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We studied the effects of overgrazing on the foraging behaviour of the lizard Pedioplanis l. lineoocellata (Spotted Sand Lizard), a sit-and-wait forager, in habitats of differing vegetation states to determine the effects of habitat degradation on this species. At high grazing intensity where vegetation cover and diversity is low, the lizard P. lineoocellata moves more frequently, spends more time moving and covers larger distances than in habitats where vegetation cover and diversity is high. These behavioural changes in movement patterns can be explained by less abundant prey in habitats with low vegetation cover and diversity. Although morphology, phylogeny and physiology of P. lineoocellata should constrain the change in foraging behaviour, the species has modified its foraging strategy from sit- and-wait to actively foraging. We assume that this behavioural flexibility of P. lineoocellata is a buffer mechanism enabling the species to use and survive in degraded (unfavourable) habitats.
Die spontane Ausbreitung nicht-einheimischer oder exotischer Arten, unabsichtlich eingeschleppt bzw. absichtlich eingefuehrt, ist heute ein weltweit zu beobachtendes Phaenomen. Arten werden in grossem Umfang zwischen Kontinenten ausgetauscht und innerhalb der Kontinente verfrachtet; in erster Linie eine Folge des weltweiten Handels und Reiseverkehrs. Einige (aber nicht alle) dieser verwilderten Exoten breiten sich rasant aus und ihr Massenvorkommen zieht nachteilige Auswirkungen auf Mensch und Umwelt nach sich. Solche invasive Arten sind heutzutage ein zentrales Thema im internationalen Naturschutz und in der oekologischen Forschung. Die Ausbreitung invasiver Organismen, als biologische Invasionen bezeichnet, gilt mittlerweile neben Lebensraumzerstoerung als die zweitwichtigste Ursache des weltweiten Artenrueckganges. Die Mechanismen, die zu einer biologischen Invasion fuehren koennen, sind sehr vielfaeltig und beruhen auf Eigenschaften der Arten sowie des betreffenden neuen Lebensraumes. Offene Habitate mit geringem Konkurrenzdruck anderer Arten und ohne spezialisierte Frassfeinde und Pathogene zeigen sich als besonders anfaellig fuer die Besiedlung invasiver Arten. Unter invasive Arten fallen auch solche, die in der Land- und Forstwirtschaft Schaeden verursachen oder die Gesundheit des Menschen gefaehrden. In der Schweiz sind ueber 800 exotische Pflanzen-, Tier-, und Pilz-Arten etabliert, von diesen gelten 107 Arten als invasiv. Welche Massnahmen ergriffen werden sollen, richtet sich nach der Haeufigkeit der Art, aber auch nach der Zielsetzung. Die kostenguenstigsten Massnahmen sind praeventive Massnahmen. Die Gruende, wie es zu biologischen Invasionen kommen kann, welche Eigenschaften invasive Arten aufweisen, ob und wie schnell sich verschleppte Arten im neuen Verbreitungsgebiet evolutiv veraendern koennen, und welches die beste Strategie im Umgang mit invasiven Arten ist, ist Gegenstand dieser Schrift.
Fault zones are the locations where motion of tectonic plates, often associated with earthquakes, is accommodated. Despite a rapid increase in the understanding of faults in the last decades, our knowledge of their geometry, petrophysical properties, and controlling processes remains incomplete. The central questions addressed here in our study of the Dead Sea Transform (DST) in the Middle East are as follows: (1) What are the structure and kinematics of a large fault zone? (2) What controls its structure and kinematics? (3) How does the DST compare to other plate boundary fault zones? The DST has accommodated a total of 105 km of left-lateral transform motion between the African and Arabian plates since early Miocene (similar to 20 Ma). The DST segment between the Dead Sea and the Red Sea, called the Arava/Araba Fault (AF), is studied here using a multidisciplinary and multiscale approach from the mu m to the plate tectonic scale. We observe that under the DST a narrow, subvertical zone cuts through crust and lithosphere. First, from west to east the crustal thickness increases smoothly from 26 to 39 km, and a subhorizontal lower crustal reflector is detected east of the AF. Second, several faults exist in the upper crust in a 40 km wide zone centered on the AF, but none have kilometer-size zones of decreased seismic velocities or zones of high electrical conductivities in the upper crust expected for large damage zones. Third, the AF is the main branch of the DST system, even though it has accommodated only a part (up to 60 km) of the overall 105 km of sinistral plate motion. Fourth, the AF acts as a barrier to fluids to a depth of 4 km, and the lithology changes abruptly across it. Fifth, in the top few hundred meters of the AF a locally transpressional regime is observed in a 100-300 m wide zone of deformed and displaced material, bordered by subparallel faults forming a positive flower structure. Other segments of the AF have a transtensional character with small pull-aparts along them. The damage zones of the individual faults are only 5-20 m wide at this depth range. Sixth, two areas on the AF show mesoscale to microscale faulting and veining in limestone sequences with faulting depths between 2 and 5 km. Seventh, fluids in the AF are carried downward into the fault zone. Only a minor fraction of fluids is derived from ascending hydrothermal fluids. However, we found that on the kilometer scale the AF does not act as an important fluid conduit. Most of these findings are corroborated using thermomechanical modeling where shear deformation in the upper crust is localized in one or two major faults; at larger depth, shear deformation occurs in a 20-40 km wide zone with a mechanically weak decoupling zone extending subvertically through the entire lithosphere.
The effect of introducing positive charges (lysines) in human cytochrome c (cyt c) on the redox properties and reaction rates of cyt c with superoxide radicals was studied. The mutated forms of this electron-transfer protein are used as sensorial recognition elements for the amperometric detection of the reactive oxygen radical. The proteins were prepared by site-directed mutagenesis focusing on amino acids near the heme edge. The 11 mutants of human cyt c expressed in the course of this research have been characterized by UV-vis spectroscopy, circular dichroism, and NMR spectroscopy to verify overall structure integrity as well as axial coordination of the heme iron. The mutants are investigated voltammetrically using promoter-modified gold electrodes with respect to redox activity and formal redox potential. The rate constants for the reaction with superoxide have been determined spectrophotometrically. Four mutants show a higher reaction rate with the radical as compared to the wild type. These mutants are used for the construction of superoxide sensors based on thiol-modified gold electrodes and covalently fixed proteins. We found that the E66K mutant-based electrode has a clearly higher sensitivity in comparison with the wild-type-based sensor while retaining the high selectivity and showing a good storage stability.