Freshwater Plankton Crustacea of the Colville River Area, Northern Alaska

Reports study of Microcrustacea from 200 water bodies, collected during the summer of 1955. Twenty-two species of Cladocera, 29 Copepoda and six larger forms were identified. Some species characteristic of lakes or pools are separated. Surface temperatures ranged from 0.5 to 20.5 C. Chemical determinations of 48 water bodies include chloride, calcium, bicarbonate and oxygen. Similarities with Siberian and other high latitude forms are noted

First Records of Two Neotropical Species of Mesocyclops (Copepoda) from Yukon Territory: Cases of Passive Dispersal?

Two species of neotropical cyclopoid copepod crustaceans, Mesocyclops longisetus curvatus and Mesocyclops venezolanus, were collected from a pond at Shingle Point, Yukon Territory, Canada, in September 1974. This is the first record of M. longisetus curvatus north of the southern United States and the first record of M. venezolanus north of Honduras. We provide amplified descriptions of both species. Four additional congeners, M. americanus, M. edax, M. reidae, and M. ruttneri, are now known from the continental U.S. and Canada. We provide a key to the identification of the six species. We hypothesize that the specimens of M. longisetus curvatus and M. venezolanus may have been passively transported to Shingle Point by migrant shorebirds.Key words: Copepoda, Cyclopoida, Mesocyclops, new record, Yukon, neotropical, zoogeography, passive dispersal, identification keyEn septembre 1974, on a recueilli deux espèces de copépodes cyclopoïdes néogènes, Mesocyclops longisetus curvatus et Mesocyclops venezolanus, dans un étang situé à Shingle Point, dans le territoire du Yukon au Canada. Cela représente la première occurrence rapportée de M. longisetus curvatus au nord de la partie méridionale des États-Unis, et la première de M. venezolanus au nord du Honduras. On donne une description détaillée des deux espèces. On sait maintenant qu'il existe quatre autres congénères, M. americanus, M. edax, M. reida et M. ruttneri, aux États-Unis américains et au Canada. On fournit un code permettant d'identifier les six espèces. On émet l'hypothèse que les spécimens de M. longisetus curvatus et de M. venezolanus ont pu être transportés de façon passive à Shingle Point par des oiseaux de rivage migrateurs.Mots clés: copépodes, cyclopoïdes, Mesocyclops, nouvelle Occurrence rapportée, Yukon, néogène, zoogéographie, dispersion passive, code d'identificatio

Oregon 2100: projected climatic and ecological changes

Greenhouse climatic warming is underway and exacerbated by human activities. Future outcomes of these processes can be projected using computer models checked against climatic changes during comparable past atmospheric compositions. This study gives concise quantitative predictions for future climate, landscapes, soils, vegetation, and marine and terrestrial animals of Oregon. Fossil fuel burning and other human activities by the year 2100 are projected to yield atmospheric CO2 levels of about 600-850 ppm (SRES A1B and B1), well above current levels of 400 ppm and preindustrial levels of 280 ppm. Such a greenhouse climate was last recorded in Oregon during the middle Miocene, some 16 million years ago. Oregon’s future may be guided by fossil records of the middle Miocene, as well as ongoing studies on the environmental tolerances of Oregon plants and animals, and experiments on the biological effects of global warming. As carbon dioxide levels increase, Oregon’s climate will move toward warm temperate, humid in the west and semiarid to subhumid to the east, with increased summer and winter drought in the west. Western Oregon lowlands will become less suitable for temperate fruits and nuts and Pinot Noir grapes, but its hills will remain a productive softwood forest resource. Improved pasture and winter wheat crops will become more widespread in eastern Oregon. Tsunamis and stronger storms will exacerbate marine erosion along the Oregon Coast, with significant damage to coastal properties and cultural resources

The mating-specific Gα interacts with a kinesin-14 and regulates pheromone-induced nuclear migration in budding yeast

As a budding yeast cell elongates toward its mating partner, cytoplasmic microtubules connect the nucleus to the cell cortex at the growth tip. The Kar3 kinesin-like motor protein is then thought to stimulate plus-end depolymerization of these microtubules, thus drawing the nucleus closer to the site where cell fusion and karyogamy will occur. Here, we show that pheromone stimulates a microtubule-independent interaction between Kar3 and the mating-specific Gα protein Gpa1 and that Gpa1 affects both microtubule orientation and cortical contact. The membrane localization of Gpa1 was found to polarize early in the mating response, at about the same time that the microtubules begin to attach to the incipient growth site. In the absence of Gpa1, microtubules lose contact with the cortex upon shrinking and Kar3 is improperly localized, suggesting that Gpa1 is a cortical anchor for Kar3. We infer that Gpa1 serves as a positional determinant for Kar3-bound microtubule plus ends during mating. © 2009 by The American Society for Cell Biology

Spatial Guilds in the Serengeti Food Web Revealed by a Bayesian Group Model

Food webs, networks of feeding relationships among organisms, provide fundamental insights into mechanisms that determine ecosystem stability and persistence. Despite long-standing interest in the compartmental structure of food webs, past network analyses of food webs have been constrained by a standard definition of compartments, or modules, that requires many links within compartments and few links between them. Empirical analyses have been further limited by low-resolution data for primary producers. In this paper, we present a Bayesian computational method for identifying group structure in food webs using a flexible definition of a group that can describe both functional roles and standard compartments. The Serengeti ecosystem provides an opportunity to examine structure in a newly compiled food web that includes species-level resolution among plants, allowing us to address whether groups in the food web correspond to tightly-connected compartments or functional groups, and whether network structure reflects spatial or trophic organization, or a combination of the two. We have compiled the major mammalian and plant components of the Serengeti food web from published literature, and we infer its group structure using our method. We find that network structure corresponds to spatially distinct plant groups coupled at higher trophic levels by groups of herbivores, which are in turn coupled by carnivore groups. Thus the group structure of the Serengeti web represents a mixture of trophic guild structure and spatial patterns, in contrast to the standard compartments typically identified in ecological networks. From data consisting only of nodes and links, the group structure that emerges supports recent ideas on spatial coupling and energy channels in ecosystems that have been proposed as important for persistence.Comment: 28 pages, 6 figures (+ 3 supporting), 2 tables (+ 4 supporting

Ultraviolet Study of the Active Interacting Binary Star R Arae using Archival IUE Data

The eclipsing and strongly interacting binary star system R Arae (HD149730) is in a very active and very short-lived stage of its evolution. R Ara consists of a B9V primary and an unknown secondary. We have collected the International Ultraviolet Explorer (IUE) archival data on R Ara, with most of the data being studied for the first time. There are 117 high resolution IUE spectra taken in 1980, 1982, 1985, 1989, and 1991. We provide photometric and spectroscopic evidence for mass transfer and propose a geometry for the accretion structure. We use colour scale radial velocity plots to view the complicated behavior of the blended absorption features and to distinguish the motions of hotter and cooler regions within the system. We observed a primary eclipse of R Ara in 2008 and have verified that its period is increasing. A model of the system and its evolutionary status is presented.Comment: 13 pages, 15 figures, accepted for publication in MNRA