News this Week

Science  24 Aug 2012:
Vol. 337, Issue 6097, pp. 896

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  1. Around the World

    1 - Washington, D.C.
    InSight to Probe Martian Innards
    2 - Washington, D.C.
    BRCA Genes Ruled Patentable
    3 - Pará, Brazil
    Court Halts Construction of Amazonian Dam
    4 - New Delhi
    New Lab for HIV Research
    5 - Washington, D.C.
    What's in a Name?

    Washington, D.C.

    InSight to Probe Martian Innards

    An artist's conception of InSight.


    In 2016, NASA will launch a mission to probe the crust, mantle, and core of Mars, seeking to understand how the planet evolved from a nascent ball of magma. InSight (Interior Exploration Using Seismic Investigations, Geodesy, and Heat Transport) is based on the designs that delivered the Phoenix lander to Mars, reducing cost and risk. That likely appealed to NASA managers, who picked InSight over proposed missions to land on a lake on Titan or an active comet.

    The new mission is designed to probe to the core of Mars with minimum effort. A single seismometer on the surface will use the seismic waves from small quakes and meteorite impacts to chart the interior. Temperature sensors sent a few meters down a drill hole will reveal how the planet is cooling. And exquisitely precise measurements of the lander's motions as Mars wobbles will refine the seismic picture of the rocky planet.

    Washington, D.C.

    BRCA Genes Ruled Patentable

    For the second time, an appeals court in Washington, D.C., has ruled that patents on BRCA genes linked to breast and ovarian cancer are valid. Patent holder Myriad Genetics of Salt Lake City has come under fire from medical organizations and scientists, including Nobelist James Watson, who opposed the patents in an amicus brief in June. The challenge, led by the American Civil Liberties Union and the Public Patent Foundation of New York City, went all the way to the Supreme Court, which earlier this year sent it back down for a lower-level review. The Court of Appeals for the Federal Circuit voted 2–1 last week in favor of the patents, again giving a green light to patents on isolated DNA and cDNA. But the court ruled that the company's method of comparing DNA sequences was too abstract to be patentable. Judge William Bryson disagreed with the majority in part, arguing that genes and gene fragments should not patentable; the ruling, he warned, “will likely have broad consequences, such as preempting methods for whole-genome sequencing.” Neither side has said whether it will appeal.

    Pará, Brazil

    Court Halts Construction of Amazonian Dam

    Construction of the Belo Monte Dam in June 2012.


    A federal court in Brazil has stopped work on the controversial Belo Monte Dam, finding that the indigenous peoples who live along the Xingu River were not adequately consulted. If completed, the $15 billion dam will be the third largest in the world, have the capacity to generate up to 11,000 megawatts, displace perhaps tens of thousands of residents, and flood hundreds of square kilometers of rainforest.

    Brazil's National Congress approved the plans in 2005. Electric company Eletro bras and a consortium of construction companies subsequently produced an environmental impact assessment, and construction of the dam began in June of last year. But the Regional Federal Tribunal ruled last week that the tribal consultations should have been completed before the Congress gave its approval.

    The decision is expected to be appealed to the Brazilian Supreme Court. In a statement, Norte Energia S.A., which is building the dam, said that many workers would lose their jobs, local governments would forgo $22 million in taxes per month, and development work would cease.

    New Delhi

    New Lab for HIV Research


    Last week, India opened a $12 million, government-backed laboratory whose mission is to create a new vaccine against HIV. The HIV Vaccine Translational Research Laboratory, which aims to recruit about 30 scientists, is embedded within the Translational Health Science and Technology Institute, a $200 million facility under development on the outskirts of New Delhi. It will work in collaboration with the New York based–International AIDS Vaccine Initiative (IAVI); operating costs will be shared equally.

    “Researchers have long known that after a few years of infection, a minority of HIV-positive people produce antibodies that can neutralize a broad spectrum of HIV variants. … Designing a new broad-spectrum HIV vaccine will be the mandate of this new lab,” says Margaret G. McGlynn, CEO of IAVI.

    India has the world's third largest burden of AIDS, despite the fact that “HIV infections have declined by 56% during the last decade, from 270,000 in 2000 to 120,000 in 2009,” says India's health minister Ghulam Nabi Azad.

    Washington, D.C.

    What's in a Name?

    A controversial attempt to change the name of the U.S. National Science Foundation's Division of Mathematical Sciences (DMS)—renaming it the Division of Mathematical and Statistical Sciences—is off the table for now. But subtler changes at DMS may lie ahead.

