Supplementary Table S1. GC levels of rRNA from the five classes of vertebrates (a).

Mammals Birds Reptiles Amphibians

GC GC GC GC M10098 Homo sapiens 56.6 AF173637 Larus glaucoides 56.2 AY217906 Emoia jakati 55.9 EF376089 Hypsiboas raniceps 55.3 AJ311673 Equus caballus 56.2 AF173621 Anthracothorax nigricollis 56.1 AY217894 Acontias percivali 55.4 X04025 Xenopus laevis 53.8 AJ31167 Erinaceus europaeus 56.1 AF173619 Apus affinus 56.1 AY217900 Feylinia grandisquamis 54.7 EF364368 Atelopus flavescens 53.8 DQ222453 Bos taurus 56.1 AF173618 Gallirex porphyreolophus 56.1 AJ311672 Crocodylus niloticus 54.6 AF169014 Hyla chrysoscelis 53.3 X00686 Mus musculus 56.0 AF173617 Urocolius macrourus 56.1 AY217915 Sphenomorphus simus 54.4 AB239574 Cynops pyrrhogaster 53.1 AJ311674 Dasypus novemcinctus 56.0 AF173620 Bubo virginianus 56.0 AY217904 Gehyra mutilata 54.3 AF542043 Rana amurensis 52.8 AJ311679 Ornithorhynchus anatinus 55.9 AF173622 Chordeiles acutipennis 56.0 AY859624 Anolis carolinensis 54.2 AJ279506 Ranodon sibiricus 52.0 M11188 Rattus norvegicus 55.8 AF173636 Ciconia nigra 56.0 AY217939 Eumeces inexpectatus 54.2 DQ235090 Cricetulus griseus 55.7 AF173630 Columba livia 56.0 AY21793 Scelotes kasneri 54.2 AJ311676 Monodelphis domestica 55.7 AF173625 Coracias caudata 56.0 AY217924 Scincus scincus 54.2 AJ311677 Didelphis virginiana 55.7 AF173629 Melopsittacus undulatus 56.0 AY217911 Mabuya hoeschi 54.2 AJ311678 Vombatus ursinus 55.6 AF173633 Neophron percnopterus 56.0 AY217909 Eugongylus rufescens 54.2 X06778 Oryctolagus cuniculus 55.3 AF173613 Ortalis guttata 56.0 AY217923 Sepsina angolensis 54.2 AB048358 Meriones unguiculatus 55.1 AF173635 Podiceps auritus 56.0 AY217909 Eugongylus rufescens 54.2 AF173634 Sula nebouxii 56.0 AY217913 Tiliqua gigas 54.1 AF173623 Trogon collaris 56.0 AY391211 Voeltzkowia lineata 54.1 AF173631 Turnix sylvatica 56.0 AY217903 Hemidactylus frenatus 54.1 AF173616 Tyrannus tyrannus 56.0 AY217892 Gambelia wislizenii 54.1 AF173627 Upupa epops 56.0 AY217898 Cordylus namaquensis 54.0 AF173638 Charadrius semipalmatus 55.9 AY217919 Takydromus septentrionalis 54.0 AF173628 Cuculus pallidus 55.9 AY217918 Psammodromus algirus 54.0 AF173624 Galbula pastazae 55.9 AY217917 Mesalina guttulata 54.0 AF173632 Grus canadensis 55.9 AY802766 Amphiglossus melanopleura 54.0 AF173615 Picoides pubescens 55.9 AY391210 Paracontias holomelas 54.0 AF173626 Tockus nasutus 55.9 AF115860 Sphenodon punctatus 54.0 AF173614 Anas platyrhynchos 55.3 AY217941 Cnemidophorus ocellatus 53.9 AF173611 Coturnix pectoralis 55.0 AY217940 Tupinambis quadrilineatus 53.9 AF173612 Gallus gallus 54.7 AY217942 Xantusia vigilis 53.7 AF173609 Apteryx australis 54.6 AY217902 Leposoma scincoides 53.7 AF173610 Dromaius novaehollandiae 54.6 AF420779 Colobosaura modesta 53.7 AF173606 Nothoprocta ornata 54.6 AY217943 Lepidophyma sylvaticum 53.7 AF173608 Rhea americana 54.6 AY217896 Gerrhosaurus nigrolineatus 53.7 AF173607 Struthio camelus 54.6 AF173605 Alligator mississippiensis 53.7 AY217899 Cordylosaurus subtesselatus 53.6 AY217897 Tracheloptychus petersi 53.6 AY859627 Chrysemys sp 53.4

