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101.
This work examined the effects of elevated CO2 and temperature and water regimes, alone and in interaction, on the leaf characteristics [leaf area (LA), specific leaf weight (SLW), leaf nitrogen content (NL) based on LA], photosynthesis (light‐saturated net carbon fixation rate, Psat) and carbon storage in aboveground biomass of leaves (Cl) and stem (Cs) for a perennial reed canary grass (Phalaris arundinacea L., Finnish local cultivar). For this purpose, plants were grown under different water regimes (ranging from high to low soil moisture) in climate‐controlled growth chambers under the elevated CO2 and/or temperature (following a factorial design) over a whole growing season (May–September in 2009). The results showed that the elevated temperature increased the leaf growth, photosynthesis and carbon storage of aboveground biomass the most in the early growing periods, compared with ambient temperature. However, the plant growth declined rapidly thereafter with a lower carbon storage at the end of growing season. This was related to the accelerated phenology regulation and consequent earlier growth senescence. Consequently, the elevation of CO2 increased the Psat, LA and SLW during the growing season, with a significant concurrent increase in the carbon storage in aboveground biomass. Low soil moisture decreased the Psat, leaf stomatal conductance, LA and carbon storage in above ground biomass compared with high and normal soil moisture. This water stress effect was the largest under the elevated temperature. The elevated CO2 partially mitigated the adverse effects of high temperature and low soil moisture. However, the combination of elevated temperature and CO2 did not significantly increase the carbon storage in aboveground biomass of the plants.  相似文献   
102.
Global phylogeographic patterns in Sanionia uncinata are addressed based on information in internal transcribed spacer (ITS) (214 specimens) and the plastid markers trnLtrnF (221) and rpl16 (217). ITS suggests a monophyletic Sanionia and a paraphyletic S. uncinata; this was neither supported nor rejected by plastid data. Northern or Eastern Eurasia and Alaska appear important in the early evolution of Sanionia and some populations dispersed into the Southern Hemisphere relatively early. Some haplotypes or groups of haplotypes are morphologically and ecologically distinct, biologically meaningful units that correspond with S. orthothecioides, S. symmetrica and S. georgicouncinata s.l. The latter includes two species that are indistinguishable by morphology, S. georgicouncinata s.s. (Southern Hemisphere) and S. nivalis (Northern Hemisphere). Tropical African and South American S. uncinata populations have separate origins and the Southern Hemisphere was colonized at least twice. In the northern circum‐Arctic region, the haplotype composition differs between the North Atlantic and Beringian areas. Eastern Eurasia has a higher S. uncinata haplotype diversity than other Holarctic regions, implying less devastating effects of recurrent glacial periods. For Eastern and Western Eurasia, North America and the Southern Hemisphere, most of the haplotype variation was found within the regions, but 14–18% can be referred to among region variation. Plastid haplotype diversity was lower in the Southern Hemisphere than in the Arctic to subarctic, possibly attributable to founder effects. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 19–42.  相似文献   
103.
  • 1 Research on mating systems and reproductive strategies is valuable for providing ethological knowledge, important for the management and conservation of a species, and in a broader sense, important for biodiversity conservation.
  • 2 We reviewed the literature to document the mating system of the brown bear Ursus arctos. We determined that many aspects of the reproduction of the brown bear remain unclear, including (i) biological aspects, such as hormone and oestrous cycling, sperm competition, mate choice, sexually selected infanticide, etc. and (ii) human impacts on the mating system, occurring when humans alter population size and structure, through, for example, hunting or habitat degradation.
  • 3 We considered three mating system classification frameworks from the literature ( Emlen & Oring 1977 , Clutton‐Brock 1989 , Shuster & Wade 2003 ) and applied various brown bear populations to them. We did this (i) to document the plasticity of the mating system of the brown bear, and (ii) to find commonalities among the reported mating system classifications in order to provide a general and common classification of the brown bear's mating system.
  • 4 The mating system of the brown bear can, in general, be classed as ‘polygamous’. Subclassifications can nevertheless be valuable on smaller spatial scales.
  • 5 Within the polygamous mating system of the brown bear, biological aspects and human impacts can influence reproductive strategies at the individual and population level. Mating system classification frameworks often lack a common terminology, which contributes to the variety of published classifications of the mating system of the brown bear.
  相似文献   
104.
  • 1 The golden jackal Canis aureus is one of the most widespread canid species with a range covering areas of central, eastern and southern Europe, northern Africa and parts of Asia. Distribution of the golden jackal in Europe has been dynamic, including dramatic declines (until the 1960s), recovery (1960s and 1970s) and expansion (from the early 1980s onwards).
  • 2 We present up‐to‐date information on golden jackal status in Europe and range expansion.