    DMS Director Sastry Pantula, a statistician and former president of the American Statistical Association, floated the idea in a letter in October 2011. “Including both disciplines in the name,” he wrote, “would allow the Division to effectively leverage the combined resources and support of two very large communities.” Funding for statistical research is currently spread throughout the agency.

    The proposal sparked sharp debate. Mathematicians overwhelmingly opposed the change, arguing that “mathematical sciences” already includes statistics and singling out one subdiscipline would be divisive. Statisticians and their organizations almost unanimously supported the change as an overdue recognition of the importance of their discipline.

    On 16 August, NSF officials announced that the name won't change, but the agency will appoint a new external committee to review the role of statistics in science and how NSF should fund statistical research. NSF will also specifically mention “statistics” alongside “mathematics” in future budget requests and solicitations for research proposals.

  2. Random Sample

    Rare Bird Learns to Fly Away Home


    After centuries away, the northern bald ibis is starting to learn its way around Europe again. Last week, a bird named Jazu became the first northern bald ibis to learn a full migration cycle in Europe without the help of humans since the birds went extinct on the continent almost 4 centuries ago.

    The northern bald ibis is critically endangered in the Middle East and North Africa, and only one long-standing wild colony still migrates in the Middle East. But for the past decade, the Austria-based Waldrappteam has been successfully using ultralight aircraft to teach hand-raised northern bald ibises to migrate from Waldrappteam colonies in Germany and Austria to Tuscany, Italy. Waldrappteam leader and biologist Johannes Fritz hopes to use the ultralight method to reestablish migrating colonies in Europe and to support conservation elsewhere.

    Enter Jazu. The bird wasn't human-raised and didn't learn to migrate by following an ultralight; instead, his natural parents raised him last year in the Waldrappteam colony in Burghausen, Germany. Then he followed one of the colony's older birds, who had previously learned to migrate from an ultralight, to the birds' wintering grounds in Tuscany.

    But last month, Jazu started back north on his own. He crossed the Alps, and on 10 August showed up in Burghausen, Fritz says. “This shows … that a stable migration tradition can be established” with northern bald ibises using the team's method. Indeed, he adds, Jazu may already be carrying on the tradition: He started back south the very next day—with a young bird in tow.

    Creative Commode


    This prizewinning toilet “user interface” could be a key to the future of toilet technology. The design won a $40,000 prize last week at the Reinvent the Toilet Fair organized by the Bill & Melinda Gates Foundation. The fair brought together scientists from 29 countries seeking to replace the flush toilet in regions without adequate sanitation.

    A toilet's attractiveness is a crucial part of any workable solution, notes Carl Hensman, the foundation's program officer for water, sanitation, and hygiene. This design—by Tove Larsen of the aquatic research center Eawag in Dübendorf, Switzerland; Harald Gründl of the design firm EOOS in Vienna; and their colleagues—comes in under the foundation's cost criteria of 5 cents per user per day.

    The top $100,000 prize at the fair went to Michael Hoffmann of the California Institute of Technology in Pasadena and his colleagues, who designed a solar-powered electrochemical reactor that breaks down human waste to produce hydrogen gas. The foundation's goal is to have a field-tested “Toilet 2.0”prototype ready for larger-scale testing by 2015.

    They Said It

    “The theory of evolution is a theory, and essentially the theory of evolution is not science—Darwin made it up.”

    —Kentucky state Representative Ben Waide (R), to The Lexington Herald-Leader, following a hearing last week on the state's decision in 2009 to bring its science curriculum up to national standards, including teaching evolution.

    “Referring to biological evolution as a theory for the purpose of contesting it would be counterproductive, since scientists only grant the status of theory to well-tested ideas.”

    —Terry Holliday, Kentucky education commissioner, in a 2011 letter.

  3. Newsmakers

    Three Q's



    Nuclear physicist and science communicator Aziza Baccouche—aka “Dr. Z”—is hoping to raise the visibility of underrepresented groups in the sciences, including minorities and people with disabilities. Baccouche—who is blind and African-American—has been a science correspondent for CNN and a producer for The Kojo Nnamdi Show. Now, through her company Aziza Productions Inc., Dr. Z is embarking on a half-hour documentary film series exploring the universe through the eyes of a legally blind scientist. The pilot airs on Howard University Television on 26 August.

    Q:What is the focus of the show?

