Increased radiation from Chernobyl decreases the expression of red colouration in natural populations of bank voles (Myodes glareolus).

Zbyszek Boratyński,Tapio Mappes,Timothy A. Mousseau,Philipp Lehmann,Anders Pape Møller

doi:10.1038/srep07141

Abstract

Pheomelanin is a pink to red version of melanin pigment deposited in skin and hair. Due to its bright colour, pheomelanin plays a crucial function in signalling, in particular sexual signalling. However, production of pheomelanin, as opposed to its dark alternative, eumelanin, bears costs in terms of consumption of antioxidants important for protection of DNA against naturally produced reactive oxidative species. Therefore, decreased expression of pheomelanin is expected in organisms exposed to severe oxidative stress such as that caused by exposure to chronic ionizing radiation. We tested if variable exposure to radiation among natural populations of bank voles Myodes glareolus in Chernobyl affected expression of red colouration in their dorsal fur. The relative redness of dorsal fur was positively correlated with weight, but also negatively correlated with the level of background radiation. These results suggest that the development of the natural red colouration in adult bank voles is affected by ionizing background radiation, and potentially causing elevated levels of oxidative stress. Reduced production of pheomelanin allows more antioxidants to mitigate the oxidative stress caused by radiation. However, changing natural animal colouration for physiological reasons can have ecological costs, if e.g. it causes mismatch with habitat colouration and conspicuousness for predators.

Highlights

Increased radiation from Chernobyl decreases the expression of red colouration in natural populations of bank voles (Myodes glareolus)
These results suggest that the development of the natural red colouration in adult bank voles is affected by ionizing background radiation, and potentially causing elevated levels of oxidative stress
Radiation was negatively correlated with relative red colouration of animal dorsal fur (r 5 20.15, t 5 22.05, df 5 187, p 5 0.042; Fig. 2a), whereas weight was positively correlated with relative red colouration of animal dorsal fur (r 5 0.30, t 5 4.36, df 5 187, p 5 0.00002; Fig 2b)

Summary

Introduction

Increased radiation from Chernobyl decreases the expression of red colouration in natural populations of bank voles (Myodes glareolus). The relative redness of dorsal fur was positively correlated with weight, and negatively correlated with the level of background radiation These results suggest that the development of the natural red colouration in adult bank voles is affected by ionizing background radiation, and potentially causing elevated levels of oxidative stress. Production of the alternative to pheomelanin, eumelanin, does not carry such a cost, and, down-regulation of red colour expression may be a useful mechanism for animals exposed to chronic stressors that cause release of free radicals[7,11]. To estimate expression level of pheomelanin we measured www.nature.com/scientificreports relative redness of colouration[7] of dorsal fur in wild rodents, bank voles Myodes (5 Clethrionomys) glareolus (Schreiber, 1780), exposed to variable levels of ionizing radiation in Chernobyl (Fig. 1). We expected to find a negative association between the level of dorsal fur redness and the level of ionizing radiation of soil if the animals’ expression of pheomelanin changes either due to adaptation or phenotypic plasticity

Methods

Results

Conclusion