“…Among examples of chemical reproductive isolation, chemical characterization has been achieved mainly in insects, reptiles and plants, in which methods are well established (for example, Gries et al, 2001;Schiestl and Ayasse, 2002;Lemaster and Mason, 2003). In the other groups (rodents, fish, annelids), experiments during which individuals are presented with olfactory stimuli only (urinary stimuli for rodents; water perfumed with odours for aquatic animals) have demonstrated olfactory mate preferences (for example, Smadja et al, 2004;Sutton et al, 2005;Rafferty and Boughman, 2006). In the house mouse, the use of habituation techniques has allowed an indirect assessment of the extent of divergence in urinary signals within and between two subspecies (Smadja and Ganem, 2008).…”