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PhD ceremony Mr. M. Hammers: Ecology of senescence in a cooperatively breeding bird. A long-term study on the Seychelles warbler

When:Fr 21-06-2013 at 16:15

PhD ceremony: Mr. M. Hammers, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Ecology of senescence in a cooperatively breeding bird. A long-term study on the Seychelles warbler

Promotor(s): prof. J. Komdeur

Faculty: Mathematics and Natural Sciences

Martijn Hammers studied the senescence in the Seychelles warbler. In many animal species reproductive output and survival probability, first increase with age and then decline during late-life. Such late-life declines in performance may be caused by senescence, which is the progressive deterioration of an individual’s physiological and cellular function with age. Evolutionary theories of senescence predict trade-offs between early-life reproductive investment and late-life reproduction and survival. A physiological mechanism that has been suggested to be one of the main determinants of late-life declines in fitness performance is the length and rate of loss of protective chromosome caps, the telomeres. The study of senescence in natural populations is challenging as the exact birth and death dates of individuals are often not known, and most individuals succumb to extrinsic mortality before reaching old age. Here, an exceptional long-term longitudinal dataset of individuals from a natural, closed, and predator-free population of the Seychelles warbler (Acrocephalus sechellensis) was used to investigate senescence. Both reproduction and survival declines in elderly individuals, consistent with senescence. The onset of the late-life decline in survival was related to the age of first breeding: individuals that started breeding at a later age showed higher survival during late life. It was shown that telomeres shortened with advancing age and that shorter telomeres and greater rates of telomere shortening were associated with future mortality. Together, these results provided important insights into the ecology of senescence in wild populations.

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