    It's dealing with perceptions and prejudices about disability, and in particular about blindness. My [college] adviser used to say that it takes sight to do physics. What I'm trying to showcase in the series is that it doesn't take sight—it's about being able to visualize intellectually.

    Some people might say, “How do you do television?” I say I'm bringing an advantage to the table: People communicating with me can't get away with pointing at things. It forces the scientists to be more descriptive.

    Q:What's the pilot about?

    In 2010, we flew with a team of scientists, including physicist [Gregory] Jenkins at Howard University in Washington, D.C., on a NASA plane into Hurricane Earl. The story focuses on hurricane science, but also connects the wider story to [Hurricane] Katrina and why this science is important.

    Q:What's next for the series?

    The National Science Foundation supported the first film through a grant to Dr. Jenkins, but we're trying to secure some ongoing underwriters. We're working on films about the big bang theory and proton therapy.

  4. Ecology and Evolution

    The Great Guppy Experiment

    1. Elizabeth Pennisi

    A tiny fish is showing how ecological and evolutionary forces interact to shape the world we live in.

    Gone fishing.

    In Trinidad, a mark-recapture study of guppies is testing the connections between evolution and ecology.


    GUANAPO RIVER VALLEY, TRINIDAD AND TOBAGO—David Reznick is on a first name basis with the hundreds of guppies living in a stretch of the Taylor River, a tropical mountain stream in Trinidad's Northern Range. Ditto for populations of these tiny fish in three other nearby streams, all headwaters of this Caribbean island's Guanapo River. For the past 4 years, this evolutionary biologist from the University of California, Riverside, and a cadre of dedicated interns and colleagues have made monthly treks up these streams to follow the lives of the guppies. They have learned how fast each fish grows, where it spends its time, and, thanks to genetic tests, who its descendents are.

    This intimacy, along with detailed studies of the streams themselves, is helping to answer a key biological question: What is the interplay between ecology and evolution in shaping how both a species and its environment change through time? “They are looking at everything from the changes in the guppies up to the ecosystem,” says Stephen Ellner, an ecologist at Cornell University. Others are also looking for these sorts of effects (see sidebar, p. 906). But “there's been nothing like it with such thoroughness and detail.”

    But the pioneering, $5 million “eco-evo” experiment hasn't always flowed smoothly. An unexpected guppy baby boom forced Reznick's team to scramble to find more work space and help, and the researchers have had to cope with flash floods and voracious army ants. And now that results are starting to come in, the project is running low on money. Nonetheless, “it's already a classical study,” Ellner says.

    Rapid evolution

    One morning this past June, Reznick steered a Suzuki Jeep along a steep, winding road into his study site at the top of the Guanapo watershed. Just 2 years ago, the condition of the road—which saves an hour's walk—was so bad that researchers and local residents spent 3 days resurfacing part of it with pitch to make it passable. Now, the entire road is sorely in need of repair, and Reznick worries that it won't last much longer.

    Reznick, 60, has been doing research in Trinidad for nearly 35 years. In 1978, he was a fourth-year graduate student at the University of Pennsylvania studying mosquito fish in New Jersey when he heard another scientist talk about the island's guppies. Soon, Reznick had persuaded his thesis committee to let him travel here for a project that changed the trajectory of his career. “I always wanted to work in the tropics,” says Reznick, who still has a childlike enthusiasm about the island's plants and animals, particularly frogs and snakes. Many evenings after the work is done, he heads into the bush, tracking down the peeps and croaks of tree frogs.

    He wasn't the first scientist to be captivated by Trinidad's guppies—or the possibility of using the island's steep mountain streams as a natural laboratory. Beginning in the late 1940s, independent biologist Caryl Haskins helped bring ecological genetics to life by exploring how ecological conditions influenced color variations among Trinidad's guppy populations. He discovered that, as one moves upstream along the rivers and their tributaries, the fish communities get simpler. Lower reaches have guppies and other fish, such as cichlids, that hunt guppies. But these predators can't make it upstream past waterfalls, so middle stream reaches tend to harbor just guppies and killifish, an omnivore that only sometimes eats guppies. And in the headwaters, Haskins found that not even guppies were present, just killifish, which are able to hop out of the water and climb up seemingly impassable falls. Most importantly, Haskins showed that male guppies from the downstream, high-predation communities had duller colors than fish in the upstream, low-predation stretches, presumably to be less attractive to predators.

