The hypothesis that increasing ultraviolet-B (UVB) radiation is a causal factor in the decline of amphibian populations has received considerable attention in the scientific and public media. To evaluate the validity of this hypothesis, it is necessary to examine the natural environmental factors and biological traits of amphibians that protect them from UVB radiation. A careful reading of the literature reveals that most published studies on the effects of ambient UVB radiation on amphibian embryos have found no increased mortality. Those few reports that show harmful effects employ experimental methods that do not place enough importance on the natural abiotic and biotic factors that provide UVB protection. In the laboratory, amphibian embryos are resistant to doses of UVB radiation far higher than those they would normally receive from ambient sunlight. The jelly surrounding amphibian eggs absorbs UVB radiation, as revealed by spectral measurements of absorbance; after UVB exposure, embryos with their jelly capsules removed show significantly higher mortality than those with the jelly intact. In light of this and other factors mitigating UVB absorption, the hypothesis that ambient UVB radiation causes amphibian mortality and population declines is without support.

Two centuries of land use in the Mississippi River watershed are reflected in the water quality of its streams and in the continental shelf ecosystem receiving its discharge. The most recent influence on nutrient loading—intense and widespread farming and especially fertilizer use—has had a more significant effect on water quality than has land drainage or the conversion of native vegetation to cropland and grazing pastures. The 200-year record of nutrient loading to offshore water is reflected in the paleoreconstructed record of plankton in dated sediments. This record illustrates that the development of fair, sustained management of inland ecosystems is linked to the management of offshore systems. Land use in this fully occupied watershed is under the strong influence of national policies affecting all aspects of the human ecosphere. These policies can be modified for better or worse, but water quality will probably change only gradually because of the strong buffering capacity of the soil ecosystem.

Over the last three decades, forest degradation in the Brazilian Amazon has diminished the availability of some widely used medicinal plant species. Results of a 9-year market study suggest that forests represent an important habitat for medicinal plants used in eastern Amazonia: Nine of the twelve top-selling medicinal plants are native species, and eight are forest based. Five of the top-selling species have begun to be harvested for timber, decreasing the availability of their barks and oils for medicinal purposes. Many of these medicinal plants have no botanical substitute, and pharmaceuticals do not yet exist for some of the diseases for which they are used. Market surveys indicate that all socioeconomic classes in Amazonia use medicinal plants because of cultural preferences, low cost, and efficacy. Degradation of Amazonian forests may signify not only the loss of potential pharmaceutical drugs for the developed world but also the erosion of the sole health care option for many of Brazil's rural and urban poor.

The principles of evolution are finding new applications in medicine, but little is known about the role of evolutionary biology in medical curricula. To determine which aspects of evolutionary biology are included in medical curricula and the factors that influence this, a questionnaire was sent to all deans at North American medical schools who are responsible for curricula. The questionnaire asked about content areas in the curriculum, their perceived importance, and the factors that influence the amount of coverage given to those areas. Forty-eight percent of the deans who responded considered evolutionary biology important knowledge for physicians. Only 32 percent of the respondents reported that their schools covered at least 8 of 16 core topics in evolutionary biology, and only 16 percent of the schools reported having any faculty with a PhD in evolutionary biology. Lack of time in the curriculum and lack of faculty expertise are the main perceived impediments to increased teaching of evolution. We conclude that the role of evolutionary biology as a basic medical science should be carefully considered by a distinguished group of biologists and medical educators. In the meanwhile, undergraduate educators need to recognize that, for now at least, most future physicians must learn evolutionary biology as undergraduates if they are to learn it at all.

The 1980 Sino-American Botanical Expedition (SABE) to the Shennongjia Forest District, Hubei Province, China, was the first botanical collecting trip by American scientists to that country since 1949. It was significant because the area visited had high species diversity and because the collected germplasm was widely distributed to a variety of botanical institutions throughout North America and Europe. This report documents the survival of this germplasm after 22 years of cultivation. Of the original 621 SABE collections, 258 are represented by plants growing in at least 18 different botanical institutions. The fact that 115 of these collections (45 percent) are represented by a single accession growing in a single location suggests that the plant introduction process is much more tenuous than has been generally assumed. This study also highlights the importance of data sharing among botanical institutions as the most effective way of determining the uniqueness of a given collection and assessing its environmental adaptability or invasiveness, or both, over a broad range.