “Der November” by Joachim von Sandrat (1606-1688)

5

A “never fail” Kansas folk remedy for reducing fever recommends making a strong tea from the dung of the wild jackrabbit and drinking it every half-hour.

Image: Black-tailed jackrabbit (Photo by Susan E. Adams)

Invasive pythons in Florida now stealing bird eggs straight from the nest

John Barrat — Fri, 06 Apr 2012 11:42:00 +0000

Smithsonian scientists and their colleagues have uncovered a new threat posed by invasive Burmese pythons in Florida and the Everglades: The snakes are not only eating the area’s birds, but also the birds’ eggs straight from the nest. The results of this research add a new challenge to the area’s already heavily taxed native wildlife. The team’s findings are published in the online journal Reptiles & Amphibians: Conservation and Natural History.

Image right: Burmese pythons (Python molurus bivittatus), native to southern Asia, have taken up a comfortable residence in the state of Florida, especially in the Everglades. In addition to out-competing native wildlife for resources and habitat, the pythons are eating the native wildlife. (Photo by Sarah L. Stewart)

Burmese pythons, native to southern Asia, have taken up a comfortable residence in the state of Florida, especially in the Everglades. In addition to out-competing native wildlife for resources and habitat, the pythons are eating the native wildlife. Burmese pythons (Python molurus bivittatus) were first recorded in the Everglades in 1979—thought to be escaped or discarded pets. Their numbers have since grown, with an estimated breeding population in Florida in the tens of thousands.

Image left: Five of ten entire Guineafowl eggs regurgitated by a Burmese python. (Photo: R.W. Snow, Everglades National Park)

In an ongoing study to better understand the impact of this snake in the Everglades, scientists from the Smithsonian Institution, the National Park Service and others have been examining the contents of the digestive tracts of pythons in the area. They have shown that Burmese pythons consume at least 25 different species of birds in the Everglades, but until now no records documented this species eating bird eggs.

“This finding is significant because it suggests that the Burmese python is not simply a sit-and-wait predator, but rather is opportunistic enough to find the nests of birds,” said Carla Dove, ornithologist at the Smithsonian’s Feather Identification Lab in the National Museum of Natural History and lead author of the study. “Although the sample size is small, these findings suggest that the snakes have the potential to negatively affect the breeding success of native birds.”

Image right: Two Limpkin (Aramus guarauna) crushed but intact eggs (top) recovered from a Burmese python digestive tract and compared to a reference Limpkin specimen from the Smithsonian’s collection (below) for size and color patterns. The arrow shows fragments of eggshells from the python sample placed on the Smithsonian specimen for color comparison. (Photo by Don Hurlbert)

Scientists collected a 14-pound male python that was 8 1/2 feet long near a property with free-ranging guineafowl. The snake regurgitated 10 whole guineafowl eggs soon after it was captured. The team discovered the remains of two bird eggs in another python collected for the study―a 30-pound female more than 10 feet long. Scientists used DNA tests on the membrane of the crushed eggs and comparisons of the shell fragments with egg specimens in the Smithsonian’s collection to determine what the female snake had eaten. Their research revealed the species to be the limpkin (Aramus guarauna), a large wading bird found in marshes and listed as a “species of special concern” by the Florida Fish and Wildlife Conservation Commission.

Image left: Everglades National Park wildlife biologist Skip Snow in the South Florida Research Center lab with rooster remains recovered from a captured Burmese python. (Photo by Lori Oberhofer, National Park Service)

There are several species of snake known to eat bird eggs. Those species are equipped with pointed or blade-like extensions on the vertebrae in their esophagus that punctures the eggshell, making it easy for the snake to crush the egg and digest its contents. Burmese pythons do not have these adaptations. However, the pythons studied were so large in relation to the eggs they ingested that the scientists believe these specialized vertebrae may not have been needed.

“Our observations confirm that invasive Burmese pythons consume not only adult birds but also eggs, revealing a previously unrecognized risk from this introduced predator to nesting birds,” said Dove. “How frequently they are predating on bird eggs is hard to know.”

In an earlier stage of the study, the scientists collected more than 300 Burmese pythons in Everglades National Park and found that birds, from the 5-inch-long house wren to the 4-foot-long great blue heron, accounted for 25 percent of the python’s diet in the Everglades.