Plankton are showing the effects of a warming climate as marine populations worldwide experience a regime shift caused by climate change. In northern oceans, biogeographical boundaries are shifting northward as warm-water species displace cold-water species, causing trophic cascades. Ocean acidification is accelerating and threatening the long-term survival of many marine species.

Perennial plants, growing in mixtures, make up most of the world's natural terrestrial biomes. In contrast, monocultures of annual crops are sown on more than two-thirds of global cropland. Grain and oilseed crops are the foundation of the human diet, but to date there are no perennial species that produce adequate grain harvests. Yet perennial plant communities store more carbon, maintain better soil and water quality, and manage nutrients more conservatively than do annual plant communities, and they have greater biomass and resource management capacity. These advantages provide a base from which to begin hybridization and selection for increased resource allocation to developing seeds, a decades-long process that must overcome or circumvent genetic complications. Breeding programs aimed at developing perennial grain crops have been initiated in wheat, sorghum, sunflower, intermediate wheatgrass, and other species.

In recent years, the study of phenotypic and genetic variation has been enhanced by combining genetic, physiological, demographic, and behavioral components of life histories. Using these new approaches, we address the problem of adaptation to environmental heterogeneity by examining in detail the variation of several fitness-related traits in a small passerine bird, the blue tit, which has been extensively studied in habitat mosaics of the Mediterranean region. The response of blue tits to spatial habitat heterogeneity depends on their range of dispersal relative to the size of habitat patches. Dispersal over short distances leads to local specialization, whereas dispersal over long distances leads to phenotypic plasticity. Gene flow between habitats of different quality may produce local maladaptation and a source–sink population structure. However, when habitat-specific divergent selection regimes are strong enough to oppose the effects of gene flow, local adaptation may arise on a scale that is much smaller than the scale of dispersal.

Globally, tidal marshes are found in small pockets or narrow bands totaling only approximately 45,000 square kilometers. The combination of salinity, low floristic and structural complexity, and regular tidal inundation, as well as unpredictable catastrophic flooding, provides a unique selective environment that shapes local adaptations, including those that are morphological, physiological, demographic, and behavioral. Although tidal marshes support a low diversity of nonaquatic vertebrate species, a high proportion of these inhabitants, at least along North American coastlines, are restricted to or have subspecies restricted to tidal marshes. Tidal marshes and their endemic fauna face broad threats from a variety of human-caused environmental changes. Future research should focus on global inventories, intercontinental comparative work, and investigation to determine why almost all presently described endemic taxa appear to be found in North America.

Although it is recognized that many factors interact to cause extinctions, it is difficult to consider multiple factors when investigating species declines. I conducted a post hoc exploration of the major hypotheses for the decline of the Allegheny woodrat (Neotoma magister), incorporated the historical environmental changes that accompanied and preceded the decline, and considered how these events may have affected the species. What emerges is a complicated picture involving multiple, relatively minor stressors, all attributable to human activities. The temporal pattern of the decline is most coherent when considered from a historical perspective. Among the factors that are likely to have affected Allegheny woodrats are two exotic tree pathogens, a native parasite, the proliferation of human-adapted competitors, and habitat fragmentation. In addition, changes in competitive and predatory regimes appear to have influenced the timing of the collapse. Although the historic record cannot give definitive answers, taking a synthetic, historical–ecological approach can enhance understanding of species declines.