Preprint volume - SIBM

Pre-print Volume - Oral presentations
Topic 1: BIODIVERSITY AND CONSERVATION SCIENCE: CONTRIBUTING TO MANAGEMENT
Fig. 1 - Bayesian Inference cladogram of relationship among Mediterranean and Atlantic specimens
of Gryphus vitreus based on COI and ITS1 concatenated sequences, rooted with Lottia
digitalis (Mollusks, Gastropods).
Cladogramma dell’Inferenza Baiesiana delle relazioni tra esemplari mediterranei ed
atlantici di Gryphus vitreus basato sulle sequenze COI e ITS1 concatenate, radicalizzato
con Lottia digitalis (Molluschi, Gasteropodi).
Conclusions – Both the analysis of molecular variance performed on ITS1 and COI
genes (low fixation index values) and the phylogenetic analysis based on the two
combined genes (polyphyly of the Mediterranean specimens and low BPP values)
rejected the null hypothesis of genetic differentiation between the Mediterranean and
Atlantic populations of G. vitreus. These data suggest the existence of panmixia
between the two populations, thus indicating that the Gibraltar sill does not represent a
barrier to gene flow for G. vitreus. This result is unusual, considering the low potential
dispersal of the species. If panmixia is maintained between geographically separated
marine populations such as the ones under study, this is usually due to an high
dispersal of planktonic larvae in ocean currents. Nevertheless, the dispersal of G.
vitreus is achieved during a short pelagic larval stage (lecitotrophic development).
Therefore it is likely that the strong currents into the Gibraltar strait, joined with the
internal waves that it can often generate, led to genetic exchange across the Atlantic-
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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