Tl. King et al., Mitochondrial DNA diversity in North American and European Atlantic salmonwith emphasis on the Downeast rivers of Maine, J FISH BIOL, 57(3), 2000, pp. 614-630
The displacement loop and NADH-I dehydrogenase regions of mitochondrial DNA
(mtDNA) were amplified by the polymerase chain reaction in 954 Atlantic sa
lmon and digested with 40 restriction endonucleases. Variation was detected
with 10 enzymes, resulting in 21 composite haplotypes which were strongly
patterned geographically with a major discontinuity observed between most N
orth American (NA) and European salmon. Significant heterogeneity of haplot
ype frequencies was found within and among all classification levels (conti
nent, country, and river). Haplotype frequencies were significantly differe
nt across continents, within European samples, within NA samples, within Ca
nadian samples, within wild Maine samples, within captive Maine strains, an
d between captive and wild Maine strains. Nine haplotypes occurred only in
NA, seven in Maine, three only in Maine, and 11 occurred only in Europe. So
me Maine rivers had only a single haplotype, suggesting that effective popu
lation sizes may be low. The second most frequent European haplotype: occur
red in tributaries to one Newfoundland river. Gene trees based on parsimony
and generic distance suggest that the haplotypes are monophyletic within e
ach continent, and that the haplotype found on both continents is intermedi
ate between those of Europe and NA, suggesting common ancestry of all haplo
types.