title: Impact of genetic diversity and inbreeding on the life-history of Chironomus midges over consecutive generations.
abstract: We report results of a multigenerational experiment with Chironomus riparius. Two strains with a high and a low level of genetic variability were exposed to a low, environmentally relevant TBT concentration of 80 μg Sn kg(-1)sedimentdw nominally (time weighted mean, based on measured concentrations: 4.5 μg Sn kg(-1)sedimentdw), and various life history traits as well as genetic diversity were monitored for eleven consecutive generations. While TBT effects are hardly visible in the outbred and genetically diverse strain, the inbred and genetically impoverished strain shows a clearly reduced population growth rate compared to the control. Moreover, the impoverished strain shows an increase in fitness over time. Analyses of variation at five microsatellite loci revealed that the level of genetic variation is strongly reduced in the inbred compared to the outbred strain. Moreover, genetic diversity increases over time in the inbred strain. This finding explains the observed increase in fitness in both inbred lineages (control and TBT exposed). The results document that inbreeding and the level of genetic diversity might be of crucial importance in populations under pollution stress. Furthermore, ecotoxicological bioassays have to consider genetic diversity if results between laboratories should be comparable. Our data provides evidence that genetic diversity strongly contributes to the survival of a population exposed to chemical pollution.
authors.affiliation: Conservation Research Section, Senckenberg Research Institutes and Natural History Museums, Clamecystrasse 12, D-63571 Gelnhausen, Germany. cnowak@senckenberg.de
authors.forename: Carsten
authors.initials: C
authors.lastname: Nowak
authors.forename: Christian
authors.initials: C
authors.lastname: Vogt
authors.forename: Jörg
authors.initials: J
authors.lastname: Oehlmann
authors.forename: Markus
authors.initials: M
authors.lastname: Pfenninger
authors.forename: Klaus
authors.initials: K
authors.lastname: Schwenk
authors.forename: Bruno
authors.initials: B
authors.lastname: Streit
authors.forename: Matthias
authors.initials: M
authors.lastname: Oetken
mesh_terms: D000818:Animals; D002683:Chironomidae / Q000187:drug effects* / Q000254:growth & development; D014644:Genetic Variation / Q000187:drug effects*; D007178:Inbreeding; D007814:Larva / Q000187:drug effects; D010575:Pesticides / Q000737:chemistry / Q000633:toxicity*; D013997:Time Factors; D014220:Trialkyltin Compounds / Q000737:chemistry / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010575:Pesticides; D014220:Trialkyltin Compounds; D014874:Water Pollutants, Chemical; C011559:tributyltin