Antarctic Science

Special Issue: The Latitudinal Gradient Project (LGP)

Exchange between populations of Adamussium colbecki (Mollusca: Bivalvia) in the Ross Sea

Marta Guidetti a1a3c1, Stefania Marcato a2, Mariachiara Chiantore a3, Tomaso Patarnello a4, Giancarlo Albertelli a1a3 and Riccardo Cattaneo-Vietti a3
a1 Museo Nazionale dell'Antartide (sez. di Genova) Viale Benedetto XV 5, 16132 Genova, Italy
a2 Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy
a3 Dipartimento per lo Studio del Territorio e delle sue Risorse, Università di Genova, Corso Europa 26, 16132 Genova, Italy
a4 Facoltà di Medicina e Veterinaria, Università di Padova, Agripolis, Legnaro, 35020 Padova, Italy

Article author query
guidetti m   [PubMed][Google Scholar] 
marcato s   [PubMed][Google Scholar] 
chiantore m   [PubMed][Google Scholar] 
patarnello t   [PubMed][Google Scholar] 
albertelli g   [PubMed][Google Scholar] 
cattaneo-vietti r   [PubMed][Google Scholar] 


The endemic Antarctic scallop Adamussium colbecki (Mollusca: Bivalvia) represents a key species in the Ross Sea littoral benthic ecosystem, locally reaching very high densities. This species has an annual gametogenic cycle, with a summer spawning event, and a pelagic larval behaviour. This paper aims at describing population structure and genetic polymorphism (using AFLP) of the large populations inhabiting the Ross Sea (Terra Nova Bay and McMurdo Sound) in order to investigate possible genetic exchange between A. colbecki in these areas. In Terra Nova Bay, size-frequency distributions show, generally, the dominance of large individuals, although site related differences are found in the abundance of smaller size classes (less than 40 mm), suggesting that recruitment is not a regular event. All McMurdo sites are characterized by large individuals and, at least during this sampling period, recruitment is completely absent. Nuclear DNA analyses show that the largest differences are found at the largest scale (between McMurdo Sound and Terra Nova Bay), but all populations sampled, even at a smaller spatial scale, have a well-settled genetic structure, notwithstanding the pelagic larval strategy. The panmixia hypothesis has therefore to be rejected for this species.

(Published Online November 14 2006)
(Received July 15 2005)
(Accepted June 22 2006)

Key Words: AFLP; Latitudinal Gradient Project; panmixia hypothesis; population structure; scallops.