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Because of their dependence on habitats and resources in different geographic regions at different phases of their annual cycle, migratory species are especially vulnerable to the impacts of climate change. In Bird Migration and Global Change, eminent ecologist George W. Cox brings his extensive experience to bear in evaluating the capacity of migratory birds to adapt to the challenges of a changing climate. The author reviews, synthesizes, and interprets recent and emerging science on the subject, beginning with a discussion of climate change and its effect on habitat, and followed by eleven chapters that examine responses of bird types across all regions of the globe. The final chapters address the evolutionary capacity of birds, and consider how best to shape conservation strategies to protect migratory species in coming decades.

In Alien Species and Evolution , biologist George W.Cox reviews and synthesizes emerging information on the evolutionary changes that occur in plants, animals, and microbial organisms when they colonize new geographical areas, and on the evolutionary responses of the native species with which alien species interact.

Publisher description: In Alien Species and Evolution, biologist George W. Cox reviews and synthesizes emerging information on the evolutionary changes that occur in plants, animals, and microbial organisms when they colonize new geographical areas, and on the evolutionary responses of the native species with which alien species interact. The book is broad in scope, exploring information across a wide variety of taxonomic groups, trophic levels, and geographic areas. It examines theoretical topics related to rapid evolutionary change and supports the emerging concept that species introduced to new physical and biotic environments are particularly prone to rapid evolution. The author draws on examples from all parts of the world and all major ecosystem types, and the variety of examples used gives considerable insight into the patterns of evolution that are likely to result from the massive introduction of species to new geographic regions that is currently occurring around the globe. Alien Species and Evolution is the only state-of-the-art review and synthesis available of this critically important topic, and is an essential work for anyone concerned with the new science of invasion biology or the threats posed by invasive species.

The activation of Janus kinases (JAKs) is crucial for propagation of the proliferative response initiated by many cytokines. The proliferation of various cell lines, particularly those of hematopoietic origin, is also modulated by mediators of oxidative stress such as nitric oxide and thiol redox reagents. Herein we demonstrate that nitric oxide and other thiol oxidants can inhibit the autokinase activity of rat JAK2 in vitro, presumably through oxidation of crucial dithiols to disulfides within JAK2. The reduced form of JAK2 is the most active form, and the oxidized JAK2 form is inactive. Nitric oxide pretreatment of quiescent Ba/F3 cells also inhibits the interleukin 3-triggered in vivo activation of JAK2, a phenomenon that correlates with inhibited proliferation. Furthermore, we observed that the autokinase activity of JAK3 responds in a similar fashion to thiol redox reagents in vitro and to nitric oxide donors in vivo. We suggest that the thiol redox regulation of JAKs may partially explain the generally immunosuppressive effects of nitric oxide and of other thiol oxidants.

The Nearctic-Neotropical bird migration system is one of the major phenomena of vertebrate ecology and evolution. The origin of this system has been accompanied by a coevolutionary adjustment of migratory species with resident species in both temperate and tropical bird communities. Potential selective pressures for migratory behavior are varied, and include extreme weather conditions, thermal and photoperiodic regimes, changes in seasonal availability of specific resources, intraspecific and interspecific competition, and predation or parasitism. Several general theories of the origin of migration incorporate these selective pressures. These include the theories of increasing seasonality, optimal energy budget, intraspecific and interspecific competition, predation and food supply, and time allocation. None of these, as outlined to date, is able to account fully for the complex Nearctic-Neotropical migration system. An integrated time-allocation and competition theory is suggested, in which the Mexican Plateau and arid southwestern United States act as a staging area for the evolution of migration. In this region, where environmental unpredictability favors the reduction of site tenacity, various forces select for the movement of birds into neighboring areas with more favorable seasonal conditions, creating partial migrants. The increased seasonality of climate, the speciation of geographically isolated migrant population segments, and the elimination of permanent resident population segments by interspecific competition lead to disjunct breeding and nonbreeding ranges. It is assumed, therefore, that species migrating between the temperate zone and the tropics have populations that are resource-limited throughout the year. By virtue of the complementarity of ecological adjustments in breeding and nonbreeding seasons, I also infer that these migrants impose year-round population limitation on the members of the resident temperate and tropical bird communities.

