Smithsonian Science

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.

Unseen planet’s gravity allows Kepler Telescope to “see” it

John Barrat — Wed, 16 May 2012 19:20:19 +0000

More than a 150 years ago, before Neptune was ever sighted in the night sky, French mathematician Urbain Le Verrier predicted the planet’s existence based on small deviations in the motion of Uranus. In a paper published today in the journal Science online, a group of researchers led by David Nesvorny of Southwest Research Institute and David Kipping of the Harvard-Smithsonian Center for Astrophysics has inferred another unseen planet, this time orbiting a distant star, marking the first success of this technique outside the solar system.

“Today’s telescopes are detecting planets around distant stars, and NASA’s Kepler Telescope, launched in 2009, is a champion among them,” Nesvorny says. It finds planets by continuously monitoring the brightness of more than 150,000 stars, searching for brief periods of time, known as transits, when a star appears fainter because it is obscured by a planet passing in the foreground. But there’s a twist.

Image right: Using Kepler Telescope transit data of planet “b”, scientists predicted that a second planet “c” about the mass of Saturn orbits the distant star KOI-872. This research, led by Southwest Research Institute and the Harvard-Smithsonian Center for Astrophysics, is providing evidence of an orderly arrangement of planets orbiting KOI-872, not unlike our own solar system. (Image courtesy Southwest Research Institute)

“For a planet following a strictly Keplerian orbit around its host star, the spacing, timing and other properties of the observed transit light curve should be unchanging in time,” said Kipping of the Harvard Smithsonian Center for Astrophysics. “Several effects, however, can produce deviations from the Keplerian case so that the spacing of the transits is not strictly periodic.”

A hidden planet, for example, can distort the sequence of transits if it gravitationally pulls on the transiting planet and delays some transits relative to others.

As part of the Hunt for the Exomoons with Kepler (HEK) project, the team analyzed recently released Kepler data and identified systems with transiting planets that show transit variations indicative of hidden companions, such as unseen moons or planets. The team identified the Sun-like star known as KOI-872 (KOI stands for Kepler Objects of Interest) as exceptional in that it shows transits with remarkable time variations over two hours.

“It quickly became apparent to us that a large hidden object must be pulling on the transiting planet,” says Nesvorny. “To put this in context, if a bullet train arrives in a station two hours late, there must be a very good reason for that. The trick was to find what it is.”

Using Le Verrier’s perturbation theory to speed up time-consuming computer calculations of many possible configurations of planetary orbits, the HEK team showed that the observed variations can be best explained by an unseen planet about the mass of Saturn that orbits the host star every 57 days. According to the analysis, the planetary orbits are very nearly coplanar and circular, reminiscent of the orderly arrangement of orbits in our solar system.

The team’s claim will be put to the test by Kepler’s new observations, which will track dozens of new transits of KOI-872, comparing their timing to published predictions.

“Whilst the principal goal of the HEK project will continue to focus on searching for moons, this first planetary system discovered by HEK demonstrates the unexpected discoveries possible with transit analysis,” Kipping says.–Source: Southwest Research Institute

Article link: “The Detection and Characterization of a Nontransiting Planet by Transit Timing Variations” by Nesvorny, Kipping, Lars Buchhave (Niels Bohr Institute), Gaspar Bakos (Princeton University), Joel Hartman (Princeton University) and Allan Schmitt (Citizen Science), was published May 10 in the journal Science online, at the Science Express website.

First ever record of insect pollination captured in 100 million-year-old amber

John Barrat — Tue, 15 May 2012 13:24:47 +0000

Amber from Cretaceous deposits (110-105 million years ago) in Northern Spain has revealed the first-ever record of insect pollination. Scientists have discovered several specimens of tiny insects covered with pollen grains in two pieces of amber, revealing the first record of pollen transport and social behavior in this group of animals. The results are published in the Proceedings of the National Academy of the Science (PNAS) dated 14-18 May 2012.

Image right: Gymnosperm pollen attached to the abdomen and wing of a thysanopteran from the Alava amber (Credit: Enrique Peñalver, IGME).

The international team of scientists comprises: Enrique Peñalver and Eduardo Barrón from the Instituto Geológico y Minero de España in Madrid; Xavier Delclòs from the University of Barcelona; Andre and Patricia Nel from the Muséum national d’histoire naturelle in Paris; Conrad Labandeira from the Smithsonian’s National Museum of Natural History in Washington D.C.; and Carmen Soriano and Paul Tafforeau from the European Synchrotron Radiation Facility in Grenoble, France. The amber samples were from the collection of the Museo de Ciencias Naturales de Álava in Spain.

Today, more than 80 percent of plant species rely on insects to transport pollen from male to female flower parts. Pollination is best known in flowering plants but also exists in so-called gymnosperms, seed-producing plants like conifers. Although the most popular group of pollinator insects are bees and butterflies, a myriad of lesser-known species of flies, beetles or thrips have co-evolved with plants, transporting pollen and in return for this effort being rewarded with food.

