Genetic differentiation of the Iceland scallop Chlamys islandica (Pectinidae) in the northern Atlantic Ocean

Abstract

Allozymic variation at gene loci encoding for glucosephosphate isomerase, phosphoglucomutase and superoxide dismutase was investigated In populations of Chlarnys islandica from waters around Jan Mayen, Spitsbergen, Bear Island and northern Norway. The Gpi locus was particularly polymorphic with at least 12 different alleles and a mean heterozygosity of 84 % Half the individuals were heterozygous at Pgm-2 and between 30 and 40 % at Sod. The high polymorphism at Gpi runs counter to an earlier hypothesis suggesting a positive correlation between environmental variability and Gpi polymorphism of pectinids. Pgm-2 and Sod revealed significant allele frequency heterogeneity among the different areas, Gpi only when the effective number of alleles was considered. The species has a large dispersal potential during a long planktonic larval stage, but information on the surface current system in the North Atlant~c suggests that restr~cted gene flow, with possible contributions from selective constraints, account for the observed pattern in gene variability. It is suggested that the conservative approach of managing each area as if it contained discrete genetic units of the species should be adopted.

Allozymic variability in the Iceland scallop Chlamys islandica: geographic variation and lack of growth-heterozygosity correlations

“…Although temperature varies spatially within the geographic range of this species (summer temperatures vary between 0.5 and 5 "C among areas sampled in the present study ;Fevolden 1989), seasonal variations in temperature may be minor. C. islandica seems to be typical of more stable thermal environments than the other pectinids that have been examined electrophoretically for enzyme polymorphism.…”

“…2.7.5.1) and superoxide dismutase (SOD; E.C. 1.15.1.1) were described by Fevolden (1989). Leucine aminopeptidase (LAP, used to designate enzymes that are able to hydrolyse the substrate L-leucyl-P-naphthylamide-HC1; E.C.…”

“…F. Miiller) from the northern Atlantic revealed that there was geographic variation in allele frequencies of 3 highly polymorphic enzyme coding loci, Gpi, Pgm, and Sod (Fevolden 1989). The most likely reason for inter-region variation in gene frequencies of C. islandica was suggested to be restricted gene flow, with a possible contribution from selective constraints (Fevolden 1989).…”

“…F. Miiller) from the northern Atlantic revealed that there was geographic variation in allele frequencies of 3 highly polymorphic enzyme coding loci, Gpi, Pgm, and Sod (Fevolden 1989). The most likely reason for inter-region variation in gene frequencies of C. islandica was suggested to be restricted gene flow, with a possible contribution from selective constraints (Fevolden 1989). This arctoboreal bivalve is the most common scallop species in Atlantic sub-Arctic and Arctic waters (Ekman 1953, Wiborg 1963, Waller 1991 and has a large dspersal potential due to its long planktonic larval stage (> 2 mo, Gruffydd 1976, Wallace 1982.…”

Veligers from different populations of sea scallop Placopecten magellanicus have different vertical migration patterns

“…This is consistent with a hypothesis of mainly self-recruiting sub-populations, and the relatively sedentary nature of the adults makes the retention or return of veligers to adult spawning beds imperative. Two other scallop species, Chlamys islandica (Fevolden 1989) and Aequipecten opercularis (Le~vis & Thorpe 1994), both show genetic evidence of self-recruitment to adult beds. Bay scallop Argopecten irradians veligers are retained in densest concentrations over adult beds, despite tidal currents (Ambrose et al 1992).…”