Figure 6From: Natural variation of outcrossing in the hermaphroditic nematode Pristionchus pacificusMean pure-strain (black bars) and hybrid (shaded bars) brood sizes. Mean pure-strain is the midparent value. Numbers above the bars indicate heterosis values. Asterisks indicate significance of difference between pure-strains and hybrids in a Student's t test. ***P < 0.001.Back to article page