Spatial variation in senescence rates in a bird metapopulation
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Investigating factors which affect the decline in survival with age, i.e. actuarial senescence, is important in order to understand how demographic rates vary in wild populations. Although the evidence for the occurrence of actuarial senescence in wild populations is growing, very few studies have compared actuarial senescence rates between wild populations of the same species. We used data from a long-time study of demography of house sparrows (Passer domesticus) to investigate differences in rates of actuarial senescence between habitats and sub-populations. We also investigated whether rates of actuarial senescence differed between males and females. We found that rates of actuarial senescence showed large spatial variation. We also found that the onset of actuarial senescence varied between sub-populations. However, these differences were not significantly explained by a general difference in habitat type. We also found no significant difference in actuarial senescence rates between males and females. This study shows that senescence rates in natural populations may vary significantly between sub-populations and that failing to account for such differences may give a biased estimate of senescence rates of a species.
KeywordsAgeing House sparrow Metapopulation Senescence Spatial
We would like to thank everyone involved in the House Sparrow Project for help with fieldwork. We are also grateful to everyone at Centre for Biodiversity Dynamics at the Department of Biology, NTNU, for helpful comments and help with statistics in R. This study was supported by Grants from the Research Council of Norway (FRIMEDBIO 204303 and 221956, SFF 223257), the European Research Council (ERC-2010-AdG 268562), and NTNU. The research was carried out in accordance with permits from the Norwegian Environment Agency and the Bird Ringing Centre at Stavanger Museum, Norway.
Author contribution statement
H. H wrote the manuscript. H. H, T. K, H. J, H. P, T. H. R contributed to field work and data collection. H. H, T. K, J. T conducted the analysis. H. H, T. H. R, B. E. S conceived the study. All authors contributed to the interpretation of results and revisions of the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable institutional and/or national guidelines for the care and use of animals were followed.
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