a, Rooted phylogenetic tree using the genomic sequence of the Drosophila FoxP gene (see Materials and Methods). The single invertebrate FoxP gene probably corresponds to the ancestral form from which the four vertebrate genes have arisen by serial duplication.

b, Location of the three insertions (black triangles) and qRT-PCR primer pairs (grey arrows) on the genomic structure of the dFoxP gene (left). Structure of the three cloned transcripts (right). IR: intron retention; FH: Forkhead-Box Domain.

c, Expression levels of the three dFoxP isoform mRNAs in heads of Canton S wildtype flies and of the three insertion lines using qRT-PCR. Horizontal lines denote averages, individual circles, trinagles and squares constitute different biological replicates. * - p<0.05, ** - p<0.01, *** - p<0.001.

d, Flight performance of Canton S wildtype flies and the three insertion lines. Asterisk denotes statistical significance compared to Canton S control flies (Kruskal-Wallis ANOVA: H(3, N = 119) = 46.02 p<0.0001, 3955: R = 77.0, p<0.4; f03746: R = 50.9, p<0.00004; c03619: R = 37.0, p<0.00001). Number of animals: 18–37. For full flight performance data see Fig. S1.