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168 Tonelli et al.
during the prehistoric period until the classical period,
although sulphur and alum were probably extracted
during the Bronze Age, and animals were possibly
kept on the island by Lipari’s earliest inhabitants,
which would account for the similarities observed
between the beetle fauna of the two islands. Owing
to its agricultural potential and availability of desirable ding to our dispersal models in figures 2 and 3. This
mineral resources (volcanic glass or obsidian), Lipari
has been the only constantly occupied island in the
Aeolian archipelago, with populations expanding
and contracting on nearby islands, which underwent
frequent episodes of abandonment (Bernabo Brea,
1958; Castagnino–Berlinghieri, 2011; Dawson, 2014).
Contacts between the island of Ustica, first colonized
by communities from Sicily in the Early Neolithic (6th–
5th millennium BC) (Mannino, 1998), and the Aeolian
Islands are already attested in the Early Bronze Age
(early 2nd millennium BC) and become more frequent
in the Middle Bronze Age (mid–2nd millennium BC),
as seen from parallel developments in pottery styles
(Spatafora, 2009, 2012). Obsidian from Pantelleria has
been found in Neolithic contexts in Tunisia (Mulazzani
et al., 2010: 57), in Malta, Linosa, and Lampedusa
(Tykot, 1996), demonstrating links between coastal and
island communities of the southern Mediterranean as
early as the 7th and 6th millennia BC. The dung beetle
data in this context support a flux from south to north
in the Sicily Channel, a scenario which warrants further
archaeological investigation and highlights the mutually
beneficial nature of such an interdisciplinary study.
Given the distribution of Pantelleria obsidian on
nearby Linosa, Malta, and the coastal areas of Tunisia
(Tykot, 1996; Mulazzani et al., 2010), we can envisage
a stop–over role for Pantelleria and nearby Linosa
in the Sicily Channel, which would account for the
distribution patterns observed for the dung beetles.
On the basis of archaeological data, the current
coprophagous beetle faunas may have originated by
dispersal mediated by the first island human settle�
ments, through the movements of mammals, domestic
and otherwise, that they were carrying. It is plausible
that the first island communities also made frequent
movements of animals between the islands, to take
advantage of shifting local resources. The patterns
detected would be the result of the distribution since
the prehistoric period of human settlers with animals as
well as of subsequent transfers between the islands.
Arguably, the initial human exploration of the islands
followed simple distance criteria. Instead, the decision
to establish permanent settlements must have been
influenced by other factors, such as the presence of
mineral resources (flint and obsidian), in favour of land�
ings, water resources, areas of pasture and arable land
(the latter often a function of the size of the islands)
as well as demographic, social and cultural factors (as
was clearly the case in the Aeolian islands), with the
establishment of preferential contacts between different
communities, such as between Ustica and Lipari and
Malta and Pantelleria (Dawson, 2011, 2014).
We should stress that our analysis considers the
entire community of each island. It is therefore pos�
sible that some single species may have colonized a
particular island following different routes from those
identified. Furthermore, these dispersal lines should
not be considered as synchronous, but rather as the
result of various events occurring over time. Howe�
ver, such events in different places and times must
have left a trace in the present–day communities
(Legendre & Legendre, 1984), decipherable accor�
implicates that further investigation is indispensable
to corroborate or refute our hypothesis. We suggest
that phylogeographic studies may help describe with
precision the spatial and temporal connections of dung
beetle fauna in these volcanic islands, especially for
the flightless species Thorectes intermedius.
Conclusion
According to our study, the dung beetle communities
of the circum–Sicilian volcanic islands display dispersal
fluxes that do not strictly underlie the stepping–stone
dynamics. This is especially true for the islands to the
north of Sicily, where Lipari and Vulcano act as core
source areas for dispersal routes. In the Sicily Channel,
small and faraway Linosa was colonized from Tunisia,
Malta and Sicily, while Pantelleria was principally co�
lonized by fauna from Tunisia and to a lesser extent
from Malta. These results, together with the fact that
a flightless species, Thorectes intermedius, is most
frequently found on these islands, are supported by
archaeological patterns in the islands’ human coloni�
zation, suggesting a strong human contribution to the
genesis of the dung beetle fauna of the circum–Sicilian
volcanic islands.
Acknowledgements
We wish to thank Imen Labidi for checking the Tu�
nisian dung beetle data, Marco Dellacasa for the
data from the Egadi Archipelago, and Vito Ailara and
Francesca Spatafora for their helpful comments on
the significance of the archaeological and biological
data from Ustica. We also thank the Editor (Jorge M.
Lobo) and an anonymous referee for their helpful and
constructive suggestions.
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