Phylogenetic reconstruction of the relationship among relaxin family DNA sequences. Phylogenetic tree reconstructed using the minimum evolution algorithm (a distance method) and including only the first two positions of each codon and employing the Tamura-3-parameter + Γ model of sequence evolution. Numbers at each node indicate the bootstrap values. Genes located at each of the four relaxin family loci, insl5 (RFLA), rln (RFLB), rln3 (RFLCI) and insl3 (RFLCII), are shown in the same colour. Paralogous copies of insl5 (insl5a and insl5b) and rln3 (rln3a and rln3b) that arose after the teleost WGD are indicated. Mammalian INSL6 is a tandemly duplicated member of the relaxin family that is linked and paralogous to mammalian RLN.