Phragmites australis, the common reed, has been a component of North American marshes for thousands of years. However, a novel genetic lineage, Phragmites australis australis, found its way to North America sometime in the 1800s, scientists believe, probably hiding in plain site as discarded packing material. Its next decades were then spent quietly growing in estuaries and coastal marshes in North America, a minor player in the community of marsh plants, attracting little more than passing notice by wetland scientists.

Suddenly, some 20 years ago in a Jekyll-and-Hyde-like scenario common among invasive plants and animals, this once humble reed “just took off,” says Patrick Megonigal of the Smithsonian Environmental Research Center in Edgewater, Md. Today it is an aggressive invader pushing into the tidal and non-tidal wetlands of North America and vigorously replacing native plants, including its very close native genotype Phragmites australis americanus.

Image above: Ecologist Thomas Mozdzer, former Smithsonian Post-Doctoral Fellow, works beside a patch of invasive Phragmites australis at SERC’s Global Change Research Wetland. There, scientists are manipulating CO2 and nitrogen levels to mimic the world of 2100 if climate change continues as expected. (All photos courtesy of SERC)

Now, a new study by Megonigal and lead author Thomas Mozdzer of Bryn Mawr College, that takes a close look at the biogeochemistry of this invasive plant and its native North American counterpart, reveals how a subtle genetic difference in the lineage of a plant species can have a major impact on greenhouse gas emissions.

The scientists found that invasive Phragmites emits much higher levels of methane (CH₄) than native Phragmites, and both emit more methane when grown under predicted future levels of atmospheric carbon dioxide and nitrogen. As methane is a principle greenhouse gas, these findings, Megonigal says, have the potential to negate the use of tidal wetlands inundated with this invasive reed as an asset in carbon offset credit systems.

Image above: Native and Introduced Phragmites: Native Phragmites (left) and invasive Phragmites (right). The invasive strain of Phragmites australis from Europe is one of the most rampant plant invaders in the eastern U.S. It can grow up to 15 feet tall and monopolizes light and nutrients, preventing any other plants from surviving in its shadow.

“Tidal wetlands store carbon at very impressive rates that are comparable to a rainforest,” Megonigal explains. “They take carbon out of the atmosphere as carbon dioxide (CO₂₎ and turn it into biomass that ends up being stored in the soil as roots or detritus, which is good for the climate. The flip side is that these systems also emit methane.” Overall, however, there is a balance of carbon intake and methane emission in many native tidal wetlands that equals a net benefit for the climate.

Not necessarily so with Phragmites australis, Megonigal says. “When Phragmites australis invades, it has the potential to upset this balance by increasing methane emissions.” Higher levels of atmospheric carbon dioxide and nitrogen also made this plant much more vigorous, a related study showed.

This information is important for people interested in using protected wetlands as credits in carbon offset systems. In order to comply with agreed upon limits to the amount of carbon dioxide they are permitted to emit, governments and companies can buy, sell and trade these credits, which can take the form of protected forests, wetlands and other natural areas that hold or sequester large amounts of carbon.

Image above: Native Phragmites (left) and invasive Phragmites (right). The invasive strain of Phragmites australis from Europe is one of the most rampant plant invaders in the eastern U.S. It can grow up to 15 feet tall and monopolizes light and nutrients, preventing any other plants from surviving in its shadow.

“Invasive Phragmites does not have the potential to vastly increase the emissions of methane globally,” Megonigal points out. “The increase in methane that we are experiencing today is mostly due to anthropogenic sources.

“Still, we suspect that as the climate changes natural sources of methane emissions will begin to increase for a variety of reasons. Our paper shows that one of those reasons could be the introduction of new, novel species that support higher rates of methane production.” –John Barrat

“Increased Methane Emissions by an Introduced Phragmites australis Lineage under Global Change” appeared in the journal Wetlands in May 2013.

Soon after a dirt road through the forests of Lambir Hills National Park in Borneo was improved in 1987, local markets selling the meat of wild animals expanded dramatically. By 1994 biologists observed that a bird known as the helmeted hornbill had vanished from the park and other species—such as the rhinoceros hornbill, the Bornean gibbon and the sun bear—had become extremely scarce. A survey conducted in 2004 found that more than 20 percent of the mammal species and 50 percent of the bird species in the park had vanished.

Rainforest at Lambir Hills National Park in Borneo. (CTFS photo by Christian Ziegler)

Now, a new study published in the journal Ecology Letters spotlights the impact the loss of these animals is having on the forest itself. Using census data from trees growing in a 52 hectare (128 acre) plot in Lambir monitored for 15 years just after the onset of intense hunting, the researchers found a marked increase in crowding of saplings beneath tree species that depend upon animals to disperse their seeds.

“Tree species that use these animals to disperse their seeds have lost the ability to displace offspring far away from the parents,” says study co-author Matteo Detto, of the Center for Tropical Forest Science, Smithsonian Tropical Research Institute. “For this reason these species appear more aggregated or clustered compared to when hunting was not present.”

A selection of seeds from Lambir Hills National Park, many of which are dependent upon animals for their dispersal. (CTFS photo by Christian Ziegler)

Fruit that would formerly have been eaten by hornbills, gibbons and other animals and dispersed far and wide now simply fall to the ground and sprout under the maternal tree. Due to overcrowding these saplings suffer high mortality. The result, the study shows, has been a small but consistent decline in local tree diversity, an effect the researchers expect will become more pronounced over time.

