Abstract

Telomeres are repetitive stretches of DNA that cap the ends of chromosomes in most eukaryotes and play a vital role in genomic maintenance and cell function. Telomeres shorten with each cell division and under cellular stress, and critically short telomeres trigger cellular senescence. There has been growing interest across diverse disciplines recently in the use of average measures of telomere length (TL) across a sample of cells (usually blood cells) as a biomarker of ageing and health. Evolutionary ecologists working in the laboratory and field have now measured blood cell TL in a remarkable range of vertebrate species and ecological settings. This work has led to TL being put forward as a useful indicator of biological ageing, physiological state, past environmental stress, and the physiological costs of investment in life history traits across vertebrates. In this talk, I will provide an overview of the evidence from recent meta-analyses of ecological and evolutionary studies to support these claims. I will then discuss recent work by my group to investigate the role of genes, environment and past life history in driving variation in TL in a wild Soay sheep population on St Kilda. Our work in Soay sheep suggests that TL does have a genetic basis and predicts lifespan, but does not support the idea that TL is an indicator of biological ageing or reflects costs of recent reproduction.