New Worlds: Join the 'movement' movement [p.6]

Organism movement research is central to the understanding of how ecological systems work.

By JUDY SIEGEL-ITZKOVICH
A new academic discipline called "movement ecology" - which focuses on how plant and animal matter travels from one place to another, sometimes over great distances and in highly surprising ways - has been developed by a Hebrew University researcher. The interdisciplinary subject combines a variety of fields, including biology, ecology, botany, environmental science, physics, mathematics, virology and others. It was launched almost singlehandedly by Prof. Ran Nathan, who heads the movement ecology lab in the department of evolution, systematics and ecology at the university's Alexander Silberman Institute of Life Sciences. His work has already triggered a first international study group in the field that has been at work at HU's Institute of Advanced Studies. The study group includes participants from the University of California at Berkeley, the University of California at Davis, Princeton, Stony Brook University and Rutgers; the Spanish Research Council; and from the Hebrew University, Ben-Gurion University of the Negev and the Technion-Israel Institute of Technology. Nathan emphasizes that organism movement research is central to the understanding of how ecological systems work, and has important implications for human life. A comprehensive understanding of movement as a process will help to conserve biodiversity, adapt to changes produced by global warming, and cope with environmental threats such as infectious diseases, invasive alien species, agricultural pests and the spread of allergens. The field (and Nathan) was given a large boost in a recent issue of Science magazine on migration and dispersal that included an article he authored about the long-distance dispersal of plants. The same issue contained a news article that focused mostly on the work of Nathan and his students, as well as others in the US, Britain and Australia. The article noted that researchers have sought for centuries "to understand when, why and how various species crawl, swim, fly, float or hoof it to new locales. That work has led to maps of migration routes and details about dispersals." "But," the article quoted Nathan as saying, "few biologists have tried to fit those data into a big picture of movement in general." Now, said the article, through the new discipline called movement ecology, Nathan and others "are beginning to derive testable hypotheses about the mobile behaviors of animals, microbes and even the seeds of plants. Their goal is to join empirical work to theories and build models that fill in gaps in our understanding of movement - be it over millimeters or continents or by groups of individuals - in the natural world." Last year, Nathan was chosen as the winner of the Hebrew University President's Prize for Outstanding Young Researcher in honor of his pioneering work on seed dispersal. In May this year he was awarded the prestigious Wilhelm Bessel Research Award from the Humboldt Foundation of Germany. WHAT KILLED THE DINOS? Debate on what finished off the dinosaurs has been going on for years. Some scientists have said the impact of a large meteorite in the Yucatan Peninsula caused the mass extinction, while others argue that there must have been additional meteorite impacts or other stresses around the same time. Now a new study by a University of Missouri-Columbia researcher provides compelling evidence that the impact of a single meteorite killed the dinosaurs - along with the majority of all other animal species on Earth - about 65 million years ago. "The samples we found strongly support the single impact hypothesis," said geological science Prof. Ken MacLeod, lead investigator. "Our samples come from very complete, expanded sections without deposits related to large, direct effects of the impact - for example, landslides - that can shuffle the record, so we can resolve the sequence of events well. What we see is a unique layer composed of impact-related material precisely at the level of the disappearance of many species of marine plankton that were contemporaries of the youngest dinosaurs. We do not find any sedimentological or geochemical evidence for additional impacts above or below this level." MacLeod and colleagues studied sediment recovered from the Demerara Rise in the Atlantic Ocean about 4,500 kilometers from the impact site on the Yucatan Peninsula. Sites closer to and farther from the site have been studied, but few intermediary sites such as this have been explored. Interpretation of samples from locations close to the crater are complicated by factors such as waves, earthquakes and landslides that likely followed the impat. Samples from farther away received little impact debris and often don't demonstrably contain a complete record of the mass extinction interval. The Demerara Rise samples thus provide an unusually clear picture of events at the time of the mass extinction.