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Palumbi 2010). Different habitat requirements have been invoked to explain the
different genetic structure in co-distributed limpets belonging to Syphonaria (Teske te
al. 2011) and Cellana genera (Bird et al. 2007). Other potential explanations may rely
on the larvallife history (e.g. Riginos and Victor 200 l). Though both species may have
similar larva! duration, the larger size and higher density of oocytes may reduce
dispersa! in P. ferruginea (Templado 200 1). Indeed, Teske et al. (2011) suggested that a
larger size of eggs may reduce the potential for long distance dispersa! as larvae are
likely to settle more quickly. Another hindrance to dispersa! in this species may be the
lower number of released larvae which may affect the recruitement in this species
(Laborel-deguen and Laborel 1991).
Results of the present work highlight that ISSR markers may be a useful tool in
analysing pattems of genetic variation in P. ulyssiponensis. At continental scale genetic
patterns were congruent with those found in other studies, whereas the lack of
differentiation between Macaronesian and European sarnples may reflect a bias due to
the poor sarnpling of this area. A more thorough sampling of the western and partly the
eastern Mediterranean sea allow us to evidence a shallow genetic structuring between
and within Mediterranean basins. In addition, our results suggest that western
Mediterranean may represent the contact zone of two genetically divergent clusters
showing clinal variation in opposite directions. Noteworthy these results are sirnilar to
those reported in severa! Mediterranean populations of P. rustica (Sa Pinto et al. 20 l 0),
albeit P. ulyssiponensis showed a shallower degree of genetic differentiation.
Sequencing of rnitochondrial DNA markers, should allow a better understanding of the
present-day and historical pattems of connectivity ofP. ulyssiponensis across the
Mediterranean, and ensure an even more detailed picture of the phylogeographical
patterns in this area.

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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 MOLECOLARl 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