Abstract
Because telomere length and dynamics relate to individual growth, reproductive investment and survival, telomeres have emerged as possible markers of individual quality. Here, we tested the hypothesis that, in species with parental care, parental telomere length can be a marker of parental quality that predicts offspring phenotype and survival. In king penguins, we experimentally swapped the single egg of 66 breeding pairs just after egg laying to disentangle the contribution of pre‐laying parental quality (e.g . genetics, investment in the egg) and/or post‐laying parental quality (e.g . incubation, postnatal feeding rate) on offspring growth, telomere length and survival. Parental quality was estimated through the joint effects of biological and foster parent telomere length on offspring traits, both soon after hatching (day 10) and at the end of the pre‐winter growth period (day 105). We expected that offspring traits would be mostly related to the telomere lengths (i.e. quality) of biological parents at day 10 and to the telomere lengths of foster parents at day 105. Results show that chick survival up to 10 days was negatively related to biological fathers’ telomere length whereas survival up to 105 days was positively related to foster fathers’ telomere lengths. Chick growth was neither related to biological nor to foster parents’ telomere length. Chick telomere length was positively related to foster mothers’ telomere length at both 10 and 105 days. Overall, our study shows that, in a species with bi‐parental care, parents’ telomere length is foremost a proxy of post‐laying parental care quality, supporting the “telomere – parental quality hypothesis”.