Table 2.
Result of comparative analyses of how minimum prey size varies as a function of predator size
| Taxonomic group/biome | n | Body mass (kg, mode, range) |
Stat | λ* | a (95% CI) | t | P | b (95% CI) | t | P | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Predator | Prey | ||||||||||
| Terrestrial mammals | 270 | 0.112 (0.002–371) | 0.0001 (0.000001–189) | OLS | (0) | 0.007 (0.004; 0.010) | −22.456 | 0.000 | 1.05 (0.90; 1.20) | 13.709 | 0.000 |
| PGLS§ | 0.929‡ | 0.0003 (0.00001; 0.013) | −4.276 | 0.000 | 0.82 (0.60; 1.03) | 7.381 | 0.000 | ||||
| PGLS¶ | 1.0† | 0.0001 (0.00001; 0.001) | −7.923 | 0.000 | 0.36 (0.15; 0.57) | 3.293 | 0.001 | ||||
| Marine Mammals | 126 | 23000 (4–154160) | 0.100 (0.00003–12) | OLS | (0) | 0.546 (0.215; 1.386) | −1.274 | 0.205 | −0.30 (−0.45; −0.15) | −3.975 | 0.000 |
| PGLS¶ | 0.978† | 0.013 (0.001; 0.232) | −2.940 | 0.004 | 0.16 (−0.13; 0.44) | 1.054 | 0.294 | ||||
| Snakes | 228 | 0.037 (0.0006–13) | 0.035 (0.000005–2.6) | OLS | (0) | 0.249 (0.151; 0.412) | −5.416 | 0.000 | 0.88 (0.72; 1.03) | 11.176 | 0.000 |
| PGLS¶ | 1.0† | 0.008 (0.001; 0.069) | −4.349 | 0.000 | 0.68 (0.52; 0.84) | 8.340 | 0.000 | ||||
| Elasmobranchs | 168 | 16.4 (0.014–4250) | 0.005 (0.0000006–15) | OLS | (0) | 0.051 (0.033; 0.077) | −13.866 | 0.000 | −0.09 (−0.22; 0.04) | −1.374 | 0.171 |
| PGLS¶ | 1.0† | 0.011 (0.001; 0.143) | −3.455 | 0.001 | 0.05 (−0.11; 0.21) | 0.648 | 0.518 | ||||
Parameter estimates, 95% CIs, t-statistics and P-values are given for a and b in the equation prey size = a*predator sizeb, for terrestrial mammals; snakes; marine mammals; elasmobranchs performed with ordinary least squares (OLS) and phylogenetic generalised least squares (PGLS).
*
λ estimated by maximum likelihood.
†
λ significantly different from 0.
‡
λ significantly different from 0 and 1.
§
phylogenetic tree with actual branch lengths.
¶
phylogenetic tree with branch lengths set to 1.