Image left: An artist’s conception of of Gymnospollisthrips with pollen attached to the body over an ovulate organ of a gingko (Credit: Enrique Peñalver, IGME).

During the last 20 years, amber from the Lower Cretaceous found in the Basque country in Northern Spain has revealed many new plant and animal species, mainly insects. Here, the amber featured inclusions of thysanopterans, so-called thrips, a group of minute insects of less than 2 millimeters long that feed on pollen and other plant tissues. They are efficient pollinators for several species of flowering plants.

Two amber pieces revealed six fossilized specimens of female thrips with hundreds of pollen grains attached to their bodies. These insects exhibit highly specialized hairs with a ringed structure to increase their ability to collect pollen grains, very similar to the ones of well known pollinators like domestic bees. The scientists describe these six specimens in a new genus (Gymnopollisthrips) comprising two new species, G. minor and G. major.

The most representative specimen was also studied with synchrotron X-ray tomography at the European Synchrotron Radiation Facility to reveal the pollen grain distribution over the insect’s body in 3D and at very high resolution. The pollen grains are very small and exhibit the adherent features needed so that insects can transport them. The scientists conclude that this pollen is from a kind of cycad or ginkgo tree, a kind of living fossil of which only a few species are known to science. Ginkgos are either male or female, and male trees produce small pollen cones whereas female trees bear ovules at the end of stalks which develop into seeds after pollination.

Image right: Synchrotron tomography image of Gymnospollisthrips minor showing pollen. (Credit: ESRF).

Why did these tiny insects collect and transport gingko pollen 100 million years ago? Their ringed hairs cannot have grown due to an evolutionary selection benefiting the trees. The benefit for the thrips can only be explained by the possibility their larvae ate pollen. This suggests that this species formed colonies with larvae living in the ovules of some kind of gingko for shelter and protection, and female insects transporting pollen from the male gingko cones to the female ovules to feed the larvae and at the same time pollinate the trees.

More than one hundred million years ago, flowering plants started to diversify enormously, eventually replacing conifers as the dominant species. “This is the oldest direct evidence for pollination, and the only one from the age of the dinosaurs,” says Carmen Soriano, who led the investigation of the amber pieces with X-ray tomography at the ESRF. “The co-evolution of flowering plants and insects, thanks to pollination, is a great evolutionary success story. It began about 100 million years ago, when this piece of amber fossil was produced by resin dropping from a tree, which today is the oldest fossil record of pollinating insects. Thrips might indeed turn out to be one of the first pollinator groups in geological history, long before evolution turned some of them into flower pollinators.” –Source: European Synchrotron Radiation Facility

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.

The amazing story of adaptation and survival in our species, Homo sapiens.

John Barrat — Fri, 11 May 2012 00:38:34 +0000

3D imaging adds remarkable new understanding of North America’s mysterious Clovis people

John Barrat — Thu, 10 May 2012 13:53:57 +0000

New high-tech 3D computer analysis of 50 spear points made more than 10,000 years ago by North America’s mysterious Clovis people has revealed the stone points display an astounding symmetry despite having been found in caches as far apart as Maryland, Arizona and Colorado. The only explanation for such symmetry across these vast distances, explains Smithsonian anthropologist Dennis Stanford, is that the method of creating the points was handed down from person to person.

“We were shocked. Basically what we are looking at is a technology that was learned from one person to another, from father to son or from uncle to nephew,” explains Stanford, co-author of a recent paper on the discovery in the Journal of Archaeological Science.

Image right: Clovis stone points from the Drake Cache of Colorado. Click to enlarge. (Photo by Chip Clark, Smithsonian)

The researchers believe encounters between Clovis knappers, or stone point makers, from different groups at stone quarry sites or in settlements certainly “facilitated the sharing of technological information by allowing knappers to observe tools and techniques used by other artisans,” explains co-author Sabrina Sholts of the Human Evolution Research Center at the University of California in Berkeley. “The tools selected by the knappers, as well as how they were handled and applied, certainly were part of the Clovis technology,” that was shared between families and tribes.

This video was created by Sabrina Sholts of the Human Evolution Research Center at the University of California in Berkeley using 3D digital scans of a Clovis stone projectile point from the collections of the Department of Anthropology, National Museum of Natural History, Smithsonian Institution.

In fact, the researchers say, through a strong communication network Clovis spear point technology spread across North America in as little as 200 years. Radiocarbon dating of the stone points backs this theory. Many Clovis points “have been recovered from kill sites, in association with the remains of animals such as mammoths and bison,” Sholts says. This “suggests that they were effective for hunting large prey.”

