Alignment of V1RL ORF protein sequences. Numbering follows human V1RL1, and only the region sequenced in this study is shown. The position marked by an asterisk (172) is inferred to be under positive selection (see text for details). Species abbreviations are as follows: Hsa, human; Ggo, gorilla; Cpy, pygmy marmoset; Asa, Bolivian red howler; Ase, red howler; Apm, mantled howler