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There are hundreds of biological resource centers (BRCs) around the world, holding many little-studied microorganisms. The proportion of bacterial strains that is well represented in the sequence and literature databases may be as low as 1%. This body of unexplored diversity represents an untapped source of useful strains and derived products. However, a modicum of phenotypic data is available for almost all the bacterial strains held by BRCs around the world. It is at the phenotypic level that our knowledge of the well-studied strains of bacteria and the many yet to be studied strains intersect. Thus, we might leverage the phenotypic data from the data-poor bacteria with the omics data from the data-rich bacteria, using our knowledge of their evolutionary relationships, to map the metabolic networks of the little-known bacteria. This systems biology—based approach is a new way to explore the diversity harbored in BRCs.
Plant responses to global changes in carbon dioxide (CO2), nitrogen, and water availability are critical to future atmospheric CO2 concentrations, hydrology, and hence climate. Our understanding of those responses is incomplete, however. Multiple-resource manipulation experiments and empirical observations have revealed a diversity of responses, as well as some consistent patterns. But vegetation models—currently dominated by complex numerical simulation models—have yet to achieve a consensus among their predicted responses, let alone offer a coherent explanation of the observed ones. Here we propose an alternative approach based on relatively simple optimization models (OMs). We highlight the results of three recent forest OMs, which together explain a remarkable range of observed forest responses to altered resource availability. We conclude that OMs now offer a simple yet powerful approach to predicting the responses of forests—and, potentially, other plant types—to global change. We recommend ways in which OMs could be developed further in this direction.
More than two-thirds of cropland in the United States is devoted to the production of just four crop species—maize, wheat, soybeans, and cotton— raising concerns that homogenization of the American agricultural landscape could facilitate widespread disease and pest outbreaks, compromising the national food supply. As a new component in national agricultural risk assessment, we employed a graph-theoretic approach to examine the connectivity of these crops across the United States. We used county crop acreage to evaluate the landscape resistance to transmission—the degree to which host availability limits spread in any given region—for pests or pathogens dependent on each crop. For organisms that can disperse under conditions of lower host availability, maize and soybean are highly connected at a national scale, compared with the more discrete regions of wheat and cotton production. Determining the scales at which connectivity becomes disrupted for organisms with different dispersal abilities may help target rapid-response regions and the development of strategic policies to enhance agricultural landscape heterogeneity.
Each May, red knots (Calidris canutus rufa) congregate in Delaware Bay during their northward migration to feed on horseshoe crab eggs (Limulus polyphemus) and refuel for breeding in the Arctic. During the 1990s, the Delaware Bay harvest of horseshoe crabs for bait increased 10-fold, leading to a more than 90% decline in the availability of their eggs for knots. The proportion of knots achieving weights of more than 180 grams by 26–28 May, their main departure period, dropped from 0.6–0.8 to 0.14–0.4 over 1997–2007. During the same period, the red knot population stopping in Delaware Bay declined by more than 75%, in part because the annual survival rate of adult knots wintering in Tierra del Fuego declined. Despite restrictions, the 2007 horseshoe crab harvest was still greater than the 1990 harvest, and no recovery of knots was detectable. We propose an adaptive management strategy with recovery goals and annual monitoring that, if adopted, will both allow red knot and horseshoe crab populations to recover and permit a sustainable harvest of horseshoe crabs.
Large mammalian carnivores are ecologically important because relatively few individuals can cause strong predation-driven direct effects or fear-driven indirect effects that can ripple through communities and, ultimately, influence ecosystem structure and function. Most mammalian carnivores are not large, however, but are small to midsized species collectively termed “mesocarnivores.” Mesocarnivores are more numerous and more diverse than larger carnivores, and often reside in closer proximity to humans, yet we know little about how they influence communities and ecosystems. In this article we review the ecological role of the mesocarnivore and present examples where mesocarnivores drive community structure and function in roles similar to, or altogether different from, their larger brethren. Together, these examples substantiate the need for an assessment of the ecological role of mammalian carnivores beyond an examination of only the largest species. In particular, we emphasize the need to study the trophic penetrance of mesocarnivores and examine how ecological context modulates their functional role.
The northeastern United States is influenced by the atmospheric deposition of mercury. Subsequent integration of methylmercury into aquatic food webs results in contamination levels in fish that are high enough to present health concerns for humans who consume fish. Resource and sampling limitations have hindered a comprehensive understanding of mercury in the environment and relative levels of methylmercury exposure. Because of these limitations, data collection should maximize the benefits of information gained through monitoring programs. In this article we review recent efforts to collect and integrate fish mercury data and offer suggestions to improve and focus future research and monitoring efforts to better address threats to human health. By selecting appropriate target species—those species and sizes of fish harvested for consumption and those with the highest and most variable mercury concentrations in a given location—health and fisheries professionals can more comprehensively advise fish consumers and protect human health.