CONSPECIFICITY OF MASTOMYS-NATALENSIS (RODENTIA, MURIDAE) FROM SENEGAL AND SOUTH-AFRICA - EVIDENCE FROM EXPERIMENTAL CROSSES, KARYOLOGY ANDBIOMETRY

On the basis of chromosomal analyses, Mastomys natalensis has recently been shown to occur in Senegal. To definitely prove the conspecificit y of these animals with specimens from South Africa, where the species has been described, crossing experiments between individuals from bot h origins have been conducted. Karyological and biometrical comparison s between samples from these regions have also been performed. They ha ve shown a very small chromosomal differentiation between individuals from Senegal and South Africa, and a morphometrical separation that ca n only be evidenced through multivariate discriminant analyses based o n cranial and mandibular measurements. Crosses between animals from th ese two origins, as well as ''backcrosses'' and crosses between ''hybr ids'' were all fertile, the latter having produced the largest litters on average. These results confirm the conspecificity of M. natalensis from Senegal and South Africa, while displaying some minor variations between these populations from the two extremes of the species' range .