NOTE ON THE ORIGIN OF THE PRESENT MAMMALIAN FAUNA FROM THE BALEARIC AND PITYUSIC ISLANDS JOSEPANTONI ALCOVER Alcover, J. A., 1980 (1982). Note on the origin of the present mammalian fauna from the Balearic and Pityusics islands. Misc. Zool., 6: 141-149. Barcelona. Given the present state of palaeontological knowledge today's mammalogical fauna of the Balearic and Pitysic Islands can be considered as coming from a recent colonization resulting from the activity, voluntary or not, of man. In this paper the number of mammalian species are considered in tems of the theory of island biogeography. The human activity would have brought about a deterministic renewai of the island's mamma- logicai fauna, with a noticeable increase of the number of species and with the substitution of some stenocorous species, subjected to K selection during many years, by euricorous species, which are typicai r strategists. Josep Antoni Alcover, Dptnt. de Zoologia (Vertebrats), Fac. de Biologia, Universitat de Barcelona, Av. Diagonal 637-647, Barcelona 28. INTRODUCTION that some components of the present ba- learic mammalian fauna may have been It is still taken for granted by various established during Messinian. In this work I authors that the colonization of the Balearic will try to demonstrate the shortcomings of and Pityusic Islands by the present mam- these ideas, on the basis of the paleonto- malian fauna is very ancient, and happened logical knowledge which we now possess long before the first arrival of man. Only about the components of the present mam- very few classical mammalogical papers pose malian fauna from the Balearic and Pityusic the question of colonization (THOMAS, Islands. 1901; CABRERA,1914; KOLLER,1941), and UERPMANN(1971), REY & REY (1974) and COLOM (1978) have very re- PHYLOGENETICAL ANALYSIS OF THE MAM- cently expressed the idea of an ancient MALIAN BIOTA FROM THE BALEARICS origin for this fauna as common place. The former (UERPMANN , 197 1) distinguishes in Before beginning the analysis of the phylo- this work those species which were introduced genetic characteristics of the species which into Mallorca by man from other species compose this fauna, it is worth noting that which, in this opinion, should be considered none of. them has ever been found in the as autochtonous and which presumably en- Quaternary of the Balearics. The remains tered in ancient times, through a "Land- indicated by ADROVER (1966) at Mu- briicke". REY & REY (1974) are amazed by leta Cave are aii Holocenic or more re- the fact that the shrew Crocidura suaveolens cent. However, from this lack of findings we is not found at present in Mallorca, while cannot conclude anything about the absence this island "se ha mantenido discontinua- of this fauna in past times, although the mente unida a Menorca (where C. suaveolens abundance of quaternary mammalian re- does now exist) a 10 largo de diversos pe- mains found ui till now makes us think riodos geológicos". In his turn COLOM that we already have a complete record of (1978) suggests, in the modified text of the the Quaternary fauna of terrestrial, non- new edition of his biogeographical book, flying, marnmalian phyla. The fact that the known Quaternary terrestrial mammals the accurate range of geographical distri- (Myotragus, Nesiotites, Hypnomys) present bution of the species. STORCH (1970) some traits which may be well understood and MALEC & STORCH(1972) consider and explained as adaptations to an insular that E. algirus has been very recently intro- environment in the absence of predators and duced by man into Malta from the neigh- in the absence or scarcity of competitors bouring African mainland. At present, the (LEINDERS & SONDAAR,1974; AL- ancestor species of E. algirus is not known; COVER & ROCA,1975; ALCOVER, 1976; in fact, not even fossil or subfossil remains SONDAAR , 1977) is not in itself conclusive; of this species are known. It seems that the nor can we draw any conclusion from the apparition of the genus took place about the knowledge of the average life of Mammalian late Upper Miocene (KURTEN, 1961 a; species, which, according to KURTEN(1961 SABAN,1958) or about Lower Pliocene b) oscillates around 540.000 years (inclu- (THENIUS,1969), so perhaps it did not yet ding, for this estimation, the Chiroptera, an exist during Messinian. The evolutive rate of order which includes very conservative Insectivora is, in addition, relatively high. species, with an average life of 1.600.00 The average life of their species oscillates years). In the orders wich we shall consider around 490.000 years. Furthermore, only in this work, the average life of the species is one species of Erinaceidae which evolved in sit uated around the following figures: insular conditions has ever been studied, 490 .O00 years (Insectivora, Rodentia), Deinogalerix koenigswaldi, from the Neo- 600.000 years (Lagomorpha), 610.000 years