Odour-genes covariance and differential investigation of individual odoursin the Mus species complex

Previous research using habituation techniques has demonstrated that greate r genetic similarity between two individuals is associated with more simila rity in the qualities of their individual odours ('odour-genes covariance') . We assessed odour similarities across species in two pairs of genetically close species within the Mus species complex (M. musculus and M. domesticu s; IM. spicilegus and M. macedonicus). Subjects treated odours within each species pair as similar compared with an odour from the other species pair. Subjects also treated odours of M. spicilegus males from the same populati on as similar compared with the odour of M. spicilegus males from a differe nt population. This confirms odour-genes covariance across species and with in populations and also supports previous findings that odour similarities are more salient than specific odour markers. When adult males were present ed with odours of females from two different heterospecific species, subjec ts spent more time investigating the odour from his own species pair than t he other species pair, indicating greater interest in the odour of the clos er heterospecific and demonstrating that odour-genes covariance is reflecte d in behavioural responses to odours. Implications of odour-genes covarianc e as a basis for identifying degrees of genetic relatedness of unfamiliar i ndividuals through similarities in individual odours are discussed. (C) 200 1 The Linnean Society of London.