“Lambir is the richest forest in the whole of the Old World tropics, there’s nowhere else in Asia or Africa that has a forest this diverse in tree species, with some 1,200 tree species growing in an area of about 125 acres [the CTFS survey area],” explains Stuart Davies, director of the Center for Tropical Forest Science and a co-author of the study. “Lambir is a tiny little national park and unfortunately what’s happening in the tropics is that many of these conservation areas have become isolated by agriculture of various kinds. In the case of Lambir it is surrounded by oil palm plantations and by a growing urban population. These isolated conservation areas have no future for surviving  if they continue to get hunted in the way they are. The great majority of tree species need vertebrates for their dispersal and most of the big vertebrates are gone.”

The study showed that overhunting of large seed-dispersing animals caused “the spatial distribution of the forest trees to change in a way that could dramatically change the composition” of the forest, says Tania BrenesArguedas, a co-author also from the Center for Tropical Forest Science at the Smithsonian Tropical Research Institute. “It was very impressive that such changes in distribution and survival could be detected in such a short period of time.”

Hylobates mulleri, or Muller’s Bornean gibbon

Among trees with animal-dispersed seeds, species with medium or large seeds had significantly lower success in sprouting new seedlings than species with small seeds. Trees that use other methods of dispersal, such as wind, gyrations and seed projection, did not show greater clustering.

“The situation at Lambir is increasingly prevalent throughout tropical Asia,” the researchers write, “and in other tropical areas with high human populations and a relatively low proportion of remaining forest, including West Africa and the Atlantic forests of Brazil. Moreover, as access improves we can also expect increasing levels of defaunation [overhunting of animals] in remaining large blocks of rain forest, such as the Amazon and Congo, unless the process is countered by strong conservation measures.

“Enhancing the protection of wildlife and restoring animal populations where they have been depleted will be essential for prevent a substantial decline in tree diversity in these forests.”

(The Center for Tropical Forest Science is a global network of forest research plots committed to the study of tropical and temperate forest function and diversity. The multi-institutional network comprises more than 40 forest research plots across the Americas, Africa, Asia, and Europe, with a strong focus on tropical regions. Through regular surveys CTFS monitors the growth and survival of about 4.5 million trees of approximately 8,500 species.)

The paper “Consequences of defaunation for a tropical tree community,” was conducted by scientists from the Chinese Academy of Sciences, the World Agroforestry Center, and the Center for Integrative Conservation in China; the Center for Tropical Forest Science, Malaysia; the University of Pennsylvania, the Smithsonian Global Earth Observatory, the Smithsonian Center for Tropical Forest Science, the Smithsonian Tropical Research Institute, and the World Agroforestry Centre, Osaka City University in Japan. --John Barrat

Previous global warming events led to more diverse tropical forests. This is a view of the lowland tropical forest on Barro Colorado Island in Panama.

South American rainforests thrived during three extreme global warming events in the past, say paleontologists at the Smithsonian Tropical Research Institute in a new report published in the Annual Review of Earth and Planetary Science. No tropical forests in South America currently experience average yearly temperatures of more than 84 degrees Fahrenheit (29 degrees Celsius). But by the end of this century, average global temperatures are likely to rise by another 1 F (0.6 C), leading some scientists to predict the demise of the world’s most diverse terrestrial ecosystem.

Carlos Jaramillo, Cofrin Chair in Palynology, and Andrés Cárdenas, post-doctoral fellow, at the Smithsonian in Panama reviewed almost 6,000 published measurements of ancient temperatures to provide a deep-time perspective for the debate.

“To take the temperature of the past we rely on indirect evidence like oxygen isotope ratios in the fossil shells of marine organisms or from bacteria biomarkers,” said Jaramillo.

When intense volcanic activity produced huge quantities of carbon dioxide 120 million years ago in the mid-Cretaceous period, yearly temperatures in the South American tropics rose 9 F (5 C). During the Paleocene-Eocene thermal maximum, 55 million years ago, tropical temperatures rose by 5 F (3 C) in less than 10,000 years. About 53 million years ago, temperatures soared again.

According to the fossil record, rainforests prospered under these hothouse conditions. Diversity increased. Because larger areas of forest generally sustain higher diversity than smaller areas do, higher diversity during warming events could be explained by the expansion of tropical forests into temperate areas. “But to our surprise, rainforests never extended much beyond the modern tropical belt, so something other than temperature must have determined where they were growing,” said Jaramillo.

Jaramillo and Cárdenas’ report also refers to findings by Smithsonian plant physiologist Klaus Winter that leaves of some tropical trees tolerate short-term exposure to temperatures up to 122 F (5 C). When carbon dioxide concentrations double, trees use much less water, which is further evidence that tropical forests may prove resilient to climate change.

They’ve got no roots or veins and grow in hanging pendants or tightly packed mats attached to stones, soil and wood. Called by some “the secret plants that surround us,” the bryophytes (mosses and liverworts) were the first plants to colonize dry land 475 million years ago. Today more than 26,000 bryophyte species populate the earth.

Now, a recent experiment with a number of tropical species of bryophytes in western Panama suggests that some of these plants may be able to adapt to the warming temperatures that global warming will bring.

Tropical moss of the species Leucoloma cruegerianum can bee seen growing to the right on this branch at a study site in western Panama. (Photo by Sebastian Wagner)

Researchers from the University of Oldenburg, Germany and the Smithsonian Tropical Research Institute in Panama, collected 15 individual plants each of 9 common species of bryophytes found growing at cool higher altitudes in the tropics and transplanted them at lower altitudes where temperatures were an average of 2.6 to 3.6 degrees Celsius warmer.

