Climate change is affecting mortality of weasels due to camouflage mismatch

Kamal Atmeh,Karol Zub,Anna Andruszkiewicz

doi:10.1038/s41598-018-26057-5

Abstract

Direct phenological mismatch caused by climate change can occur in mammals that moult seasonally. Two colour morphs of the weasel Mustela nivalis (M. n.) occur sympatrically in Białowieża Forest (NE Poland) and differ in their winter pelage colour: white in M. n. nivalis and brown in M. n. vulgaris. Due to their small body size, weasels are vulnerable to attacks by a range of different predators; thus cryptic coat colour may increase their winter survival. By analysing trapping data, we found that the share of white subspecies in the weasel population inhabiting Białowieża Forest decreases with decreasing numbers of days with snow cover. This led us to hypothesise that selective predation pressure should favour one of the two phenotypes, according to the prevailing weather conditions in winter. A simple field experiment with weasel models (white and brown), exposed against different background colours, revealed that contrasting models faced significantly higher detection by predators. Our observations also confirmed earlier findings that the plasticity of moult in M. n. nivalis is very limited. This means that climate change will strongly influence the mortality of the nivalis-type due to prolonged camouflage mismatch, which will directly affect the abundance and geographical distribution of this subspecies.

Highlights

In the last decade, the number of studies on the adaptation of mammals to changing environmental conditions has increased remarkably due to rapid climate change[1,2,3,4,5]
Camouflage mismatch in seasonal coat colour is a major consequence of climate change[5] and may result in selective predation pressure, which can be an important outcome of natural selection[5,11,12]
Our main hypothesis is that due to increasing phenotypic mismatch, which might be caused by further climate change, the proportions of both colour morphs of weasel will change according to the prevailing weather conditions

Summary

Introduction

The number of studies on the adaptation of mammals to changing environmental conditions has increased remarkably due to rapid climate change[1,2,3,4,5]. Studies on snowshoe hares (Lepus americanus) that considered different climate change scenarios have shown that phenotypic mismatch in seasonally moulting species will increase in the future[5]. This would lead to extreme decreases in individual fitness if no evolutionary or adaptational changes occur[13]. The main aim of our study was to examine how camouflage mismatch and moult plasticity affect the fitness and distribution of individuals representing different phenotypes in two colour morphs of the least weasel Mustela nivalis. These morphs exhibit some variation of the patterns of their summer colouration, but the differences between their winter pelages are far more important, www.nature.com/scientificreports/. Based on the results of this study, we propose possible explanations for the present distribution of different weasel morphs and potential shift of their ranges due to climate change

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