Fig. 1

Sequenced species with B chromosomes and their karyotypes and genomic data. a A. mexicanus, b A. correntinus and c A. flavolineata. The plots are given for each corresponding species to show the comparison between B- (0B) and B+ (1B and 2B) coverage. The significant higher coverage of B+ (red peaks) as compared to B- (blue peaks) indicates the amplified genomic region on the B chromosome and extremely underrepresented sequence of this region on the A chromosomes. The X-axis and Y-axis represent read depth and genomic position of the B-block. The blocks are named according to their position in the respective genome assembly. The scatterplots provide the comparison of read abundance for the extracted blocks (upto 2000 reads) between the B- and B+ genomes. Each red dot in these plots is a single block, with X-axis and Y-axis representing the number of mapped reads for B- and B+ genomic libraries. Notice that the blocks above the diagonal lines inclining towards the Y-axis, providing evidence to the extracted B-blocks with higher reads coverage of B+ harbor extra copies of these sequences on B chromosomes