In the tropics bryophytes are scarce in the warm, drier lowland areas but prolific in higher mountain areas where temperatures are lower and the humidity is higher. As botanist Gerald Zotz, of the University of Oldenburg and the Smithsonian explains, a bryophyte’s survival is a balancing act between its daytime intake of carbon during photosynthesis and its nighttime loss of carbon through respiration. This balance is dependent on temperature and humidity.

Specimens of pendant mosses of the Frullania species hang from wires in a study plot in western Panama. (Photo by Sebastian Wagner)

Higher temperatures and dry conditions can reduce daytime photosynthesis in bryophytes, leading to lower carbon intake. Warmer, dry conditions also increase carbon loss at night through higher respiration rates. (Earlier studies have shown that at optimum temperatures bryophytes lose at night on average 60 percent of the carbon they gained the previous day.) If a bryophyte’s carbon loss is greater than its carbon intake over an extended period the plant will die.

For the experiment, bryophytes growing at altitudes of 1,200 meters were transplanted in study plots at 500 meters. Bryophytes collected at an altitude of 500 meters were transplanted in study plots at sea level. The researchers then observed the transplanted plants for nearly two years to determine how the bryophytes responded in the short term and long term to the warmer temperatures and drier conditions of their new environments.

A majority of the bryophytes transplanted downhill to warmer spots died, but “the most striking result of our study was the finding that at least a few samples of most of the tested species survived higher temperatures for at least 20 months and totally recovered growth during this time,” botanists Sebastian Wagner, M.Y. Bader and Zotz write in a paper which appeared recently in the journal Plant Biology.

Research student Steve González takes growth measurements in a study plot of transplanted bryophytes at the Smithsonian Tropical Research Institute where scientists are assessing the ability of these plants to acclimate to global warming. (Photo by Sebastian Wagner)

“All species have a few individuals that can apparently deal with increased temperatures of 3 degrees Celsius,” Zotz says. “This indicates that there is indeed quite a bit of potential for acclimation.”

In light of these new findings, “it may be puzzling why we do not find more of these species in the lowlands,” Zotz points out. In fact, he continues, some highland bryophytes are found living in the warmer lowlands but they are usually restricted to moist microsites, such as the pendant mosses growing on Annona glabra trees around Lake Gatun, in Panama. Increased moisture may weaken the adverse impact of higher temperatures on bryophytes in the lowlands.

Bryophytes living in the lowlands in the tropics already seem to “live at the edge,” of their temperature tolerance,” Zotz adds. In an upcoming experiment “we are planning to expose lowland species to higher temperatures to see whether they are already at the very limit of their adaptive range,” Zotz says. “If this were true the predicted temperature increases in the future would have serious implications for lowland habitats.”

As the researchers conclude in their paper many species of bryophytes “from higher altitudes indeed will experience problems at higher temperatures,” with their population ranges potentially being shifted uphill.

Still, a second scenario for the impact of rising temperatures on bryophytes in the tropics is for “individuals having the acclimation potential to maintain populations at the present altitude, evolving to be better adapted to high temperatures,” the study says. Some species with a large acclimation potential might even benefit from global changes due to elevated carbon dioxide concentrations and/or reduced competition.  –John Barrat

There is little doubt that human activity is affecting planet Earth, but just how much? And is it all negative? Rick Potts is the director of the Human Origins Program and curator of anthropology at the National Museum of Natural History. In his nearly 30 years at the Smithsonian, Potts has studied the relationship between environmental change and human adaptation, leading excavations in the East African Rift Valley. In the interview below, Potts explores the human period of Earth’s history, the Anthropocene, and what it means for the future by looking far into the past.

Rick Potts studies and samples a portion of the long climate core obtained by drilling at the early human site of Olorgesailie. The core contains clues to the climate of the past 500,000 years, associated with the origin of our species. (Photo by Jennifer Clark)

Q: What exactly is the Anthropocene?

Potts: The Anthropocene is sometimes viewed as a new geological era on earth: the age of humans. But for many of us, that age has been so short-lived at this point that it’s more of a way of thinking about ourselves–acknowledging the enormous impact of human beings on planet earth.

Q: When was the beginning of the Anthropocene?

Potts: Asking to pinpoint the beginning of the Anthropocene is like asking, “When was the beginning of being human?” One could point to walking upright and making tools to do things and manipulate the world. Or one could look to recent times of the enormous population explosion since the industrial age. But there are all sorts of steps in between and I would say that the making of a stone tool more than 2 million years ago and controlling fire nearly a million years ago were the first real signs that something new was on the scene.

Approximately 2 million years old the Kanjera Stone Tool from Kanjera South, Kenya, is the oldest man-made object in the Smithsonian. According to anthropologist Rick Potts at the Smithsonian’s National Museum of Natural History, the start of the Anthropocene is marked by the use of the first man-made tools.

Q: What are three major ways humans are impacting the earth’s ecosystems?

Potts: Humans control six times more water – fresh water – than is free flowing across the continents. Eighty-three precent of all viable land on earth is occupied, used or altered by human beings, so the imprint of human beings on the landscape is extensive. We have done so much to alter the ocean. Just from silts eroded from agricultural land into the ocean, we can totally alter the nature of marine ecosystems.

Q: What do you say to people who say global warming is a hoax?

Potts: I would say that the scientific evidence is really profound that the earth is warming. These problems are going to need to be solved by a concerted action across the world. Denying climate change is unfortunately part of the range of the ways people try to adjust to a fairly difficult situation.

