“…Telomeres are noncoding DNA repeats forming the end‐caps of linear chromosomes, thereby safeguarding chromosome integrity (Blackburn, ). TL is to a large extent genetically determined, although heritability estimates vary widely between studies (range h 2 : 0–1; overviews in Atema et al, ; Dugdale, Richardson, & Richardson, ). TL generally shortens with age, and telomere shortening is accelerated by environmental challenges (Boonekamp, Mulder, Salomons, Dijkstra, & Verhulst, ; Reichert et al, ; Watson, Bolton, & Monaghan, ), reproductive effort (Bauch, Becker, & Verhulst, ), stress during adulthood (Hau et al, ) and disease (Asghar et al, ; Beirne, Delahay, Hares, & Young, ), and can differ between habitats (Angelier, Vleck, Holberton, & Marra, ; Stier et al, ).…”