title: Sex-biased survival predicts adult sex ratio variation in wild birds.
abstract: Adult sex ratio (ASR) is a central concept in population demography and breeding system evolution, and has implications for population viability and biodiversity conservation. ASR exhibits immense interspecific variation in wild populations, although the causes of this variation have remained elusive. Using phylogenetic analyses of 187 avian species from 59 families, we show that neither hatching sex ratios nor fledging sex ratios correlate with ASR. However, sex-biased adult mortality is a significant predictor of ASR, and this relationship is robust to 100 alternative phylogenetic hypotheses, and potential ecological and life-history confounds. A significant component of adult mortality bias is sexual selection acting on males, whereas increased reproductive output predicts higher mortality in females. These results provide the most comprehensive insights into ASR variation to date, and suggest that ASR is an outcome of selective processes operating differentially on adult males and females. Therefore, revealing the causes of ASR variation in wild populations is essential for understanding breeding systems and population dynamics.
authors: Biodiversity Laboratory, Department of Biology and Biochemistry, University of Bath, Bath, UK Department of Sociobiology/Anthropology, University of Göttingen, Göttingen, Germany t.szekely@bath.ac.uk.
authors: Tamás
authors: T
authors: Székely
authors: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK Department of Limnology, University of Pannonia, Veszprém, Hungary.
authors: András
authors: A
authors: Liker
authors: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.
authors: Robert P
authors: RP
authors: Freckleton
authors: Behavioral Ecology and Sociobiology Unit, German Primate Center, Göttingen, Germany.
authors: Claudia
authors: C
authors: Fichtel
authors: Department of Sociobiology/Anthropology, University of Göttingen, Göttingen, Germany Behavioral Ecology and Sociobiology Unit, German Primate Center, Göttingen, Germany.
authors: Peter M
authors: PM
authors: Kappeler
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology*; D005260:Female; D008136:Longevity; D008297:Male; D010802:Phylogeny; D012737:Sex Factors; D012744:Sex Ratio
keywords: parental care; sex allocation; sex ratio; sexual selection