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While population cycles are geographically widespread, it is on arctic tundra that such cycles appear to be most influential for the functioning of the whole ecosystem. We give an overview of tundra species that exhibit population cycles and describe what are currently believed to be the causal mechanisms. Population cycles most likely originate from trophic interactions within the plant-based tundra food web, where lemmings, either as prey for carnivores or as consumers of plants, play the key role. The predominance of trophic interaction cycles at northern latitudes is ultimately related to climate, and such cycles should therefore be vulnerable to climate change. Recent evidence indicates that changes have already taken place in the dynamics of some key herbivores and their predators, consistent with the expected impacts of climate change. There is a strong need for large-scale integrated monitoring and research efforts to further document such changes and their ecosystem consequences.
Vibrational communication is widespread in insect social and ecological interactions. Of the insect species that communicate using sound, water surface ripples, or substrate vibrations, we estimate that 92% use substrate vibrations alone or with other forms of mechanical signaling. Vibrational signals differ dramatically from airborne insect sounds, often having low frequencies, pure tones, and combinations of contrasting acoustic elements. Plants are the most widely used substrate for transmitting vibrational signals. Plant species can vary in their signal transmission properties, and thus host plant use may influence signal divergence. Vibrational communication occurs in a complex environment containing noise from wind and rain, the signals of multiple individuals and species, and vibration-sensitive predators and parasitoids. We anticipate that many new examples and functions of vibrational communication will be discovered, and that study of this modality will continue to provide important insights into insect social behavior, ecology, and evolution.
Invasive species pose a major, yet poorly addressed, threat to sustainable forestry. Here we set forth an interdisciplinary science strategy of research, development, and applications to reduce this threat. To spur action by public and private entities that too often are slow, reluctant, or unable to act, we recommend (a) better integrating invasive species into sustainable forestry frameworks such as the Montréal Process and forest certification programs; (b) developing improved cost estimates to inform choices about international trade and pest suppression efforts; and (c) building distributed information systems that deliver information on risks, identification, and response strategies. To enhance the success of prevention and management actions, we recommend (a) advancing technologies for molecular identification, expert systems, and remote sensing; (b) evolving approaches for ecosystem and landscape management; and (c) better anticipating interactions between species invasions and other global change processes.
Scientists conducting kindergarten through twelfth-grade (K–12) outreach often use an expert-driven innovation-adoption model for the dissemination of ideas, similar to the model used in agricultural extension programs. However, social-learning approaches that emphasize the ongoing professional development of educators and the importance of learning from peers may be more appropriate for K–12 classrooms and nonformal educational settings. Building on the innovation-adoption and social-learning literature, I propose a model for K–12 program dissemination. How well a program reaches its dissemination goals depends on the interaction of educators and their context with factors related to program designers and their context, to dissemination strategy, and to the innovation being disseminated. Dissemination goals include the number of educators who either adopt a standard curriculum or adapt program principles and resources to meet their needs, and how well the educators' programs reflect the designers' educational philosophy. The proposed model can be used to inform program design and educational research.
Population trends for 1095 species listed as threatened and endangered under the Endangered Species Act were correlated with the length of time the species were listed and the presence or absence of critical habitat and recovery plans. Species with critical habitat for two or more years were more than twice as likely to have an improving population trend in the late 1990s, and less than half as likely to be declining in the early 1990s, as species without. Species with dedicated recovery plans for two or more years were significantly more likely to be improving and less likely to be declining than species without. The proportion of species improving increased, and the proportion declining decreased, with increasing time listed throughout the 1990s, irrespective of critical habitat and recovery plans. On the basis of these results, we recommend increased funding for earlier listing of imperiled species and prompt provision of critical habitat and recovery plans.
H. B. D. Kettlewell's work on the phenomenon of industrial melanism is widely regarded as the classic demonstration of natural selection and one of the most beautiful experiments in evolutionary biology. The following essay discusses the mark–release–recapture experiments Kettlewell conducted in 1953 and 1955, with reference to Robert Crease's analysis of what it means for an experiment to be considered beautiful (significance of results, overall conceptual simplicity, conclusiveness). In fact, much of the apparent beauty of these experiments is illusory: the phenomenon of industrial melanism and Kettlewell's work on it are much more complicated than they are usually depicted in textbooks and the popular media. These complexities do not undermine the continued use of Kettlewell's work in science teaching, but they do suggest that the very features that lead scientists to appreciate Kettlewell's experiments as “beautiful” may be largely an artifact of how they have been portrayed.