Genetic Status of Atlantic Salmon in Maine Interim Report from the Committee on Atlantic Salmon in Maine (2002) / Chapter Skim
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4 Genetics of Wild Maine Salmon Populations
4 Genetics of Wild Maine Salmon Populations
Pages 22-36
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From page 22... ...
Finally, to what degree are salmon populations in the eight DPS rivers in Maine distinct from each other? The answers to these questions are relevant to questions about the most effective methods for protecting and restoring wild populations of Atlantic salmon in Maine (e.g., Hedrick 2001)
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From page 23... ...
In either case, the variation observed is compared among populations, and a variety of tests are performed to decide whether the populations are statistically distinct from each other and how accurately an individual salmon can be identified correctly with its source population. Although there might be some relationship between the genetic variation detected in these analyses and adaptively significant differences among the various populations, none can be inferred from these analyses.
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From page 24... ...
Several earlier genetic data sets provide us with information on the geographic structure of genetic variation in Atlantic salmon, and they are useful in setting the stage for more in-depth (and more recent) analyses using microsatellite~ DNA markers of the North American populations.
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From page 25... ...
Restriction fragment length polymorphism. Bacteria have enzymes that cut DNA strands containing particular sequences useful in degrading invasive viral DNA.
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using RAPID markers of samples from the Sheepscot, Ducktrap, Penobscot, Narraguagus, Pleasant, Machias, East Machias, Dennys, and Saint John rivers showed that genetic divergence among watershed popula4In salmon, the highest percentage of genetic variation is normally among individuals in a population. 5Long sequences of DNA repeated sequentially.
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From page 27... ...
King et al. (200 measured the relative amounts of genetic variation found within single populations, among watersheds, among North American provincial and state populations, and between European and North American collections.
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Further genetic characterization of aquacultural stocks used in North America is needed. From Table la, we discover that ACT (the fraction oftotal variation among individuals that is accounted for by continental average differences in allele frequencies)
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From page 29... ...
This pattern is fairly typical for salmon and their relatives, including various Pacific salmon species (Ryman 1983, Allendorfand Waples
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From page 30... ...
The RAPD studies indicate that 5.7% to 8.0% of the variation in populations from the Saint John River and southwestward is accounted for by watershed-to-watershed differences, the rest being accounted for within populations. Assignment Analyses Another approach to determine the level of genetic divergence among populations, particularly when separation is less than complete, is to determine the likelihood that one fish can be identified correctly as to its population of origin based on the genetic information.
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From page 31... ...
Although the European national collections (not the focus of this report) are more strongly separated than provincial and state collections in North America, the latter are markedly distinct from each other, despite an extended history of wide movements of Canadian genetic material forrestocking purposes in Maine.
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From page 32... ...
32 Genetic Status of Atiantic Salmon in Maine TABLE 2 Numbers of Genetic Assignments of Individual AtIantic Salmon to Regional Populations ME 1SB NS QB NF LB IC NO FN SC IR SP ME NB NS QB NF LB IC NO O O O FN O O O SC O O O IR O O O 571 36 9 1 12 5 8 76 7 23 5 8 88 6 0 25 5 89 5 7 5 4 O O O SO o 5 3 0 0 2 0 0 1 2 0 0 6 1 2 2 32 0 0 o o o o o o o o o O O O O O O O O o o o o o o O o o o o O O O o o O O O O O O O O O O O O 1 0 0 0 0 7 0 95 1 0 99 Percentages Correctly Assigned O O O O 0 2 0 0 61 0 0 0 0 38 8 7 0 11 48 4 5 4 68 1 89 62 80 73 76 71 1 99 98 100 72 75 81 Abbreviations: ME, Maine; NB, New Brunswick; NS, Nova Scotia; QB, Quebec; NF, Newfoundland; LB, Labrador; IC, Iceland; NO, Norway; FN, Finland; SC, Scotland; IR, Ireland; SP, Spain. Source: Adapted from King et al.
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From page 33... ...
If substantial numbers of the misclassified individuals are placed in the wrong tributary, that argues against the reality of genetic differences among them and in favor of sampling effects. If they are placed in the wrong cohort but the correct tributary, that argues in favor ofthe sort of cohort-to-cohort temporal variation expected of an organism with overlapping generations.
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From page 34... ...
34 Genetic Status of Atlantic Salmon in Maine TABLE 3 Numbers of Genetic Assignments of Individual Atlantic Salmon to Watershed-specif~c Populations KB SH DT PB NA PL MA EM DE KB SH DT PB NA PL MA EM DE Watershed 140 1 5 8 2 7 9 0 2 0 4 1 17 0 4 0 6 5 14 4 4 2 6 0 3 0 13 1 0 124 1 3 0 5 0 20 4 3 4 13 2 1 1 2 38 16 7 2 0 2 5 4 3 24 4 1 6 0 0 2 0 11 19 30 3 7 2 3 0 5 7 6 5 41 4 1 3 17 Percentages Correctly Assigned 74 30 57 84 32 56 10 41 57 Abbreviations: KB, Kennebec; SH, Sheepscot; DT, Duck Trap; PB, Penobscot; NA, Narraguagus; PL, Pleasant; MA, Machias; EM, East Machias; DE, Dennys Source: Adapted from King et al. 1999, Table 18.
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From page 35... ...
2001. OVERALL SUMMARY OF GENETIC STUDIES The overall pattern that emerges from all of these studies is that European and North American populations are substantially different.
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From page 36... ...
populations; broad regional divergence on both sides of the Atlantic, European national populations being about twice as divergent as North American provincial and state populations; and comparable interwatershed divergence within Maine and within the Canadian provinces. In addition, intertributary divergence in a major watershed (e.g., the Penobscot River)
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