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166 Tonelli et al.

Table 2. Results of coefficient of dispersal Table 3. Results of coefficient of dispersal

direction DD2 (scenario 1): DD2. DD2 value; direction DD2 (scenario 2): DD2. DD2 value;
M. McNemar value; P. McNemar probability M. McNemar value; P. McNemar probability
(* P < 0.05; ** P < 0.01; *** P < 0.001; (* P < 0.05; ** P < 0.01; *** P < 0.001;
**** P < 0.0001). **** P < 0.0001).

Tabla 2. Resultados del coeficiente de dirección Tabla 3. Resultados del coeficiente de dirección
DMdeDcNl2a;emdMias.pr e(V*r asPilóo<nr 0D,M0D5c2;N(*es*u mPpa<ure;0s,t0Po1. ;1P*)*:r*oD PbDa<2b.0iVl,i0da0alo1dr; dMDeDcNl2a;emdMisa.pr e(V*r asPilóo<nr 0D,M0D5c2;N(*es* muPpa<ure;0s,0tPo1. ;2P*)*:r*oD PbDa<2b.0iVl,i0da0alo1dr;
**** P < 0,0001). **** P < 0,0001).

Dispersal flux DD2 M P Dispersal flux DD2 M P
Lipari ž Ustica 0.21 14.36 *** Lipari ž Ustica 0.21 14.36 ***
Vulcano ž Alicudi 0.24 30.97 **** Vulcano ž Alicudi 0.24 30.97 ****
Lipari ž Alicudi 0.23 13.21 *** Lipari ž Alicudi 0.23 13.21 ***
Vulcano ž Filicudi 0.21 22.89 **** Vulcano ž Filicudi 0.21 22.89 ****
Sicily ž Lipari 0.29 85.94 **** Sicily ž Lipari 0.29 85.94 ****
Salina ž Panarea 0.27 4.93 * Salina ž Panarea 0.27 4.93 *
Lipari ž Salina 0.28 24.28 **** Lipari ž Salina 0.28 24.28 ****
Vulcano ž Stromboli 0.27 38.14 **** Vulcano ž Stromboli 0.27 38.14 ****
Sicily ž Vulcano 0.33 69.70 **** Sicily ž Vulcano 0.33 69.70 ****
Sicily ž Linosa 0.14 104.97 **** Malta ž Linosa 0.28 24.45 ****
Tunisia ž Linosa 0.14 143.49 **** Tunisia ž Pantelleria 0.18 137.94 ****
Tunisia ž Pantelleria 0.18 137.94 **** Malta ž Pantelleria 0.18 12.32 ***

Channel, lying 120 km from Malta, 160 km from Sicily, domestic mammals from which to draw the manure
and 165Â km from Tunisia. Our results seem to reflect necessary to feed and nest. Indeed, although some
this geographical centrality, with no specific source species are polyphagous, they need dung for nesting
area with major importance. Pantelleria seems to be and larvae development (Palestrini & Zunino, 1985;
more related with Tunisia, 70 km away. However, Verdú et al., 2007).
Malta (distance 200 km to Pantelleria) also seems to
have played a role as source area. The importance of In view of these results, we propose that human
North Africa for Pantelleria is corroborated by studies movement was the principal factor accountable for
carried out on other taxa. Magnano & Osella (1973), dung beetle dispersal resulting in the colonization of
for example, reported that the curculionido–fauna of the circum–Sicilian islands. Human activity and move�
Pantelleria have the highest number of species with ment have played an important role as a medium for
North African affinities compared to all other circum– animal and plant dispersal (Pimentel, 2001; Forcina
Sicilian islands. et al., 2015). Pimentel (2001) estimates that since
the origin of farming (10,000 years ago), humans
Our results do not strictly support the stepping– moved more than 400,000 species from one region
stone model which supports dispersal from one island of Earth to another. This phenomenon was particularly
to its nearest neighbour. Rather, north of Sicily, Lipari intense in the Mediterranean basin and its islands and
and Vulcano islands might have acted as core source increased as farming spread into this region (starting
areas; while in the Sicily Channel, Linosa would have ca. 7,500Â years ago) (Blondel & Vigne, 1993; Masseti,
been the favourite target area and Pantelleria would 1998; Blondel, 2006; Masseti & De Marinis, 2008,
have had two source areas (Tunisia and Malta) that Vigne, 2014). The dispersal fluxes we have identified
are very far apart. Furthermore, the most frequent spe� are in broad agreement with the ancient human colo�
cies in the volcanic islands is Thorectes intermedius, nization of the islands. In general, the circum–Sicilian
a flightless species unable to survive for long periods islands were colonized directly from Sicily but, in the
in contact with sea water (Zunino, unpublished raw case of the Aeolian Islands, Lipari has played a role
data; Colomba et al., 1995). Thus, the maintenance of as main source area in the human colonization of the
a viable dung beetle population on far–away islands archipelago since the Neolithic Age (ca. 5,000 BC).
was necessarily linked to the presence of humans and There is limited evidence of settlement on Vulcano