In September 2012, Rick Potts’s team recovered the first long climate core from an early human site by drilling to the floor of the East African Rift Valley in southern Kenya. The core reached sediments more than 160 meters below the ground. (Photo by Jennifer Clark)

Q: Can we reverse some of the negative effects of the Anthropocene?

Potts: I think there are some things that are too late. For example, the use of carbon-based fuels. Even if we stop right now the earth is going to warm immensely. Population increase – it’s hard to get people to stop having fulfilling lives with families. I think a vision for the Anthropocene is really a matter of–do you try to lower the river or raise the bridge? Lowering the river is really hard to do when the flood of Anthropocene events are coming closer to our own communities. Is raising the bridge an option? Well, I think we need to look at a third option: that is, accommodate the rising tide of problems that the Anthropocene poses and realize we’re all in the same ship together. I believe we need to figure out a way to have a ship that is larger than ourselves and includes as much biological diversity and cultural diversity that can fit into the large boat. –Emily Grebenstein

All bear species except for one live in either temperate or tropical woodlands. Only the polar bear is a stranger to the forest, living and foraging instead across vast expanses of barren polar ice. But don’t be deceived, its habitat is not thin and flat like a skating rink but a thick and complex mix of old multi-year ice, new seasonal ice and open water. Polar bears hunt seals in this environment and live and breed on top of their frozen habitat. Recently, warming temperatures have had an enormous impact on the domain of this remarkable mammal.

Here, bear expert Don Moore, associate director of Animal Care Sciences at the Smithsonian’s National Zoological Park, answers a few questions about polar bears, rising temperatures and the future for Smithsonianscience.org.

A polar bear on an ice floe in Wagner Bay, Canada (Photo by Ansgar Walk)

Q: How many polar bears are found in the wild today?

Moore: Polar scientists estimate there are 20,000 to 25,000 polar bears in the five polar bear countries—the United States/Alaska, Canada, Russia, Denmark/Greenland and Norway.

Q: How much ice does one polar bear require?

Moore: Polar bears range over hundreds and even thousands of miles. They come ashore only when their ice melts in summer, in the Western Hudson Bay for instance.

Q: Can you compare the amount of ice sheets in their ecosystem 10 years ago to now? 

Moore: Ten years ago the Arctic Ocean was land-fast with a lot of year-round ice. Recent summer ice losses have been enormous, and in 2012 summer ice losses in the Arctic were larger than the area of the United States. Since Arctic ice is the polar bear’s habitat, bear populations are declining as the ice declines.

Q: Has the polar bear population decreased significantly since you started to study them?

A polar bear on the Islands of Svalbard, the Netherlands. (Photo by Paul W.J. Groot)

Moore: More populations are declining now than before. For example, the Western Hudson Bay population in Churchill, Manitoba in Canada has declined by more than 20 percent in the last 30 years.

Q: When the polar bears’ habitat melts, how do they adapt? Do they use more land to migrate and hunt? What impact does that have on other land animals?

Moore: Polar bears whose habitat melts seasonally must move onto land. But it has been hundreds of thousands of years since polar bears evolved from brown bears. Polar bears are built for eating seals, and cannot live a healthy life for long periods of time eating rodents and plants that brown bears eat. Some have adapted by eating harbor seals or beluga whales, but this behavior will be short-term.

Q: How have changes in the polar bears’ habitat changed the way you conduct your research?

Moore: The Arctic is a forbidding place, and very dangerous to travel in during the 6 months of darkness when winter sets in. Most of my biologist friends take helicopters from land bases to the ice offshore where polar bears live in spring and fall. These times of year can be very stormy, and as the ice has melted it has gotten farther away from shore. Biologists take huge risks flying hundreds of miles by helicopter to the nearest ice. Many researchers have cancelled research trips in recent years so they don’t endanger their study teams.

Q: For most of us, the problems of the polar bear are remote and far away. How do our actions impact these animals hundreds of miles away?

Moore: To help slow climate change we need to change our behavior and put less carbon into the atmosphere. Carbon comes from factories, cars, and other polluting, man-made objects on the planet. If we reduce, recycle and reuse we can reduce the amount of gas going into the atmosphere. Every single person can make a difference and help conserve the planet’s resources.

–Emily Grebenstein

Striking Caribbean sunsets occur when particles in the air scatter incoming sunlight. But a particulate shadow over the sea may have effects underwater. A research team, including staff scientist Héctor Guzmán from the Smithsonian Tropical Research Institute, linked airborne particles caused by volcanic activity and air pollution to episodes of slow coral-reef growth.

Sunset over the Caribbean. A key driver of reduced growth rates at some Caribbean reef locations is regional climate change due to volcanic and human source aerosol emissions, a new study suggests.

Like tree rings, long-lived coral skeletons preserve a record of coral growth. Previously, scientists linked coral-growth patterns in the Caribbean to a phenomenon called the Atlantic Multi-decadal Oscillation—fluctuations in sea-surface temperatures and incoming sunlight.

In order to better predict the effects of climate change and human disturbance on reefs, Lester Kwiatkowski, University of Exeter, and researchers from the University of Queensland, the Australian Nuclear Science and Technology Organization and STRI analyzed coral-growth records from Belize and Panama spanning the period from 1880 to 2000. An Earth-system model simulation told them how well sea-surface temperature, short-wave radiation and aragonite-saturation state, a measure of ocean acidification, predicted changes in coral growth.

