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Supplementary Materials
2
Table S1. Analysis of covariance for individual morphometric traits comparing lake
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versus stream fish. MANCOVA results: Population: Pillai's Trace = 0.392, F7,170 ~ 18, P
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= 2.45*10-16. Sex: Pillai's Trace = 0.468, F7,170 ~ 25, P < 2.2*10-16. Population*sex
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interaction: Pillai's Trace = 0.039, F7,170 ~ 1, P = 0.337. Standard length: Pillai's Trace =
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1, F = 868, P < 2.2*10-16
Population
Sex
Population*sex
Standard length
Trait
F1,175
P
F1,175
P
F1,175
P
F1,175
P
Mass
60.95
<0.001
88.40
<0.001
0.11
0.741
3827.25
<0.001
Standard length
0.18
0.668
5.37
0.021
0.64
0.426
n/a
Body width
45.00
<0.001
19.29
<0.001
0.79
0.373
1141.57
<0.001
Spine length
0.41
0.523
2.68
0.103
1.24
0.266
67.13
<0.001
Gape width
10.78
0.001
8.50
0.004
1.37
0.243
616.9
<0.001
Gill raker number
0.13
0.712
1.04
0.309
0.07
0.790
0.676
0.412
Gill raker length
32.02
<0.001
19.43
<0.001
0.09
0.764
34.63
<0.001
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8
1
9
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Table S2. Analysis of covariance for individual morphometric traits comparing stream
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fish from above versus below the dam. All interaction terms were evaluated in the
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ANCOVAs (Population*Sex; Population*SL; and Sex*SL), though we only present the
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Sex*SL effects here because all other interaction terms were non-significant for all
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morphological variables. All morphometric traits except gill raker number were log-
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transformed prior to analysis. MANCOVA results: Population: Pillai's Trace = 0.398,
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F6,167 ~ 18, P = 2.44*10-16. Sex: Pillai's Trace = 0.472, F6,167 ~ 25, P < 2.2*10-16. Standard
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length: Pillai's Trace = 1, F6,167 ~ 861, P < 2.2*10-16 ; Population*sex interaction: Pillai's
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Trace = 0.039, F7,170 ~ 1, P = 0.346 ; Population*Standard length interaction: Pillai's
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Trace = 0.012, F6,167 ~ 0.339, P = 0.915 ; Sex*Standard length interaction: Pillai's Trace =
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0.104, F6,167 ~ 0.3, P = 0.0.00483 ; Population*Sex*Standard length interaction Pillai's
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Trace = 0.032, F6,167 ~ 1, P = 0.485.
Population
Sex
Standard length (SL)
Sex * SL
Trait
F1,172
P
F1,172
P
F1,172
P
F1,172
P
Mass
69.18
<0.001
100.34
<0.001
4369.85
<0.001
0.54
0.463
Standard length
0.1845
0.668
5.38
0.021
n/a
Body width
44.56
<0.001
19.09
<0.001
1126.98
<0.001
4.03
0.046
Spine length
0.41
0.523
2.66
0.104
66.00
<0.001
2.78
0.097
Gape width
11.2
0.001
8.82
0.003
645.70
<0.001
2.75
0.099
Gill raker number
0.138
0.720
1.05
0.305
0.766
0.382
4.63
0.033
Gill raker length
32.07
<0.001
19.46
<0.001
35.86
<0.001
1.28
0.259
n/a
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2
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Table S3. Principal Component Axis loadings for the seven morphometric variables in
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the study, with percent variance explained by each principal component axis, and a verbal
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interpretation of the meaning of each axis.
Trait
PC1
PC2
PC3
PC4
PC5
PC6
PC7
% variance
60.15
16.12
11.08
9.62
1.83
1.05
0.14
Mass
-0.479
0.072
0.089
-0.052
0.292
0.063
0.815
Standard length
-0.472
0.066
0.094
-0.003
0.305
0.679
-0.456
Body width
-0.464
0.105
0.128
-0.141
0.293
-0.723
-0.355
Spine length
-0.290
-0.279
-0.226
0.873
-0.110
-0.101
-0.017
Gape width
-0.448
0.109
0.198
-0.166
-0.848
0.028
-0.002
Gill raker number
0.030
-0.794
0.599
-0.083
0.037
0.001
0.004
Gill raker length
-0.210
-0.507
-0.718
-0.423
-0.037
0.008
-0.014
Large positive
Small
Fewer, shorter
Shorter rakers
Long first
Narrow gape
Narrower,
High mass given
body size
gill rakers
given raker
dorsal spine
longer body
a body size
explained
score indicates:
number
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3
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Table S4. Mean Principal Component Axis loadings for lake and stream stickleback,
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distinguishing between above and below-dam stream populations. Letters next to PC
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means indicate statistical similarity or difference among subpopulations, using pairwise t-
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tests with Holm adjustment to p-values to correct for multiple comparisons. F and P
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values for population differences are given for ANOVAs with population, sex, and
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subpopulation*sex interaction terms (only population effects provided here).
