Research output

Article in Journal ()

Asynchrony of senescence among phenotypic traits in a wild mammal population

Citation
Hayward A, Moorad J, Regan CE, Berenos C, Pilkington JG, Pemberton JM & Nussey DH (2015) Asynchrony of senescence among phenotypic traits in a wild mammal population, Experimental Gerontology, 71, pp. 56-68.

Abstract
The degree to which changes in lifespan are coupled to changes insenescencein different physiological systems andphenotypictraits is a central question in biogerontology. It is underpinned by deeper biological questions about whether or not senescence is a synchronised process, or whether levels of synchrony depend on species or environmental context. Understanding how natural selection shapes patterns of synchrony in senescence across physiological systems and phenotypic traits demands thelongitudinal studyof manyphenotypesunder natural conditions. Here, we examine the patterns of age-related variation in late adulthood in a wild population of Soay sheep (Ovis aries) that have been the subject of individual-based monitoring for thirty years. We examined twenty different phenotypic traits in both males and females, encompassing vital rates (survival and fecundity), maternal reproductive performance (offspring birth weight, birth date and survival), male rutting behaviour, home range measures, parasite burdens, and body mass. We initially quantified age-related variation in each trait having controlled for annual variation in the environment, among-individual variationand selective disappearance effects. We then standardised our age-specific trait means and tested whether age trajectories could be meaningfully grouped according to sex or the type of trait. Whilst most traits showed age-related declines in later life, we found striking levels of asynchrony both within and between the sexes. Of particular note, female fecundity and reproductive performance declined with age, but male annual reproductive success did not. We also discovered that whilst home range size and quality decline with age in females, home range size increases with age in males. Our findings highlight the complexity of phenotypic ageing under natural conditions and, along with emerging data from other wild populations and laboratory models, suggest that the long-standing hypothesis withinevolutionary biologythat fitness-related traits should senesce in a synchronous manner is seriously flawed.

Keywords
Ageing; Home range; Natural selection; Ovis aries; Sexual selection; Soay sheep

StatusPublished
AuthorsHayward Adam, Moorad Jacob, Regan Charlotte E, Berenos Camillo, Pilkington Jill G, Pemberton Josephine M, Nussey Daniel H
Publication date11/2015
Publication date online13/08/2015
Date accepted by journal04/08/2015
PublisherElsevier
ISSN 0531-5565
LanguageEnglish

Journal
Experimental Gerontology: Volume 71

© University of Stirling FK9 4LA Scotland UK • Telephone +44 1786 473171 • Scottish Charity No SC011159
My Portal