Sex-specific early survival drives adult sex ratio bias in snowy plovers and impacts mating system and population growth

Luke J. Eberhart-Phillips, Clemens Küpper, Tom E.X. Miller, Medardo Cruz-López, Kathryn H. Maher, Natalie Dos Remedios, Martin A. Stoffel, Joseph I. Hoffman, Oliver Krüger, Tamas Székely

Research output: Contribution to journalArticlepeer-review

63 Citations (SciVal)


Adult sex ratio (ASR) is a central concept in population biology and a key factor in sexual selection, but why do most demographic models ignore sex biases? Vital rates often vary between the sexes and across life history, but their relative contributions to ASR variation remain poorly understood-an essential step to evaluate sex ratio theories in the wild and inform conservation. Here, we combine structured two-sex population models with individual-based mark-recapture data from an intensively monitored polygamous population of snowy plovers. We show that a strongly male-biased ASR (0.63) is primarily driven by sexspecific survival of juveniles rather than adults or dependent offspring. This finding provides empirical support for theories of unbiased sex allocation when sex differences in survival arise after the period of parental investment. Importantly, a conventional model ignoring sex biases significantly overestimated population viability. We suggest that sex-specific population models are essential to understand the population dynamics of sexual organisms: Reproduction and population growth are most sensitive to perturbations in survival of the limiting sex. Overall, our study suggests that sex-biased early survival may contribute toward mating system evolution and population persistence, with implications for both sexual selection theory and biodiversity conservation.

Original languageEnglish
Pages (from-to)E5474-E5481
Number of pages8
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number27
Early online date20 Jun 2017
Publication statusPublished - 3 Jul 2017


  • ASR
  • Charadrius nivosus
  • Mark-recapture
  • Sex allocation
  • Two-sex matrix model

ASJC Scopus subject areas

  • General


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