Nucleotide frequencies in splice site positions differ among insect genomes. The figure plots the nucleotide frequency difference (relative to D. melanogaster) of the 23,499 real introns for the donor positions +3…+6 and the acceptor positions −7…−3 for 14 insect species. While differences are often small, D. willistoni, T. castaneum, and A. mellifera have a strong preference for A over G at position +3 and for T over C at −3, which is still consistent with the splice site consensus (sequence logo made using http://weblogo.berkeley.edu/). These preferences correlate with the A+T content of these genomes (D. willistoni, 63%; T. castaneum, 67%; A. mellifera, 67%; compared with D. melanogaster, 58%) (Bergman et al. 2002; Honeybee Genome Sequencing Consortium 2006; Tribolium Genome Sequencing Consortium 2008). Donor position +2 is not shown due to tiny frequency differences between the two possible nucleotides (C and T).