Cool, dry nights and short heatwaves during growth result in longer telomeres in temperate songbird nestlings

Abstract

Exposure to rising sublethal temperatures can affect development and somatic condition, and thereby Darwinian fitness. In the context of climate warming, these changes could have implications for population viability, but they can be subtle and consequently difficult to quantify. Using telomere length (TL) as a known biomarker of somatic condition in early life, we investigated the impact of pre‐hatching and nestling climate on six cohorts of wild nestling superb fairy wrens (Malurus cyaneus) in temperate south‐eastern Australia. Models incorporating only climate information from the nestling phase were best supported compared to those including the (pre‐)laying to incubation phase (previously shown to affect mass) or both phases combined. This implies that nestling TL is most sensitive to ambient climate in the nestling phase. The top model showed a negative relationship between early‐life TL and nestling mean daily minimum temperature when rainfall was low which gradually became positive with increasing rainfall. In addition, there was a positive relationship between TL and the frequency of hot days (daily maximum temperature ≥35°C), although these temperatures were rare and short‐term. Including other pre‐hatching and nestling period, climate variables (e.g., mean daily maximum temperature and mean diurnal temperature variability) did not improve the prediction of nestling TL. Overall, our results suggest that cooler nights when conditions are dry and short‐term temperature spikes above 35°C during development are conducive for somatic maintenance. While these findings indicate a potential pathway for climate warming to impact wildlife fitness, they emphasize the need to elucidate the mechanisms underlying these complex associations.

Short-term heat waves have long-term consequences for parents and offspring in stickleback

“…While offspring of heat wave males were not smaller nor weighed less, they were in worse body condition. Ambient heat during development often results in smaller size and lower body condition for offspring ( Corregidor-Castro and Jones, 2021 ; Oswald et al 2021 ; Bourne et al 2022 ; Eastwood et al 2023 ; Khera et al 2023 ); in fishes and other ectotherms, this may be due to heat decreasing development time ( Allen and Wootton 1982 ; Atkinson 1994 ; Arendt 2011 ; L. Trip et al 2014 ). Importantly, all offspring in our study were reared at 18°C and provided the same food resources and space relative to rearing density; therefore, changes to offspring are most likely to be due to paternal influence.…”

No effect of testosterone or sexual ornamentation on telomere dynamics: A case study and meta‐analyses

“…Telomere loss during adulthood, while significant, is often much smaller in magnitude (Salomons et al., 2009; Spurgin et al., 2018; Vedder et al., 2017). As a consequence, early‐life conditions exhibit an outsized effect on telomere length at sexual maturity (Boonekamp et al., 2014; Eastwood et al., 2023,b; van Lieshout et al., 2021). Thus, in comparison with telomere length (measured at a single time point), of greater relevance in the study of telomeres in adulthood are telomere dynamics (measured over multiple time points).…”