Senescence in the wild: Insights from a long-term study on Seychelles warblers.
Senescence--the progressive age-dependent decline in performance--occurs in most organisms. There is considerable variation in the onset and rate of senescence between and within species. Yet the causes of this variation are still poorly understood, despite being central to understanding the evolution of senescence. Long-term longitudinal studies on wild animals are extremely well-suited to studying the impact of environmental and individual characteristics (and the interaction between the two) on senescence, and can help us to understand the mechanisms that shape the evolution of senescence. In this review, we summarize and discuss the insights gained from our comprehensive long-term individual-based study of the Seychelles warbler (Acrocephalus sechellensis). This species provides an excellent model system in which to investigate the evolution of senescence in the wild. We found that Seychelles warblers show senescent declines in survival and reproduction, and discuss how individual characteristics (body condition, body size) and environmental effects (low- versus high-quality environments) may affect the onset and rate of senescence. Further, we highlight the evidence for trade-offs between early-life investment and senescence. We describe how key cellular and physiological processes (oxidative stress and telomere shortening) underpinning senescence are affected by individual and environmental characteristics in the Seychelles warbler (e.g. food availability, reproductive investment, disease) and we discuss how such physiological variation may mediate the relationship between environmental characteristics and senescence. Based on our work using Seychelles warblers as a model system, we show how insights from long-term studies of wild animals may help unravel the causes of the remarkable variation in senescence observed in natural systems, and highlight areas for promising future research.
Behavioural & Physiological Ecology, GELIFES, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands. Electronic address: martijnhammers@gmail.com.
Martijn
M
Hammers
Behavioural & Physiological Ecology, GELIFES, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands.
Sjouke A
SA
Kingma
School of Biological Sciences, University of East Anglia, Norwich Research Park, Norfolk, NR4 7TJ, UK.
Kat
K
Bebbington
Behavioural & Physiological Ecology, GELIFES, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands.
Janske
J
van de Crommenacker
School of Biological Sciences, University of East Anglia, Norwich Research Park, Norfolk, NR4 7TJ, UK.
Lewis G
LG
Spurgin
School of Biological Sciences, University of East Anglia, Norwich Research Park, Norfolk, NR4 7TJ, UK; Nature Seychelles, Roche Caiman, Mahé, Republic of Seychelles.
David S
DS
Richardson
Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
Terry
T
Burke
Behavioural & Physiological Ecology, GELIFES, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands; Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK.
Hannah L
HL
Dugdale
Behavioural & Physiological Ecology, GELIFES, University of Groningen, P.O. Box 11103, 9700 CC, Groningen, The Netherlands.
Jan
J
Komdeur
D000375:Aging / Q000235:genetics / Q000502:physiology*; D000818:Animals; D000835:Animals, Wild / Q000235:genetics / Q000502:physiology; D005075:Biological Evolution; D000068884:Immunosenescence / Q000502:physiology; D023421:Models, Animal; D018384:Oxidative Stress / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D020308:Songbirds / Q000235:genetics / Q000502:physiology*; D059506:Telomere Shortening / Q000502:physiology
Aging; Cooperative breeding; Immunosenescence; Oxidative stress; Senescence; Telomeres