    During the 1970s, Haskins's findings prompted John Endler, now at Deakin University, Geelong Waurn Ponds Campus, in Australia, to try follow-on experiments: He took some of those downstream, dull guppies and moved them upstream into a low-predation environment. Within about five generations, the fish evolved brighter color patterns.

    Such findings helped add heft to conceptual work done in the 1960s by ecologist David Pimentel of Cornell University. At the time, the fledging field of evolutionary ecology considered ecology to be the template that shaped evolution. Pimentel had a different idea. He proposed that ecology and evolution were like two actors in a play, constantly interacting and influencing each other. For example, he suggested that as organisms increased in number in a given environment, they consumed local resources, reducing what was available to support population growth. This change altered the selection pressures exerted by the environment, which in turn altered the organism's evolutionary course. Pimentel's experiments with house flies and parasitoid wasps bore out his idea, but “he didn't gain any traction at all,” Reznick says.

    Guppy hunter.

    For 35 years, David Reznick has used isolated stretches of Trinidad's tropical streams as natural laboratories to test ideas about evolution by transferring and studying guppies.


    One problem was that most biologists thought evolution happened too slowly to observe in nature, so they didn't try. “People didn't see evolution as a contemporary process,” Reznick says. But in 1978, when Reznick heard Endler describe his work translocating guppies in Trinidad's streams, he had an epiphany: “His system was perfect for studying rapid evolution.” The Trinidad guppies potentially reproduced quickly enough—producing up to four generations per year—to exhibit evolutionary changes in just a few years.

    Soon, Reznick had convinced his thesis committee to let him go to the island to test one theory: that fish exposed to an abundance of predators should evolve to mature faster, at a smaller size, and put more resources into reproducing more young more often. He spent 21 days collecting fish from 20 locations, bringing five groups of guppies back to the lab. Ultimately, he showed that the higher-predation guppies evolved as predicted, and that the changes were due to fundamental genetic shifts and not just short-term exposure to a new and different environment.

    The Trinidad studies weren't the only ones suggesting that evolution could happen on an observable time scale. Over the course of their several-decade study, Peter and Rosemary Grant of Princeton University had observed rapid changes in the size and shape of the beaks of Darwin's finches on the Galápagos Islands. Beaks varied from year to year, depending on how weather, particularly droughts, changed the types of seeds available for birds to eat. Soon, Reznick—who was by then a researcher at the Academy of Natural Sciences of Philadelphia in Pennsylvania—was following up with more studies in Trinidad that involved transplanting guppies into new stream environments and observing the changes over 4 to 11 years. The studies provided “an experimental test of evolution in nature,” he says.

    While Reznick was chasing his guppies, Cornell University ecologists Nelson Hairston and Ellner were following evolution from a different perspective. In the lab, they set up a model ecosystem that included microscopic freshwater organisms called rotifers and either one or two strains of their algal prey. In 2004, they monitored this enclosed environment, tracking the rise and fall in the abundances of the rotifers and algae. The rotifers preferred to eat one strain of algae, and so over time they changed the relative abundance of the two strains. Ultimately, the algae population “evolved” to have the genetic background of the less tasty strain. That shift, in turn, changed the ecology of the system by altering predator-prey dynamics. The experiment neatly demonstrated Pimentel's concept: “Eco” and “evo” acted together to stage an unfolding biological play. Observers “couldn't explain the [ecological] dynamics without understanding what's going on with the evolution in the system,” says David Post, a community ecologist at Yale University.

    Reznick wondered whether he might be able to document similar eco-evo interactions among transplanted guppies in his natural streams. In 2005, he decided to pull out all the stops to try to find out. He recruited ecosystem experts, geneticists, theorists, and population biologists to help develop a proposal and in 2006 won a $5 million grant from the U.S. National Science Foundation's (NSF's) Frontiers in Integrative Biological Research program to carry out the experiments. His plan: to mimic natural migration patterns by transplanting guppies into stream reaches that didn't previously harbor the fish. “I'm taking the results from theory and lab studies and asking, ‘Are they important in nature?’” Reznick says.

    Eco-evo test bed

    At the end of the potholed road, Reznick parks the Jeep and walks along an old plantation trail, overgrown to a narrow path and flanked by tall cocoa and coffee trees. It ends on the banks of the Guanapo River, whose tributaries are at the heart of his eco-evo test bed. Reznick starts sloshing his way upstream. “We wind up walking in the rivers,” he says. Boots with studded soles are the shoe du jour. At times the water is chest deep. Some places require the researchers to clamber up small waterfalls, often with two butterfly nets and a backpack full of water bottles in tow. (The bottles are used to take live guppies back to the lab.)

