Large, wetland-associated mayflies (Ephemeroptera) of Glacier National Park, Montana

We describe species richness and habitat associations of mayflies (Ephemeroptera) collected during amphibian surveys of 355 water bodies in Glacier National Park (NP), Montana, in 2006–2008. We collected 9 taxa (in 7 genera) of mayflies that were identifiable to species. Callibaetis ferrugineus hageni was collected most frequently, followed by Siphlonurus occidentalis, S. phyllis, Ameletus celer, A. similior, Parameletus columbiae, Ephemerella dorothea infrequens, Baetis bicaudatus, and Leptophlebia cupida. Siphlonurus phyllis had not been reported in the western United States prior to our surveys, and P. columbiae is a species of concern in the region. The identifications of 4 additional taxa were uncertain due to the poor condition of specimens found at only one site ( Centroptilum sp. and Paraleptophlebia sp.) or because nymphal specimens could not be confidently identified ( Cinygma sp. and Cinygmula sp.). Species richness of mayflies in wetlands seems low compared to that in streams and lakes in Glacier National Park. We found the most species of mayflies in beaver ponds, where we detected some species not commonly associated with lentic water bodies. Our survey was the first extensive survey of wetland invertebrates in Glacier NP and only the second that we are aware of in western Montana.     

Crystallographic studies of the dynamic properties of lysozyme.

The patterns of atomic displacements in the crystals of hen and human lysozyme derived from independent crystallographic refinement are broadly similar. Analysis of the pattern indicates a close correlation with molecular structure, strongly suggestive of intramolecular motion. The active site of lysozyme is located in a region of high displacement. It is concluded that protein mobility may play a significant part in biological activity and that X-ray crystallography can contribute to its analysis.     

开放·边缘·民间——第四届人类学高级论坛之观察员评论

第四届人类学高级论坛所涉及的所有问题都具有人类学的学术价值。学者们认为人类学是一门开放的学科,中国人类学学者应放在开放的田野工作中提升和构建新的人类学理论。     

Response of sagebrush steppe species to elevated CO 2 and soil temperature

Elevated atmospheric CO 2 may cause long-term changes in the productivity and species composition of the sagebrush steppe. Few studies, however, have evaluated the effects of increased CO 2 on growth and physiology of species important to this ecosystem. Since the response of plants to elevated CO 2 may be limited by environmental factors, soil temperature was also examined to determine if low soil temperatures limit CO 2 response. To determine how CO 2 and soil temperature affect the growth of species native to the sagebrush steppe, bottlebrush squirreltail [ Elymus elymoides (Raf.) Swezey], Thurber needlegrass ( Stipa thurberiana Piper), and Wyoming big sagebrush ( Artemisia tridentata ssp. wyomingensis Beetle) were grown in ambient (374 mL L -1 ) or high (567 mL L -1 ) CO 2 and low (13° C) or high (18° C) soil temperature for approximately 4 months. Although soil temperature affected the growth of squirreltail and needlegrass, temperature did not modify their response to elevated CO 2 . Total biomass of sagebrush was consistent across soil temperature and CO 2 treatments, reflecting its slow-growing strategy. All 3 species had higher leaf water-use efficiency at elevated CO 2 due to higher net photosynthesis and lower transpiration rates. We conclude that elevated CO 2 and soil warming may increase the growth of grasses more than shrubs. Field studies in the sagebrush steppe are necessary to determine if differences in biomass, resulting from changes in CO 2 and soil temperature, are exhibited in the field.     

Recent decreases in fossil-fuel emissions of ethane and methane derived from firn air

Methane and ethane are the most abundant hydrocarbons in the atmosphere and they affect both atmospheric chemistry and climate. Both gases are emitted from fossil fuels and biomass burning, whereas methane (CH(4)) alone has large sources from wetlands, agriculture, landfills and waste water. Here we use measurements in firn (perennial snowpack) air from Greenland and Antarctica to reconstruct the atmospheric variability of ethane (C(2)H(6)) during the twentieth century. Ethane levels rose from early in the century until the 1980s, when the trend reversed, with a period of decline over the next 20?years. We find that this variability was primarily driven by changes in ethane emissions from fossil fuels; these emissions peaked in the 1960s and 1970s at 14-16 teragrams per year (1?Tg = 10(12)?g) and dropped to 8-10?Tg yr(-1) by the turn of the century. The reduction in fossil-fuel sources is probably related to changes in light hydrocarbon emissions associated with petroleum production and use. The ethane-based fossil-fuel emission history is strikingly different from bottom-up estimates of methane emissions from fossil-fuel use, and implies that the fossil-fuel source of methane started to decline in the 1980s and probably caused the late twentieth century slow-down in the growth rate of atmospheric methane.