title: Telomere length reflects reproductive effort indicated by corticosterone levels in a long-lived seabird.
abstract: Telomere length (TL) is a candidate biomarker of ageing and phenotypic quality, but little is known of the (physiological) causes of TL variation. We previously showed that individual common terns Sterna hirundo with high reproductive success had short telomeres independent of age, and this pattern was particularly strong in the longer telomeres of the within-individual TL distribution. To test whether this relation can be attributed to effects of reproductive effort, we investigated baseline corticosterone in relation to reproductive success (number of fledglings) and TL. In this context, we assume that variation in baseline corticosterone can be interpreted as index of energy expenditure and allostatic load. Males with higher corticosterone levels during incubation, compared between and within individuals, achieved higher reproductive success and had shorter telomeres. The effect on telomeres was more pronounced in corticosterone measured later in incubation and in the longer telomeres of the within-individual TL distribution. Female corticosterone level during incubation was neither related to reproductive success nor to TL. That we observed these effects only in males mirrors different parental roles during reproduction in the common tern, where males do most of the chick provisioning. The negative association between reproductive success and TL suggests individual differences in reproductive effort as reflected in, or mediated by, baseline corticosterone. We see this result as a promising step towards unravelling the physiological causes of variation in TL and the costs of reproduction.
authors.affiliation: Behavioural and Physiological Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747AG, Groningen, The Netherlands.|Institute of Avian Research "Vogelwarte Helgoland", An der Vogelwarte 21, 26386, Wilhelmshaven, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Bauch
authors.affiliation: Institute of Avian Research "Vogelwarte Helgoland", An der Vogelwarte 21, 26386, Wilhelmshaven, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Riechert
authors.affiliation: Behavioural and Physiological Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747AG, Groningen, The Netherlands.
authors.forename: Simon
authors.initials: S
authors.lastname: Verhulst
authors.affiliation: Institute of Avian Research "Vogelwarte Helgoland", An der Vogelwarte 21, 26386, Wilhelmshaven, Germany.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Becker
mesh_terms: D000375:Aging; D000818:Animals; D046091:Charadriiformes / Q000502:physiology*; D003345:Corticosterone / Q000097:blood*; D005260:Female; D008297:Male; D012098:Reproduction; D016615:Telomere / Q000648:ultrastructure*; D059506:Telomere Shortening
chemical_list: D003345:Corticosterone
keywords: ageing; fitness; glucocorticoids; life history; phenotypic quality; reproduction