Figure 2. Relationship between the level of sperm competition (measured as relative testes size) and a) the proportion of motile sperm in ejaculates, b) the proportion of viable sperm in sperm stores, and c) the proportion of morphologically normal sperm in sperm stores.

Unlike all analyses, figures are not controlled for phylogeny. The values for relative testes mass are the residuals obtained from a linear regression of testes mass on body mass. Proportion data are arcsine-transformed. Each data point represents a species. See main text for further statistical details.