Genotoxic responses and population level effects of mutagen exposure in bisexual and parthenogenetic Artemia

Genotoxic chemicals in the aquatic environment induce DNA damage and mutations causing emergent effects on populations and ecosystem. The vulnerability of organisms to these chemicals also depends on life histories and reproductive mode. This thesis explored the population consequences of exposure to a reference genotoxicant/mutagen, ethyl methane sulfonate in sexual and asexual species of Artemia. A holistic approach was adopted by studying molecular markers (comet assay and ISSR), whole organism (changes in demographic parameters) and population level consequences (prospective and retrospective analysis of effects on population growth rate ft.) in laboratory conditions. EMS elicited predictable genotoxic responses in both the species of Artemia in comet assay and ISSR profiling. The genotoxic responses were associated with reductions in whole organism performance and population growth in the parental generation of both the species and Fl and F2 generations of asexual species showing the predictability of biomarkers about population level effects, more efficiently in asexuals. Population growth rate was proportionally more sensitive to juvenile survival whereas the effect of EMS on juvenile fertility contributed more to the variations in population growth rate in both the species in perturbation analysis and this effect was due to the high growth rate of Artemia. Simulations of lower population growth rate in the model showed that, adult fertility and survival are also of importance. Asexual species showed substantial reductions in whole organism performance and population growth rate in all the three generations whereas in sexual species substantial effects occurred only in parental generation. Thus the inability of asexual species to purge deleterious mutations by a genotoxicant/mutagen was demonstrated conclusively. These findings provided strong empirical evidence of the evolutionary hypotheses about the advantages and disadvantages of asexual and sexual reproduction. Thus asexual species may be vulnerable to extinction in environmentally challenging conditions affecting community structure and ecosystem dynamics.EThOS - Electronic Theses Online ServiceGBUnited Kingdo