Their data came from several coral cores drilled in reefs near the Atlantic entrance of the Panama Canal formed by the coral species Siderastrea siderea between 1880 and 1989, whereas samples from the Turneffe atoll in Belize showed growth fluctuations in the coral species Montastrea faveolata from 1905 to 1998.

Particles from air pollution, primarily sulfate, reflect incoming sunlight and make clouds brighter reducing the amount of sunlight reaching the sea surface. Coral growth corresponded closely to sea surface temperatures and light levels. Growth fluctuations in the late 19th and early 20th centuries were largely driven by volcanic activity.

Researchers explain a dive in surface temperatures and coral growth in the 1960s by increased air pollution associated with post-World War II industrial expansion in North America and to a lesser extent in Central and South America.

The influence of human aerosol emissions was more pronounced in coral cores from Belize, perhaps because Belize is closer to sources of industrial emissions. Fluctuations unexplained by the model, especially in the growth records from Panama, probably result from runoff from deforestation and from the construction of the Panama Canal waterway.

“The coral growth chronology for Panama allowed us to identify the effects of human interventions at the beginning of 1900s,” said Guzmán, “but the decline in growth observed by the middle of the 20th century corresponding to the beginnings of the industrial era in coastal Panama remained unresolved by the model.”

“Our study suggests that coral ecosystems are likely to be sensitive to not only future global atmospheric carbon dioxide concentration but also to regional aerosol emissions associated with industrialization and decarbonization,” said Kwiatkowski.

Africa isn’t the kind of place you might expect to find penguins. But one species lives along Africa’s southern coast today, and newly found fossils confirm that as many as four penguin species coexisted on the continent in the past. Exactly why African penguin diversity plummeted to the one species that lives there today is still a mystery, but changing sea levels may be to blame, the researchers say.

Only one penguin species lives in Africa today — the endangered black-footed penguin, or Spheniscus demersus. But newly found fossils confirm that as many as four penguin species coexisted on the continent in the past. (Harvey Barrison photo)

The fossil findings, described in a recent issue of the Zoological Journal of the Linnean Society, represent the oldest evidence of these iconic tuxedo-clad seabirds in Africa, predating previously described fossils by 5 to 7 million years.

Co-authors Daniel Thomas of the Smithsonian’s National Museum of Natural History and Dan Ksepka of the National Evolutionary Synthesis Center happened upon the 10-12 million year old specimens in late 2010, while sifting through rock and sediment excavated from an industrial steel plant near Cape Town, South Africa.

Jumbled together with shark teeth and other fossils were 17 bone fragments that the researchers recognized as pieces of backbones, breastbones, wings and legs from several extinct species of penguins.

Based on their bones, these species spanned nearly the full size spectrum for penguins living today, ranging from a runty pint-sized penguin that stood just about a foot tall (0.3 m), to a towering species closer to three feet (0.9 m).

Only one penguin species lives in Africa today—the black-footed penguin, or Spheniscus demersus, also known as the jackass penguin for its loud donkey-like braying call. Exactly when penguin diversity in Africa started to plummet, and why, is still unclear.

Only one penguin species lives in Africa today — the endangered black-footed penguin. (Photos by Daniel Thomas)

Gaps in the fossil record make it difficult to determine whether the extinctions were sudden or gradual. “[Because we have fossils from only two time periods,] it’s like seeing two frames of a movie,” said co-author Daniel Ksepka. “We have a frame at five million years ago, and a frame at 10-12 million years ago, but there’s missing footage in between.”

Humans probably aren’t to blame, the researchers say, because by the time early modern humans arrived in South Africa, all but one of the continent’s penguins had already died out.

A more likely possibility is that rising and falling sea levels did them in by wiping out safe nesting sites.

Although penguins spend most of their lives swimming in the ocean, they rely on offshore islands near the coast to build their nests and raise their young. Land surface reconstructions suggest that five million years ago — when at least four penguin species still called Africa home — sea level on the South African coast was as much as 90 meters higher than it is today, swamping low-lying areas and turning the region into a network of islands. More islands meant more beaches where penguins could breed while staying safe from mainland predators.

But sea levels in the region are lower today. Once-isolated islands have been reconnected to the continent by newly exposed land bridges, which may have wiped out beach nesting sites and provided access to predators.

Although humans didn’t do previous penguins in Africa in, we’ll play a key role in shaping the fate of the one species that remains, the researchers add.

Numbers of black-footed penguins have declined by 80% in the last 50 years, and in 2010 the species was classified as endangered. The drop is largely due to oil spills and overfishing of sardines and anchovies — the black-footed penguin’s favorite food.

“There’s only one species left today, and it’s up to us to keep it safe,” Thomas said.–Source: National Evolutionary Synthesis Center/ Robin Ann Smith

Going for the gut will soon become standard protocol for scientists working to unravel the complex living web of interactions between plants and animals on Earth a recent groundbreaking Smithsonian study predicts.

In the study botanists Carlos García-Robledo, David Erickson and John Kress, with entomologists Charles Staines and Terry Erwin, all staff of the National Museum of Natural History, gathered detailed diet data for a guild of rolled leaf beetles in a Costa Rican rainforest. They focused on 20 species of beetles, observing and taking notes as the insects munched away on some 33 different Zingiberales, the flowering plants these beetles eat and lay eggs upon almost exclusively. They documented which Zingiberales species each beetle species ate; some species ate only one while others fed upon a variety. The scientists then created a baseline library of DNA barcodes for each beetle and Zingiberales species in this insect herbivore-plant network.