The scientists used high-tech 3D scanning to create detailed images of the Clovis points from the collection of the Smithsonian’s National Museum of Natural History. The researchers focused particularly on the contours of the scars on the front and back of each bi-face spear point where individual stone flakes were carefully and systematically removed centuries ago by striking with an implement made of antler, bone, ivory or even perhaps hardwood. Each 3D scan records millions of minute measurements, revealing “subtle differences in the various steps of reduction [flaking off tiny pieces of stone] and nuances that you can’t see with your eyes,” Stanford explains.

Right: Images of 3D models and overlaid front and back flake scar contours from projectile points from the Colby Cache, Wyoming (left), Drake Cache, Colorado (center left), and two modern replicas (center right and right). The Colby and Drake points have markedly different bases, but this difference is much less prominent in the flake scar contours. For the two modern replicas, their flake scar contours are generally more uneven, and also display larger differences between the overlaid contours.

“One nice thing about the study is its relative objectivity,” Sholts points out. With the 3D imaging, “it is really very automated. What we are doing is essentially data analysis, capturing the contours and curvature of the surface of each biface in a standard way. The results were surprising to me.”

This 3D study has laid to rest the theory that Clovis technology spread region by region from knappers who copied lost or discarded stone points they had found, Stanford says. In fact, the paper reveals, part of the research included projectile points made by an expert modern-day knapper who closely studied and copied Clovis points in the Smithsonian collection. Computer analysis revealed these modern creations do not share the same symmetry as do the authentic Clovis points—further proof that the real Clovis points were a learned technology.

“We are now working on a new study with Clovis points from California that we are putting into that same computer matrix,” Stanford says.–John Barrat

Article link: “Flake scar patterns of Clovis points analyzed with a new digital morphometrics approach: evidence for direct transmission of technological knowledge across early North America,” authored by Sabrina Sholts, Dennis Stanford, Louise Flores and Sebastian Wärmländer, will appear in a forthcoming issue of the Journal of Archaeological Science.

Old Woman Meteorite

John Barrat — Wed, 09 May 2012 18:14:59 +0000

Roy Clarke, curator at the Smithsonian’s National Museum of Natural History, is shown in 1977 with the Old Woman Meteorite, the second largest meteorite ever discovered in the United States. It was found in March 1976 in the Mojave Desert some 167 miles east of Los Angeles, by two prospectors searching for a lost Spanish Conquistador gold mine rumored to be there. In September 1980, the Smithsonian sent most of the meteorite back to California to be placed on display at the Desert Discovery Center in Barstow. (Photo courtesy Smithsonian Institution Archives)

One supernova type, two different sources

John Barrat — Mon, 07 May 2012 18:31:42 +0000

The exploding stars known as Type Ia supernovae serve an important role in measuring the universe, and were used to discover the existence of dark energy. They’re bright enough to see across large distances, and similar enough to act as a “standard candle” – an object of known luminosity. The 2011 Nobel Prize in Physics was awarded for the discovery of the accelerating universe using Type Ia supernovae. However, an embarrassing fact is that astronomers still don’t know what star systems make Type Ia supernovae.

Two very different models explain the possible origin of Type Ia supernovae, and different studies support each model. New evidence shows that both models are correct – some of these supernovae are created one way and some the other.

Image above: The Tycho supernova remnant is the result of a Type Ia supernova explosion. The explosion was observed by Danish astronomer Tycho Brahe in 1572. More than 400 years later, the ejecta from that explosion has expanded to fill a bubble 55 light-years across. In this image, low-energy X-rays (red) show expanding debris from the supernova explosion and high energy X-rays (blue) show the blast wave – a shell of extremely energetic electrons. (Credit: X-ray: NASA/CXC/Rutgers/K.Eriksen et al.; Optical: DSS)

“Previous studies have produced conflicting results. The conflict disappears if both types of explosion are happening,” explained Smithsonian astronomer and Clay Fellow Ryan Foley (Harvard-Smithsonian Center for Astrophysics).

Type Ia supernovae are known to originate from white dwarfs – the dense cores of dead stars. White dwarfs are also called degenerate stars because they’re supported by quantum degeneracy pressure.

In the single-degenerate model for a supernova, a white dwarf gathers material from a companion star until it reaches a tipping point where a runaway nuclear reaction begins and the star explodes. In the double-degenerate model, two white dwarfs merge and explode. Single-degenerate systems should have gas from the companion star around the supernova, while the double-degenerate systems will lack that gas.

“Just like mineral water can be with or without gas, so can supernovae,” said Robert Kirshner, Clowes Professor of Astronomy at Harvard University and a co-author on the study.

Foley and his colleagues studied 23 Type Ia supernovae to look for signatures of gas around the supernovae, which should be present only in single-degenerate systems. They found that the more powerful explosions tended to come from “gassy” systems, or systems with outflows of gas. However, only a fraction of supernovae show evidence for outflows. The remainder seem to come from double-degenerate systems.

