Replicated, urban-driven exposure to metallic trace elements in two passerines

Marion Chatelain,Marta Szulkin,Marta Celej,Michela Corsini,Eliza Kurek,Ewa Bulska,Arnaud Da Silva

doi:10.1038/s41598-021-99329-2

Marion Chatelain, Marta Szulkin + Show 5 more

Open Access

https://doi.org/10.1038/s41598-021-99329-2

Copy DOI

Journal: Scientific Reports	Publication Date: Oct 4, 2021
Citations: 7	License type: open-access

Affiliation: University of Warsaw, Universität Innsbruck

Abstract

While there are increasing examples of phenotypic and genotypic differences between urban and non-urban populations of plants and animals, few studies identified the mechanisms explaining those dissimilarities. The characterization of the urban landscape, which can only be achieved by measuring variability in relevant environmental factors within and between cities, is a keystone prerequisite to understand the effects of urbanization on wildlife. Here, we measured variation in bird exposure to metal pollution within 8 replicated urbanization gradients and within 2 flagship bird species in urban evolutionary ecology: the blue tit (Cyanistes caeruleus) and the great tit (Parus major). We report on a highly significant, positive linear relationship between the magnitude of urbanization—inferred as either tree cover, impervious surface cover, or an urbanization score computed from several environmental variables, and copper, zinc and lead concentrations in bird feathers. The reverse relationship was measured in the case of mercury, while cadmium and arsenic did not vary in response to the urbanization level. This result, replicated across multiple cities and two passerine species, strongly suggests that copper, zinc, lead and mercury pollution is likely to trigger the emergence of parallel responses at the phenotypic and/or genotypic level between urban environments worldwide.

Highlights

While there are increasing examples of phenotypic and genotypic differences between urban and non-urban populations of plants and animals, few studies identified the mechanisms explaining those dissimilarities
One of the reasons is that the majority of studies focussing on wildlife ecology and biology in the urban space uses an extremely simplified urban ecology framework that often lacks (i) adequate replication stemming from a comparison of multiple cities and (ii) knowledge stemming from multiple and contrasted urban habitats contributing to the urban mosaic
We define urbanization using high-resolution environmental data. This quantitative approach was compared with a qualitative approach where sampling sites were sorted into 5 habitat categories. Thanks to this unique study design, we address whether bird exposure to metalloid trace elements (MTEs), assessed in two passerine species, varies consistently, linearly and in a replicated fashion along multiple urbanization gradients

Summary

Introduction

While there are increasing examples of phenotypic and genotypic differences between urban and non-urban populations of plants and animals, few studies identified the mechanisms explaining those dissimilarities. Such study design ignores the diversity of environments within and between urbanized areas[20], which prevents from (i) establishing firm conclusions about the effects of urbanization per se on wildlife, (ii) disentangling the effect of the different abiotic and biotic environmental factors that vary in response to u rbanization[21], and (iii) drawing universal conclusions about the impact of urbanization on the biology of wild organisms at a continental or global scale For this reason, recent reviews in urban ecology urge future research to focus on replicated and continuous gradients of disturbance[2,3,14,19]. While MTE pollution might be a significant driver of phenotypic and/or genotypic changes triggered by urbanization, we currently lack knowledge on MTE pollution levels within complex urban–rural gradients To fill in this gap, we measured 6 of the most common MTE pollutants (i.e. copper, zinc, lead, cadmium, arsenic and mercury) in the feathers of 179 males of blue tits (Cyanistes caeruleus) and great tits (Parus major).

Methods

Results

Conclusion