Indel gaps per context. (a) Absolute number of gaps per context (left: insertions, right: deletions). Contexts are represented in the form α ℓ, where α indicates the base of the homopolymer and ℓ indicates its length (e.g. T 5=TTTTT). (b) Ratio between the number occurrences of an homopolymer as a context of a gap and its number of exact match alignments (ln the x-axis, the contexts are listed in the order A 1, C 1, G 1, T 1, A 2, C 2, G 2, T 2,...).