Evolutionary Toxicology: Population-Level Effects of Chronic Contaminant Exposure on the Marsh Frogs ( Rana ridibunda ) of Azerbaijan

Abstract

We used molecular methods and population genetic analyses to study the effects of chronic contaminant exposure in marsh frogs from Sumgayit, Azerbaijan. Marsh frogs inhabiting wetlands in Sumgayit are exposed to complex mixtures of chemical contaminants, including petroleum products, pesticides, heavy metals, and many other industrial chemicals. Previous results documented elevated estimates of genetic damage in marsh frogs from the two most heavily contaminated sites. Based on mitochondrial DNA (mtDNA) control region sequence data, the Sumgayit region has reduced levels of genetic diversity, likely due to environmental degradation. The Sumgayit region also acts as an ecological sink, with levels of gene flow into the region exceeding gene flow out of the region. Additionally, localized mtDNA heteroplasmy and diversity patterns suggest that one of the most severely contaminated sites in Sumgayit is acting as a source of new mutations resulting from an increased mutation rate. This study provides an integrated method for assessing the cumulative population impacts of chronic contaminant exposure by studying both population genetic and evolutionary effects.

Assessing triclosan-induced ecological and trans-generational effects in natural phytoplankton communities: a trait-based field method

“…A number of studies observed genetic responses in populations exposed to chemical pollution (e.g. (Theodorakis and Shugart 1997;Baker et al 2001;Matson 2006;Wirgin et al 2011). Similarly to more traditional effect end-points, trans-generational and evolutionary impacts can result in altered population dynamics and possibly ecosystem structure and functioning.…”

It’s All in the Genes: How Genotype Can Impact Upon Response to Contaminant Exposure and the Implications for Biomonitoring in Aquatic Systems

“…A central goal of evolutionary toxicology is to examine both the direct and indirect effects of toxicant and contaminant exposure on the genetic structure of natural populations (Bickham et al, 2000;Matson et al, 2006;Theodorakis et al, 2001). A chief advantage of evolutionary toxicology over traditional ecotoxicological studies is that the utilisation of molecular and population genetics methodologies means these studies are based on fundamental evolutionary concepts.…”

“…contaminant-induced increases in mutation rates, resulting in changes in genetic frequencies in impacted populations (e.g. Matson et al, 2006;Theodorakis et al, 2001); 2. contaminant-induced selection at loci affecting survival success, resulting in changes in genetic frequencies in the population (e.g. Cohen, 2002;; 3. alterations to patterns of genetic distribution and migration, leading to demographic shifts (e.g.…”

“…Cohen, 2002;; 3. alterations to patterns of genetic distribution and migration, leading to demographic shifts (e.g. Maes et al, 2005;Matson et al, 2006); and 4. genome-wide changes in genetic diversity (e.g. Armendariz et al, 2004;Connon et al, 2008;Poynton et al, 2008; for reviews on evolutionary toxicology, see : Bickham, 2011;Theodorakis & Wirgin, 2002;van Straalen & Timmermans, 2002).…”

“…Given its relatively recent history in the region G. holbrooki populations are expected to be relatively homogeneous, with novel mutational events easily traceable (Rinner et al, 2011). In conjunction with the work by Matson et al (2006), the genetic diversity at the mitochondrial control region was assessed in G. holbrooki sampled from the heavily contaminated Sumgayit region and surrounding reference sites. It was found that fish sampled from the contaminated region possessed four novel haplotypes and heteroplasmies, of which only one was found to occur among fish from reference populations.…”