Electronic Supplementary Material
(b) Comparison of observed versus expected frequency distributions
To determine whether the observed ratio frequency distribution differed from a random
distribution of size ratios, a random selection of 10 of the 100 original body size-corrected
frequency distributions were statistically compared to a random selection of 10 of the 100
expected frequency distributions using Kolmogorov-Smirnoff (KS) tests. A cumulative
frequency distribution of the p-values resulting from these 10 comparisons was then compared to
a uniform distribution of p-values using a final KS test (figure 2). If a significant difference
exists between the observed and expected frequency distributions, the distribution of p-values
was expected to be skewed due to an abundance of p-values close to zero, and the skewed
distribution of p-values should differ significantly to that of a uniform distribution of p-values. If
no significant difference exists between the observed and expected distributions, the distribution
of p-values was expected to range more evenly from zero to one, and thus there should be no
significant difference between this and a uniform distribution of p-values.
cumulative frequency
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p value
Figure 2. Cumulative frequency distributions of Kolmogorov-Smirnov P-values
generated from 10 comparisons between the corrected observed and expected ratio
frequency distributions (solid line), and from a uniform distribution of p-values (dotted
line). The 2 distributions were significantly different (Kolmogorov-Smirnov test: p =
0.0007).