| Summary: | The selective effects of Copper, Mercury, Cadmium, and sump oil on three bisexual species of <i>Artemia</i> were examined in both short and long term tests. The frequencies of alleles and genotypes of five loci were monitored, using starch gel electrophoresis, in populations of <i>Artemia</i> exposed to high doses of pollutant. Several indications of resistance being associated with particular genotypes or alleles were found. Competition experiments of bisexual and asexual species were also conducted under various regimes of temperature and salinity. Cyclical dominance found in natural co-existing populations of asexual and bisexual <i>Artemia</i> was successfully modelled in the laboratory and evidence obtained of preferred conditions for each mode of reproduction. The relative advantages of sexual and asexual reproduction are discussed, with reference to <i>Artemia</i>. An attempt was made to determine the heritability in <i>A. franciscana</i> of resistance to Carbon Dioxide saturated waters in order to establish a pathway of gene exchange with <i>A. monica</i>, which is found in carbonate waters. This does not appear to be a significantly heritable trait. Seventeen new strains obtained from cyst samples were analysed using starch gel electrophoresis. This information was added to the database of <i>Artemia</i> electrophoretic data compiled by Abreu (1983), and using the BIOSYS computer programme the following were produced for <i>A.salina, A.franciscana</i> and the asexual strains: - Similarity and Distance Coefficients - Phenetic analysis. - Phylogenetic analysis.
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