“There are definitely two kinds of environments – with and without outflows of gas. Both are found around Type Ia supernovae,” Foley said.

This finding has important implications for measurements of dark energy and the expanding universe. If two different mechanisms are at work in Type Ia supernovae, then the two types must be considered separately when calculating cosmic distances and expansion rates.

“It’s like measuring the universe with a mix of yardsticks and meter sticks – you’ll get about the same answer, but not quite. To get an accurate answer, you need to separate the yardsticks from the meter sticks,” Foley explained.

This study raises an interesting question – if two different mechanisms create Type Ia supernovae, why are they homogeneous enough to serve as standard candles?

“How can supernovae coming from different systems look so similar? I don’t have the answer for that,” said Foley.

The paper describing this research will appear in the Astrophysical Journal and is available online.

Mexico’s Popocatépetl volcano active again

John Barrat — Thu, 03 May 2012 19:24:02 +0000

According to the weekly report of the Smithsonian’s Global Volcanism Program, gas-and-ash plumes rose nearly one mile above the crater of Mexico’s Popocatépetl volcano from April 25 to 27. On April 28 incandescent fragments ejected from the crater and landed on the east flank of the volcano, traveling as far as one-half mile. On May Day, gas-and-steam plumes that occasionally contained low amounts of ash, again rose more than half-a-mile above Popocatépetl’s crater. The volcano’s Alert Level remained at Yellow Phase. This image shows Popocatépetl at night on May 3.

$35-million donation will build new dinosaur hall at National Museum of Natural History

John Barrat — Thu, 03 May 2012 16:58:22 +0000

The National Museum of Natural History announced today that it will construct a new dinosaur exhibition hall made possible by a $35 million donation from David H. Koch, executive vice president of Koch Industries and philanthropist. This renovation—the largest and most complex in the museum’s history—offers an opportunity to showcase the museum’s unrivaled collection of 46 million fossils and present the most up-to-date scientific research possible in the exhibition. Design preparations for the renovation will begin immediately.

The existing dinosaur hall will remain open until spring 2014, when it will be closed to the public to allow construction to begin; selected dinosaur specimens will remain on view in other public areas of the museum.

Image right and below: The Dinosaur Hall at the Smithsonian’s National Museum of Natural History.

The Smithsonian Board of Regents approved the naming of the 25,000-square-foot exhibition space April 30 in recognition of Koch’s gift—$35 million of the exhibition’s total estimated cost of $45 million. This is the largest single gift in the history of the Natural History Museum. Koch has contributed to many cultural, educational and health organizations, including Lincoln Center, the Metropolitan Museum of Art, American Museum of Natural History and Massachusetts Institute of Technology. Koch has been a member of the National Museum of Natural History’s board for five years and provided the lead gift for the David H. Koch Hall of Human Origins, which opened in 2010.

“Dinosaurs have always been one of the Smithsonian’s most important and popular exhibitions,” said Cristián Samper, director of the National Museum of Natural History. “The new paleobiology and dinosaur hall will enable us not only to show remarkable fossils, but also to present the latest scientific findings about how life on Earth has evolved.”

“We are grateful to David Koch for this gift that will allow the Smithsonian to update one of the most important and popular exhibitions in the Smithsonian’s National Museum of Natural History,” said Secretary of the Smithsonian Wayne Clough. “Millions of Americans and visitors from all over the world will learn and be inspired for years to come.”

The current dinosaur hall began as “The Hall of Extinct Monsters” when the museum opened in 1910. The museum’s most recent public display of dinosaurs and paleontology has been essentially unchanged for more than 30 years. Although the museum has one of the most comprehensive collections of fossils and a staff of eminent paleobiologists, the exhibition has become outdated because the museum lacked the funding for a total renovation of the space. With this gift, the museum can begin work on a complete overhaul of the exhibition, which has always been a “must-see” destination for families and students visiting the Smithsonian. The new hall will present the fossil record in fresh, new ways to show how dinosaurs and other extinct creatures lived in changing environments.

Renovation of the new hall requires extensive infrastructure work, which will be paid for with federal funds. Crews will later disassemble and conserve the enormous specimens in the exhibit spaces. It is estimated that more than 10,000 bones and other fragile specimens will be removed from the current exhibition before construction begins.

The National Museum of Natural History has an annual federal budget of $68 million in FY 2012, with a professional staff of more than 460 employees. The museum houses 127 million specimens and artifacts—the largest collection at the Smithsonian—and hosts an average of 7 million visitors a year. Its scientists publish approximately 500 scientific research papers every year. Recent renovations of major exhibitions in the museum include the Behring Family Hall of Mammals (2003), the Butterfly Pavilion (2007), the Sant Ocean Hall (2008) and the David H. Koch Hall of Human Origins (2010).