Telomere dynamics in maturing frogs vary among organs

It is important to know whether organs age at the same rate and are equally affected by developmental conditions as this provides insights into causes of ageing. However, data on organ-specific telomere dynamics remain scant. In a previous study of the early life of the amphibian <i>Xenopus laevis</i>, we detected changes in telomere lengths in gut cells, while liver, heart and muscle telomeres were unchanged; larval rearing temperature had minimal effects. Here, we extend that study to examine telomere dynamics in the same four organs and larval temperature treatments from 70-day post-metamorphic juvenile <i>Xenopus</i> through to sexually mature (2-year-old) adults. Telomeres shortened from juvenile to adult in the gut, heart and hindlimb muscle. In contrast, liver telomere lengths did not change with age but were shorter if the early life temperature was warm. Organ telomere lengths were influenced by sex only in adults. Warmer larval temperatures were also associated with longer gut telomeres in juveniles. Hence, pre-metamorphic conditions can influence post-metamorphic telomere dynamics, and telomere loss between juvenile and adult life stages occurs in different organs from those affected earlier in life. These findings indicate the existence of organ-dependent ageing rates across lifetimes, potentially related to developmental and environmental history.