    The Taylor is one of four streams that Reznick and his colleagues picked from more than a dozen candidates for their study, which began in 2008. Each has a 100- to 180-meter stretch of relatively flat water between two waterfalls that serve as barriers to fish migration. Prior to the experiment, the stream segments had no guppies, just killifish.

    Before seeding each stretch with 40 male and 40 female guppies derived from a high-predation site downriver, ecologists carefully documented the ecosystems. They characterized the killifish and invertebrates, looked at primary productivity, measured the standing algal crop, and even took into account the organic contributions of leaves falling into the stream. At two streams, they also removed some of the overhanging canopy, increasing the amount of available light, potentially an important ecological variable. Then, every month, they began repeating their measurements—and capturing and releasing the guppies in order to monitor changes in both individual fish and the populations as a whole.

    It's a laborious process. Three days before the Jeep trip, field manager William Roberts and several interns had trekked up to the Taylor River on a fishing expedition. Using a tape measure, they marked off distinct pools, riffles, and side pools. Then, with butterfly nets, they caught every fish they could see in each section and transferred the fish to marked Nalgene bottles filled with river water for the 2-hour trip back to the lab. The anglers had to stay out of the water to avoid disturbing the stream's ecology, so the netting took some creativity. “You have to contort your body into funny positions,” Roberts says. It's not unusual, he says, to find someone draped over a rock reaching into a pool. And, 2 years ago, the collectors had to scramble to rescue their bottled fish from a flash flood that threatened to sweep away their research subjects. “Now we pay more attention to the weather,” Roberts says.

    Once the collecting was done, the researchers hauled the now-25-kilogram packs back to the lab, a covered veranda in the back of the house where they live. There they transferred the fish to a series of aquaria lining a wall. Now, however, processing the fish is delayed. As rain pours down outside, army ants invade the lab, covering the floors and walls in black streams and devouring termites that have flown into the room the night before as part of their breeding migration. An unlucky gecko that strays into the ants' path is also gobbled up. By midmorning, the ants are gone without a trace and the interns set up an assembly line.

    Reznick, eager to help, anesthetizes each fish and then hands it off to an intern, who puts it under a microscope to check for identifying tattoos. (When a guppy reaches 14 millimeters, the researchers inject two microscopic dots of colored plastic under its skin. There are 12 colors and eight possible injection points, creating enough combinations to give thousands of fish a unique tattoo.) Fish that aren't yet marked get a tattoo, and workers take three scales for DNA sequencing. They weigh and photograph the fish, and add information on any distinguishing characteristics to a master data sheet. There is a sense of urgency, as the researchers try to minimize their handling of the fish and get them through the process quickly before they wake up. Finally, the researchers are ready for a return trip to the Taylor, where they will release the fish into the same sections where they were caught.

    Guppy boom

    Early on, the grand guppy experiment almost became a victim of its own success. At first the numbers were manageable—populations in each stream grew to about 300 the first year. But by 2009, one stream had 1600 fish and by 2010, it had 2600. Populations in other streams were also exploding. Reznick got a panicked call from Andrés López-Sepulcre, the postdoc in charge of the census. “We didn't have the means to deal with that scale of fish,” Reznick recalls. But they scrambled to hire more people and developed the high-speed production line. Now, the team has dossiers on 30,000 fish (about 15% of which are currently alive). For each, “We have a personal history, where it lives, who it lives with, what its weight gain is,” Reznick says.

    The rich database is giving the researchers a detailed look at how the eco-evo script is playing out for the Trinidad guppies. The guppy population explosion, for example, meant fish numbers in the test streams reached densities 10 times higher than those in the high-predation stream where the guppies originated. The denser populations led to changes in the amount and type of available food, and within three generations, the fish had begun to shift to different reproduction and growth patterns. For example, instead of growing fast and maturing young, as guppies in high-predation streams do, males are now older and larger at maturity. “We can see them changing their environment and evolving,” Reznick says. “The question is whether they are imposing selection on themselves and helping to transform the great-grandchildren into low-predation guppies.”

    The fish are also affecting the ecology of their new homes. In the test streams, certain invertebrates, such as midges and mayflies, have become less abundant. Also, it seems that adding guppies increased primary productivity a little. And guppies have reduced the number of small killifish, as they eat or outcompete the newborns. “Guppies are in the process of changing their environment in all four streams,” Reznick says.

