Table 2.

Nucleotide composition of third codon positions of the (+)strand encoded gene cox1, demonstrating strand bias in nucleotide frequencies within chelicerates.

Species	Taxon	A	C	G	T	CG skew	Accession number
Lithobius forficatus	Myriapoda	0.411	0.200	0.061	0.329	0.534	[GenBank:NC_002629]
Daphnia pulex	Crustacea	0.273	0.211	0.166	0.350	0.119	[GenBank:NC_000844]
Penaeus monodon	Crustacea	0.388	0.133	0.053	0.427	0.432	[GenBank:NC_002184]
Limulus polyphemus	Xiphosura	0.434	0.229	0.023	0.315	0.814	[GenBank:NC_003057]
Oltacola gomezi	Solifugae	0.407	0.199	0.055	0.339	0.569	[GenBank:EU024482]
Centruroides limpidus	Scorpiones	0.094	0.045	0.264	0.597	-0.709	[GenBank:NC_006896]
Mesobuthus martensii	Scorpiones	0.161	0.020	0.309	0.511	-0.881	[GenBank:NC_009738]
Heptathela hangzhouensis	Araneae	0.374	0.096	0.061	0.470	0.225	[GenBank:NC_005924]
Ornithoctonus huwena	Araneae	0.326	0.033	0.166	0.475	-0.667	[GenBank:NC_005925]
Habronattus oregonensis	Araneae	0.361	0.012	0.101	0.526	-0.792	[GenBank:NC_005942]
Nephila clavata	Araneae	0.379	0.016	0.109	0.496	-0.750	[GenBank:NC_008063]
Pseudocellus pearsei	Ricinulei	0.405	0.281	0.031	0.283	0.801	[GenBank:EU024483]
Leptotrombidium akamushi	Acariformes	0.356	0.176	0.084	0.384	0.354	[GenBank:NC_007601]
Leptotrombidium deliense	Acariformes	0.389	0.123	0.074	0.413	0.247	[GenBank:NC_007600]
Leptotrombidium pallidum	Acariformes	0.388	0.114	0.055	0.444	0.349	[GenBank:NC_007177]
Amblyomma triguttatum	Parasitiformes	0.392	0.106	0.043	0.459	0.421	[GenBank:NC_005963]
Haemaphysalis flava	Parasitiformes	0.433	0.105	0.043	0.419	0.421	[GenBank:NC_005292]
Rhipicephalus sanguineus	Parasitiformes	0.431	0.086	0.025	0.458	0.545	[GenBank:NC_002074]
Ixodes hexagonus	Parasitiformes	0.380	0.197	0.043	0.380	0.642	[GenBank:NC_002010]
Ixodes holocyclus	Parasitiformes	0.420	0.093	0.035	0.451	0.455	[GenBank:NC_005293]
Ixodes persulcatus	Parasitiformes	0.388	0.103	0.031	0.478	0.536	[GenBank:NC_004370]
Ixodes uriae	Parasitiformes	0.410	0.173	0.039	0.379	0.633	[GenBank:NC_006078]
Carios capensis	Parasitiformes	0.446	0.185	0.020	0.349	0.809	[GenBank:NC_005291]
Ornithodoros moubata	Parasitiformes	0.413	0.164	0.041	0.382	0.600	[GenBank:NC_004357]
Ornithodoros porcinus	Parasitiformes	0.378	0.164	0.064	0.394	0.436	[GenBank:NC_005820]
Metaseiulus occidentalis	Parasitiformes	0.400	0.214	0.037	0.349	0.708	[GenBank:NC_009093]
Varroa destructor	Parasitiformes	0.363	0.018	0.062	0.557	-0.560	[GenBank:NC_004454]

Bold numbers indicate higher values in comparison of G and C proportions. Only those taxa (24 chelicerate and 3 outgroup taxa) included in our phylogenetic analysis (Fig. 4) are listed.