Stress in the city: meta-analysis indicates no overall evidence for stress in urban vertebrates

Iglesias‐Carrasco, Maider; Aich, Upama; Jennions, Michael D.; Head, Megan L.

doi:10.1098/rspb.2020.1754

Cited by 42 publications

(30 citation statements)

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“…The results of this study assessed effects of ALAN on two measures of physiological stress and contribute to an increasing body of evidence that the relationship between urbanization and CORT concentrations is complex and may vary depending on the species, city, age, sex, and time of the year ( Bonier 2012 ; Iglesias-Carrasco et al 2020 ). The results demonstrated that pCORT concentrations on day 13 of life were higher in forest than urban blue tit nestlings, but the concentrations of CORT in feathers were not significantly different between forest and urban populations (although the direction of the effect is the same).…”

Section: Discussionmentioning

confidence: 99%

“…Glucocorticoids are secreted by the adrenal gland after activation of the hypothalamic–pituitary–adrenal (HPA) axis and are considered to represent the allostatic demand on an animal ( Romero 2004 ; Crespi et al 2013 ; MacDougall-Shackleton et al 2019 ). Thereby, glucocorticoids have been widely used in urban ecological studies that have investigated effects of the urban environment on wildlife health and fitness ( Bonier 2012 ; Iglesias-Carrasco et al 2020 ). Urban life is often regarded as “stressful” for wild species, but an emerging body of evidence suggests that this may not always be true.…”

Section: Introductionmentioning

confidence: 99%

“…Urban life is often regarded as “stressful” for wild species, but an emerging body of evidence suggests that this may not always be true. Several reviews and meta-analyses have highlighted the lack of a clear pattern between urbanization and markers of physiological stress, with urban populations of wild species having higher, lower, or equal glucocorticoid concentrations when compared with rural conspecifics ( Bonier 2012 ; Ouyang et al 2018b ; Murray et al 2019 ; Iglesias-Carrasco et al 2020 ; Injaian et al 2020 ). For instance, a meta-analysis by Murray et al (2019) demonstrated a negative effect of urbanization on toxicant load and parasitism, but glucocorticoid concentrations were unaffected.…”

Section: Introductionmentioning

confidence: 99%

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Feather, But Not Plasma, Glucocorticoid Response to Artificial Light at Night Differs between Urban and Forest Blue Tit Nestlings

Dominoni

Teo

Branston

et al. 2021

Integrative and Comparative Biology

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Urbanization drives phenotypic variation in many animal species. This includes behavioral and physiological traits such as activity patterns, aggression, and hormone levels. A current challenge of urban evolutionary ecology is to understand the environmental drivers of phenotypic variation in cities. Moreover, do individuals develop tolerance to urban environmental factors, which underlie adaptative responses and contribute to the evolution of urban populations? Most available evidence comes from correlative studies and rare experiments where a single urban-related environmental factor has been manipulated in the field. Here we present the results of an experiment in which we tested for differences in the glucocorticoid (CORT) response of urban and rural blue tits nestlings (Cyanistes caeruleus) to artificial light at night (ALAN). ALAN has been suggested to alter CORT response in several animal species, but to date no study has investigated whether this effect of ALAN differs between urban and rural populations. Immediately after hatching, urban and forest broods were either exposed to 2 lux of ALAN (using an LED source mounted inside the nestbox) or received no treatment (dark control). The experiment lasted until the chicks fledged. When the chicks were 13 days old plasma samples were collected to measure baseline CORT concentrations, and feather samples to provide an integrative measure of CORT during growth. Forest birds had higher plasma CORT (pCORT) concentrations than their urban counterparts, irrespective of whether they were exposed to ALAN or not. Conversely, we found population-specific responses of feather CORT to ALAN. Specifically, urban birds that received ALAN had increased feather CORT compared with the urban dark controls, while the opposite was true for the forest birds. pCORT concentrations were negatively associated to fledging success, irrespective of population and treatment, while feather CORT was positively associated to fledging success in broods exposed to ALAN, but negatively in the dark control ones. Our results demonstrate that ALAN can play a role in determination of the glucocorticoid phenotype of wild animals, and may thus contribute to phenotypic differences between urban and rural animals.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Feather, But Not Plasma, Glucocorticoid Response to Artificial Light at Night Differs between Urban and Forest Blue Tit Nestlings

