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331.
The Dartford Warbler Sylvia undata has recently expanded its range northwards and upwards in the UK, consistent with the hypothesis that this cold‐sensitive species has responded to a warming climate. We interrogated distribution data, collected during four national surveys of this species between 1974 and 2006, to assess whether this large‐scale range expansion has been accompanied by finer‐scale changes in topographic characteristics of breeding locations. Within sites occupied in successive surveys, there was some evidence of limited altitudinal expansion between surveys. Within wider landscapes occupied in successive surveys, the preceding winter climate tended to be harsher at newly colonized sites than at sites that had already been occupied in the previous survey, while territories in newly colonized sites also tended to be on steeper slopes, especially if at higher altitude, and (in 1994 only) to be more south‐facing. Territories in sites that had already been occupied in the previous survey tended to be lower altitude, less steep and more north‐facing than territories in newly colonized landscapes. In 2006 only, the winter climate was significantly milder in newly colonized landscapes than in already occupied sites. The combined effects of a changing climate and topography may have influenced the pattern of in‐filling in the existing range, while colonization of distant areas, especially more latterly, may have been facilitated by a combination of increased dispersal pressure from the existing range and warming of climate which made higher altitude habitat in the new areas more suitable for occupancy. Careful consideration needs to be given to the importance of fine‐scale topographical variation in determining species’ responses to climate change in order to underpin robust adaptation strategies.  相似文献   
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Isoperoxidase A3 from tobacco tissue culture, Nicotiana tabacam W-38, apparently does not have a subunit structure. Its molecular weight is approximately 54,000. The oxidation of scopoletin appears to occur in more than a single step since a blue intermediate is first formed. This is followed by the production of the final yellow product. A plausible explanation for this observation is the coupling of free radicals generated by the primary enzyme catalyzed reaction.  相似文献   
335.
Error and uncertainty in habitat models   总被引:9,自引:2,他引:7  
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Abstract:  A new suite of arthropod trace fossils, attributed to a decapod crustacean, is described from the Lower Jurassic Saltford Shale Member of the Blue Lias Formation of Southam Cement Works Quarry, eastern Warwickshire, England. Solusichnium southamensis igen. et isp. nov. consists of small, isolated, bilaterally symmetrical, suboval hypichnia, comprising three regions. The concave anterior region contains imprints of chelate appendages, antennae and antennules. The elongate middle region contains abdominal appendage imprints that extend laterally, separated by a bifurcated medial imprint. The convex posterior region terminates in a globular V-shaped telson imprint. The large sample size and range of trace morphologies allows identification of five morphotypes within a taphoseries. S. southamensis is found on the base of siltstone lenses in what is otherwise a dysaerobic laminated mudstone unit, associated with epichnial Rusophycus , and the suite of trace fossils is interpreted as the resting traces (Cubichnia) and escape reactions (Fugichnia) of small decapods that were trapped below a distal storm deposit. The producer of S. southamensis was possibly an Eryon -like decapod, similar to those known from the slightly older Wilmcote Limestone Member of southwestern Warwickshire.  相似文献   
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Lapwing Vanellus vanellus is known to be declining throughout much of its UK breeding range. The ecological requirements of the species are well known and a variety of mechanisms exist which can be implemented to help recovery. Arable options within agri-environment schemes can be used to provide breeding habitat throughout the species' UK range, and targeted recovery projects have been shown to have the potential to deliver increases in breeding pairs at the local level. The farming community need to be made aware of the requirements of Lapwing if agriculture and conservation needs are to be integrated.  相似文献   
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Stigmas in 24 species of 11 genera, classified in three groups, Caesalpinia, Peltophorum and Dimorphandra, of the tribe Caesalpinieae have been examined by light and scanning electron microscopy. All are of the WN (wet, non-papillate) form. The receptive stigmatic surface comprises a crater, generally at the apex of the style, which in fresh flowers is full of clear fluid. The crater rim may be fringed with non-receptive hairs, and its shape and depth are variable between species. Extreme forms are found in Caesalpinia sappan where crater hairs are short and the crater funnel-shaped and very deep, and C. vesicaria and Delonix regia where crater hairs are long and the crater appears very shallow.  相似文献   
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