    No easy task.

    Monthly, researchers hike up to test streams to capture all the guppies (inset) there. They bring the live fish to the lab to weigh and photograph, then put them back into the streams.


    To help clarify how the fish influence stream ecology, Reznick's team has also set up 16 small artificial streams. “We put in different combinations of guppies from low- and high-predation streams and ask how the ecosystem changes over time,” Reznick explains.

    As the stream ecosystems shift, the new environments favor guppies with different traits, such as body shape and coloration, from those of their ancestors. To distinguish which of these traits are genetically based and which are influenced by the environment, once a year the researchers collect young guppies from each test stream and their source river. They bring these populations back to the lab to be raised in identical aquarium environments for two generations (essentially controlling for environmental factors). One finding from such studies is that the overhanging canopy appears to be playing a role: In streams with an intact canopy, and thus more limited light and plant growth, “we can see the evolution of male age and size at maturity occurs more quickly,” Reznick says. The males are maturing later in life and at larger sizes than those living in the two streams where researchers pruned the canopy.

    The DNA taken from the scales is also enabling the scientists to glean details about reproductive success. Geneticist Paul Bentzen of Dalhousie University in Halifax, Canada, is using DNA markers to build guppy pedigrees that identify who mated with whom and the offspring. What they know so far is that there was a wide variation in reproductive success among the founding 40 females. After 4 months, numbers of their surviving young ranged from 0 to 16. Males also varied in their success.

    By looking for shifts in how many offspring each male and female produces, Reznick hopes to detect eco-evo effects. Theory suggests that if eco-evo forces are at work, then selection should be weak at first—most females should be able to reproduce successfully—and become stronger over time, as the guppies modify their environment by using up resources. At that point, most females should have no offspring and a few should have many.

    Reznick is convinced the guppy project will eventually put the spotlight on such compelling eco-evo examples. But he's worried the story might go unfinished. The NSF program that is funding the work has ended, and Reznick is uncertain how he will continue the monthly mark-and-recapture studies beyond 2012. He's already started using personal funds and frequent-flyer miles to stretch budgets. It's an unfamiliar situation for the researcher, who has been continuously funded by NSF since 1978. He'd like to continue his work in Trinidad for another decade, estimating that's how long it will take to nail everything down. “We know that guppies are ecosystem engineers,” he says, but “we're only partway to showing that the way guppies adapt to their environment is part of that impact.”

    Other researchers also worry that funding issues could bring the curtain down on the Trinidad project too early. “Things are going to start happening in the next 5 to 10 years,” predicts field manager Roberts. “It's been going on for such a long time, it would be kind of a waste to stop what we are doing.”

  5. Ecology and Evolution

    Eco-Evo Effects Up and Down the Food Chain

    1. Elizabeth Pennisi

    Researchers are investigating how the alewife, a fish that lives in lakes in eastern North America, shapes and is shaped by its freshwater ecosystem.

    Ripple effect.

    Both prey and predator, Daphnia affect lake food web dynamics.


    A decade ago, few ecologists factored evolution into their studies. How species changed over time was important, but it happened too slowly to be worth considering as they sought to understand ecosystem processes today. That attitude, however, is changing. Using guppies living in natural streams (see main text, p. 904) and other organisms, researchers are exploring links between evolution and ecology in a number of different settings, documenting interconnections that extend down to genetic changes. “It's a very dynamic field,” says Andrew Hendry, an evolutionary biologist at McGill University in Montreal, Canada. “Everyone is getting involved.”

    In one notable example, David Post is focusing on how the alewife, a fish that lives in lakes in eastern North America, shapes and is shaped by its freshwater ecosystem. The community ecologist from Yale University and his colleagues have shown how these so-called eco-evo effects can ripple across a food web in unexpected ways. “It's one of the best examples of how ecology and evolution interact in a contemporary time frame,” Hendry says.

    Post's work follows in the footsteps of two other Yale researchers, John Langdon Brooks and Stanley Dodson. In 1965, they showed the key role that alewives (Alosa pseudoharengus), which grow to 25 centimeters, play in determining the makeup of lake zooplankton, particularly Daphnia, tiny crustaceans commonly known as water fleas. Typically, alewives are anadromous: They spend their adult lives in the Atlantic Ocean. Each spring, the fish swim up coastal streams from Nova Scotia south to the Carolinas into lakes for a few weeks to mate and spawn. The young spend the summer and fall in fresh water before they head out to sea again.

