Adaptive variation in senescence: reproductive lifespan in a wild salmon population

The antagonistic pleiotropy theory of senescence postulates genes or traits that have opposite effects on early-life and late-life performances. Because selection is generally weaker late in life, genes or traits that improve early-life performance but impair late-life performance should come to pre...

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Bibliographic Details
Published in:	Proceedings of the Royal Society. B, Biological sciences Vol. 271; no. 1536; pp. 259 - 266
Main Authors:	Hendry, A.P, Morbey, Y.E, Berg, O.K, Wenburg, J.K
Format:	Journal Article
Language:	English
Published:	England The Royal Society 07-02-2004
Subjects:	Adaptation, Physiological Adaptation-By-Time Age Factors Ageing Aging Aging - physiology Alaska Animal nesting Animals Body Composition Breeding Breeding seasons Cellular senescence Eggs Energy Allocation Evolution Female Female animals Game Theory Genetic variation Genetics, Population Microsatellite Repeats - genetics Models, Biological Nesting Behavior - physiology Oncorhynchus nerka Reproduction - physiology Reproductive Trade-Offs Salmon Salmon - physiology Selection, Genetic Sockeye Salmon Superposition principle Alaska
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Summary:	The antagonistic pleiotropy theory of senescence postulates genes or traits that have opposite effects on early-life and late-life performances. Because selection is generally weaker late in life, genes or traits that improve early-life performance but impair late-life performance should come to predominate. Variation in the strength of age-specific selection should then generate adaptive variation in senescence. We demonstrate this mechanism by comparing early and late breeders within a population of semelparous capital-breeding sockeye salmon (Oncorhynchus nerka). We show that early breeders (but not late breeders) are under strong selection for a long reproductive lifespan (RLS), which facilitates defence of their nests against disturbance by later females. Accordingly, early females invest less energy in egg production while reserving more for nest defence. Variation along this reproductive trade-off causes delayed or slower senescence in early females (average RLS of 26 days) than in late females (reproductive lifespan of 12 days). We use microsatellites to confirm that gene flow is sufficiently limited between early and late breeders to allow adaptive divergence in response to selection. Because reproductive trade-offs should be almost universal and selection acting on them should typically vary in time and space, the mechanism described herein may explain much of the natural variation in senescence.
Bibliography:	ark:/67375/V84-M1N0D72M-T istex:672D7A30BACDAFD7D13DE00D88EBEE88E4DAE151 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0962-8452 1471-2954
DOI:	10.1098/rspb.2003.2600