Fig. 3

Maximum likelihood phylogenetic trees of expanded gene families in the Clarias batrachus genome. a Phylogenetic tree of myoglobin (mb) in vertebrates showing gene expansion of mb in the C. batrachus genome. The red solid circles represent the genes in the C. batrachus genome. Bootstrap support values (1000 replications) are indicated on the nodes. b Phylogenetic tree of the olfactory receptor related to class A G protein-coupled receptor (ora) gene family in vertebrates showing the expansion of ora1 in the C. batrachus genome with taste receptor of type 2 member 1 (T2R1) as an outgroup. The three clades (ora1-ora2, ora3-ora4 and ora5-ora6) formed from six members are indicated on the right of the figure. The dark green solid triangle represents the expansion of vomeronasal type 1 receptors (V1Rs) in mammals. The red solid triangle represents the 15 copies in the C. batrachus genome. The term “teleosts” here is used to indicate the non-air-breathing fish species discussed in this study. The detailed phylogenetic tree with species names and sequence names is displayed in the Additional file 1: Figure S2. c Phylogenetic tree of sulfotransferase 6b1 (sult6b1) in vertebrates showing gene expansion of sult6b1 in the C. batrachus genome. The red solid circles represent the genes in the C. batrachus genome. Bootstrap support values (1000 replications) are indicated on the nodes. D. rerio, Danio rerio; G. aculeatus, Gasterosteus aculeatus; T. nigroviridis, Tetraodon nigroviridis; T. rubripes, Takifugu rubripes; O. latipes, Oryzias latipes; G. morhua, Gadus morhua; A. mexicanus, Astyanax mexicanus; O. niloticus, Oreochromis niloticus; X. maculatus, Xiphophorus maculatus; P. formosa, Poecilia formosa; I. punctatus, Ictalurus punctatus; C. carpio, Cyprinus carpio; P. annectens, Protopterus annectens; M. musculus, Mus musculus; H. sapiens, Homo sapiens; X. tropicalis, Xenopus tropicalis; L. chalumnae, Latimeria chalumnae; A. carolinensis, Anolis carolinensis