Klaus Wöhrmann

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It is generally believed that recombination by sexual reproduction is unfavourable in constant environments but is of adaptive value under changing environmental conditions. To test this theory, experimental populations of yeast (Saccharomyces cerevisiae) were set up and maintained at different levels of environmental heterogeneity. Recombination was(More)
Populations of the rose aphid (Macrosiphum rosae) from various latitudes show differences in their life cycles. In warm climates they are exclusively parthenogenetic, whereas in cold climates sexual reproduction allows the aphid to overwinter in the egg stage. In temperate zones both holocyclic and anholocyclic clones occur within the same population. It is(More)
Competition experiments between yeast strains which were either inducible or constitutive for maltase synthesis were performed. The experiments showed a selective advantage of cells with an inducible maltase over cells with a constitutive maltase. However, with respect to the carbon source of the media, the most remarkable decrease of frequency of(More)
Capsella bursa-pastoris (L.)Med. is a partially self-pollinating, autogamous plant. The selfing-rate depends on ecological factors. High atmospheric humidity at temperatures over 15 °C and low light intensity, i.e. cloudy and rainy weather, lead to almost exclusive self-pollination, while dry and sunny weather favours outcrossing. At low temperatures (about(More)
Problems which might be caused by the release of transgenic organisms are discussed from the viewpoint of genetics, population genetics and ecology. On this background, the differences between "classical" methods to recombine genetic information and the more recent ones of gene engineering are pointed out and the predictability of gene interactions is(More)
Problems which might be caused by the release of transgenic organisms are discussed from the viewpoint of genetics, population genetics and ecology. On this background, the differences between "classical" methods to recombine genetic information and the more recent ones of gene engineering are pointed out and the predictability of gene interactions is(More)
This paper analyses the fate of artificially induced mutations and their importance to the fitness of populations of the yeast, Saccharomyces cerevisiae, an increasingly important model organism in population genetics. Diploid strains, treated with UV and EMS, were cultured asexually for approximately 540 generations and under conditions where the asexual(More)
Competition experiments were carried out under varying exogenic and endogenic conditions. The genotypes were marked by combinations of two esterase loci, each with two alleles. When genotypes of the line W7 were used, there was no demonstrable influence of the gene blocks marked by the Est-1 locus on the competitive ability at temperatures of 21 and 29 C.(More)