Beacham et al Population structure of Oncorhynchus gorbuscho in British Columbia and Washington, determined with microsatellites 
247 
Table 4 
Mean number of alleles observed per locus at 16 microsatellite loci for pink salmon (Oncorhynchus gorbuscha) from 14 geographic 
broodline areas standardized to a sample size of 240 fish per geographic area. Regional groups (see Table 2), are as follows: 1) 
Washington odd-year, 2) Fraser River (upper-i- lower) odd-year, 3) east coast Vancouver Island odd-year, 4) south coast British 
Columbia odd-year, 5) central coast British Columbia odd-year, 6) Skeena River odd-year, 7) north coast British Columbia odd- 
year, 8) Queen Charlotte Islands odd-year, 9) east coast Vancouver Island even-year, 10) south coast British Columbia even-year, 
11) central coast British Columbia even-year, 12) Skeena River even-year, 13) north coast British Columbia even-year, 14) Queen 
Charlotte Islands even-year. The two Fraser River regions in Table 2 were combined for the analysis. 
Locus 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
Odd 
Even 
OkilO 
30.77 
33.14 
41.59 
40.84 
47.21 
40.53 
48.42 
44.81 
26.93 
31.14 
38.21 
36.03 
43.31 
35.67 
40.91 
35.21 
OkilOl 
50.95 
53.09 
54.73 
55.30 
55.83 
51.38 
54.65 
55.79 
49.88 
48.04 
51.90 
52.11 
55.65 
48.74 
53.96 
51.05 
OnelOl 
35.30 
37.33 
35.93 
37.70 
36.39 
36.18 
36.36 
35.78 
35.78 
36.66 
39.15 
36.55 
39.41 
39.42 
36.37 
37.83 
Onel02 
22.73 
22.25 
23.22 
23.45 
24.44 
20.79 
24.40 
23.99 
23.94 
25.73 
25.53 
26.08 
26.16 
25.68 
23.16 
25.52 
Onel04 
30.29 
31.81 
30.85 
31.78 
30.64 
28.23 
31.10 
30.49 
29.89 
27.95 
30.04 
24.63 
30.40 
27.40 
30.65 
28.39 
One 109 
17.31 
18.00 
17.51 
19.13 
19.62 
20.18 
20.23 
18.90 
16.00 
18.00 
18.60 
18.54 
19.33 
16.98 
18.86 
17.91 
Onelll 
19.79 
21.45 
21.52 
21.81 
21.01 
19.73 
21.24 
20.54 
21.97 
24.05 
25.27 
22.29 
23.51 
22.40 
20.88 
23.25 
Onell4 
37.24 
39.89 
38.61 
38.84 
37.30 
34.99 
36.19 
35.26 
30.00 
32.23 
34.74 
35.46 
35.78 
34.58 
37.29 
33.80 
Ots213 
43.25 
42.92 
45.32 
49.90 
51.23 
50.38 
51.77 
50.54 
43.91 
50.37 
50.34 
48.99 
51.27 
46.15 
48.16 
48.51 
Ots7e 
5.79 
5.90 
7.00 
6.43 
7.68 
7.12 
7.80 
6.48 
4.00 
5.84 
5.82 
6.17 
7.27 
4.92 
6.77 
5.67 
OtsG311 
16.65 
15.91 
17.97 
18.32 
20.50 
20.44 
20.24 
21.25 
20.00 
21.41 
21.06 
18.75 
21.49 
19.69 
18.91 
20.40 
OtsG68 
24.95 
25.11 
25.12 
24.44 
26.38 
27.07 
26.01 
23.80 
20.98 
21.94 
21.99 
20.99 
25.23 
21.14 
25.36 
22.04 
OtsG253b 
33.96 
33.88 
34.08 
35.64 
33.92 
31.77 
34.03 
32.57 
32.83 
34.17 
35.74 
34.44 
36.26 
33.12 
33.73 
34.43 
Ssa407 
27.87 
27.35 
31.41 
31.74 
33.37 
31.83 
32.28 
25.33 
47.90 
48.86 
52.42 
51.36 
51.01 
49.25 
30.15 
50.13 
Ssa408 
52.54 
53.04 
54.75 
51.62 
52.89 
49.94 
54.09 
52.31 
49.90 
48.73 
54.88 
52.09 
55.73 
51.32 
52.65 
52.11 
Ssa419 
36.33 
40.19 
49.00 
46.13 
53.07 
47.58 
52.36 
50.93 
48.00 
46.94 
47.97 
44.46 
50.95 
44.42 
46.95 
47.12 
Total 
485.69 
501.24 
528.60 
533.04 
551.46 
518.14 
551.17 
528.78 
501.90 
522.06 
553.65 
528.92 
572.73 
520.90 
524.76 
533.36 
coast of Vancouver Island (502 alleles), and those popu- 
lations with the greatest number of alleles originated 
from the northern coastal region of British Columbia 
(573 alleles). The greatest difference in number of al- 
leles between the broodlines was observed at the locus 
Ssa407, with an average of 30 alleles observed at the 
locus in the odd-year populations, and 50 alleles ob- 
served in the even-year populations (P<0.01). Within 
the odd-year broodline, lower numbers of observed al- 
leles of Washington populations, and to some extent 
Fraser River populations, compared with other regional 
groups of populations, were concentrated in the OkilO 
and Ssa419 loci (Table 4). 
Distribution of genetic variance 
Gene diversity analysis of the 16 microsatellites sur- 
veyed was used to evaluate the distribution of genetic 
variation between two broodlines, among regions (15 
regions, Table 2) within broodlines, and among popula- 
tions within regions (146 odd-year, 116 even-year popu- 
lations). The amount of variation within populations 
ranged from 85.1% ( Onelll ) to 99.8% ( OkilOl , OnelOl ), 
and averaged 98.1% across all loci (Table 5). Variation 
between the two broodlines accounted for 1.5% of total 
observed variation and was the largest source of varia- 
tion after within-population variation. Variation among 
regions within broodlines was the next largest source 
of variation and accounted for 0.3% of total observed 
variation. Variation among populations within regions 
accounted for 0.2% of total observed variation. Differen- 
tiation between the broodlines was approximately three 
times greater than any combined regional or population 
source of variation. Significant broodline differentia- 
tion in allele frequencies was observed in 13 of the 16 
loci surveyed, with the greatest difference observed at 
Onelll , which was nine times larger than that observed 
at any other locus (Table 5). For the geographic range of 
populations surveyed in the study, broodline differences 
contributed more to differentiation of allele frequencies 
than any regional or population source of differentiation. 
Population structure 
Regional genetic differentiation was observed among 
pink salmon populations sampled in the different geo- 
graphic regions. As expected, the largest differences in 
genetic differentiation were observed between regional 
groups of populations when compared with populations 
in the alternate broodline (regional F ST values ranging 
from 0.014 to 0.036) (Table 6). In the odd-year brood- 
line, the largest average population differentiation 
was observed in comparisons of populations originat- 
ing from Washington compared with populations from 
British Columbia (regional F ST values ranging from 
0.011 to 0.016) (Table 6). Within British Columbia, 
pink salmon in the odd-year broodline originating from 
the Fraser River were the most genetically distinct 
