1

Supplement for ESM

Table S1 Statistical tables for ANOVAs and ANCOVAs

Dependent variables and sources of variation / DF / SS / MS / F / P
Wave exposure (asin √ %)
Site / 4 / 3.6228 / 0.9057 / 51.48 / < 0.0001
Penis length (ln mm)
site (error = MS for block(site)) / 4 / 0.111862 / 0.0280 / 0.3700 / 0.8271
number / 1 / 0.008986 / 0.0090 / 0.1300 / 0.7190
number*site / 4 / 0.141478 / 0.0354 / 0.5100 / 0.7276
density / 1 / 0.002555 / 0.0026 / 0.0400 / 0.8478
density*site / 4 / 0.496915 / 0.1242 / 1.8000 / 0.1317
number*density / 1 / 0.013502 / 0.0135 / 0.2000 / 0.6592
number*density*site / 4 / 0.193653 / 0.0484 / 0.7000 / 0.5932
block(site) / 73 / 5.471156 / 0.0749 / 1.0800 / 0.3314
volume / 1 / 2.430374 / 2.4304 / 35.1200 / < 0.0001
Penis length in annulations
site (error = MS for block(site)) / 4 / 0.062186 / 0.015547 / 0.95 / 0.4423
number / 1 / 0.019205 / 0.019205 / 2.34 / 0.1288
number*site / 4 / 0.034343 / 0.008586 / 1.05 / 0.3863
density / 1 / 0.26191 / 0.26191 / 31.95 / < 0.0001
density*site / 4 / 0.051296 / 0.012824 / 1.56 / 0.1889
number*density / 1 / 0.000848 / 0.000848 / 0.1000 / 0.7483
number*density*site / 4 / 0.028242 / 0.007061 / 0.8600 / 0.4897
block(site) / 72 / 1.182648 / 0.016426 / 2.0000 / 0.0005
volume / 1 / 0.133978 / 0.133978 / 16.3400 / < 0.0001
Penis diameter (ln mm)
site / 4 / 0.322346 / 0.080586 / 3.54 / 0.0108
volume / 1 / 1.9112 / 1.9112 / 89.97 / < 0.0001
volume*site / 4 / 0.299249 / 0.074812 / 3.52 / 0.0084
block(site) / 73 / 1.663977 / 0.022794 / 1.07 / 0.3460
Penis Mass (ln mg)
site / 4 / 4.452626 / 1.113156 / 5.32 / 0.0004
volume / 1 / 19.33615 / 19.33615 / 92.33 / < 0.0001
block(site) / 73 / 17.75691 / 0.243245 / 1.16 / 0.2058

Table S2 Statistical tables for regressions

Dependent variables and parameters (R2) / DF / Parameter (SE) / T / P
Annulations in the penis of densely crowded barnacles as a function of nearest neighbor (0.0012)
Intercept / 1 / 5.3339 (0.02711) / 196.74 / < 0.0001
Nearest Neighbor / 1 / 0.0061 (0.0186) / 0.33 / 0.7438
Annulations in the penis of sparsely crowded barnacles as a function of nearest neighbor (0.0057)
Intercept / 1 / 5.4082 (0.01263) / 428.05 / < 0.0001
Nearest Neighbor / 1 / 0.01133 (0.0145) / 0.78 / 0.4366
Residual variation in penis annulations (with effect of test volume removed) for densely crowded barnacles, as a function of nearest neighbor (0.0001)
Intercept / 1 / 0.0017 (0.02611) / 0.07 / 0.9481
Nearest Neighbor / 1 / 0.00125 (0.01791) / 0.07 / 0.9445
Residual variation in penis annulations (with effect of test volume removed) for sparsely crowded barnacles, as a function of nearest neighbor (0.0000)
Intercept / 1 / 0.0001 (0.01175) / 0.01 / 0.9951
Nearest Neighbor / 1 / 0.0002 (0.01349) / -0.02 / 0.9860
Variation in penis diameter (ln mm) as a function of relative wave exposure (asin √ %) (0.7942)
Intercept / 1 / -0.52065 (0.04864) / -10.7 / 0.0017
Relative wave exposure / 1 / 0.1501 (0.04412) / 3.4 / 0.0424
Variation in penis mass (ln mg) as a function of relative wave exposure (asin √ %) (0.0015)
Intercept / 1 / -2.40113 (0.25776) / -9.32 / 0.0026
Relative wave exposure / 1 / -0.01567 (0.23379) / -0.07 / 0.9508

Fig. S1 A) Aggregation of the acorn barnacle, Semibalanus balanoides. B) A penis dissected from Semibalanus balanoides. Scale bar is one millimeter. C) An image of greater magnification, showing annulated folds in the cuticle

Fig.S2 Schematic of the four treatments from the experiment: Low numbers of individuals, sparsely aggregated (LS), low numbers of individuals, densely aggregated (LD), high numbers, sparsely aggregated (HS) and high numbers, densely aggregated (HD). Each plot was a complete block and contained one of each treatment, haphazardly positioned

Fig.S3 Back-transformed size-adjusted means of penis mass plotted against relative wave exposure.Error bars show 95% CI