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Age-related changes in reproductive performance early in life are shaped by individual quality and optimization of reproductive effort.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
(English)Manuscript (Other (popular science, discussion, etc.))
URN: urn:nbn:se:uu:diva-95691OAI: oai:DiVA.org:uu-95691DiVA: diva2:170002
Available from: 2007-04-04 Created: 2007-04-04 Last updated: 2010-01-14Bibliographically approved
In thesis
1. Age, Longevity and Life-History Trade-Offs in the Collared Flycatcher (Ficedula albicollis)
Open this publication in new window or tab >>Age, Longevity and Life-History Trade-Offs in the Collared Flycatcher (Ficedula albicollis)
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Age is often a neglected factor in ecological studies. However, age-related changes in reproduction and survival of organisms may strongly influence population dynamics. The Gotlandic population of collared flycatchers is a perfect system for studying age-related changes in the wild, as the exact age and reproductive history of most individuals is known. Collared flycatchers (Ficedula albicollis) on Gotland show the typical pattern of age-related changes in survival and reproductive success; both factors show an increase early in life and a decrease late in life.

This thesis presents a broad study not only of age-related patterns of reproduction and immunity, but also proposes the mechanisms driving these patterns. My results show that in addition to survival probability and reproductive performance, reproductive costs and life-history trade-offs also change with progressing age.

There is a significant increase in reproductive performance at the population level during first years of life which result from selection against low quality phenotypes. On the individual level this pattern is best explained by an optimization of reproductive effort. However, high quality individuals have higher reproductive success as early as their first breeding event and are long-lived. Thus, they seem to adopt a different strategy than lower quality, short-lived individuals. Differences in individual quality seem to be shaped by the developmental conditions experienced as nestlings. Fledglings with longer tarsi, but lower body mass become long-lived, high quality adults.

Young individuals breeding for first time pay higher costs of reproduction. They also express a limited ability to reduce these costs by breeding in high quality territories when compared to middle-aged individuals.

Young individuals seem to invest more into self-maintenance, whereas old individuals reduce the level of self-maintenance (measured as immune response) and redistribute their investment towards reproduction. Thus, old individuals are limited in their ability to reduce reproductive costs under favorable conditions, especially as they also senesce, which pattern is also shaped by individual quality. Variation in individual quality appears to have an strong effect on age-related survival probability, reproductive performance, reproductive costs, and even life-history decisions. Therefore, taking this factor into account in studies of life-history patterns is necessary to obtain reliable results.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 44 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 288
Ecology, age, collared flycatcher, Ficedula albicollis, long-term study, senescence, longevity, reproductive success, selection, individual quality, breeding experience, reproductive effort optimization, terminal investment, life-history trade-offs, reproductive costs, Ekologi
urn:nbn:se:uu:diva-7787 (URN)978-91-554-6852-1 (ISBN)
Public defence
2007-04-27, Zootissalen, Villavägen 9, Uppsala, 10:00 (English)
Available from: 2007-04-04 Created: 2007-04-04 Last updated: 2009-03-31Bibliographically approved

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