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The Green Revolution that brought advances in crop genetics to Asia and Latin America completely bypassed the African continent. Africa's smallholder farmers finally joined the movement in 2006, when the Bill and Melinda Gates Foundation joined the Rockefeller Foundation to create the Alliance for a Green Revolution in Africa. Its goal is to develop 100 new crop varieties in 5 years, so that within 20 years farmers will double or triple their yields.
The advanced colonial state of eusociality has evolved in insects as a defense of nest sites within foraging distance of persistent food sources. In the Hymenoptera, the final step in the approach to eusociality is through a suite of preadaptations comprising simultaneous provisioning, fidelity to the nest, and a preexisting propensity toward dominance behavior and the selection of tasks according to opportunity. The only genetic change needed to cross the threshold to the eusocial grade is the foundress's possession of an allele that holds the foundress and her offspring to the nest. The preadaptations provide the phenotypic flexibility required for eusociality, as well as the key emergent traits arising from interactions of the group members. Group (colony-level) selection then immediately acts on both of these traits. The rarity of the origin of eusociality is evidently due to the rarity of the combination of progressive provisioning with environments of the kind that give an edge to group selection over individual direct selection, causing offspring to stay at the natal nest rather than disperse. Several lines of evidence, examined here, suggest that collateral kin selection does not play a significant role.
Marine ecosystems provide essential services to humans, yet these services have been diminished, and their future sustainability endangered, by human patterns of exploitation that threaten system robustness and resilience. Marine ecosystems are complex adaptive systems composed of individual agents that interact with one another to produce collective effects, integrating scales from individual behaviors to the dynamics of whole systems. In such systems, small changes can be magnified through nonlinear interactions, facilitating regime shifts and collapses. Protection of the services these ecosystems provide must therefore maintain the adaptive capacities of these systems by preserving a balance among heterogeneity, modularity, and redundancy, tightening feedback loops to provide incentives for sound stewardship. The challenge for management is to increase incentives to individuals, and tighten reward loops, in ways that will strengthen the robustness and resilience of these systems and preserve their ability to provide ecosystem services for generations to come.
The study of ecosystems in action, by measuring ecosystem recovery from disturbance, resistance to alterations, and the reversibility of ecosystem changes, highlights features of natural communities that contribute to resilience. Examples from marine intertidal and subtidal communities document the importance of species redundancy and complementarity in resistance and recovery, and they also show why recovery potential and resistance can differ from place to place within the same ecosystem. Whether a change is considered reversible may depend on the timescale of interest, and on whether fundamental new ecological processes have taken hold after a disturbance. By focusing on recovery, resistance, and reversibility as key components of resilience, marine ecologists have provided a much-needed empirical database about the response of the living world to human-mediated change.
The goal of this article is to highlight evolving tools, recent advances, and emerging techniques that are being used to understand natural variability in marine ecosystems. These technical approaches range from the tagging of large pelagic organisms to the use of genomics to provide insight into the abundance and health of marine organisms. Although these techniques vary dramatically in scale, they share the potential to remove critical impediments to the effective management of marine systems.
Ecosystem-based management (EBM) in the ocean is a relatively new approach, and existing applications are evolving from more traditional management of portions of ecosystems. Because comprehensive examples of EBM in the marine environment do not yet exist, we first summarize EBM principles that emerge from the fisheries and marine social and ecological literature. We then apply those principles to four cases in which large parts of marine ecosystems are being managed, and ask how including additional components of an EBM approach might improve the prospects for those ecosystems. The case studies provide examples of how additional elements of EBM approaches, if applied, could improve ecosystem function. In particular, two promising next steps for applying EBM are to identify management objectives for the ecosystem, including natural and human goals, and to ensure that the governance structure matches with the scale over which ecosystem elements are measured and managed.
Biofuel feedstocks are being selected, bred, and engineered from nonnative taxa to have few resident pests, to tolerate poor growing conditions, and to produce highly competitive monospecific stands—traits that typify much of our invasive flora. We used a weed risk-assessment protocol, which categorizes the risk of becoming invasive on the basis of biogeography, history, biology, and ecology, to qualify the potential invasiveness of three leading biofuel candidate crops—switchgrass, giant reed, and miscanthus (a sterile hybrid)—under various assumptions. Switchgrass was found to have a high invasive potential in California, unless sterility is introduced; giant reed has a high invasive potential in Florida, where large plantations are proposed; miscanthus poses little threat of escape in the United States. Each biofuel crop shares many characteristics with established invasive weeds with a similar life history. We propose genotype-specific preintroduction screening for a target region, which consists of risk analysis, climate-matching modeling, and ecological studies of fitness responses to various environmental scenarios. This screening procedure will provide reasonable assurance that economically beneficial biofuel crops will pose a minimal risk of damaging native and managed environs.
There has been little discussion about how to apply population genetics methods to monitor the spread of transgenes that are detected outside the agricultural populations where they are deployed. Population geneticists have developed tools for analyzing the genetic makeup of individuals in hybrid zones, estimating migration and selection of genes, studying the influence of migration and selection on the shape of clines, and assaying the fitness of hybrids and backcrossed individuals. These tools may prove useful for monitoring the dynamics of escaped transgenes, but their effective application is likely to require access to information on the genetic makeup of transgenic organisms—information that is often proprietary. At present, depending on the jurisdiction involved, developers and regulators of transgenic organisms may be under no obligation to provide such information, thereby impeding independent public research of transgene escape and the refinement of methods used to study it.
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