AT% vs AT-skew and GC% vs GC-skew in the 26 Acari mitochondrial genomes. Measured in bp percentage (Y-axis) and level of nucleotide skew (X-axis), following . Values are calculated on J-strands for full length mitochondrial genomes. A, A + T% vs AT-skew; B, G + C% vs GC-skew. Genome sequence from Limulus polyphemus is also shown for a comparative analysis. See Additional file 11 for the GenBank accession numbers and full names of species.