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Malaria kills about one million people each year, but efforts to destroy disease-carrying mosquitoes have succeeded only in breeding tougher bugs. Researchers have begun to look for ways to create malaria-resistant mosquitoes. One approach is to bioengineer transgenic mosquitoes that, when released into the wild, would lead to a new race of malaria-proof young. Another approach uses mosquitoes' natural resistance to Plasmodium infection.
Green roofs (roofs with a vegetated surface and substrate) provide ecosystem services in urban areas, including improved storm-water management, better regulation of building temperatures, reduced urban heat-island effects, and increased urban wildlife habitat. This article reviews the evidence for these benefits and examines the biotic and abiotic components that contribute to overall ecosystem services. We emphasize the potential for improving green-roof function by understanding the interactions between its ecosystem elements, especially the relationships among growing media, soil biota, and vegetation, and the interactions between community structure and ecosystem functioning. Further research into green-roof technology should assess the efficacy of green roofs compared to other technologies with similar ends, and ultimately focus on estimates of aggregate benefits at landscape scales and on more holistic cost-benefit analyses.
Although most people think of pollen merely as an allergen, its true biological function is to facilitate sexual reproduction in flowering plants. The angiosperm pollen grain, upon arriving at a receptive stigma, germinates, producing a tube that extends through the style to deliver its cargo to the ovule, thereby fertilizing the egg, and completing the life cycle of the plant. The pollen tube grows rapidly, exclusively at its tip, and produces a cell that is highly polarized both in its outward shape and its internal cytoplasmic organization. Recent studies reveal that the growth oscillates in rate. Many underlying physiological processes, including ionic fluxes and energy levels, also oscillate with the same periodicity as the growth rate, but usually not with the same phase. Current research focuses on these phase relationships in an attempt to decipher their hierarchical sequence and to provide a physiological explanation for the factors that govern pollen tube growth.
Despite a growing awareness that the herbaceous layer serves a special role in maintaining the structure and function of forests, this stratum remains an underappreciated aspect of forest ecosystems. In this article I review and synthesize information concerning the herb layer's structure, composition, and dynamics to emphasize its role as an integral component of forest ecosystems. Because species diversity is highest in the herb layer among all forest strata, forest biodiversity is largely a function of the herb-layer community. Competitive interactions within the herb layer can determine the initial success of plants occupying higher strata, including the regeneration of dominant overstory tree species. Furthermore, the herb layer and the overstory can become linked through parallel responses to similar environmental gradients. These relationships between strata vary both spatially and temporally. Because the herb layer responds sensitively to disturbance across broad spatial and temporal scales, its dynamics can provide important information regarding the site characteristics of forests, including patterns of past land-use practices. Thus, the herb layer has a significance that belies its diminutive stature.
Soil organisms undertake every major ecosystem process, from primary production to decomposition to carbon sequestration, and those processes they catalyze have a bearing on the management of issues from agriculture to global climate change. Nonetheless, until recently, research to measure the dynamics of microscopic organisms living belowground has largely been limited to infrequent field sampling and laboratory extrapolation. Now, however, new sensor technologies can measure and monitor soil organisms and processes at rapid and continuous temporal scales. In this article, we describe these technologies and how they can be arrayed for an integrated view of soil dynamics.
Habitat destruction has driven much of the current biodiversity extinction crisis, and it compromises the essential benefits, or ecosystem services, that humans derive from functioning ecosystems. Securing both species and ecosystem services might be accomplished with common solutions. Yet it is unknown whether these two major conservation objectives coincide broadly enough worldwide to enable global strategies for both goals to gain synergy. In this article, we assess the concordance between these two objectives, explore how the concordance varies across different regions, and examine the global potential for safeguarding biodiversity and ecosystem services simultaneously. We find that published global priority maps for biodiversity conservation harbor a disproportionate share of estimated terrestrial ecosystem service value (ESV). Overlap of biodiversity priorities and ESV varies among regions, and in areas that have high biodiversity priority but low ESV, specialized conservation approaches are necessary. Overall, however, our findings suggest opportunities for safeguarding both biodiversity and ecosystem services. Sensitivity analyses indicate that results are robust to known limitations of available ESV data. Capitalizing on these opportunities will require the identification of synergies at fine scales, and the development of economic and policy tools to exploit them.
Natural history museums are the principal repositories of the collections that represent much of the objective evidence for evolution. With approximately 50 million visitors annually, US natural history museums can significantly influence the public's understanding of evolution. Here we present the results of a study that investigated the knowledge of key evolutionary concepts exhibited by high-school students and adults who visited natural history museums. Ninety-five percent of the study participants understood relative geological time (superposition), but only 30 percent explained biological change (microevolution) in terms of natural selection, and 11 percent explicitly rejected evolution. In general, museum visitors have an incomplete understanding of evolutionary concepts. For example, while participants have a good understanding that fossils represent evidence for evolution, they have a poor understanding of the mechanisms of evolution. Natural history museums can foster visitors' understanding of evolution by integrating this content—particularly concepts that are difficult to understand—throughout all relevant exhibits and public programs.