Fig. 6

Changes in OGGs during the evolution of marine mammals and their related terrestrial mammals. The numbers of OGGs with intact OR genes for different species are shown in blue boxes. The numbers of OGGs with intact OR genes on the ancestor node are shown in yellow ellipses. Additionally, the numbers of OGGs that expanded and contracted (or were lost) are shown on each branch. For instance, 190 of 830 OGGs were gained by expansion in opossum, but 423 OGGs were contracted or lost (35 contractions and 388 losses), resulting in 442 intact OR genes in opossum. Notably, because the number of OGG contractions (or losses) includes both gene size reduction and total loss, the number of MRCAs minus the number of OGG contractions (or losses) on the branch does not necessarily equal the number of OGGs on the next node. The divergence time of each node was obtained from the TimeTree (http://www.timetree.org/) database