Sperm measurements

Excel file with three sheets. First sheet contains measurements of sperm head, midpiece, tail and total length for each individual sperm cell for each male, identified by journal number or accession number. Second sheet contains averages of sperm morphology measurements per male, with corresponding journal number, accession number, band number and sample number. The third sheet contains sperm motility measurements, as well as body morphology for each male

Genotypes

Excel file with three sheets for the three years of this study (2013, 2014 and 2015), containing the genotypes of all individuals. The columns are as follows: individual ID, nest number (0 if not associated with a nest), age (f = adult female, m = adult male, u = chick), sample number, and then the two alleles for each marker

Sperm characteristics and paternity success.

<p>Total sperm length (left) and sperm velocity (right) compared to three measures of fertilization success: within-pair (WP) fertilization success (top two plots), extra-pair (EP) fertilization success (middle two plots), and total fertilization success (total number of offspring sired; bottom two plots). The variables have been centered to the mean of each year. In the boxplots, the left and the right of the boxes are the first and third quartiles, and the line inside the box is the median. The whiskers represent the lowest and highest points still within the 1.5 interquartile range, and dots outside of the whiskers are outliers.</p

Within-season repeatability, comparing measurements of males that have been sampled twice in the same year^a.

<p><i>R</i>² is the repeatability, mean ± SE is shown for first and second measure, along with <i>F</i> value, number of males (<i>N</i>), and <i>p</i> value. All significant correlations (<i>p</i> < 0.05) were robust to correction for multiple testing using false discovery rate correction [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref059" target="_blank">59</a>], and are marked in bold.</p

Estimated slope relating male morphological characters to sperm characteristics in generalized linear mixed models.

<p>The table shows uncorrected p-values; none were significant after correcting for multiple testing using false discovery rate correction [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref059" target="_blank">59</a>].</p

Sperm morphology, sperm motility and paternity success in the bluethroat (<i>Luscinia svecica</i>)

<div><p>Postcopulatory sexual selection may select for male primary sexual characteristics like sperm morphology and sperm motility, through sperm competition or cryptic female choice. However, how such characteristics influence male fertilization success remains poorly understood. In this study, we investigate possible correlations between sperm characteristics and paternity success in the socially monogamous bluethroat (<i>Luscinia svecica svecica</i>), predicting that sperm length and sperm swimming speed is positively correlated with paternity success. In total, 25% (15/61) of broods contained extra-pair offspring and 10% (33/315) of the offspring were sired by extra-pair males. Paternity success did not correlate significantly with sperm morphology or any aspects of sperm motility. Furthermore, sperm morphology and sperm motility did not correlate significantly with male morphological characters that previously have been shown to be associated with paternity success. Thus, the sperm characteristics investigated here do not appear to be strong predictors of paternity success in bluethroats.</p></div

Between-year repeatability, comparing measurements of males sampled in both years.

R2 is the repeatability, mean ± SE is shown for the first year of capture (2013 or 2014) and the second year of capture (2014 or 2015), along with F value, number of males (N) and p value. All significant correlations (p 59], and are marked in bold.</p

Correlations between sperm characteristics and fertilization success in generalized linear mixed models.

<p>Fertilization success was measured as within-pair (WP) fertilization success (males that had not been cuckolded = 0; males that had been cuckolded = 1), extra-pair (EP) fertilization success (males that had not sired extra-pair offspring = 0; males that had sired extra-pair offspring = 1), and total fertilization success (total number of offspring sired). Red border width and age were added as covariates to the models, but their results are not shown here (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.s004" target="_blank">S4 Table</a>).</p

Paired comparisons of total sperm length (left) and sperm velocity (VCL; right) between within-pair (WP) males and the extra-pair (EP) males that cuckolded them.

<p>Paired comparisons of total sperm length (left) and sperm velocity (VCL; right) between within-pair (WP) males and the extra-pair (EP) males that cuckolded them.</p

Summary of species where the relationship between sperm morphology and paternity success has been assessed in the wild.

<p>For each species, we report the between-male variation in sperm total length (expressed as the coefficient of variation, CV_bm), the percent of offspring sired by an extra-pair male (EPY), the percent of broods containing at least one extra-pair offspring (EPB), and whether published works found significant relationships between sperm morphology and paternity. Where more than one published source is available for estimates of EPY and EPB, we preferentially use the estimate from the population and/or year where CV_bm was assessed. Our sources are as follows: Tree swallow: [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref023" target="_blank">23</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref065" target="_blank">65</a>], Superb fairywren: [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref035" target="_blank">35</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref066" target="_blank">66</a>], Collared flycatcher: [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref037" target="_blank">37</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref043" target="_blank">43</a>], Bluethroat: this study, House wren: [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref036" target="_blank">36</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref067" target="_blank">67</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0192644#pone.0192644.ref068" target="_blank">68</a>].</p