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Study of adaptive responses of a population of benthic invertebrates (Chironomus riparius) subjected to chronic metallic exposure: the case of uranium

Victor Dias has defended his thesis on the 14th December 2010.

Document type > *Mémoire/HDR/Thesis

Keywords >

Research Unit > IRSN/DEI/SECRE/LRE

Authors > DIAS Victor

Publication Date > 14/12/2010


The intensity of selection on populations caused by polluted environment often exceeds which is caused by an unpolluted environment. Therefore, micro evolution can occur in response to this anthropic-directionnal force over a short period. In this context, this thesis focused on studying phenotypic changes in Chironomus riparius populations exposed during several consecutive generations to uranium-contaminated sediments. In laboratory-controled conditions experiments were conducted with same origin populations exposed to a range of uranium concentration inducing toxic effects. Over eigth-generations of exposure, life-history traits measures revealed micro evolution in exposed populations, including increase of adult reproductive success. Other experiments (acute toxicity test, common garden experiment) performed in parallel enabled to link these micro evolution with a tolerance induction, as a consequence of genetic adaptation. Nonetheless this adaptation also induced cost in terms of fitness and genetic diversity for pre-exposed populations. These results lead to the hypothesis of a selection by uranium that acted sequentially on populations. They also underline the need to better-understand the adaptive mechanisms to better assess the ecological consequences of chronic exposure of populations to a pollutant.


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