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eastem cost of Sardinia and Alghero in the north-westem Sardinian coast (Fig. 4c). The
haplogroup P4 is the most frequent in eastem Mediterranean and it is found exclusively
in Grecian and Tunisian populations in which displays high rates of frequency (Fig. 4d).

PCA carried out on the basis of frequencies' distribution of the COI
mitochondrial haplogroups identified by Bayesian analysis (Pl, P2, P3 and P4) was
displayed by drawing frequencies maps (Fig. 5). The first principal component, which
accounts for 47.28% of total variance, displays two centres of expansion in eastern
Mediterranean corresponding to Grecian and Tunisian areas (Fig. 5a). The second
principal component, which accounts for 21.0 l% of total variance, displays a centre of
expansion in the western Mediterranean with the highest leve) of variability in the
Tyrrhenian Sea (Fig. 5b). The third principal component, which accounts for 18.30% of
total variance, displays a centre of expansion in the Adriatic Sea corresponding to the
Venetian Lagoon (Fig. 5c).

Grouping populations within seven Mediterranean macro-areas (Sardinia, Sicily,
Elba Island, Venetian Lagoon, Greece and Tunisia), AMOVA was performed setting y

= 0.367 after jModeltest estimation (Table 4). Samples with less than 5 individuals were

excluded from the analysis.
The datasets showed a within-population variation higher (81.17%) than that

among groups (37.82%). Three groups of populations were identified as divergent with
correspondent highly significant P values (Table 4): i) the group (SES) correspondent to
the Mediterranean westernmost areas (Sardinia and Elba Island) and Sicily; ii) the group
(VL) correspondent to the Adriatic Sea area (Venetian Lagoon); and iii) the group (GT)
correspondent to the Mediterranean easternmost areas among those considered (Greece)
and Tunisia.

59

Gìan Luca Dedola: ANALISI DELLA VARIABILITÀ GENETICA DI PATELLA FéRRUGINEA, PATEL-LA ULl'SSIPONENSIS (MOLLUSCA: GASTROPODA) E PINNA
NOBILIS (MOLLUSCA: BIVALVIA): lLCONTRJBUTO DEl DATI MOLECOLARI ALLA CONSERVAZIONE DI SPECIE MINACCIATE - Tesi di douorato in Scienze
della natura e delle sue risorse • indiri7.zo BK>logi.a Ambientale, Università degli Studi di Sassarl