Figure 4.

Similar developmental effects of chromosome 21 QTL in two independently derived freshwater populations. F₂ fish from two marine × freshwater F₂ crosses ((a,c) FTC × LITC; (b,d) PAXB × LITC) were raised to four time points (given in days post-fertilization, dpf; or adults > 150 dpf) and tested for effects of chromosome 21 genotype on size-corrected bone length residuals. See the electronic supplementary material, table S1 for a summary of the fish included in each time point. (a,b) Chromosome 21 controlled dorsal (EB1) bones at all time points in the FTC cross and at all time points except 20 dpf in the PAXB cross, and the effect was strongest at 80 dpf in both crosses. (c,d) The effect of chromosome 21 on ventral bone length (CB4) was significant at 80 dpf in the FTC cross and nearly significant at 80 dpf in the PAXB cross. ANOVA p-values for the marker Stn489 are indicated with asterisks when significant (p < 0.05; see the electronic supplementary material, table S6 for complete listing of ANOVA results for all branchial bones). Error bars = standard deviation.