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The amount of initial genetic variability, as well as the potential for dispersa] and a high
growth rate, may play an important role in determining the spread of an invasive species
by favoring its adaptation to new environments (Roman and Darling, 2007; Estoup and
Guillemaud, 20 l 0). Furthermore, a high genetic variability may overcome the
deleterious effects of inbreeding on population growth (Bakker et al., 2009; Eales et al.,
20 l 0). Notably, the evolutionary potential of an invasive species relies more on the
initial amount of genetic variability than the number of introduction events (Eales et al.,
2010).
Despite the importance of following the evolution of genetic variability of
allochthonous species, few studies on the genetic structure ofthe Manila clam bave
been performed to date (Kijima et al., 1987; Oniwa et al., 1988; Yokogawa, 1998;
Sekine et al., 2006; Vargas et al., 2008; Chiesa et al., 2011). To our knowledge, only
two ofthese studies focused on Mediterranean clam populations: Hurtado et al. (2011)
uncovered evidence for hybridization between R. philippinarum and R. decussatus
along North-West Spain, and Chiesa et al. (20 11) suggest that pattems of genetic
variation in clam populations from the North Adriatic sea may bave been shaped by
multiple introduction events.
Therefore, our study was designed to analyze the genetic variation of microsatellites
among R. philippinarum specimens collected at different sites in tbe Gulf of Olbia, with
the twofold aim of detecting whether i) genetic substructuring is present within this area
and whether ii) a recent founder effect occurred in the Gulf ofOlbia. To this end, we
compared estimates of within-population genetic variability of Sardinian samples with
those of a formerly established, farmed population from the North Adriatic.

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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