A. Rigaa et al., MITOCHONDRIAL-DNA FROM THE SCALLOP PECTEN-MAXIMUS - AN UNUSUAL POLYMORPHISM DETECTED BY RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM ANALYSIS, Heredity, 79, 1997, pp. 380-387
We present an analysis of mitochondrial DNA diversity within the scall
op Pecten maximus. Twenty-seven individuals of Pecten maximus were sam
pled from three populations from the west coast of Brittany (France) a
nd their mtDNA assayed for restriction site polymorphism. Thirty-four
variable and conserved cleavage sites have been mapped. They occur in
the coding region as well as in the noncoding one, which has also prev
iously been shown to be variable in length. Nucleotide divergence betw
een two P. maximus mtDNA types can reach 3.4 per cent and the nucleoti
de diversity is 1 per cent. Data using seven restriction endonucleases
clearly distinguished 27 genotypes; each individual possessed a uniqu
e mitochondrial genotype. Phylogenies derived from mtDNA restriction a
nalysis are not concordant with data on reproductive behaviour or ecol
ogical studies. The three populations sampled present similar distribu
tions of the different mitochondrial genotypes, although the scallop s
tock of the Bay of Saint Brieuc is considered, from physiological para
meters, to be genetically distinct from all other populations. Therefo
re, we suggest that P. maximus should fall into category IV of phyloge
ographical pattern, i.e. continuous mtDNA genotypes with a high gene f
low.