Six of dozens of rolled leaf beetles collected in Costa Rica for the study. High-quality plant DNA was obtained from the gut contents of these beetles, revealing exactly which Zingiberales plants they had been eating. (Photo by Charles Staines)

The aim of this study, which took more than two years to complete, was to verify a second, much faster method of learning the same information. For this second method, the scientists collected a number of rolled leaf beetles of each species, extracted plant material from each of the beetle’s guts and sequenced the DNA of both the beetles and their gut-plant material.

Matched against the network data and DNA species library created in the first study, the information derived from beetle-gut content study was nearly identical, yet had taken only fraction of the time and effort.

Here, Carlos García-Robledo, principle author of this new research paper in Plos One, answers a few questions about it for Smithsonainscience.org.

Carlos García-Robledo in Costa Rica. (Photo by Erin Kuprewicz)

Q: Why is knowing the network of plant-herbivore associations of a given area important?

García-Robledo: Plants and their associated insect herbivores are a main component of biodiversity. Together they include about 50 percent of all known species on earth. This outstanding diversity is the product of an evolutionary arms race between plants that evolve defenses against insect herbivores and insect herbivores adapting to those defenses. The result after millions of years of these co-evolutionary processes is complex plant-herbivore networks. The first step to understand the processes generating biodiversity on earth is to develop methods to identify such ecological interactions.

The rolled leaf beetle C. alternans inside a Zingiberales leaf with its eggs in Costa Rica.

Q: Is the visual study of the full diet of the beetles done in this paper something that entomologists normally have time to do while collecting specimens?

García-Robledo: No. Studies on insect diets are extremely difficult and time consuming, especially in diverse ecosystems such as the tropical rain forest. It can take years for a researcher to fully understand the diets of a community of insect herbivores in a tropical rain forest without the help of DNA barcodes.

Q: How might this new method of determining plant-insect associations impact this area of entomology and botany? What other areas of biology might it impact?

García-Robledo: These new methods can be used to reconstruct plant-herbivore networks with high accuracy and in shorter time. Direct observation of insects feeding on their host plants can be very challenging for species living on top of the canopy of the forest or feeding underground on roots. Using DNA barcodes it is possible to identify diets of insects in those habitats. This method will help ecologists and evolutionary biologists to understand the ecology and evolution of plant-herbivore interactions.

Entomologist Terry Erwin washes insects that have fallen from high forest branches onto a collection sheet, into a collection container..

These DNA barcode methods were developed for a larger project where we are modeling how climate change will generate plant extinctions and the co-extinctions of associated insect herbivores in tropical mountains. To model the effects of climate change on plant and insect extinctions we need to know the diets of each insect species at different elevations in a tropical mountain. Therefore DNA barcode methods to study insect diets also are tools for conservation research.

Q: Was plant material actually extracted from the guts of the beetles?

García-Robledo: Yes, using DNA extraction methods we obtained a mix of DNA both from the gut contents (plants) and the insects (animal DNA). Using DNA barcodes specific for plants we can identify insect diets. Also, we use DNA markers specific to animals to obtain DNA barcodes specific for each insect species. Although in this study we did not include these results, in a study soon to be published we demonstrate that using the animal DNA barcodes we can identify adult beetles, eggs and larvae to the species with 100 percent accuracy.

Q: Is this the first study of its kind using DNA?

García-Robledo: In a couple of previous studies, molecular biologists tried to use DNA markers to identify insect herbivore diets with limited success. The main problem in these studies was that the extraction methods from gut contents amplified low-quality DNA. Also, the public reference DNA libraries available to identify diets are not complete. As a result, these studies were able to identify host plants usually to the family or genus level.

Botanist John Kress holds a Zingiberales specimen.

What makes this study unique is that we developed DNA extraction techniques and full DNA barcode libraries that allowed us to identify host plants to the species level. Another unique feature of this study is that we invested several years in the field identifying the diets of insect herbivores using direct observations. This baseline data allowed us for the first time to test the accuracy of DNA barcodes to identify insect diets.

According to legend St. Patrick (circa 387–460 or 492 AD) banished all snakes from Ireland, chasing them into the sea after they attacked him during a 40-day fast atop a hill.

Today we suspect that snakes never lived in Ireland, likely because Ireland is an island surrounded by a frigid ocean inhospitable to these creatures. Still, banishing or removing snakes from any environment is a bad idea, says James Murphy, curator in the Reptile House at the Smithsonian’s National Zoo. His office is surrounded by a wide variety of different snake species.

Emerald tree boa at the National Zoo (Photo by Jessie Cohen)

Being carnivorous, some snakes keep down populations of certain animals such as rodents so they are beneficial to farmers, Murphy says. In addition, rodents can carry diseases to which humans can be susceptible. Snakes also are eaten by other animals, providing food. Snake venom has been shown to have medicinal qualities that have helped in the development of certain medicines. Snakes are an integral part of many ecosystems and, “from a personal perspective, they are just plain fascinating,” Murphy says. “The more I learn about them the more interesting they become. They always surprise me.”

As far as attacking St. Patrick, “snakes basically survive by avoiding conflict, not attacking. Many of them are secretive and generally not aggressive toward humans,” Murphy explains. “I’ve collected snakes literally throughout the world all my life and the only snake that I can say was actually aggressive toward me was a nonvenomous black snake when I was in high school,” the 73-year old herpetologist says. “A male was courting a female and he probably just wanted me away from there.”

