Maximum Likelihood NCX Phylogenetic Tree. The ML phylogenetic tree was generated with the PHYML program with 500 replicates using all known and postulated NCX protein sequences. Pirellula bacterial strain (Rhodopirellula baltica) was used to root this tree. The five-point stars () indicate NCX duplication after Ciona intestinalis divergence and the four-point stars () indicate teleost-specific NCX duplication. Branches are colour coded for vertebrate species, in which red designates mammals, purple indicates birds/aves, teal branches are for reptiles, green are amphibians, and blue are teleosts/fish. The dashed branch (---) indicates the division between invertebrate and vertebrate NCX sequences. The asterisk (*) indicates complete transcripts and those without an asterisk are genomic sequences. The letters 'a' and 'b' correspond to the teleost duplicate versions of NCX1, NCX2 and NCX4. Underlined species are new NCX sequences added in comparison to a previous paper .