Unconstrained Bayesian phylogenetic tree and species tree.

(a) Unconstrained Bayesian phylogenetic tree based on Slc2a4 coding sequences, under the model of TPM2uf+Γ. Values on the nodes are posterior probabilities. (b) The species tree of 23 mammals based on references 28, 29 and 30. Branch lengths are based on nucleotide substitutions per codon. The blue and green thick lines labeled with ‘OWFBs’ and ‘NWFBs’ represent the ancestral branches of Old World fruit bats and New World fruit bats, respectively. Nonsynonymous amino acid substitutions were mapped onto several selected branches. Six sites on the ancestral branch of Old World fruit bats that had estimated omega values >1 are shown in blue.