Divergent Patterns of Age-dependence in Ornamental and Reproductive Traits in the Collared Flycatcher
2011 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 65, no 6, 1623-1636 p.Article in journal (Refereed) Published
Sexual ornaments are predicted to honestly signal individual condition. We might therefore expect ornament expression to show a senescent decline, in parallel with late-life deterioration of other characters. Conversely, life-history theory predicts the reduced residual reproductive value of older individuals will favor increased investment in sexually attractive traits. Using a 25-year dataset of more than 5000 records of breeding collared flycatchers (Ficedula albicollis) of known age, we quantify cross-sectional patterns of age-dependence in ornamental plumage traits and report long-term declines in expression that mask highly significant positive age-dependency. We partition this population-level age-dependency into its between- and within-individual components and show expression of ornamental white plumage patches exhibits within-individual increases with age in both sexes, consistent with life-history theory. For males, ornament expression also covaries with life span, such that, within a cohort, ornamentation indicates survival. Finally, we compared longitudinal age-dependency of reproductive traits and ornamental traits in both sexes, to assess whether these two trait types exhibit similar age-dependency. These analyses revealed contrasting patterns: reproductive traits showed within-individual declines in late-life females consistent with senescence; ornamental traits showed the opposite pattern in both males and females. Hence, our results for both sexes suggest that age-dependent ornament expression is consistent with life-history models of optimal signaling and, unlike reproductive traits, proof against senescence.
Place, publisher, year, edition, pages
2011. Vol. 65, no 6, 1623-1636 p.
aging, life-history, ornamentation, plumage coloration, senescence, sexual selection
IdentifiersURN: urn:nbn:se:uu:diva-155254DOI: 10.1111/j.1558-5646.2011.01253.xISI: 000291270300009OAI: oai:DiVA.org:uu-155254DiVA: diva2:424814