Cytochrome b sequences reveal Acomys minous (Rodentia, Muridae) paraphyly and answer the question about the ancestral karyotype of Acomys dimidiatus

Sequences of the cytochrome b (cyt b) mitochondrial gene show that the spin y mouse Acomys from Crete, known as the endemic species A. minous, is compo sed of two distinct maternal lineages ("A" and "B"). Group "A" sequences cl uster with A. nesiotes (Cyprus) and group "B" sequences cluster with A. cil icicus (Turkey), which is evidence of paraphyly of A. minous in regard to t hese two species. From cyt b sequences, the three taxa are very closely rel ated to A. cahirinus (Egypt): the maximum divergence found among these sequ ences is 1.6%, which is equivalent to the intraspecific diversity observed in other Acomys species. Paleozoology evidenced that man unintentionally in troduced Acomys into Crete and Cyprus during antiquity. The divergence time between Acomys cyt b sequences found in Crete was estimated at 0.4 Myr, wh ich means that the diversity observed did not appear after the introduction but reflects a much more ancient polymorphism. Cytochrome b phylogeny and cytogenetic data together comprise evidence that, within the species A. dim idiatus (Saudi Arabia, Israel, Egypt), it is the karyotypic form with 36 ch romosomes that derives from the form with 38 chromosomes, due to a single a crocentric fusion. (C) 2000 Academic Press.