Evolution's Impact On Ecosystems Shown Directly For First Time

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ScienceDaily (Apr. 12, 2009) — Scientists have come to agree that different environments impact the evolution of new species. Now experiments conducted at the University of British Columbia are showing for the first time that the reverse is also true.

Researchers from the UBC Biodiversity Research Centre created mini-ecosystems in large aquatic tanks using different species of three-spine stickleback fish and saw substantial differences in the ecosystems in as little as 11 weeks.
Their findings are published in the April 1 Advanced Online Publication of the journal Nature.
Stickleback fish originated in the ocean but began populating freshwater lakes and streams following the last ice age. Over the past 10,000 years – a relatively short time span in evolutionary terms – different species with distinct physical traits have emerged in some fresh water lakes.
The UBC study involved new species found in British Columbia lakes that have evolved distinct physical traits: limnetic sticklebacks (smaller open water dwellers with narrow mouths), benthic sticklebacks (larger bottom dwellers with a wide gape) and a generalist species to represent the probable ancestor of the two species.
“Simply by what they eat and how they live, even young species that have ‘recently’ diversified can have a major impact on their food web,” says study lead author Luke Harmon, who conducted the study while a post-doctoral fellow at UBC. He is now an assistant professor at the University of Idaho. “This study adds to a broader body of literature showing that species diversity matters in important ways.”
Further analysis showed the tanks with the two newest species had larger molecules of dissolved organic carbon, or bits of decaying plants and animals. This prevented sunlight from penetrating the water and inhibited plant growth. “Our study shows that through evolution, sticklebacks can engineer the light environment of their own ecosystems,” says co-author Blake Matthews, a UBC post-doctoral fellow who is now a researcher at Eawag, the Swiss Federal Institute of Aquatic Science and Technology. “It also demonstrates how speciation of a predator might alter the evolutionary course of other organisms in the food web.”
“As new species arise from a common ancestor and evolve new ways of exploiting the environment, each inadvertently reshapes the dynamics of the ecosystem around it,” says co-author UBC Prof. Dolph Schluter. “We are just beginning to understand how.”
Journal reference:
Luke J. Harmon, Blake Matthews, Simone Des Roches, Jonathan M. Chase, Jonathan B. Shurin, Dolph Schluter. Evolutionary diversification in stickleback affects ecosystem functioning. Nature, 2009; DOI: 10.1038/nature07974
Adapted from materials provided by University of British Columbia.

Public Trust Doctrine Could Aid Management Of U.S. Ocean Waters

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ScienceDaily (Apr. 13, 2009) — Since Congress lifted a moratorium on offshore drilling last year, federal lawmakers have grappled with the issue of how best to regulate U.S. ocean waters to allow oil, wave and wind energy development, while sustainably managing critical fisheries and marine animal habitats.

