Page 3 - mamm.73.3.169
P. 3
Article in press - uncorrected proof
M. Masseti: Homogenisation and the loss of biodiversity of mammals of the Mediterranean islands 171
findings include a genet Genetta plesictoides Bate 1903, dormouse Eliomys morpheus Bate 1918. Both of these
as well as some lesser known small mammals: one or were also clearly relics from the Tertiary (Alcover 1979,
two species of rodent (Mus sp.) – with the possible inclu- Alcover et al. 1981, 1999).
sion of the recently discovered extant Cypriot mouse,
Mus cypriacus Cucchi T., Orth A., Auffray J.-C., Renaud The composition of the endemic insular mammalian
S., Fabre L., Catalan J., Hadjisterkotis E., Bonhomme F., assemblages, despite consisting of only a few taxa, were
and Vigne J.-D. 2006 (Reumer and Oberli 1988, Bon- repeated monotonously on most of the islands. Never-
homme et al. 2004, Cucchi et al. 2006) – one or two theless, they displayed peculiar endemic elements which
species of bat and, perhaps, one shrew (Boekschoten differed greatly from one island to another. The most
and Sondaar 1972, Reese 1995, Theodorou et al. 2007b). common trends of endemisation are the decrease in the
The two largest Balearic islands, Mallorca and Menorca, size of macromammals, such as proboscideans and arti-
are the only Mediterranean islands where the dominant odactyls, and the increase in the size of micromammals,
mammalian species was a representative of the Caprinae such as shrews and rodents (Azzaroli 1971, 1977, Son-
subfamily, possibly of the tribe Rupicaprini, the so-called daar 1971, 1977, 1986). Regarding this aspect, it is
‘‘cave goat’’, Myotragus balearicus Bate 1909 (cf. Kurte´ n assumed that the specific genome of these taxa is so
1968, Waldren 1982, Alcover et al. 2000) (Figure 2). From plastic as to allow these phenomenic modifications to
a geological point of view, Mallorca was isolated from the take place. Effectively, if the characteristics of the
nearest land masses for at least 5.35 million years (Mya). genome did not permit such adaptation, the species
The phyletic lineage of M. balearicus evolved starting would logically be destined to extinction. All these mod-
from this era, as further confirmed by recent studies on ifications are generally assumed to be primarily a con-
the fossil DNA of the species (Lalueza-Fox et al. 2000, sequence of the genetic isolation from continental
2002, 2005) (Figure 3). The other two mammalian species populations, a quantitative and qualitative reduction in
of the greatly impoverished local fauna were the large- food supply, an alteration of intraspecific competition, the
sized shrew Soriculus hidalgo Bate 1945, and the giant absence of large carnivores and perhaps, where the
micromammals are concerned, also of endothermic
adaptations (cf. Masseti and Mazza 1996). Islands that
provided such faunas can be considered as ‘‘natural
laboratories’’ (cf. Davis 1987).
Soricomorpha and Rodentia on islands
Figure 2 Complete skeleton of the Mallorcan cave goat, As observed above, one of the most common trends of
Myotragus balearicus Bate 1909, on display at the Museo endemisation is the increase in size of both Soricomor-
Arqueolo´ gico Nacional, Madrid (courtesy of the Museo Arqueo- pha and Rodentia. The Sicilian giant dormouse, Leithia
lo´ gico Nacional de Madrid). melitensis Adams 1863, was, for example, twice the size
of the extant edible dormouse, Glis glis (L. 1766) (Petro-
Figure 3 Artist’s reconstruction of Myotragus balearicus (cour- nio 1970). There is also evidence of the occurrence in the
tesy of Joan Mayol Serra, Govern de les Illes Balears). Middle/late Pleistocene of the Siculo-Maltese archipela-
go of at least two other dormice, such as Leithia carthei
Adams 1863 and Eliomys wiedincitensis Zammit Maem-
pel and de Bruijn 1982, from the faunal stages of Spi-
nagallo and Maccagnone (Burgio 1997). The first taxon
was described as a form of smaller size, but according
to Adams (1870): ‘‘«not differing in any other respect’’
from the Sicilian giant dormouse. And we have already
seen that a giant dormouse was also comprised within
the endemic fauna of the Balearics. Palaeontological
evidence, however, suggests that Late Pleistocene dis-
persal of the representatives of the Gliridae family
occurred only on the islands of the western Mediterra-
nean basin (Figure 4). According to Boekschoten and
Sondaar (1972), glirids are in fact absent from the eastern
islands where they were more or less replaced by diver-
sified murids. This difference may be caused by faunal
differences on the nearest mainland, and would lead us
to assume a predominance of glirids in the western Med-
iterranean coastal areas and of murids in the eastern
Mediterranean at the time of immigration.
Rodents and shrews of large dimensions have also
been yielded by the archaeological exploration of several
other Mediterranean islands. Two large shrews, Episori-
