Mitochondrial control region variation in bank voles (Clethrionomys glareolus) is not related to Chernobyl radiation exposure

Abstract

Abstract-Three previous studies at Chernobyl, Ukraine, documented elevated mitochondrial DNA diversity in bank voles (Clethrionomys glareolus) from radioactively contaminated sites. Little evidence was found to link patterns of diversity in contaminated areas to radiation exposure, but the experimental design precluded discriminating among alternative explanations for elevated diversity in exposed groups. Reference sites selected for the studies were relatively distant from contaminated sites and, additionally, were separated from contaminated sites by large river systems; thus, we hypothesized that differences among sites were correlated with geographic isolation rather than with radiation exposure. For the present study, we added three reference sites, which were selected based on minimal radioactive contamination, proximity to contaminated sites, and absence of obvious barriers to dispersal. We hypothesized that neighboring reference sites should exhibit levels and patterns of diversity similar to those of contaminated sites if the previously detected differences were, in fact, caused by geographic isolation. Indeed, levels of diversity in nearby reference sites are comparable to levels in contaminated sites. Additionally, nearby reference sites contain several haplotypes not observed at other study sites. Our results suggest that levels of diversity in contaminated regions are more plausibly explained by ecological and historical factors than by increased mutational pressure resulting from exposure to Chernobyl radiation.

Understanding the genetic consequences of environmental toxicant exposure: Chernobyl as a model system

“…Only two haplotypes exclusive to populations in radioactive sites were detected, despite extensive sampling over multiple years. Data from additional uncontaminated sites thus alters the conclusions drawn from previous Chernobyl research [4,6,16,17], in which radioactively contaminated sites were shown to harbor a greater number of endemic lineages.…”

“…The investigative tactic is considered to be particularly valuable in instances when preexposure data are unavailable but the nature, extent, and temporal boundaries of the contamination event are documented. Such methodology has been represented as a practical approach for assessing the causal relationships between multigenerational exposure to polluted environments and biological effects [1–4]. Selecting reference sites and/or populations useful for comparative purposes can be complicated, however, both because of the numerous factors that can influence the demographic characteristics of a species and because the relative impact of these factors differs across taxonomic lines [5,6].…”

“… Map of Ukraine, with collection sites for bank voles ( Myodes glareolus ) assessed for the present study. Shown are Chernobyl (Ch) sites evaluated in previous studies [4,15–17], including radioactively contaminated sites Glyboke Lake and Red Forest, as well as reference sites Nezamozhnya, Nedanchichy, Oranoe, Krasnoye, Paryshev, and Stupnikovo. Sites added for the present study include sites in northern Ukraine (Ko = Korostyshev), western Ukraine (E = Ezyaslav; Kl = Klementsy; R = Rakhiv; T = Terebovlya), and central Ukraine (Ne = Nemirov; Sm = Smela).…”

Challenging the European southern refugium hypothesis: Species‐specific structures versus general patterns of genetic diversity and differentiation among small mammals

“…Despite the availability of over 1,000 mtDNA control region sequences sampled from individuals of C. glareolus from multiple studies (see Table 1 and Supporting Information Appendix S2), use of these sequences has primarily been restricted to investigating the associated Puumala virus (Dekonenko et al, 2003;Johansson et al, 2008;Razzauti, Plyusnina, Niemimaa, Henttonen, & Plyusnin, 2012) or the effects of Chernobyl radiation (Matson, Rodgers, Chesser, & Baker, 2000;Meeks et al, 2007;Meeks, Chesser, Rodgers, Gaschak, & Baker, 2009;Wickliffe et al, 2006) on C. glareolus. Figure 2b indicates diversity values generally reflective of the aforementioned complexity; however, regionally restricted sampling does not enable accurate phylogeographical inferences to be made using the control region sequences available here.…”

Aspermy, Sperm Quality and Radiation in Chernobyl Birds

“…Admittedly, the literature reports heterogeneous results on DNA damage and mutation rate in organisms living in areas around Chernobyl with low levels of contamination [46]–[49]. However, the susceptibility of sperm to DNA damage stems partly from the down-regulation of DNA repair systems during late spermatogenesis [24].…”