A NEW PERSPECTIVE ON THE ZOOGEOGRAPHY OF THE SIBLING MOUSE-EARED BAT SPECIES MYOTIS-MYOTIS AND MYOTIS-BLYTHII - MORPHOLOGICAL, GENETIC AND ECOLOGICAL EVIDENCE

The actual geographic distribution of the two sibling mouse-eared bat species Myotis myotis and Myotis blythii, which occur widely sympatric ally in the western Palaearctic region, remains largely controversial. This concerns particularly the specific attribution of marginal popul ations from the Mediterranean islands and from adjacent areas of North Africa and Asia, which are morphologically intermediate between conti nental M. myotis and M. blythii from Europe. This study attempts to cl arify this question by using four different approaches: cranial morpho logy, external morphology, genetics and trophic ecology. The three lat ter methods show unambiguously that North Africa, Malta, Sardinia and Corsica are presently inhabited by monospecific populations of M. myot is. In contrast, cranial morphometrics do not yield conclusive results . These results contradict all recent studies, which attribute North A frican and Maltese mouse-eared bats to M. blythii and consider that Sa rdinia and Corsica harbour sympatric populations of the two species. A s concerns south-eastern populations, doubts are also expressed about the attribution of the subspecific taxon omari which may actually refe r to M. myotis instead of M. blythii. Protein electrophoresis is prese ntly the only absolute method available for determining M. myotis and M. blythii throughout their distribution ranges. However, species iden tification may be approached by relying on less sophisticated morphome trical methods as presented in this study. Species-specific habitat sp ecializations are probably responsible for the differences observed be tween the geographic distributions of M. myotis and M. blythii, as the y provide a logical groundwork for a coherent model of speciation for these two bat species.