DOI: 10.5061/dryad.5x69p8d02
title: Data from: Proximity to roads, but not exposure to metal pollution, is associated with accelerated developmental telomere shortening in nestling great tits

description: Comprehensively understanding the factors affecting physiology and fitness
 in urban wildlife requires concurrently considering multiple
 stressors.  To this end, we simultaneously assessed how
 metal pollution and proximity to roads affect body condition and telomere
 shortening between days 8 and 15 of age in nestling great tits (Parus
 major), a common urban bird.  We employed a
 repeated-measures sampling design to compare telomere shortening and body
 condition between nestlings from four urban study sites south of Antwerp,
 Belgium, which are located at different distances from a metal pollution
 point source.  In addition, we explored associations
 between metal exposure and telomere dynamics on the individual level by
 measuring blood concentrations of five metals/metalloids, of which lead,
 copper and zinc were present at concentrations about the limit of
 detection.  To assess whether roadway-associated
 stressors (e.g. noise and air pollution) might affect nestling condition
 and telomere shortening, we measured the proximity of nest boxes to
 roads.  Metal exposure was not associated with nestling
 telomere length or body condition, despite elevated blood lead
 concentrations close to a metal pollution source
 (mean ± SE = 0.270 ± 0.095 µg/g wet
 weight at the most polluted study site), suggesting that nestlings may
 have some capacity to detoxify metals.  However,
 nestlings from nest boxes near roads exhibited more telomere shortening
 between days 8 and 15 of age, and shorter telomeres at day
 15. Nestlings in poorer condition also had shorter telomeres, but
 proximity to the road was unrelated to body
 condition.  Thus, nutritional stress is unlikely to
 mediate the relationship between proximity to roads and telomere
 length.  Rather, proximity to roads could have affected
 telomere shortening by exposing nestlings to air or noise
 pollution.  Our study highlights that traffic-related
 pollution, which is implicated in human health problems, might also affect
 urban wildlife.
description: This dataset contains the relative telomere lengths (RTL) of
 great tit nestlings from study sites exposed to different levels of metal
 pollution, measured using qPCR.  Raw crossing points (CPs) from the qPCR
 are also given.  GAPDH was used as a reference gene, and
 we used the following formula to calculate calibrator-normalized relative telomere length (RTL; amount of telomere sequence relative to GAPDH; T/S ratio):  RTL = E<sub>T</sub><sup>CtT(C)-CtT(S)</sup> * E<sub>R</sub><sup>CtR(S)-CtR(C)</sup>.  Additional variables in the data set are study site, distance from the road, nest box identity, clutch identity, year, mass, tarsus length and nestling sex, nestling age (8 or 15 days), and blood concentrations of metals (Pb, Zn, Ni, Cu, Cr).  The RunID is the identity of the qPCR reaction, and was controlled for in statistical analyses involving telomere length.
description: Outlying lead concencentrations were dropped from statistical
 analyses involving blood metal levels (outlier Lww2 column), and duplicate
 measurements on nestlings at the same age were also dropped (drop column).
  Telomere measurements with CVs above 0.35 were dropped.