title: Evolutionary consequences of historical metal contamination for natural populations of Chironomus riparius (Diptera: Chironomidae).
abstract: Populations inhabiting metal-impacted freshwater systems located nearby industrial and urban areas may be under intense selection. The present study aims to address two fundamental microevolutionary aspects of metal contamination in the midge Chironomus riparius (Meigen): Are populations inhabiting historically metal contaminated sites genetically adapted to metals? And, are populations from these sites genetically eroded? To answer these questions, C. riparius populations were sampled from three sites with well-known histories of metal contamination and three nearby-located references. Genetic adaptation to metals was investigated through acute and chronic exposures to cadmium (Cd), after rearing all populations for at least six generations under laboratory clean conditions. Genetic diversity was estimated based on the allelic variation of seven microsatellite markers. Results showed higher acute tolerance to Cd in populations originating from metal contaminated sites compared to their respective references and significant differences in two out of three pairwise comparisons. However, there was a mismatch between acute and chronic tolerance to Cd with results of the partial life-cycle tests suggesting fitness costs under control clean conditions in two metal-adapted populations. Despite no evidences of genetic erosion in populations sampled from metal contaminated sites, our results suggest genetically inherited tolerance to Cd in populations inhabiting historically contaminated sites. These findings lend support to the use of C. riparius as a model organism in evolutionary toxicology and highlight the importance of coupling measures of neutral genetic diversity with assessments of chemical tolerance of populations for a better understanding of contaminant-induced adaptation and evolutionary processes.
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193, Aveiro, Portugal.|Conservation Genetics Group, Senckenberg Research Institute and Natural History Museum of Frankfurt, Clamecystrasse 12, 63571, Gelnhausen, Germany.
authors.forename: João
authors.initials: J
authors.lastname: Pedrosa
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193, Aveiro, Portugal.
authors.forename: Diana
authors.initials: D
authors.lastname: Campos
authors.affiliation: Conservation Genetics Group, Senckenberg Research Institute and Natural History Museum of Frankfurt, Clamecystrasse 12, 63571, Gelnhausen, Germany.
authors.forename: Berardino
authors.initials: B
authors.lastname: Cocchiararo
authors.affiliation: Conservation Genetics Group, Senckenberg Research Institute and Natural History Museum of Frankfurt, Clamecystrasse 12, 63571, Gelnhausen, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Nowak
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193, Aveiro, Portugal.
authors.forename: Amadeu M V M
authors.initials: AMVM
authors.lastname: Soares
authors.affiliation: Department of Environmental Chemistry (IDAEA-CSIC), Jordi Girona 18-26, 08034, Barcelona, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Barata
authors.affiliation: Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193, Aveiro, Portugal. jpestana@ua.pt.
authors.forename: João
authors.initials: J
authors.lastname: L T Pestana
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005075:Biological Evolution; D002683:Chironomidae / Q000502:physiology*; D014644:Genetic Variation; D007814:Larva; D008018:Life Cycle Stages; D008670:Metals / Q000633:toxicity*; D018895:Microsatellite Repeats; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D008670:Metals; D014874:Water Pollutants, Chemical
keywords: Cadmium; Freshwater; Genetic diversity; Invertebrates; Metal adaptation; Metal contamination