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For more information on these science news and feature story tips, please contact the public information officer at the end of each item at (703) 292-8070. Editor: Cheryl Dybus Contents of this News Tip:
ECOSYSTEMS ON HAWAIIAN ISLANDS SUSTAINED BY DISTANT DUST--FROM ASIA, 6,000 KILOMETERS AWAYAs soils develop, rock-derived elements gradually leach out. In the absence of erosion, ecosystems should reach a state of profound and irreversible nutrient depletion that would limit rates of plant production, scientists once believed. Researcher Oliver Chadwick of the University of California at Santa Barbara selected sites in Hawaii at which to study the sources and fates of ecosystem nutrients. Funded by the National Science Foundation (NSF), he used locations on Hawaii's islands to look at most environmental influences on ecosystem development, except for the passage of time. Investigations in ecology, geochemistry and atmospheric chemistry have documented that drastic nutrient depletion does not occur as predicted. Says Chadwick, "Ecosystems on highly weathered lava on older Hawaiian islands, in particular, are sustained at productive levels by nutrients dissolved in rainwater -and added as phosphorus in atmospheric dust transported from Asia, more than 6,000 kilometers away." The dependence of biological processes in Hawaii on conditions in, and transport mechanisms from, central Asia demonstrates that the dynamics of long-term soil and ecosystem development cannot be evaluated as a local phenomenon in isolation, Chadwick believes. "Nowhere on Earth," he says, "is that isolated." [Cheryl Dybas] NSF-SUPPORTED MATH TEXTBOOKS ARE RANKED HIGHEST BY AAAS: ANALYSIS PROCESS WILL HELP SCHOOLS SELECT TEXTSFour middle school mathematics textbooks developed with NSF grants were ranked at the top among 12 textbooks evaluated in a recent independent study by the American Association for the Advancement of Science (AAAS). In fact, these top four texts were the only ones to receive a "high" rating, while the other eight, which are more wellestablished texts, were rated as "unsatisfactory." The rankings were based on various rigorous criteria. Content and instructional analyses were conducted by independent teams of classroom teachers and college and university faculty. Funding for the evaluative study was provided by the Carnegie Corporation of New York. Evaluators used a procedure developed by AAAS' Project 2061 (a research-based K-12 national science and math education reform effort) to determine how likely the texts are to help students accomplish six primary learning goals. Established in Project 2061's Benchmarks for Science Literacy, the set of learning indicators is consistent with the National Council of Teachers of Mathematics (NCTM) Standards. The AAAS report indicates that because there has not been an accepted conceptual basis for evaluating textbooks in the past, such efforts have largely been unreliable. AAAS reviewed the texts systematically in terms of what is to be learned by students and emerging content standards and benchmarks relating to science literacy. Also compared was instructional effectiveness based on the standards and benchmarks. According to the study, "there are few excellent middle-grades mathematics textbook series," and none of the most popular commercially produced textbooks (i.e., "best-sellers") are among the most highly rated books. [Lee Herring] GENE STUDY SHOWS TURTLES NEXT OF KIN TO CROCS AND ALLIGATORSTurtles, not birds, have been found to be the closest relatives of crocodiles and alligators, according to an analysis of the largest available collection of reptile genes. The study's conclusions contradict decades of research based on anatomical and fossil studies, which had firmly positioned birds as the reptile group most closely related to crocs and alligators, a group known as crocodilians. Previous studies of gene similarities -- a relatively new tool for determining relationships between species -- have never agreed with the more traditional anatomical methods on this issue, say some scientists. "Turtles turned out to be not where they were supposed to be on the family tree whenever their genes were included in a research study," says Blair Hedges, a biologist at Penn State University who conducted the research with funding from NSF. Hedges and graduate student Laura Poling collected new genetic data and added this new information to all gene-sequence data available for these species in databases worldwide. The results, says Hedges, provide stong evidence that the turtle is the crocodile's closest living relative. With the results of this study, says Hedges, "I hope paleontologists will take a closer look at reptile fossils." [Cheryl Dybas]
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