9780521861724htl 1..2

Table 13.1Summary of analysis one of the population consequences of body size

on population density, the response variable. M¼body mass, S¼species richness,

T¼trophy, TB¼bacterivores, TO¼omnivores. M:T¼interaction term between M

and T. *¼p<0.05; **¼p<0.01; ***¼p<0.001.

Analysis of variance (ANOVA) table

Df Sum sq Mean sq F value Pr(>F)

M 1 482.36 482.36 805.1509 <2.2e16***

S 1 4.34 4.34 7.2508 0.007734**

T 2 8.35 4.17 6.9687 0.001207**

M:T 2 5.26 2.63 4.3883 0.013734*

Residuals 186 111.43 0.60

Coefficients

Estimate Std. error t value Pr(>|t|)

(Intercept) 0.84994 0.42476 2.001 0.04685*

M 0.92967 0.06802 13.668 <2e16***

S 0.04101 0.01331 3.081 0.00237**

TB 0.22936 0.50877 0.451 0.65265

TO 1.25460 0.54686 2.294 0.02290*

M:TB 0.13027 0.09105 1.431 0.15420

M:TO 0.43899 0.14999 2.927 0.00385**

2 species

4 species

6 species

8 species

1

2

3

4

(a)

–7 –6 –5 –4 –3 –2

Log 10 (Cell mass (mg))

Log

(Density per ml) 10

Constant

Fast variation

Slow variation

1

2

3

4

(b)

–7 –6 –5 –4 –3 –2

Log 10 (Cell mass (mg))

Log

10

(Density per ml)

Figure 13.3Size-abundance relationship for analysis three, which tests for influence of

(a) species richness, (b) environmental variability on the slope of the relationship.

254 O.L. PETCHEYET AL.