title: Age-related sex differences in body condition and telomere dynamics of red-sided garter snakes.
abstract: Life-history strategies vary dramatically between the sexes, which may drive divergence in sex-specific senescence and mortality rates. Telomeres are tandem nucleotide repeats that protect the ends of chromosomes from erosion during cell division. Telomeres have been implicated in senescence and mortality because they tend to shorten with stress, growth and age. We investigated age-specific telomere length in female and male red-sided garter snakes,Thamnophis sirtalis parietalisWe hypothesized that age-specific telomere length would differ between males and females given their divergent reproductive strategies. Male garter snakes emerge from hibernation with high levels of corticosterone, which facilitates energy mobilization to fuel mate-searching, courtship and mating behaviours during a two to four week aphagous breeding period at the den site. Conversely, females remain at the dens for only about 4 days and seem to invest more energy in growth and cellular maintenance, as they usually reproduce biennially. As male investment in reproduction involves a yearly bout of physiologically stressful activities, while females prioritize self-maintenance, we predicted male snakes would experience more age-specific telomere loss than females. We investigated this prediction using skeletochronology to determine the ages of individuals and qPCR to determine telomere length in a cross-sectional study. For both sexes, telomere length was positively related to body condition. Telomere length decreased with age in male garter snakes, but remained stable in female snakes. There was no correlation between telomere length and growth in either sex, suggesting that our results are a consequence of divergent selection on life histories of males and females. Different selection on the sexes may be the physiological consequence of the sexual dimorphism and mating system dynamics displayed by this species.
authors.affiliation: School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building (A08), New South Wales 2006, Australia.
authors.forename: Nicky
authors.initials: N
authors.lastname: Rollings
authors.affiliation: Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.|Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Uhrig
authors.affiliation: Department of Biological Sciences, Saint Xavier University, Chicago, IL, USA.
authors.forename: Randolph W
authors.initials: RW
authors.lastname: Krohmer
authors.affiliation: Division of Science and Mathematics, University of Minnesota, Morris, MN, USA.
authors.forename: Heather L
authors.initials: HL
authors.lastname: Waye
authors.affiliation: Department of Integrative Biology, Oregon State University, Corvallis, OR, USA.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Mason
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Olsson
authors.affiliation: School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building (A08), New South Wales 2006, Australia.|Sydney School of Veterinary Science, Faculty of Science, University of Sydney, Sydney, Australia.
authors.forename: Camilla M
authors.initials: CM
authors.lastname: Whittington
authors.affiliation: School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building (A08), New South Wales 2006, Australia christopher.friesen@sydney.edu.au.
authors.forename: Christopher R
authors.identifier: http://orcid.org/0000-0001-5338-7454
authors.initials: CR
authors.lastname: Friesen
mesh_terms: D000367:Age Factors; D000818:Animals; D017812:Colubridae / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D008297:Male; D012727:Sex Characteristics; D012726:Sexual Behavior, Animal; D016615:Telomere / Q000648:ultrastructure*
keywords: condition; life-history strategies; reptile; sex-differences; telomeres