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areas as a valuable management practice. Recent studies also suggest that patellid larvae
can be recruited on artificial surfaces, which can later be successfully translocated
(Rivera-Ingraham et al. 20llb). However, although low-diversity mtDNA lineages are
typically regarded as unimportant from a conservation viewpoint, our results based on
multilocus nuclear markers suggest that great caution should be exercised when
translocations are planned due to the genetic heterogeneity observed even on a very
smalllocal scale. In this context, the ISSR genetic differentiation found within the SCR
group may be of crucial importance to conservation efforts. Whatever the causes, a
strong genetic structuring in the North-Westem Sardinia has been observed. In this area
the Argentiera sample, in which individuals show the genetic makeup of samples from
North-Eastem Sardinia and Corsica (cluster B) (Fig 2a, b), may represent a conservation
unit.

Another population that may be regarded as a conservation unit is that from the
protected area of Asinara Island (North-Western Sardinia). The three subsamples
analysed (Cala Sant'Andrea, Punta Sabina, and Pedra Bianca, Table l , Fig. l) show a
high degree of identity, suggesting an efficient gene flow within the island.
Furthermore, the scattering of its individuals is greater than that of other samples from
both the SCR group and the SAS group, as evidenced by the PCA ordination (Fig. 3a,
b), which suggests the presence of a preserved population on this island. However, this
population appears to be isolated from the neighbouring, non protected areas ofNorth-
Western Sardinia (such as Coscia di Donna and Isola dei Porri), leading to potential
determination ofthe Asinara population as a peripheral isolate (Frey 1993). More
studies on larva! recruitment in this area may help to better understand whether the
Asinara population also represents a "source population" (sensu Pulliam 1988) of
genetic variability. This variability must be preserved to assure the viability of the

29

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