AVERAGE 55.8 AVERAGE 55.7 AVERAGE 54.1 AVERAGE 53.4

(a) GC levels of rRNA from the five classes of vertebrates. The sequences are sorted according to decreasing GC. Ray-finned fishes were splitted into tropical/temperate and polar (see text). Ray-finned Chondrichthyes temperate/tropical polar GC GC GC AF133089 Cyprinus carpio 56.4 AF518194 Patagonotothen brevicauda 53.7 AY049861 Urobatis jamaicensis 52.9 EF189737 Carassius auratus 56.4 AF518191 Lepidonotothen nudifrons 53.6 AY049846 Potamotrygon hystrix 52.9 AJ876375 Kryptopterus bicirrhis 56.0 AF518193 Notothenia rossii 53.5 M97576 Rhinobatos lentiginosus 52.7 AF021880 Ictalurus punctatus 55.6 AF518188 Dissostichus mawsoni 53.4 AY049810 Apristurus profundorum 52.6 AJ87639 Channallabes longicaudatus 55.5 AF518187 Champsocephalus esox 53.4 AY049840 Mitsukurina owstoni 52.5 AJ876381 Clarias stappersii 55.5 AF518190 Harpagifer antarcticus 53.2 M91183 Notorynchus cepedianus 52.3 AJ876382 Heterobranchus isopterus 55.5 AF518202 Trematomus newnesi 52.9 AY049858 Squatina californica 52.2 AJ876376 Pangasianodon hypophthalmus 55.5 AF518205 Gadus morhua 52.9 AY049835 Hemiscyllium ocellatum 52.2 AJ876390 Clariallabes longicauda 55.5 AF518185 Artedidraco shackletoni 52.8 AY049827 Dalatias licha 52.2 AJ876385 Dinotopterus cunningtoni 55.5 AY049830 Deania sp. 52.2 AJ876380 Tanganikallabes mortiauxi 55.4 M91179 Squalus acanthias 52.2 AJ876377 Heteropneustes fossilis 55.3 AY049849 Pristiophorus cirratus 52.2 X98845 Clupea harengus 54.6 AY049816 Carcharias taurus 52.1 EF126043 Verasper variegatus 54.4 AY049807 Alopias pelagicus 52.1 M91180 Fundulus heteroclitus 54.2 AY049833 Galeocerdo cuvier 52.1 EF431912 Cyprinodon variegatus 54.2 AY049819 Centroscyllium fabricii 52.1 AB028214 Chrysophrys major 54.1 M91181 Echinorhinus cookei 52.0 AB112469 Hippoglossoides dubius 54.0 AY049855 Scyliorhinus torazame 52.0 AB105163 Oryzias latipes 54.0 X98837 Lepisosteus osseus 53.9 X98844 Echiophis punctifer 53.8 X98841 Elops hawaiiensis 53.8 X98840 Hiodon alosoides 53.8 EF126042 Solea senegalensis 53.7 AF518201 Trachinus draco 53.7 X98843 Ophichthus rex 53.7 AB089345 Acanthopagrus latus 53.7 AB089347 Dentex dentex 53.7 EF126038 Scophthalmus maximus 53.7 X98846 Megalops atlanticus 53.6 AB193567 Auxis thazard 53.6 EF126039 Cleisthenes herzensteini 53.5 AF518198 Sebastes brevispinis 53.5 AF518197 Scorpaena scrofa 53.5 AJ564776 Megalaspis cordyla 53.5 AJ564777 Decapterus maruadsi 53.4 AB089346 Lateolabrax japonicus 53.4 AF518195 Perca fluviatilis 53.4 AJ866983 Parablennius rouxi 53.4 AJ564774 Trichiurus haumela 53.3 AB158298 Paralichthys olivaceus 53.3 AF518189 Gobius paganellus 53.2 X98836 Amia calva 53.1 X98839 Salmo trutta 53.1 X98842 Albula vulpes 53.1 AJ564775 Pampus argenteus 53.1 AY866435 Micropogonias undulatus 53.0 AY850370 Seriola quinqueradiata 53.0 M91182 Sebastolobus altivelis 53.0 AF497908 Oreochromis mossambicus 52.9 AJ564778 Rastrelliger kanagurta 52.9 AY544131 Psephurus gladius 52.5 AF030250 Oncorhynchus kisutch 52.5 AY544133 Acipenser sturio 52.4 X98838 Polyodon spathula 52.1

AVERAGE 53.9 AVERAGE 53.3 AVERAGE 52.3