Unrooted phylogenetic tree of human and mouse ORs. (a) Unrooted phylogenetic tree of the consensus protein sequences of mouse and human OR gene families. Human OR families are indicated by filled triangles. A few groups (clades) with high (>90%) bootstrap value are labeled by red dots. The Class I OR families, shaded in gray, form a group with more than 90% bootstrap value. A group with high bootstrap value and including mostly mouse OR families is shaded with light blue. The Iva1 ORs (mouse OR families 258 and 259) are indicated by open diamonds and shaded with green; families close to the Iva1 OR families are shaded with yellow. (b) Unrooted phylogenetic tree of the intact fulllength ORs belonging to families in the group shaded in light blue in (a), which contains 11 mouse OR families and only 1 human family. Although there are only 10 intact human ORs in this group, they do not form one tight subgroup but intermingle with the 76 intact full-length mouse ORs covering more than half of the subgroups. (c) Unrooted phylogenetic tree of the intact full-length ORs of the Iva1 ORs (mouse OR families 258 and 259), shaded in yellow in (a), and families close to them. Iva1 ORs form two families, which compose a group with high bootstrap value. None of the human ORs can be found in these two families, although they intermingle with other mouse families.