Figure 2

Sex-specific reproductive success during direct competition. Cumulative lifetime reproductive success (as measured by number of offspring over 35 weeks of competition) for promiscuous line (open circles) and monogamous line (filled squares) males (A) and females (B). Promiscuous line males had significantly more offspring than monogamous line males (Table 1). Male reproductive success values are calculated from number of sons only (see Methods). (C) interaction of sex-specific effects of breeding treatment: promiscuous line (circles) male reproductive success was negatively correlated with promiscuous line female reproductive success (P = 0.027). Shown are means and standard errors per offspring sweep cycle; male reproductive success values were multiplied by two.