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located in Southem Spain and North Africa (Espinosa and Ozawa 2006). In contrast,
Inter-simple sequence repeat (ISSR) markers bave shown significant genetic structuring
between populations in two Sardinian marine protected areas (MPAs) located only 150
km apart (Casu et al. 2006).

The lack of genetic data from across the entire extant range ofP. f erruginea
represents an issue in managing its conservation because the knowledge of the amount
of genetic variability and distribution in space and time is criticai fora correct diagnosis
ofthe status, threats and viability ofpopulations (Frankham 1995; Escudero et al.
2003). Indeed, genetic approaches are particularly useful in addressing issues such as
the determination of the dispersa! capabi lities of marine species. In fact, a direct
determination of dispersal ability in marine species is difficult to quantify (Kinland and
Gaines 2003) and therefore estimates of dispersa! are often indirectly inferred by
assessing the genetic differentiation among populations (Chambers et al. 2006;
Pannacciulli et al. 2009).

To perform a comprehensive assessment ofthe genetic population structure of P.
ferruginea, we sampled individuals across the entire extant range. In doing so, we
investigated the presence of genetic discontinuities across the sampled area and
explored the potential causes of any genetic structuring. To achieve these goals, we used
both nuclear ISSR markers and partial sequences ofthe following three mtDNA genes:
COI, 12S (small-subunit ribosomal RNA gene) and 16S (large-subunit ribosomal RNA
gene). As molecular markers of choice we used ISSRs because this technique is
affordable and less laborious compared with other fingerprinting methods. Simulations
indicate that dominant markers, such as ISSRs, may be as efficient as the codominant
ones in estimating genetic diversity (Mariette et al. 2002). Furthermore, ISSRs generate
highly reproducible bands, and detect high levels of genetic variability in populations of

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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