ACOUSTICALLY DIMORPHIC ADVERTISEMENT CALLS SEPARATE MORPHOLOGICALLY AND GENETICALLY HOMOGENOUS POPULATIONS OF THE GREY MOUSE LEMUR (MICROCEBUS-MURINUS)

Sexual advertisement calls of male mouse lemurs from two neighbouring demes in a dry deciduous forest of western Madagascar were recorded du ring the breeding season. Demes were located about 1.5 km apart with n o geographic barrier between them. They were characterised morphometri cally and genotyped by RAPD fingerprinting. According to univariate an d multivariate statistical analysis, demes differed neither in body me asurements, nor in the banding patterns produced by RAPD fingerprintin g. The acoustic pattern of the advertisement call, however, showed sig nificant differences: Six variables of the frequency and time domain d iffered between the demes. Discriminant function analysis revealed tha t one variable, total call duration, was sufficient to classify more t han 89% of the calls correctly to the corresponding deme. We postulate that these differences are comparable to dialects in birds, because d emes were morphologically and genetically indistinguishable and no bar rier prevented genetic exchange between them. Possible explanations fo r the emergence of dialects in a prosimian species are outlined.