Refine
Has Fulltext
- no (1246) (remove)
Year of publication
- 2003 (1246) (remove)
Document Type
- Article (839)
- Monograph/Edited Volume (212)
- Doctoral Thesis (131)
- Review (59)
- Other (4)
- Course Material (1)
Keywords
- Deutschland (2)
- Germany (2)
- Außenpolitik (1)
- DDR (1)
- European Union (1)
- Europäische Union (1)
- Foreign Policy (1)
- GDR (1)
- German-Polish Relationship (1)
- Poland (1)
- Polen (1)
- Political System (1)
- Real Socialism (1)
- Realsozialismus (1)
- Soviet Union (1)
- Sowjetunion (1)
- deutsch-polnische Beziehungen (1)
- politisches System (1)
Institute
- Institut für Biochemie und Biologie (105)
- Wirtschaftswissenschaften (94)
- Institut für Physik und Astronomie (89)
- Department Sport- und Gesundheitswissenschaften (75)
- Institut für Umweltwissenschaften und Geographie (72)
- Institut für Romanistik (65)
- Department Psychologie (62)
- Historisches Institut (61)
- Institut für Germanistik (60)
- Sozialwissenschaften (58)
Ecological and evolutionary dynamics can occur on similar timescales. However, theoretical predictions of how rapid evolution can affect ecological dynamics are inconclusive and often depend on untested model assumptions. Here we report that rapid prey evolution in response to oscillating predator density affects predator-prey (rotifer-algal) cycles in laboratory microcosms. Our experiments tested explicit predictions from a model for our system that allows prey evolution. We verified the predicted existence of an evolutionary tradeoff between algal competitive ability and defence against consumption, and examined its effects on cycle dynamics by manipulating the evolutionary potential of the prey population. Single-clone algal cultures (lacking genetic variability) produced short cycle periods and typical quarter-period phase lags between prey and predator densities, whereas multi-clonal (genetically variable) algal cultures produced long cycles with prey and predator densities nearly out of phase, exactly as predicted. These results confirm that prey evolution can substantially alter predator-prey dynamics, and therefore that attempts to understand population oscillations in nature cannot neglect potential effects from ongoing rapid evolution.
From the stem bark of Erythrina burttii, a new isoflavone, 5,2',4'-trihydroxy-7-methoxy-6-(3- methylbut-2-enyl)isoflavone (trivial name, 7-O-methylluteone) and a new flavanone, 5,7-dihydroxy-4'-methoxy- 3'-(3-methylbutadienyl)-5'-(3-methylbut-2-enyl)flavanone (trivial name, burttinonedehydrate) along with three known isoflavonoids (8-prenylluteone, 3-O-methylcalopocarpin and genistein) were isolated. The structures were detd. on the basis of spectroscopic evidence.
We present the first separate spectra of both components of the small-separation double QSO HE 0512-3329 obtained with HST/STIS in the optical and near UV. The similarities especially of the emission line profiles and redshifts strongly suggest that this system really consists of two lensed images of one and the same source. The emission line flux ratios are assumed to be unaffected by microlensing and are used to study the differential extinction effects caused by the lensing galaxy. Fits of empirical laws show that the extinction properties seem to be different on both lines of sight. With our new results, HE 0512-3329 becomes one of the few extragalactic systems which show the 2175 Å absorption feature, although the detection is only marginal. We then correct the continuum flux ratio for extinction to obtain the differential microlensing signal. Since this may still be significantly affected by variability and time-delay effects, no detailled analysis of the microlensing is possible at the moment. This is the first time that differential extinction and microlensing could be separated unambiguously. We show that, at least in HE 0512-3329, both effects contribute significantly to the spectral differences and one cannot be analysed without taking into account the other. For lens modelling purposes, the flux ratios can only be used after correcting for both effects.