Figure 2.
Sexual selection differentials in the Western Australian seahorse. The figure shows head length (mm) of unmated and mated male and female seahorses. For each sex, z1 (solid vertical line) is the mean head length of all mated and unmated individuals and z2 (dotted vertical line) is the mean head length of mated ones. The difference between z1 and z2 gives the selection differential s. For females, s is clearly positive (36.95−35.41=1.54), whereas for males s is slightly negative (33.82−33.84=−0.02).