The syntenic relationship between D. pseudoobscura and D. melanogaster. Synteny dot-plots showing the shuffled syntenic relationships between D. pseudoobscura and D. melanogaster for the five chromosome arms. In each case the D. melanogaster chromosome is shown on the x-axis and the D. pseudoobscura chromosome on the y-axis. Note that lines within the graph are all of the same thickness, but are of varying length. Owing to the compression inherent in the figure, many of the lines are shorter than they are wide. Chromosomes have been color coded to allow identification of interchromosomal synteny blocks. For example, in the top left of the D. pseudoobscura Chromosome 4–D. melanogaster Chromosome 2L plot, a small region of sequence on D. pseudoobscura Chromosome 4 with similarity to D. melanogaster Chromosome X can be seen. Muller element F is not shown because of the lack of sequence anchoring data on this chromosome.