A new policy paper, published April 10 in Science by a team of Duke University experts, argues that establishing a public trust doctrine for federal waters could be an effective and ethical solution to this and similar conflicts.
"The public trust doctrine could provide a practical legal framework for restructuring the way we regulate and manage our oceans. It would support ocean-based commerce while protecting marine species and habitats," says lead author Mary Turnipseed, a PhD student at Duke's Nicholas School of the Environment.
The public trust doctrine is "a simple but powerful legal concept," Turnipseed says, that obliges governments to manage certain natural resources in the best interests of their citizens, without sacrificing the needs of future generations.
The doctrine already is well established in the United States at the state level, where natural resource agencies are legally bound to seek legal action against private parties who are infringing on the public trust.
Extending the public trust doctrine to U.S. ocean waters would help federal agencies better manage conflicting demands such as conservation, offshore energy development, fisheries and shipping in the 3.6 million nautical square miles of water included in the nation's territorial sea and Exclusive Economic Zone (EEZ), Turnipseed says. Currently, more than 20 different federal agencies, operating under dozens of laws, regulate species and activities in these waters, without any mandated, systematic effort to coordinate their actions for the public good.
"In the Gulf of Maine, as an example, a wide range of different activities -- including shipping lanes, ferry routes, U.S. Navy operations, fisheries and proposed wind farms -- overlap critical habitat of the endangered right whale," she says. "Most of these are regulated by separate agencies, with only piecemeal coordination. A public trust doctrine would identify these agencies as trustees of the U.S. ocean public trust, unifying them for the first time under a common mandate to manage the gulf's resources sustainably."
Many analysts, including the presidentially appointed U.S. Commission on Ocean Policy, have simply assumed that the public trust doctrine already extends to these federal waters, notes co-author Stephen Roady, senior lecturing fellow at Duke's School of Law and an environmental lawyer at Earthjustice. "Though the public trust doctrine is well suited to serve as a critical legal foundation for a coordinated, ecosystem-based federal ocean policy, it has not yet been formally articulated by the executive branch, nor has it been recognized by federal courts or expressly established in statutory law," Roady says.
The Duke researchers identify three possible avenues for establishing a public trust doctrine for federal waters.
"Each of the three branches of government has the authority to take action," says Larry B. Crowder, Stephen Toth Professor of Marine Biology at the Nicholas School and director of Duke's Center for Marine Conservation. "The doctrine could be established by a Presidential executive order; federal courts could extend it to the U.S. territorial sea and EEZ by invoking the same precedents and statutes relied upon by state courts; or Congress could mandate it by unambiguously writing the doctrine into a federal oceans law."
Regardless of which approach is used, the need to establish the doctrine is pressing, says Raphael Sagarin, associate director for coastal and ocean policy at Duke's Nicholas Institute for Environmental Policy Solutions.
"We need to move past the failing status quo of current U.S. ocean management policies and build a vigorous mandate that provides both the authority and the responsibility for federal agencies to work jointly to manage our oceans as whole ecosystems," Sagarin says. "As we contemplate managing our ocean resources, not only for today but for future generations, we need to ask ourselves two critical questions: For whom should the country's oceans be managed? And for what purpose? The public trust doctrine answers both of these questions."
Journal reference:
Mary Turnipseed, Larry B. Crowder, Raphael D. Sagarin, and Stephen E. Roady. OCEANS: Legal Bedrock for Rebuilding America's Ocean Ecosystems. Science, 2009; 324 (5924): 183 DOI: 10.1126/science.1170889
Adapted from materials provided by Duke University, via EurekAlert!, a service of AAAS.

Amphibians May Develop Immunity To Fatal Fungus

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ScienceDaily (Apr. 10, 2009) — Amphibian populations are declining worldwide, principally because of the spread of the fungal disease chytridiomycosis. Researchers know that some amphibian populations and species are innately more susceptible to the disease than others.

Recent preliminary evidence, described in the April issue of BioScience, suggests also that individual amphibians can sometimes develop resistance to chytridiomycosis, which is caused by the fungus Batrachochytrium dendrobatidis (Bd). Jonathan Q. Richmond, of the US Geological Survey, and three coauthors argue that researchers should broaden their studies of chytridiomycosis to include so-called acquired immunity, because this might improve predictive models of Bd's spread and so suggest ways to protect threatened frog and toad populations.
Richmond and colleagues discuss experimental studies indicating that two species of New Zealand frogs infected with Bd but treated with the antimicrobial drug chloramphenicol were later resistant to reinfection with the fungus. Other studies indicate that North American toads that survived after being first exposed to Bd in dry conditions survived longer when reinfected in wet conditions than did toads that were exposed to Bd in wet conditions.
Richmond and colleagues emphasize that innate immunity has to be activated in an animal before acquired immunity can develop. They point to several key immune-system components—notably, toll-like receptors and major histocompatibility complex molecules—that most likely play a role in bridging the innate and the acquired immune systems, and urge researchers to undertake collaborative studies of the genetics of how these systems interact as Bd spreads.
Adapted from materials provided by American Institute of Biological Sciences.