Mapping the antigenic and genetic evolution of influenza virus

The antigenic evolution of influenza A (H3N2) virus was quantified and visualized from its introduction into humans in 1968 to 2003. Although there was remarkable correspondence between antigenic and genetic evolution, significant differences were observed: Antigenic evolution was more punctuated than genetic evolution, and genetic change sometimes had a disproportionately large antigenic effect. The method readily allows monitoring of antigenic differences among vaccine and circulating strains and thus estimation of the effects of vaccination. Further, this approach offers a route to predicting the relative success of emerging strains, which could be achieved by quantifying the combined effects of population level immune escape and viral fitness on strain evolution.     

Transformation of the nitrogen cycle: recent trends, questions, and potential solutions

Humans continue to transform the global nitrogen cycle at a record pace, reflecting an increased combustion of fossil fuels, growing demand for nitrogen in agriculture and industry, and pervasive inefficiencies in its use. Much anthropogenic nitrogen is lost to air, water, and land to cause a cascade of environmental and human health problems. Simultaneously, food production in some parts of the world is nitrogen-deficient, highlighting inequities in the distribution of nitrogen-containing fertilizers. Optimizing the need for a key human resource while minimizing its negative consequences requires an integrated interdisciplinary approach and the development of strategies to decrease nitrogen-containing waste.     

Rise and fall of species occupancy in Cenozoic fossil mollusks

In the time between speciation and extinction, a species' ecological and biogeographic footprint-its occupancy-will vary in response to macroecological drivers and historical contingencies. Despite their importance for understanding macroecological processes, general patterns of long-term species occupancy remain largely unknown. We documented the occupancy histories of Cenozoic marine mollusks from New Zealand. For both genera and species, these show a distinct pattern of increase to relatively short-lived peak occupancy at mid-duration, followed by a decline toward extinction. Thus, species at greatest risk for extinction are those that have already been in decline for a substantial period of time. This pattern of protracted rise and fall stands in contrast to that of incumbency, insofar as species show no general tendency to stay near maximal occupancy once established.     

癞蟋科4种蟋蟀发声器的比较(直翅目:癞蟋科)

利用扫描电镜观察并描述了直翅目Orthoptera癞蟋科Mogoplistidae奥蟋属Ornebius Guerin和铁蟋属Sclerogryllus Gorochov4种蟋蟀,即凯纳奥蟋Ornebius kanetataki(Matsumura)、台湾奥蟋Q formosanus(Shiraki)、刻点铁蟋Sclerogryllus punctatus(BrHnrlerv．Wattenwyl)、革翅铁蟋S．coriaceus(De Haan)的声锉和声齿形态特征,并对其分类意义进行了比较。结果表明,发声器超微特征在种内个体间差异小,而种间和属间差异明显,且性状稳定。