Trait
Lake
Stream below dam
Stream above dam
F2,174
P
PC1
0.522 A
-0.385 A
0.112 A
2.88
0.058
PC2
0.301 A
0.096 A
-0.332 B
5.36
0.005
PC3
0.327 A
0.165 A
-0.437 B
13.90
2.50* 10-6
PC4
0.296 A
-0.164 B
-0.004 AB
4.69
0.010
PC5
0.029 A
-0.066 A
0.061 A
2.39
0.094
PC6
0.177 A
-0.058 B
-0.053 B
13.77
2.78 * 10-6
PC7
-0.025 A
-0.003 A
0.022 A
2.95
0.054
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4
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Table S5. Results from piecewise regression. Estimated slopes and statistical
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significance are presented for a single linear regression of each principal component axis
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against location (0 represents the inlet, with positive values further upstream). Three
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piecewise regressions are tested against this simple linear model using a partial F-test: a
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break-point selected by finding the least squares break point (location of the breakpoint is
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listed as meters upstream); a break where the lake and stream join (0 meters); and a break
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at the beaver dam (75 m upstream).
Linear regression
Break-point
Inlet break
Dam break
Trait
Slope
F3,175
P
Location
F3,175
P
F3,175
P
F3,175
P
PC1
-0.00213
2.13
0.146
40
5.75
0.004
1.43
0.236
3.17
0.045
PC2
-0.00198
7.09
0.008
60
3.52
0.032
0.74
0.532
2.14
0.121
PC3
-0.00343
35.65
< 0.001
5
2.75
0.067
1.85
0.1392
0.757
0.471
PC4
-0.00035
0.35
0.557
60
5.15
0.007
3.15
0.026
1.95
0.146
PC5
0.00067
7.06
0.009
40
4.52
0.012
2.62
0.052
1.83
0.164
PC6
-0.00059
9.92
0.002
15
12.33
< 0.001
6.18
< 0.001
4.40
0.014
PC7
0.00027
16.02
< 0.001
300
2.31
0.078
0.62
0.600
0.75
0.475
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5
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Table S6. Slopes of regression lines below and above the optimal break-point, with
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standard errors of the slope estimates, t, and P-values. Asterisks mark PC axes for which
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a piecewise regression was only a marginally significant improvement over a simple
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linear regression (0.05 < P < 0.1; all others are significant). The break points in these two
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cases are very close to the edges of the range of distances upstream from the lake.
Below break-point
Above break-point
Trait
Slope
se
t
P
Slope
se
t
P
PC1
-0.0184
0.0077
-2.41
0.017
-0.0052
0.0019
-2.68
0.009
PC2
-0.0008
0.0030
-0.25
0.803
0.0002
0.0011
0.22
0.828
PC3 *
0.0088
0.0053
1.66
0.103
-0.0033
0.0007
-4.60
< 0.001
PC4
-0.0075
0.0025
-3.00
0.003
-0.0002
0.0008
-0.29
0.775
PC5
0.0030
0.0012
-2.41
0.018
0.0009
0.0004
2.53
0.013
PC6
-0.0069
0.0011
-6.56
<0.001
-0.0004
0.0003
-1.45
0.148
PC7 *
0.0002
0.0001
2.43
0.016
0.0029
0.0006
4.68
0.003
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Supplementary Materials
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Figure A1. Distribution of dinucleotide microsatellite alleles (PCR amplicon length) in lake
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versus stream populations for the five microsatellites examined here.
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Figure A2. Morphological clines as a function of the distance in meters upstream from the
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inlet mouth. Lake samples further from and closer to the mouth are assigned distances of -
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50 and -20, respectively. Split-line regressions are shown when they fit the data significantly
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better than a linear regression. Significant slopes are indicated by solid lines, non-significant
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slopes are indicated by dashed lines. For PC axes 3 and 7, which are best described by simple
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linear regressions, a heavier line represents the significant regression slope. Principal
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component loadings are provided in the Supplementary Materials (Table A3). PC1 is
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negatively correlated with size, PC2 is negatively correlated with gill raker length and
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number, PC3 represents deviations from the correlation between gill raker length and
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number (positive values reflect shorter rakers given raker number), PC4 is positively
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correlated with spine length, PC5 is negatively correlated with gape width, PC6 is negatively
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correlated with body depth/length, PC7 is positively correlated with body mass.
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