Page 1 - mamm.73.3.169

Article in press - uncorrected proof
Mammalia 73 (2009): 169–202 ᮊ 2009 by Walter de Gruyter • Berlin • New York. DOI 10.1515/MAMM.2009.029
Review
Mammals of the Mediterranean islands: homogenisation
and the loss of biodiversity
Marco Masseti
Dipartimento di Biologia Evoluzionistica ‘‘Leo Pardi’’
dell’Universita` di Firenze, Laboratori di Antropologia ed
Etnologia, Via del Proconsolo, 12 – 50122 Firenze, Italy,
e-mail: marco.masseti@unifi.it
Abstract
There is possibly no other location in the world which has
been so intensively influenced by human activity over a
prolonged period as the Mediterranean. Virtually no eco-
systems have been left untouched. Since prehistory, the
human settlers of the Mediterranean islands brought
about a radical turnover between ancient and modern
mammalian faunas, introducing a variety of allochtho-
nous continental taxa. The data available for the Medi-
terranean islands point to endemic mammalian extinction
being largely the result of human activities of land clear-
ance and the introduction of allochthonous animals.
Today, this fauna is no longer characterised by the
majority of the endemic mammals previously reported.
It displays virtually the same species composition, being
almost exclusively characterised by continental
mammals whose appearance on the islands has essen-
tially been influenced by man, and dominated by gener-
alist species. The invasion of ecosystems by exotic taxa
is currently viewed as one of the most important causes
of the loss of biodiversity. Today, in view of the vulnera-
bility of the insular ecosystems it is critically important to an expression used to designate insular territories that
prevent further introductions. But this results in the ques-
tion of how to treat the allochthonous mammalian pop-
ulations of certified ancient anthropochorous origin,
which instead deserve to be protected and considered in
terms of a veritable ‘‘cultural heritage’’. Moreover, their
protection and their study can provide an opportunity for
testing a range of different evolutionary theories.
Keywords: anthropochorous mammals; endemic
faunas; generalist species; Holocene; Mediterranean
islands; Upper Pleistocene.
Introduction
The Mediterranean shores have always offered a unique
range of peculiar biological elements. Amongst these, it
may be interesting to recall the former existence of
endemic insular mammals. In fact, the late Quaternary
island ecosystems were quite different in some ways
from the adjacent continental ecosystems. Palaeontolog-
ical and archaeozoological evidence demonstrates that
several of the fossil and subfossil island faunas differed
considerably from contemporary continental faunas, and
were characterised by a very low taxonomic diversity
(Azzaroli 1971, 1977, Sondaar 1971, 1977). The great
number of islands in the Mediterranean made this region
highly favourable to the evolution of island endemics
(Sondaar and Boekschoten 1967, Dermitzakis and Son-
daar 1978, Kotsakis et al. 1980, Sondaar et al. 1986,
Marra 2005). Examples from the Balearics, Corsica and
Sardinia, the Tuscan archipelago, Capri, Sicily, Malta,
Crete, many Aegean islands, and Cyprus are significant
(Azzaroli 1971, 1977, Sondaar 1971, 1977, Vigne 1992,
Masseti and Mazza 1996) (Figure 1). From a biogeo-
graphical point of view, all these insular territories have
to be regarded as ‘‘oceanic islands’’ (cf. Wallace 1876,
Ghigi 1950, Dermitzakis and Theodorou 1994). In effect,
within the Mediterranean basin it is almost impossible to
ascertain the existence of islands of an authentically
‘‘oceanic type’’, which is the term generally adopted to
indicate volcanic islands formed independently of conti-
nental land masses. In conceptual terms, oceanic islands
are indeed the opposite of ‘‘continental islands’’, the lat-
ter being territories that are instead close to a continental
landmass, and geologically related to it, having been
formed by separation from the nearest mainland (cf.
Lincoln and Boxshall 1987). Perhaps it would be more
precise to refer to them as ‘‘oceanic-like islands’’ (cf.
Alcover et al. 1998), or genuinely ‘‘true islands’’, which is
have been separated from the closest mainland for a very
long time, since at least the beginning of the Upper Pleis-
tocene (Vigne 1999, cf. Gorman 1979). Addressing the
obvious difficulties faced by most organisms in trying to
cross salt water, biogeographers used to postulate that
most remote islands were once linked to continents by
land-bridges now sunk from view (Gorman 1979). It is in
fact commonly assumed that, before becoming dwarfed,
many of the Mediterranean macromammals reached the
islands from the mainland via temporary land-bridges
that originated as a result of the lowering of the sea level
during glacial episodes. According to Azzaroli (1971,
1977, 1983), this may have happened in Sardinia and
Sicily. On the basis of tectonic factors, Malatesta (1980)
observes that Crete may also have been joined to con-
tinental Greece during the Pleistocene. However, as not-
ed by Davis (1987), it is then difficult to explain why the
Pleistocene faunas of the latter islands are relatively rich
compared to that of Cyprus. It may be that only a few
species migrated to this eastern Mediterranean island,
which was somewhat more difficult to reach (cf. Azzaroli
1977).
2009/29