Sinaloan milk snake is native to Sonora, Sinaloa and into southwestern Chihuahua, Mexico

Snakes are representatives of earth’s incredible diversity and important pieces of its ecological puzzle, Murphy continues. “People are afraid of snakes because they are so much different than we are. They don’t have limbs, they don’t have eyelids, they aren’t very tall, they don’t scream from pain, and they don’t have the kinds of human characteristics comforting to us.  Anything that is so unusual, humans are just unsettled by as opposed to cute, fuzzy mammals like giant pandas or great apes.”

The abnormal fear of snakes is called ophiophobia, after Ophion, the great serpent of the waters in Greek mythology, who mated with Eurynome, the goddess of all things. Eurynome took on the appearance of a bird, laid a giant egg, and Ophion coiled around and incubated the egg until it hatched, producing all living creatures.

“Those of us who work with snakes are bewildered by the widespread fear and loathing directed toward them by humans,” Murphy says.

A newly born tentacled snake at the National Zoo. Tentacled snakes are aquatic and live in South East Asia.

Today, says Murphy, modern humans, like St. Patrick, seem to be driving many animal species, including snakes, not into the sea but to extinction. A recent study published in January in the journal Elsevier predicts that nearly one in five reptilian species are threatened with extinction due in part to human-induced habitat loss and animal harvesting. Extinction risks for certain snakes species may be underestimated due to lack of information on their numbers.

“As herpetologists my colleagues and I are very concerned about the loss of snake diversity,” Murphy says. “What we are watching today is basically an extinction event that includes many snakes, as well as a number of other reptiles and amphibians. An unprecedented number of animals are disappearing from the planet.”

The uplift of the Isthmus of Panama 2.6 million years ago formed a land-bridge that has long thought to be the crucial step in the interchange of animals between the Americas. This includes the  movement of armadillos and giant sloths up into North America, and the relatives of modern horses, rabbits, foxes, pigs, cats, dogs, and elephants down into South America.

This image shows a life reconstruction of Culebrasuchus mesoamericanus, gen. et sp. nov., in its ancient near coastal environment during the early Miocene of Panama. (Original artwork by Danielle Byerley © Florida Museum of Natural History)

However, in the March 2013 issue of the Journal of Vertebrate Paleontology, researchers from the University of Florida and the Smithsonian Tropical Research Institute describe fossil crocodilians that shed a surprising new light on the history of interchange and animal distributions between the Americas.

The fossils are partial skulls of two new species of caiman, relatives of alligators, who live exclusively in South America today. They were discovered in rocks dated from 19.83 and 19.12 million years old and that were exposed by excavations associated with the expansion of the Panama Canal.

“These are the first fossil crocodilian skulls recovered from all of Central America. They fill a gap in evolution between the alligators of North America and the caimans of South America. It’s quite incredible.” says lead author Alex Hastings, a fossil crocodilian specialist at Georgia Southern University.

The presence of the fossils in Panama indicates that caimans dispersed North from South America by the early Miocene, which is over 10 million years earlier than the spread of mammals. This discovery is additionally important because caimans lack the ability to excrete excess salt from their bodies and are restricted to freshwater environments. As a result, they could have only dispersed a short distance across sea water, which supports a recent hypothesis that Central and South America were much closer to each other 19 million years ago than previously thought, and paints a new picture of the past histories of American animals.

“We are starting to understand that while the mammals in Panama 19-21 million years ago were very similar to those found in Mexico, Texas, and Florida at that time, the reptiles tell a different story,” says co-author Jonathan Bloch, a vertebrate paleontologist at the Florida Museum of Natural History. “Somehow, they were able to cross over from South America when it was completely isolated by seaways—this is one of the mysteries that will drive future inquiry and research in this region.”

Journal link:  Hastings, Alexander K, Jonathan I Bloch, Carlos Jaramillo, Aldo F Rincon, and Bruce J. MacFadden. “Systematics and biogeography of crocodylians from the Miocene of Panama.’ Journal of Vertebrate Paleontology, 33(2):1-125. Source: Society of Vertebrate Paleontology.

A new genetic analysis has revealed that many Amazon tree species are likely to survive human-caused climate warming in the coming century, contrary to previous findings that temperature increases would cause them to die out.

However, the authors of the new study warn that extreme drought and forest fires will impact Amazonia as temperatures rise, and the over-exploitation of the region’s resources continues to be a major threat to its future. Conservation policy for the Amazon should remain focused on reducing global greenhouse-gas emissions and preventing deforestation, they said.

The study by University of Michigan evolutionary biologist Christopher Dick, Eldredge Bermingham of the Smithsonian Tropical Research Institute, Simon Lewis of University College London and the University of Leeds and colleagues demonstrates the surprising age of some Amazonian tree species – more than 8 million years – and thereby shows that they have survived previous periods as warm as many of the global warming scenarios forecast for the year 2100.

The paper was published online Dec. 13 in the journal Ecology and Evolution. The new study is at odds with earlier papers, based on ecological niche-modeling scenarios, which predicted tree species extinctions in response to relatively small increases in global average air temperatures.

“Our paper provides evidence that common Amazon tree species endured climates warmer than the present, implying that – in the absence of other major environmental changes – they could tolerate near-term future warming under climate change,” said Dick, an associate professor of ecology and evolutionary biology and acting director of the U-M Herbarium.

But Lewis cautioned that “the past cannot be compared directly with the future.”

