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

Abstract

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.

Age-specific reproduction in female pied flycatchers: evidence for asynchronous aging

“…Owing to the natural stochasticity of these factors and potentially the lack of alternative nesting sites, it might be difficult for pied flycatchers to find nesting sites in the first place and assess nesting site safety at settlement and thus to control nest success. In small passerines, the stochasticity in nest success can be an important process to mask potential age effects in fecundity (Fay et al 2020b;Mitrus 2004 but see Horie and Takagi 2012;Robertson and Rendell 2001;Pärt 2001). This contrasts with long-lived species for which nest success is more frequently associated with age (Berman et al 2009;Froy et al 2017;Murgatroyd et al 2018;Newton et al 1981).…”

“…This contrasts with long-lived species for which nest success is more frequently associated with age (Berman et al 2009;Froy et al 2017;Murgatroyd et al 2018;Newton et al 1981). Because breeding failure is a key component of breeding performance, nest success may affect the overall relationship between age and fecundity (Fay et al 2020b). Thus, more studies are needed to seek for generality in the critical relationship between nest success and age, especially in short-lived species.…”

Strong evidence supporting a relationship between colour pattern and apparent survival in common crossbills

“…It could be because within adult group, we include birds of several years, older birds, with a shorter life expectancy. That is, we are putting the effect of senescence in survival estimates (Fay et al 2020).…”

Alternative Animal Models of Aging Research

“…Although birds and mammals show similar age-related decline and pathology (Holmes and Ottinger, 2003), their reproductive senescence seems to differ. For example, in the short-lived whinchat, virtually no sign of reproductive senescence could be identified until the age of 4 years, although survival started to decline at an age of only 1 year (Fay et al, 2020). Furthermore, in contrast to mammals, female birds display similar or partially even shorter life expectancies than males (Orell and Belda, 2002;Fay et al, 2020).…”

“…For example, in the short-lived whinchat, virtually no sign of reproductive senescence could be identified until the age of 4 years, although survival started to decline at an age of only 1 year (Fay et al, 2020). Furthermore, in contrast to mammals, female birds display similar or partially even shorter life expectancies than males (Orell and Belda, 2002;Fay et al, 2020). In a comprehensive study including 339 bird species, it was demonstrated that brain size, independently from body mass, correlates with longevity (Jiménez-Ortega et al, 2020).…”