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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)
  • K Wöhrmann
  • 1970
In the third part of this paper the influence of genotypically determined outcrossing rates on the composition of tetraploid populations has been investigated for the stage of genetic equilibrium. In accordance with the results from diploid populations (2nd part) it could be shown that an equilibrium situation could be established simply by genotypic ally(More)
The behaviour of populations due to fluctuating fitness values has been investigated using a computer. Six model systems were considered. The results have been illustrated by figures showing the composition of the populations as a function of the number of generations. The curves obtained for the genotype frequencies of the zygotes and adults (Z i and f i)(More)
Aspects of the stability of the host-pathogen interaction of baculoviruses Risk assessment of genetically modified plants introduced into the environment A. Dietz 209 Treatment of human disorders with gene therapy and its consequences for the human gene pool Hj. Müller 229 The release of microorganisms-ethical criteria D. Mieth 245 Summary Current theories(More)
A new fitness function is proposed. It is a balance function which results from a combination of a turnover function defining the expression of favourable genetic factors and a cost function describing the costs of metabolism. A favourable genetic factor is defined as the heterozygote state at a locus. Five loci with two alleles each are considered. In(More)
Using two different buffer systems and up to 6 different electrophoretic polyacrylamide gel concentrations, hidden enzymatic variability was investigated in samples of the rose aphid Macrosiphum rosae. MDH1, PGM1, SDH, EST and LAP were found to be polymorphic. No additional variation was observed by changing the test conditions compared to those of earlier(More)
  • K Wöhrmann
  • 1970
In the first part of this paper the interaction of selfing, double reduction, and selection has been investigated with regard to the genetic variability in equilibrium populations. Out of the theoretically infinite number of combinations of factors some typical combinations have been chosen and the effect on these of individual factors or factors acting(More)
A simple mathematical model is analyzed which describes the behaviour of a population under the influence of viability and fertility as well as carrying capacity and competition by another species. One locus with two alleles determining viability, fertility, and carrying capacity is considered. Throughout the analysis absolute rather than relative numbers(More)