  • 3 For data collection we reviewed the scientific literature and contacted scientists from the relevant countries. We distinguished between vagrant animals and established populations.
  • 4 In the last decade, there has been an increase in jackal records in areas where the species has not been reported before. Increased presence is recorded northwards and westwards of the distribution range of the golden jackal, specifically in Hungary, Serbia and Slovakia. In Austria, the first case of reproduction was confirmed in 2007; reproduction has also recently been reported in Italy.
  • 5 Results indicate an ongoing expansion in Europe's jackal population, with a particular spread of the Balkan populations towards central Europe. Although there are numerous reports of sightings, only few originate from confirmed sources and in many areas status is unknown or vague. There is a general lack of ecological data and almost no information on ecological consequences associated with the golden jackal expansion.
  相似文献   
105.
106.
Crystal Structure of Human Carbonic Anhydrase C   总被引:16,自引:0,他引:16  
The three dimensional structure of human carbonic anhydrase C has been determined at 2.0 Å resolution. The active site has been identified by the binding of inhibitors and the location of the zinc ion.  相似文献   
107.
It has been reported that the use of dimethylsulfoxide (DMSO) as a solvent for fixatives enhances preservation of cellular ultrastructure. By contrast, we have shown that DMSO alters the ultrastructural integrity of glutaraldehyde fixed cells. The cell membrane, nuclear envelope, endoplasmic reticulum, ribosomes, microtubules and intracytoplasmic organelles are most susceptible to the action of DMSO. We hypothesize that DMSO exerts intracellular alterations via its interaction with remnant interfacial water in fixed cells. DMSO-induced alterations of these and related cellular components may result in the formation of artefactual structures and networks. Thus, it appears that DMSO containing glutaraldehyde neither accelerates fixation nor enhances stabilization of cellular ultrastructure. For these reasons, addition of DMSO to fixatives is not recommended.  相似文献   
108.
Genetic variation in many invasive species shows little or no signs of a founder event, suggesting that high genetic diversity may facilitate establishment success. The rocky‐shore, plankton‐feeding cichlid fish Cynotilapia afra is endemic to Lake Malawi, but naturally absent from many suitable sites. In the 1960s, this species was introduced to the southern areas of the lake, presumably as a result of the aquarium fish trade. It has now become established on a number of rocky areas within the Lake Malawi National Park. Here, we analysed DNA sequence variation in the mitochondrial control region of six native and four introduced populations of C. afra, and three populations of the closely‐related and hybridizing Pseudotropheus zebra. In contrast to previous studies of Lake Malawi rock dwelling cichlids, network analyses suggested that native populations of C. afra showed high levels of lineage sorting in mtDNA. Introduced populations showed higher sequence and haplotype diversity than their native counterparts. Our analyses suggested that the elevated gene diversity was largely attributed to the fact that the introduced C. afra populations were derived from several genetically distinct and geographically separate populations, and to a lesser extent because of introgressive hybridization with native P. zebra. The establishment and spread of C. afra may be partly because of its ability to occupy a vacant ecological niche, but it may also have been facilitated by its enhanced genetic diversity.  相似文献   
109.
Stress adaptations often include a trade‐off of weakened performance in nonlocal conditions, resulting in divergent selection, and potentially, genetic differentiation and evolutionary adaptation. Results of a two‐phase (greenhouse and field) common garden experiment demonstrated adaptation of mountain birch (Betula pubescens subsp. czerepanovii) populations from industrially polluted areas of the Kola Peninsula, north‐western Russia, to heavy metals (HM), whereas no adaptations to wind or drought stress were detected in populations from wind‐exposed sites. HM‐adapted seedlings were maladapted to drought but less palatable (co‐resistant) to insect herbivores, even under background HM concentrations. The absence of adaptations to harsh microclimate and the generally high adaptive potential of mountain birch, a critical forest forming tree in subarctic Europe, need to be accounted for in models predicting consequences of human‐driven environmental changes, including the projected climate change.  相似文献   
110.
An Atlantic salmon (Salmo salar L.) expressed sequence tag (EST) database consisting of 58 146 ESTs was screened for microsatellite sequences. Subsequent development of 75 polymorphic EST‐associated microsatellite markers in this species is described together with cross‐species amplification results of 133 gene‐associated tandem repeat markers in five salmonid species (Salmo trutta, Oncorhynchus mykiss, Salvelinus aplinus, Thymallus thymallus, Coregonus lavaretus). The number of alleles among EST‐linked microsatellites in Atlantic salmon ranged from two to 41 with an average of 12 alleles per locus. Cross‐species amplification resulted in detection of a total of 111 polymorphic locus‐species combinations (12–32 loci per species).  相似文献   
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