Data from: Sex allocation patterns across cooperatively breeding birds do not support predictions of the repayment hypothesis
Hatchwell, Ben J.
Freckleton, Robert P.
Green, Jonathan P.
Published May 19, 2017 on Dryad.
Cite this dataset
Khwaja, Nyil; Hatchwell, Ben J.; Freckleton, Robert P.; Green, Jonathan P. (2017). Data from: Sex allocation patterns across cooperatively breeding birds do not support predictions of the repayment hypothesis [Dataset]. Dryad. https://doi.org/10.5061/dryad.9bk88
The repayment hypothesis predicts that reproductive females in cooperative breeding systems overproduce the helping sex. Thanks to well-documented examples of this predicted sex ratio bias, repayment has been considered an important driver of variation in sex allocation patterns. Here we test this hypothesis using data on population brood sex ratios and facultative sex allocation from 28 cooperatively breeding bird species. We find that biased sex ratios of helpers do not correlate with production biases in brood sex ratios, contrary to predictions. We also test whether females facultatively produce the helping sex in response to a deficiency of help (i.e., when they have fewer or no helpers). Although this is observed in a few species, it is not a significant trend overall, with a mean effect size close to zero. We conclude that, surprisingly, repayment does not appear to be a widespread influence on sex ratios in cooperatively breeding birds. We discuss possible explanations for our results and encourage further examination of the repayment model.
coop brood sr
Brood (mprop_brood) and helper (mprop_help) sex ratios, expressed as proportions of males, from published studies of cooperatively breeding birds. See references from appendices for full references. See manuscript for criteria used to determine data quality (3 = high, 1 = low). See Table A1 for abbreviations used in helper_effects (UK = ?, these species were excluded from restricted analysis; NP species were excluded from all analyses). Created in Microsoft Excel.
Effect sizes used in meta-analysis of sex ratio adjustment in response to a lack of helpers in cooperatively breeding birds. Test statistics used to calculate effect size are provided, except where these were taken directly from a previous publication (detailed in technique column). Magnitude of effect given in effect_size; effect_exp includes positive/negative direction relative to prediction (biased production of helpful sex in response to deficiency of help). Variance is given in v and used to calculate weight (1/v) for calculation of weighted mean. Columns containing max and/or min are the same as for effect_exp but with the effect sizes of unknown direction treated as positive or negative respectively. Overall weighted mean and confidence interval reported in the manuscript.