Data from: Is telomere length a molecular marker of past thermal stress in wild fish?

Telomeres protect eukaryotic chromosomes; variation in telomere length has
been linked (primarily in homoeothermic animals) to variation in stress,
cellular ageing and disease risk. Moreover, telomeres have been suggested
to function as biomarker for quantifying past environmental stress, but
studies in wild animals remain rare. Environmental stress, such as extreme
environmental temperatures in poikilothermic animals, may result in
oxidative stress that accelerates telomere attrition. However, growth,
which may depend on temperature, can also contribute to telomere
attrition. To test for associations between multitissue telomere length
and past water temperature while accounting for the previous individual
growth, we used quantitative PCR to analyse samples from 112
young-of-the-year brown trout from 10 natural rivers with average water
temperature differences of up to 6°C (and an absolute maximum of 23°C). We
found negative associations between relative telomere length (RTL) and
both average river temperature and individual body size. We found no
indication of RTL–temperature association differences among six tissues,
but we did find indications for differences among the tissues for
associations between RTL and body size; size trends, albeit nonsignificant
in their differences, were strongest in muscle and weakest in fin.
Although causal relationships among temperature, growth, oxidative stress,
and cross-sectional telomere length remain largely unknown, our results
indicate that telomere-length variation in a poikilothermic wild animal is
associated with both past temperature and growth.