Telomere length as a biomarker for stress in Eastern bluebird nestlings (Sialia sialis) reared in urban habitats

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Gabriel de la Iglesia (Creator)
Western Carolina University (WCU )
Web Site:
Barbara Ballentine

Abstract: Eastern bluebirds (Sialia sialis) are often found in urban areas and have seemingly adapted to the changing conditions, however, an often-overlooked potential threat for urban dwellers is anthropogenic stress or human-induced environmental stressors. Anthropogenic stressors may initiate a physiological cascade which leads to oxidative damage, including telomere loss. The intricate relationship between stress (physiological and oxidative stress) and telomere length (TL) has led to the utilization of TL as an index for stress. I hypothesized that Eastern bluebird nestlings developing in more urbanized settings experience higher levels of stress. Moreover, I predicted that urban nestlings have shorter telomeres than rural nestlings. This is in line with previous studies that found an association between stress exposure and shortened telomeres in other urban-raised birds. In this study, I used telomere length (TL) as a biomarker for stress in bluebird nestlings reared in an urban-rural gradient. I measured the relative telomere length (TL) of 35 nestlings reared in urban (17) and rural (18) habitats located in Carroll County, GA using quantitative "real-time" PCR (qPCR). The technique involves the measurement of amplified target (T) telomere sequences relative to a reference single copy gene (S); GAPDH was chosen as the single copy gene due to its conserved nature in all passerines. I found that urban nestlings have shorter telomeres as demonstrated by their lower mean T/S ratios when compared to those of rural nestlings. Therefore, the results of this study suggest that urban-reared Eastern bluebird nestlings are, in fact, stressed and incur a greater physiological cost than their rural counterparts. Future studies could explore the physiological processes behind the reduction of TL in Eastern bluebird nestlings by measuring the release of glucocorticoid stress hormones (e.g. CORT) in tandem with TL.

Additional Information

Language: English
Date: 2018
Eastern bluebird -- Infancy -- Georgia -- Carroll County
Eastern bluebird -- Habitat -- Georgia -- Carroll County
Eastern bluebird -- Effect of stress on -- Georgia -- Carroll County
Telomere -- Physiology

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