gene of Gargano (Italy; FREUDENTHAL, (Carnivora). The morphological plasticity of 1972) and we know that it acquired a phy- the Rodents has been well studied by siognomy which makes it very different BERRY and his collaborators, who re- from any mainland Insectivora. Another corded, under insular conditions, morpho- fossil insular Erinaceidae has been found at logical changes that took place in Muridae in Capo Mannu (Sardinia; PECCORINI,RAGE only 70 years (BERRY,1964). In any case, & THALER,1974). As far as the genus for our purposes we shall analyse the em- Erinaceus is concerned we know that the pirical data supplied by phylogeny and species E. europaeus, phylogenetically rather spatial and temporal paleodistribution of the close to E. algirus, is found occasionally in different taxa involved. deposits of Upper Pleistocene and Holocene The Hedgehog inhabiting the Balearic and from Europe (ALTUNA,1972). Their re- Pityusic Islands, Erinaceus algirus, lives also mains found in wiirm-I1 of Grotte Hortus along a narrow coastal strip of eastem and "sont d'une taille nettement tres supérieure southem Spain, in southern France, as well aux plus grands indvidus actuels" (JUL- as in vast regions of northern Africa and in LIEN, 1972). All these facts, namely, the the islands of Malta and Djerba. The pattern plasticity of this related species, the data on of distribution which this species present the average life of Insectivora species, the made COLOM (1978) think -following tirne of apparition of the genus, the con- perhaps the considerations of CABRERA sideration of the evolution of an Erinaceidae (19 14)- that it was autochtonous, with an in insular conditions, the identical morpho- assigned entrance during Messinian. logy of the Iberian and insular populations KOLLER(1941) also assigned it an ancient of E. algirus (belonging to the same sub- origin, and concluded that it had spread species, vagans), and the fact that this spe- from southern Spain. UERPMANN(1971), cies may be easly transported by man who did not find it at S'Illot, also assumed it (VERICAD& BALCELLS,1065;MALEC & to be autochtonous. KAHMANN& VES- STORCH,1972) make us think that E, al- MANIS (1977) say that they have not con- girus was brought by man to the Balearic sidered human interventions in presenting and Pityusic Islands. As far as the shrews, Cvocidura russula all of these (finds being) Late Pleistocene from Eivissa and C. suaveolens from Me- age ...Even more uncertain are records from norca, are concerned, the present state of the Middle Pleistocene of small forms that knowledge does not allow any conclusion at may belong in the ancestry of its species". all. The fossil fmdings of both species re- In the Middle Pleistocene of Cartagena, the corded in Europe all date from Upper Pleis- present species of rabbit has not been found, tocene. All the findings in the Iberian Pe- but instead a relative, Oryctolagus cf. lacosti ninsula belong to Upper Pleistocene or to (PONS & MOYA, 1978). It appears that Holocene. Numerous remains of another both taxa of Lagomorpha now iiving in the species, C. kornfeldi, have been found in Balearic and Pityusic Islands are of very re- Middle Pleistocene from Cartagena (Murcia: cent origin. UERPMANN (1971) when re- PONS& MOYA, 1978). These data make us ferring to the rabbit and hare, consider them think that both the present species are very as autochtonous, because their "hohe phylo- recent, and thus they would only have genetische Alter" (sic). COLOM (1978) con- been able to colonize Eivissa and Menorca sider also an ancient origin for both Lago- through the action (direct or indirect) of morpha. The ideas expressed by these man. In addition it must be mentioned that authors do not fit present-day knowledge of C. suaveolens has not been found in subfossil their phylogeny. These two species must be state in Menorca, in spite of the nurnerous considered as very recent and therefore we remains of small mammals coming from a set must accept their presence in the Balearic of deposits of the talaiotic age already ana- and Pityusic Islands as due to importation lysed. It is also noticeable that C. russula has by man. not appeared in the early subfossiliferous de- The Rodentia fauna from the Balearic posit which we know in Eivissa (Cova des and Pityusic Islands contains 6 species: Cuieram). It seems clear that C. suaveolens is Eliomys quercinus (F. Giiridae), Apodemus a species that colonized Menorca after 500 sylvaticus, Mus musculus, M. spretus, Rattus years B. C. (date of the later subfossiliferous rattus and R. norvegicus (F. Muridae). deposit studied in Menorca). Unfortunately Among these species, M. musculus, R. rattus the deposit of Cova des Cuieram is very and R. norvegicus are typical comrnensals of poor, and of undetermined age, so it does man. All the authors consider them as not allow us to say anything about the chro- allochtonous.