Fig. 2

Maximum likelihood phylogenetic analysis of D. delphis and other cetaceans with Ovis aries outgroup. Each branch site shows the estimated species divergence time (million years ago). The majority of the branches exhibit a branch support of 100. A notable exception is the branching point leading to Eschrichtius robustus and the common ancestor of both B. physalus and Megaptera novaeangliae, which has a branch support of 94. The green numbers indicate the number of gene families that expanded during the evolution of the species and the red numbers indicate the number of gene families that contracted. The sources of species images are provided in Table S1