Ref ID : 781
Hans Buchner; [Studies in the control of heterogonous reproduction in Rotifers II. The control of parthenogenesis on Brachionus urceolaris]. Arch.Hydrobiol/suppl.64 3:399-441, 1982
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The production of mictic females of Brachionus urceolaris was inhibited by low temperature, low population density, and occasionally by a shift of algal diet from Kirchneriella to Stichococcus. However, it was impossible to sustain parthnogenesis for prolonged periods of time. During six years of constant environmental conditions favouring parthenogenesis, mictic and amictic phases alternated at irregular intervals. Therefore one has to assume that mixis is not exclusively determined by environmental factors but may occur spontaneously. The six tested clones differed in their rates of mixis. Also lines of the same clone showed marked differences. Such differences arise, when lines are cultured at warm temperatures for long time: The initial high rate of mixis declined gradually toward complete amixis. The capacity for mictic determination. This was never observed in lines kept at low temperature. The loss was reversible: Transferring the warm lines to cold conditions restored the capacity for mixis within several months.