Figure 1.

Experimental set-up and sex ratios of the offspring. (a) Experimental set-up of crossings and temperature treatments. Eggs were obtained from crossing sires known from previous trials to produce offspring with lower (sires a and b) or higher (sires c and d) percentage of females. The sires were crossed with two females, however the offspring of one dam only represented 0.9% of the total offspring and was thus excluded from further analysis. Two days post fertilization (dpf) eggs were mixed according to the male prone and female prone groups. On day 13, larvae from the two groups were divided into four with half of the fish being raised at low temperature (LT; 16.5ºC) and the other half at high temperature (HT; 21ºC) until 65 dpf, the end of the thermosensitive period. In each tank, an equal number of albino fish was added as a control for tank effects. Fish were sampled at one year of age (323 dpf) and gonad samples were taken from 10 females and 10 males for the LT groups and 10 females and 20 males from the HT groups from each tank. b) Paternal effects on European sea bass sex ratio and effects of elevated temperature. Percent of female (red) and male (blue) offspring of each sire (a, b, c and d) raised at low (LT) or high (HT) temperature. Absolute numbers of analyzed fish are shown in the bottom of each bar. The dotted lines indicate the differences of sex ratios between the LT and the HT offspring of each sire. The numbers between the dotted lines inside the LT bars indicate the percent of sex-reversed females among the LT females, while the numbers inside the HT bars indicate the percent of presumed neomales (sex-reversed females into males) among the HT males. The effects of temperature on sex ratios were assessed by Fisher’s exact test for count data and shown with the following equivalence: ** = p < 0.01.