Telomere length, non‐breeding habitat and return rate in male American redstarts

Abstract

Summary 1.Telomeres are long repetitive noncoding sequences of DNA located at the ends of chromosomes. Recently, the study of telomere dynamics has been increasingly used to investigate ecological questions. However, little is currently known about the relationships that link environmental conditions, telomere dynamics and fitness in wild vertebrates. 2. Using a small migratory bird (American redstart, Setophaga ruticilla), we investigated how telomere dynamics can be affected by non-breeding habitat quality and to what extent telomere length can predict the return rate of males. 3. We show that telomeres shorten in most individuals over a 1-year period and, importantly, that telomeres of individuals wintering in a low-quality habitat shorten more than those of individuals wintering in a high-quality habitat. 4. In addition, we found that longer telomeres are associated with a higher return rate than shorter telomeres, although the relationship between return rate and telomere length did not depend on habitat quality. 5. Our study suggests that telomere dynamics are affected by environmental conditions and are related to indices of fitness in a migratory bird species.

Bill size correlates with telomere length in male American Redstarts

“…Birds with large bills may be better able to cope with their environment (e.g., better foraging ability) or they may adopt different strategies than birds with small bills and this could result in slower telomere shortening. Although a previous study reported that non-breeding habitat occupancy affects adult telomere dynamics (Angelier et al 2013), habitat occupancy is not related to body size in Redstarts (Marra 2000), suggesting that bill size is disconnected from telomere dynamics in adults. If bill size and telomere shortening were connected, most of the Redstarts with short bills should be found in the habitat where telomere shortening is the fastest (i.e., dry scrubs), but this is not the case (Marra 2000).…”

“…We did not focus on body mass in this study because body mass is known to fluctuate quickly in response to short-term changes in rainfall abundance in the non-breeding grounds (Angelier et al 2011), and it could therefore not be used to reliably assess body size. Following methods previously described (Angelier et al 2013), DNA was extracted and telomeres were measured using a real-time quantitative PCR technique validated for birds ) and American Redstarts (Angelier et al 2013). Morphometric measures were correlated and, therefore, we used a principal component analysis to calculate the body size of Redstarts: most of the variance was explained by two uncorrelated axes (PC1, PC2) that respectively explained 49.02 and 25.91 % of the variance.…”

“…Telomeres appear to shorten throughout the life of individuals (Pauliny et al 2006;Bize et al 2009;Salomons et al 2009;Heidinger et al 2012;Angelier et al 2013;Barrett et al 2013;Bauch et al 2013;Boonekamp et al 2014) and, importantly, telomere length (TL) has been shown to be a reliable predictor of survival under some circumstances (Haussmann et al 2005;Pauliny et al 2006;Bize et al 2009;Salomons et al 2009;Heidinger et al 2012;Angelier et al 2013;Barrett et al 2013) but not others (Pauliny et al 2006;Beaulieu et al 2011;Caprioli et al 2013;Boonekamp et al 2014). Therefore, specific attention has been paid to the determinants of TL in wild vertebrates.…”

“…Indeed, poor environmental conditions have recently been associated with an acceleration of telomere shortening in two bird species (Angelier et al 2013;Mizutani et al 2013). However, adult TL is not only determined by events occurring during adult life but also by the initial TL at the time when individuals enter the adult life stage.…”

“…During adulthood, different individuals experience different environmental conditions and this can result in variable rates of telomere shortening between individuals Salomons et al 2009;Angelier et al 2013;Barrett et al 2013). Importantly, and contrary to TL, body size does not change after the developmental phase since birds have determinate growth, suggesting that telomere dynamics will become independent of structural body size in adults.…”