“…The repertoire of the fish V1R gene family is small (i.e., six genes in most species), and it is rigidly maintained in five distantly related model fish species, with the exception that fugu and pufferfish lack V1R2 (Saraiva and Korsching, 2007). Furthermore, the sequences of orthologous V1R genes are highly conserved among distantly related rockfish species (Johansson and Banks, 2011) and also among salmonid species (Johnson and Banks, 2011). These attributes are in striking contrast to other olfactory receptor gene families (e.g., OR, V2R, TAAR), which have large and highly variable gene repertoires owing to extensive lineage-specific expansions (Hashiguchi et al, 2008;Hussain et al, 2009;Nei et al, 2008;Niimura and Nei, 2005).…”