    That cycle has profound implications for a lake's population of Daphnia, which are usually the dominant zooplankton. The newly arrived alewives and their young are hungry and feast on the water fleas. “They are a slash-and-burn fish,” Post says. Daphnia populations are not restored until the following spring, when eggs resting in the lake bottom hatch.


    Chain pickerel have moved offshore in lakes with landlocked alewives.


    About 300 years ago, however, the building of dams stranded some alewives in lakes, creating landlocked populations. More than 40 years ago, Brooks and Dodson showed the Daphnia had all but disappeared from those lakes. The landlocked alewives were left with smaller prey and, consequently, have evolved smaller mouths and smaller gill rakers inside their mouths that are better suited to catching those prey. That shift itself likely reflects how ecological change imposed by the alewife led to an evolutionary change in the fish.

    But Post and postdoctoral fellow Matthew Walsh decided to go a step further: They looked at whether the ecological impact of the alewife on the Daphnia had evolutionary consequences for the Daphnia as well. Walsh collected eggs from the sediments of lakes with landlocked ale-wives, as well as lakes that were still connected to the sea and those that had no alewives at all. Then, he raised several generations of Daphnia in the lab. He found genetically based differences: Daphnia from lakes with anadromous alewives grew faster, matured sooner, and produced many more offspring than Daphnia from landlocked or ale-wife-free lakes. “There was an overall shift in life history evolution,” says Walsh, who is now based at the University of Texas, Arlington. In undammed lakes, the strategy allows Daphnia populations to thrive in early spring and deposit plenty of resting eggs before hungry alewives arrive, Walsh and Post reported in 2011.

    This ecologically induced evolution in turn has another ecological effect. The spring population explosion of Daphnia takes a serious toll on the algae the water fleas eat, in turn shaping overall ecosystem function, Walsh and his colleagues reported in the 23 May issue of the Proceedings of the Royal Society B. Walsh grew Daphnia in large 56-liter tubs stocked with algae and monitored the growth of both the algae and the Daphnia, as well as the primary productivity of the tubs. In the tubs with Daphnia from lakes that harbored seasonal alewives, there was a rapid and sharp decline in the phytoplankton population that also caused the clarity of the water to improve. At the same time, primary productivity dropped by 32%. Those changes did not occur in tubs with water fleas from landlocked and alewife-free lakes. “More and more studies are showing that evolution can have strong effects on ecology,” says Patrik Nosil, an ecologist at the University of Sheffield in the United Kingdom. Whether these ecological changes in turn affect evolution in the phytoplankton remains to be determined, Walsh says.

    Voracious youngsters.

    In lakes, young alewives devour all the Daphnia.


    Meanwhile, Post and postdoc Jakob Brodersen have now looked in a different direction along the food web. Chain pickerel are a native predator in eastern North American lakes, lurking close to shore to catch other fish. For a year, Post and his colleagues intensely sampled 10 lakes, three with landlocked alewives, three with seasonal alewives, and four with none. To their surprise, they found pickerel in the middle of landlocked lakes, far from their usual shoreline lairs. These fish were not just passing through, either. They tended to have a deeper body and a slender head compared to their counterparts close to shore, and their stomachs were full of alewives. Carbon-isotope ratios in the pickerels' tissues, which can differ depending on whether the fish has an offshore or inshore diet, indicated that these pickerel are offshore residents, Post reported last month at the First Joint Congress on Evolutionary Biology in Ottawa. That's important because it suggests that the change in the alewives' life history—to a landlocked population—has rippled out to affect the pickerel.

    “We believe they are undergoing a novel niche shift,” Post says. Pickerel probably don't hang out in the middle of lakes with seasonal alewives, he notes, because the prey disappear each fall. But in landlocked lakes, there appears to be an advantage to heading out to the lake's middle: Offshore pickerel had a higher fat content than inshore pickerel, suggesting they have found a better way of making a living.

    Hendry says the alewife system is a “particularly elegant example” of “how evolutionary and ecological effects cascade throughout the food web.”

  6. Archaeology

    Economic Crisis Forces Spanish Archaeology to Rethink Its Roots

    1. Elisabeth Pain*

    After riding high for a decade, commercial archaeology in Spain faces a crisis in the wake of a real estate and economic bust.


    Archaeologists uncovered a statue of the Roman goddess Fortuna (inset) in Valencia in 2007, but most commercial digs have now stopped in Spain.


