Multigenerational demographic responses of sexual and asexual Artemia to chronic genotoxicity by a reference mutagen

Abstract

tGenotoxins are capable of multigenerational impacts on natural populations via DNA damage and muta-tions. Sexual reproduction is assumed to reduce the long term consequences of genotoxicity for individualfitness and should therefore reduce population level effects. However, rather few empirical studies havequantified the magnitude of this effect. We tried to analyse the multigenerational demographic responsesof sexual Artemia franciscana and asexual Artemia parthenogenetica due to chronic genotoxicity by a ref-erence mutagen, ethyl methane sulfonate (EMS). A prospective (elasticity analysis) and retrospective(differences and contributions) perturbation analysis was carried out to understand the interactions oflife history traits with population growth rate by comparing elasticities, differences and contributionsof vital rates to . None of the previous studies have compared the effects of chronic genotoxicity usingprospective and retrospective perturbation analyses in a sexual and asexual species over generations.The behaviour of a population with lower growth rate in the presence of genotoxicants in the field wasstudied by simulating reduced fertilities in the LTRE design. The results of prospective and retrospec-tive perturbation analyses of effects on showed that population growth rate was proportionally moresensitive to juvenile survival whereas the effect of EMS on juvenile fertility contributed more to thevariations in population growth rate in both the species and this effect was due to the high growth rateof Artemia. Simulations of lower population growth rate in the model showed that adult fertility andsurvival are also of importance. Sexual reproduction substantially mitigated the long term consequencesof genetic damage, although these would be greater if population growth rate were lower. So multi-generational population level consequences of genotoxicity were much greater in an asexual species. Soasexual species, and those with a parthenogenetic phase in their life cycle, may be particularly vulnerableto the effects of environmental mutagens. Ecological risk assessments should include information frommultigenerational studies, as responses to genotoxicity may vary depending on the life history strate-gies and reproductive modes of the species under consideration. Single generation studies may under orover-estimate risks.