Preprint volume - SIBM

Pre-print Volume - Oral presentations
Topic 1: BIODIVERSITY AND CONSERVATION SCIENCE: CONTRIBUTING TO MANAGEMENT
F. EVANGELISTI, P.G. ALBANO, B. SABELLI
Department of Evolutionary Experimental Biology, University of Bologna, Via Selmi, 3 – 40126 Bologna, Italy.
francesc.evangelist2@unibo.it
GENETIC VARIATION OF THE BRACHIOPOD GRYPHUS VITREUS
(BORN, 1778) ACROSS THE GIBRALTAR SILL
VARIABILITÀ GENETICA DEL BRACHIOPODE GRYPHUS VITREUS
(BORN, 1778) ATTRAVERSO LA SOGLIA DI GIBILTERRA
Abstract – Genetic analysis based on two molecular markers, the nuclear Internal Transcribed Spacer 1
(ITS1) and the mitochondrial cytochrome oxidase subunit 1 (COI), was used to investigate the phylogenetic
relationship between two populations of the eurybathic species Gryphus vitreus (Born, 1778)
(Brachiopoda) across the Gibraltar sill. No genetic differentiation was found, thus indicating that Gibraltar
sill is not a barrier to gene flow for the species, and that a likely panmixia occurs between the two
populations, despite the lecitotrophic development (low potential dispersal).
Key-words: Gryphus vitreus, Gibraltar sill, gene flow, lecitotrophic development.
Introduction - Planktonic larval duration (PLD) is a key factor in shaping patterns of
dispersal and degree of connectivity among populations of marine species (Shanks et
al., 2003). Species having a longer planktonic larval stage (planktotrophic
development) show a major dispersion ability than species having a short planktonic
larval stage (lecitotrophic development). Nevertheless, the dispersion ability of species
depends also on other factors such as past geological events and geographic features
(currents and physical barriers) of the area where they are distributed. Studying the
relationship among populations of species which are distributed across geographic
marine barriers is particularly interesting because, being generally less obvious than
continental barriers, they can influence the gene flow through them in a way that not
always coincides with a reduction of the dispersal of a species. One of the most wellknown
oceanic fronts in the Northern Hemisphere is the strait of Gibraltar, formed by
the encounter of the incoming Atlantic surface waters with the modified higher density
Mediterranean waters. Most studies on population genetics of marine species with an
Atlantic-Mediterranean distribution have focused on the genetic differentiation of
populations found at both sides of the strait of Gibraltar. Many of them have revealed
some degree of genetic differentiation among populations from both marine areas
(Stamatis et al., 2004) but other ones have shown clearly no or very low genetic
diversity (Triantafyllidis et al., 2005). These discordant results about the
biogeographical separation between Atlantic and Mediterranean biota indicate that the
hypothesis of the strait of Gibraltar as a phylogeographic break is controversial
(Patarnello et al., 2007). In this study two different genetic markers, the Internal
Transcribed Spacer 1 (ITS1) and the cytochrome oxidase subunit 1 (COI), were used to
investigate the phylogenetic relationship between two populations of the eurybathic
and Atlantic-Mediterranean distribution brachiopod species Gryphus vitreus (Born,
1778) across the Gibraltar sill, in order to establish the role of the Gibraltar strait in
preventing or not gene flow between them.
Materials and methods – A total of 31 specimens of G. vitreus were collected by
dredge across the Gibraltar strait, 22 from the Balearic Sea and 9 from the Gulf of
Cadiz. Total genomic DNA was extracted from the lophophore using the CTAB
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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