Distributions of N50 values in relation to different read length illustrated using box plots. An N50 length of x kbp indicates that 50% of the source sequence is covered by contigs of x kbp or larger. The data was collected from assemblies under perfect assumptions (all possible reads are present exactly once, no sequencing errors), based on 20 BACs with an average size of 110 kbp for each species. The boxes stretch from the first to the third quartile of the respective distribution, thus covering 50% of the corresponding data. The boxes are split with a line at the median. For sake of clarity, the median value is given for each box plot. Whiskers indicated with dashed lines are 1.5 times longer than the box but do not stretch beyond minima and maxima. They are used to define the outliers, data points outside the range of the whiskers, which are marked as small circles.