    In 2007, Spanish archaeologist Tina Herreros and her company dug up a prize in the city of Valencia: a unique, 1-meter-tall marble statue of the goddess Fortuna from the 2nd or 3rd century C.E. The statue was unearthed in the ancient Roman necropolis of La Boatella as part of a major, 5000-square-meter dig her crew had undertaken at a site where a three-story parking garage and housing complex were about to be built. The Dama de La Boatella, as the statue is now known, heralded good fortune for Herreros's company. The 10-month project employed eight archaeologists, 60 field workers, and three drafters, and bumped the company's revenue to about €1 million that year.

    But the statue didn't bring lasting luck. The burst of the property bubble and the economic crisis have since brought construction in Spain to a standstill and essentially halted new digs. Today, Herreros has let go all of her staff members and is making do with minor prospecting in rural areas. Commercial archaeologists have “been the first to start paying for the crisis, because the payments started to run short, and then the projects started to run short,” she says.

    The real estate boom and economic bonanza were the foundation of commercial archaeology in Spain. The country has many precious remains, from the ancient hominins of the Atapuerca Mountains—where fossils were first discovered when digging for a railway—to cities such as Seville, where key remains go back to the Lower Paleolithic. In bustling regions such as Madrid, there has been so much commercial archaeology that ancient physical landscapes of each period “could be reconstructed almost completely,” says archaeologist Jaime Almansa Sánchez, who runs a public archaeology company in Madrid. Archaeologists salvaged thousands of artifacts during the boom, but now many worry about the future of commercial archaeology, and some call for reshaping the field. “This business model, with companies building themselves under the umbrella of the construction sector, … has come to an end in Spain,” says social scientist Eva Parga-Dans of the Carlos III University of Madrid, who studies commercial archaeology.

    The demand for commercial archaeology took off in 1985, when the national government launched the Law of Spanish Historical Heritage, which led to the requirement that building sites with potentially interesting ancient remains be assessed for their archaeological value before the bulldozers came in. (Other European nations and the United States have similar laws or governmental guidance.) The legislation coincided with growth in urban construction and public infrastructure. Starting in the mid-1990s and for more than a decade, the expansion spawned “a large boom of archaeology companies,” Parga-Dans says.

    Back then, each local government wanted its own infrastructure—“very large building works for harbors, roads, railways, and big centers of all kinds,” says Almansa, who is former president of the Madrid Association of Male and Female Workers in Archaeology. In 1990, there were about 225,000 municipal construction licenses for buildings in Spain, Parga-Dans says, using data from the National Institute of Statistics. By 2007, that had risen to more than 737,000.

    All that building required archaeology—but no longer. In 2001, the main Spanish regions together licensed more than 2300 archaeological projects, and in 2007 that number soared to a peak of 5819. But in 2010, it dropped to 3700, according to Parga-Dans. In most regions of Spain, archaeological “companies are going bankrupt, and those that aren't going bankrupt are below minimums,” Almansa says. “Practically all the people who used to be contracted are without a job right now. The only ones who are working … are the partners in the companies.” He estimates that in Madrid the number of active commercial archaeologists plunged from about 2000 during the heyday of the bubble to fewer than 100 people today.

    Every crisis has a silver lining, and in this case, as building halts, archaeological sites stay untouched. “At least we can be pleased that the destruction of heritage is stopping,” Almansa says.

    But researchers worry that hard times will shred the nation's commitment to archaeology. The autonomous region of Madrid has in the works a draft bill that would allow new building without archaeological assessment, leaving only known sites protected; Almansa says the bill could be aimed at smoothing the way for megaprojects such as the EuroVegas casino complex. “We are still scared,” he says.

    Archaeologists add that the system, which follows the British and U.S. model in having developers contract out the digging, has offered no incentive for them to study what they have found and permits digs of widely varying quality. “It is impressive … how much money got spent [on commercial archaeology], but the return … has certainly not been optimum,” says archaeologist José Beltrán Fortes of the University of Seville. With building stopped, one option would be to finally look at what's already been dug up. But for this, “we need a great deal of political commitment and money,” Almansa says.

    Given all this, researchers expect a drop in discoveries in the next few years. But there might be an opportunity to remake the field in a new mold, one more amenable to solid research, protection, and diffusion of the nation's heritage, Beltrán Fortes says: “We are in a propitious moment to … with this forced halt, redirect and reconsider what ought to be the archaeology in the future.”

    • * Elisabeth Pain is a contributing editor for Science Careers.