The number of habitats occupied and relative abundance of birds on the West Indian islands of Jamaica, St. Lucia, and St. Kitts were compared for species in different stages of the taxon cycle. Each species was assigned to one of four taxon cycle categories: (I) expanding and undifferentiated, (II) widespread but differentiated, (III) with a fragmented distribution, and (IV) endemic. Nonpasserines exhibit no distinct trends in relation to stage of taxon cycle. Among passerines, species tend to have more restricted habitat distributions, which are shifted toward tall forest and montane habitats, and reduced population densities as they progress through the taxon cycle. These trends are well marked on Jamaica, with a fauna of 35 passerine species, but they are difficult to detect on St. Kitts, with 13 species, none of which are endemic. Patterns of ecological release and density compensation evident within the islands are due mostly to the absence of late-stage species with low abundance on small islands with few species. On Jamaica, several stage IV passerines exhibit uncharacteristically broad habitat breadths representing, perhaps, incipient cycles of expansion. Furthermore, stage IV species in genera endemic to the Caribbean had broader habitat occupancy than stage IV species belonging to wide-ranging genera. This suggests that with continued persistence in the islands, populations may become sufficiently differentiated that new colonists do not compete strongly with them. This study reinforces the general conclusion that the geographical and taxonomic patterns on which the taxon cycle is based are paralleled by changes in habitat breadth and abundance in individual islands. The mechanism that drives the cycle remains to be described.

To account fully for the pattern of translocation of soil by pocket gopher activity in Mima moundfields, I investigated soil mining in relation to location along the mound-intermound topographic gradient. From September 1986 to November 1987, at Miramar Mounds National Landmark in coastal San Diego County, California, the total soil mined by pocket gophers (Thomomys bottae) was estimated by measuring the mass of soil deposited in surface heaps and counting the number of plugged surface-access tunnels on mound and intermound zones associated with 10 Mima-type mounds. Surface heap deposition was greatest in late fall and early winter, whereas the digging of surface-access tunnels was most frequent in spring and early summer. Both the mass of soil in surface heaps per unit area and the number of surface-access tunnels per unit area tended to decrease with distance from the center of mounds. When the areas of concentric zones at increasing distance from the mound center were taken into account, however, the total mas of soil mined increased with distance from mound centers. At this site, deposition of soil in surface heaps estimated to be 8.23 Mg·ha-1 · yr-1 and subsurface deposition to be 20.31 Mg·ha-1 ·yr-1, so that total soil mining equalled 28.54 Mg·ha-1 ·yr-1. Total mass of soil mined bore a log-linear relation to distance from the mound center. This relation was combined with that relating distance of movement of mined soil to mound height and distance from the mound center, to give a preliminary model of mound growth dynamics as influenced by pocket gopher activity. This model suggests that maximum mound size is largely determined by the pattern of soil mining and translocation by these mammals.

We analyzed trapping success, reproductive status, surface-heap deposition, surface-access tunneling, and clearing of experimentally plugged tunnels to determine the relation of activity of Thomomys bottae to air temperature, rainfall, and food availability in a mima-mound and vernal-pool habitat in San Diego, California. All activities varied seasonally. Trapping success and clearing of plugged tunnels, reflecting use and maintenance of tunnels, were negatively correlated with air temperature for the preceding week and time since rainfall of ≥2.5 mm. Surface heaps, an indicator of expansion of the main tunnel system, were weakly correlated with the same variables. Production of surface-access tunnels did not correlate with either temperature or rainfall, but peaked late spring-early summer at the end of the growing season. Expansion of the main tunnel system is favored by moist soil and cool temperatures, but probably is triggered by growth of herbaceous food plants and recrudescence of sexual activity, whereas digging of surface-access tunnels is related directly to availability of harvestable aboveground foods.

In North America, Mima-type earth mounds are found west of the Mississippi River from southern Canada to northern Mexico. They occur on poorly drained soils with a shallow basement layer or permanent water table. In San Diego County, California, Mima mounds are found at the edge of coastal salt marshes above a shallow water table, on coastal marine terraces having a cemented, clay-capped hardpan, on foothill slopes and stream-cut terraces over shallow bedrock, and in cismontane valleys, mountain meadows, and the margins of desert-edge marshes where a dense subsurface clay horizon creates poor drainage. Major hypothesis of mound orgin involve (1) frost-sorting, (2) erosion, (3) wind disposition, and (4) fossorial rodent actitivy. At Miramar Mounds National Landmark in San Diego, soil samples (1980 cm^3) were collected from the tops, edges, and neighboring basin centers of 10 mounds for analysis of small rock content. Soil plugs containing metal markets were inserted in pocket gopher tunnels at mound edges, and the movement of these markers traced with a metal detector. Mounds on a 0.58-ha plot were mapped and their dimensions measured. Contray to all but the fossorial rodent hypothesis, gravel and small pebbles that such rodents are able to move were concentrated in mound soils. Clearing of the experimental soil plugs by pocket gophers was accompanied by a significant moundward translocation of mined soil. The spacing of mounds tended towards uniformity, but intermound distance increased with increased significantly with increase in mound size. The distribution of mound fields in San Diego County corresponds closely to the distribution of original valley grassland inferred for a 10-yr fire cycle. It is hypothesized that Mima mounds are an indicator of original grassland environments.