Closed bars represent the FCB and open bars represent the FSB populations. Since the females and competitors males have recessive scarlet eye marker and the FSB and FCB males have dominant red eye marker, progeny sired by FSB and FCB males will show red eye color. Hence, in this experiment, the proportion of red eyed progeny is an indicator of sperm offense ability. (A) These data come from females that produced at least one progeny from the FSB or FCB male (that is non-zero sperm offense ability). Compared to FCB males, FSB males had higher sperm offense ability under cold shocked and non-shocked conditions. Selection and treatment had significant effect on P2. However, selection × treatment interaction was not significant. (B) Proportion of males that had zero-sperm offense ability (P2). Significantly lesser proportion of FSB males had zero sperm offense compared to FCB males. Selection and treatment effects were significant. However, selection × treatment interaction was not significant.