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 o...

Suboptimal conditions during development can shorten telomeres, the protective DNA caps on the end of chromosomes. Shorter early‐life telomere length (TL) can indicate reduced somatic maintenance, leading to lower survival and shorter lifespan. However, despite some clear evidence, not all studies show a relationship between early‐life TL and survival or lifespan, which may be due to differences in biology or study design (e.g...

Climate warming has been shown to affect the timing of the onset of breeding of many bird species across the world. However, for multi‐brooded species, climate may also affect the timing of the end of the breeding season, and hence also its duration, and these effects may have consequences for fitness. We used 28 years of field data to investigate the links between climate, timing of breeding, and breeding success in a coopera...

Extra‐pair paternity ( EPP ), where offspring are sired by a male other than the social male, varies enormously both within and among species. Trying to explain this variation has proved difficult because the majority of the interspecific variation is phylogenetically based. Ideally, variation in EPP should be investigated in closely related species, but clades with sufficient variation are rare. We present a comprehensive mul...

Despite extensive research on the topic, it has been difficult to reach general conclusions as to the effects of climate change on morphology in wild animals: in particular, the effects of warming temperatures have been associated with increases, decreases or stasis in body size in different populations. Here, we use a fine‐scale analysis of associations between weather and offspring body size in a long‐term study of a wild pa...

Molecular ecologists, in search of suitable molecular markers, frequently PCR‐amplify regions of mitochondrial DNA from total DNA extracts. This approach, although common, is prone to the co‐amplification of nuclear copies of transposed DNA sequences (numts), which can then generate apparent mitochondrial sequence heteroplasmy. In this study we describe the discovery of apparent mitochondrial sequence heteroplasmy in Thalassar...