Figure 1.

Example results from a no-choice experiment testing for postzygotic reproductive isolation. Along with parental survivorship (right axis, solid circles) we report the number of reproducing pairs, an asterisk denoting week 1 for comparisons of parental fecundity and F1 viability. Mean offspring per pair (left axis) shows both fecundity plotted as open circles and offspring survivorship as a bar graph. The bars are standard errors of the mean.