“While tree species seem likely to tolerate higher air temperatures than today, the Amazon forest is being converted for agriculture and mining, and what remains is being degraded by logging and increasingly fragmented by fields and roads,” Lewis said. “Species will not move as freely in today’s Amazon as they did in previous warm periods, when there was no human influence. Similarly, today’s climate change is extremely fast, making comparisons with the past difficult.

“With a clearer understanding of the relative risks to the Amazon forest, we conclude that direct human impacts, such as forest clearance for agriculture or mining, should remain a focus of conservation policy,” Lewis said. “We also need more aggressive action to reduce greenhouse gas emissions in order to minimize the risk of drought and fire impacts to secure the future of most Amazon tree species.”

The scientists used a molecular clock approach to determine the ages of 12 widespread Amazon tree species, including the kapok and the balsa. Then they looked at climatic events that have occurred since those tree species emerged. In general, they inferred that the older the age of the tree species, the warmer the climate it has previously survived.

The researchers determined that nine of the tree species have been around for at least 2.6 million years, seven have been present for at least 5.6 million years, and three have existed in the Amazon for more than 8 million years.

Air temperatures across Amazonia in the early Pliocene Epoch (3.6 million to 5 million years ago) were similar to Intergovernmental Panel on Climate Change projections for the region in 2100 using moderate carbon-emission scenarios. Air temperatures in the late Miocene Epoch (5.3 to 11.5 million years ago) were about the same as IPCC projections for the region in 2100 using the highest carbon-emission scenarios.

The 12 tree species used in the study are broadly representative of the Amazon tree flora. Primary forest collection sites were in central Panama, western Ecuador and Amazonian Ecuador. Additional collections were made in Brazil, Peru, French Guiana and Bolivia. Other plant samples were obtained from herbarium specimens.

“The most lasting finding of our study may be the discovery of ancient geographic variation within widespread species, indicating that many rain forest tree species were widely distributed before the major uplift of the northern Andes,” said Eldredge Bermingham of the Smithsonian Tropical Research Institute.

To determine the age of each tree species, the researchers extracted and sequenced DNA from plant samples, then looked at the number of genetic mutations contained in those sequences. Using a molecular clock approach and population genetic models, they estimated how long it would take for each of the tree populations to accumulate the observed number of mutations, which provided a minimum age for each species.

“An important caveat is that because we’ve been in a cold period over the past 2 million years – basically the whole Quaternary Period – some of the trees’ adaptations to warmth tolerance may have been lost,” Dick said. “Additional research is needed to test whether this has occurred.”

The Ecology and Evolution paper is titled “Neogene origins and implied warmth tolerance of Amazon tree species.” In addition to Dick, Bermingham and Lewis, Mark Maslin of University College London is a co-author. Financial support for the research was provided by the Smithsonian Tropical Research Institute, the University of Michigan, the National Science Foundation and the Royal Society.–Source: University of Michigan News Service

The Smithsonian Astrophysical Observatory has been awarded a NASA project to build the Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument. TEMPO will be the first space-based instrument to monitor major air pollutants across the North American continent hourly during daytime. The instrument, to be completed in 2017 at a cost of $90 million, will share a ride on a commercial satellite to a geostationary orbit about 22,000 miles above Earth’s equator.

TEMPO will measure North American air pollution, from Mexico City to the Canadian tar/oil sands, and from the Atlantic to the Pacific, hourly and at high spatial resolution. This will enable scientists to monitor daily variations in pollution amounts, and follow pollution transport. The instrument will resolve pollution levels to a region of several square miles – far better than existing limits of about 100 square miles.

“TEMPO will provide an order of magnitude improvement over our current capabilities,” said Smithsonian principal investigator Kelly Chance.

Together, this temporal and spatial resolution will enable researchers to improve emission inventories, monitor population exposure, and evaluate effective emission-control strategies. It also will provide near-real-time air quality products that will be made publicly available, and will help reduce uncertainty in air quality predictions by 50 percent.

TEMPO will measure ozone, nitrogen dioxide, sulfur dioxide, formaldehyde, glyoxal, water vapor, aerosols, cloud parameters, and harmful ultraviolet radiation. These are major elements in the lower atmospheric ozone chemistry cycle. TEMPO will quantify and track the evolution of aerosol loading.

TEMPO was chosen from 14 proposals submitted to NASA’s Earth Venture Instrument program. Earth Venture missions, part of the Earth System Science Pathfinder program, are small, targeted science investigations that complement NASA’s larger research mission.

The TEMPO team has extensive experience in measuring the components of air quality from low-Earth orbit. Chance is on the science teams of the Ozone Monitoring Instrument, now in orbit on NASA’s Aura satellite, and two European air quality space sensors. The team includes partnerships with Ball Aerospace and Technologies Corp., in Boulder, CO; NASA’s Langley Research Center in Hampton, VA; NASA’s Goddard Space Flight Center in Greenbelt, MD; the U.S. Environmental Protection Agency in Research Triangle Park, NC; the National Center for Atmospheric Research, in Boulder, CO; and a number of U.S. universities and research organizations.

After being deployed on a geostationary satellite, TEMPO will observe Earth’s atmosphere in ultraviolet and visible wavelengths of light to determine concentrations of many key atmospheric pollutants. From geostationary orbit, these observations can be made several times each day when North America is facing the sun instead of once per day, which is the case with current satellites orbiting a few hundred miles above the surface. Other space agencies are planning similar observations over Europe and Asia concurrent with the deployment of TEMPO, forming a global constellation of geostationary air-quality satellites.