Dominoni

Teo

Branston

et al. 2021

Integrative and Comparative Biology

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“…Urban areas are exposed to continuous stressful stimuli that are expected to alter CORT physiology. However, a recent meta-analysis has found no consistent differences between urban and rural birds (Iglesias-Carrasco et al 2020). Regarding noise pollution specifically, results are also contrasting.…”

Section: Introductionmentioning

confidence: 93%

Influence of growing up in the city or near an airport on the physiological stress of tree sparrow nestlings (Passer montanus)

et al. 2021

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Urbanization constitutes one of the major transformations of natural habitats, creating new areas characterized by multiple potential wildlife stressors. Birds that live in highly anthropized zones are confronted with physiological and behavioural challenges caused by these stressors. Here, we investigated if several health parameters differed between three subpopulations of tree sparrow nestlings subjected to different levels of anthropogenic pollution, and particularly noise pollution: a quiet rural area, a noisy rural area adjacent to an airport and a heavily urbanized area. We compared body condition, oxidative stress markers and baseline corticosterone levels, expecting urban nestlings to be in overall worse condition as compared to rural (rural and rural airport) birds. In addition, we expected nestlings exposed to aircraft noise to show intermediate stress levels. We found that rural-airport nestlings had the highest levels of antioxidant capacity of plasma and did not differ from rural counterparts in the rest of the parameters. By contrast, urban nestlings were in slightly worse body condition and had lower antioxidant capacity than rural and rural-airport individuals. Our results suggest that aircraft noise does not constitute a significant stressor for nestlings. In contrast, urban conditions constitute a more challenging situation, negatively impacting different physiological systems. Although nestlings seem able to buffer these challenges in the short-term, further research should explore the long-term potential consequences of early exposure to these conditions.

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“…Second, meta-analyses estimate the overall strength of evidence for a particular hypothesized effect by examining associations within many independent studies that have each addressed the hypothesis (e.g. effect of the environment on physiology and phenotype; Noble et al, 2018a;Gunderson and Stillman, 2015;Iglesias-Carrasco et al, 2020;Wu and Seebacher, 2020). Finally, qualitative comparative reviews of a research question provide synthesis of a topic and data, but do not present analyses of data (e.g.…”

Section: Introductionmentioning

confidence: 99%

Best practices for building and curating databases for comparative analyses

Schwanz

Gunderson

Iglesias‐Carrasco

et al. 2022

Journal of Experimental Biology

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Comparative analyses have a long history of macro-ecological and -evolutionary approaches to understand structure, function, mechanism and constraint. As the pace of science accelerates, there is ever-increasing access to diverse types of data and open access databases that are enabling and inspiring new research. Whether conducting a species-level trait-based analysis or a formal meta-analysis of study effect sizes, comparative approaches share a common reliance on reliable, carefully curated databases. Unlike many scientific endeavors, building a database is a process that many researchers undertake infrequently and in which we are not formally trained. This Commentary provides an introduction to building databases for comparative analyses and highlights challenges and solutions that the authors of this Commentary have faced in their own experiences. We focus on four major tips: (1) carefully strategizing the literature search; (2) structuring databases for multiple use; (3) establishing version control within (and beyond) your study; and (4) the importance of making databases accessible. We highlight how one's approach to these tasks often depends on the goal of the study and the nature of the data. Finally, we assert that the curation of single-question databases has several disadvantages: it limits the possibility of using databases for multiple purposes and decreases efficiency due to independent researchers repeatedly sifting through large volumes of raw information. We argue that curating databases that are broader than one research question can provide a large return on investment, and that research fields could increase efficiency if community curation of databases was established.

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Stress in the city: meta-analysis indicates no overall evidence for stress in urban vertebrates

Cited by 42 publications

References 100 publications

Feather, But Not Plasma, Glucocorticoid Response to Artificial Light at Night Differs between Urban and Forest Blue Tit Nestlings

Feather, But Not Plasma, Glucocorticoid Response to Artificial Light at Night Differs between Urban and Forest Blue Tit Nestlings

Influence of growing up in the city or near an airport on the physiological stress of tree sparrow nestlings (Passer montanus)

Best practices for building and curating databases for comparative analyses

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