Evidence for senescence in survival but not in reproduction in a short‐lived passerine

• Published in: Ecology and evolution Vol. 10; no. 12; pp. 5383 - 5390
• Main Authors: Fay, Rémi, Schaub, Michael, Border, Jennifer A., Henderson, Ian G., Fahl, Georg, Feulner, Jürgen, Horch, Petra, Müller, Mathis, Rebstock, Helmut, Shitikov, Dmitry, Tome, Davorin, Vögeli, Matthias, Grüebler, Martin U.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.06.2020; John Wiley and Sons Inc; Wiley
• Subjects: actuarial senescence; Age; age‐specific demographic rate; aging; Animal populations; Animal reproduction; Bayesian analysis; Boxes; Breeding; Datasets; Empirical analysis; Evolution; Males; Mortality; Nest boxes; Original Research; Physiology; Populations; Reproduction; Reproduction (biology); Saxicola rubetra; Senescence; Sex; Sexes; Studies; Success; Survival; whinchat; Slovenia; United Kingdom > UK; Switzerland; Germany; Russia; actuarial senescence; whinchat; aging; Saxicola rubetra; age‐specific demographic rate
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6281

Senescence has been studied since a long time by theoreticians in ecology and evolution, but empirical support in natural population has only recently been accumulating. One of the current challenges is the investigation of senescence of multiple fitness components and the study of differences between sexes. Until now, studies have been more frequently conducted on females than on males and rather in long‐lived than in short‐lived species. To reach a more fundamental understanding of the evolution of senescence, it is critical to investigate age‐specific survival and reproduction performance in both sexes and in a large range of species with contrasting life histories. In this study, we present results on patterns of age‐specific and sex‐specific variation in survival and reproduction in the whinchat Saxicola rubetra, a short‐lived passerine. We compiled individual‐based long‐term datasets from seven populations that were jointly analyzed within a Bayesian modeling framework. We found evidence for senescence in survival with a continuous decline after the age of 1 year, but no evidence of reproductive senescence. Furthermore, we found no clear evidence for sex effects on these patterns. We discuss these results in light of previous studies documenting senescence in short‐lived birds. We note that most of them have been conducted in populations breeding in nest boxes, and we question the potential effect of the nest boxes on the shape of age‐reproductive trajectories. In this article, we jointly analyzed seven datasets investigating for the first time age‐specific breeding success and survival in whinchats, a ground‐nesting passerine species. Our results supported the occurrence of senescence in survival but, in contrast to our expectations, not in breeding success. We note that previous studies documenting senescence in short‐lived birds have been conducted in populations breeding in nest boxes, and we question the potential effect of the nest boxes on the shape of age‐reproductive trajectories.