Table 3. Freshwater turtle life-history model comparisons.
Comparisons of the Generalized Additive Models created for each life-history trait to estimate capacity for sustainable harvest in freshwater turtles. Models for each trait ordered by decreasing AICc (Akaike information criterion corrected for small sample sizes) values.
| Life-history trait | Modela | Dev. Exp | Loglik | BIC | AICc | Δ AICc | Wi AICcb |
|---|---|---|---|---|---|---|---|
| Clutch size | |||||||
| Continuous latitude | 77.6 | -69.35 | 207.05 | 168.09 | 0.00 | 1.00 | |
| Categorical latitude | 75.8 | -80.04 | 237.57 | 193.80 | 25.71 | 0.00 | |
| Bioclimate - rain | 69.8 | -95.48 | 256.12 | 218.85 | 50.77 | 0.00 | |
| Bioclimate - temp | 70.5 | -98.96 | 261.27 | 224.98 | 56.90 | 0.00 | |
| Clutch frequency | |||||||
| Continuous latitude | 17.9 | -14.42 | 81.83 | 54.94 | 0.00 | 0.93 | |
| Bioclimate - temp | 9.9 | -19.25 | 85.31 | 61.22 | 6.28 | 0.04 | |
| Bioclimate - rain | 7.0 | -21.01 | 83.69 | 62.00 | 9.79 | 0.03 | |
| Categorical latitude | 9.3 | -19.61 | 91.34 | 64.84 | 12.62 | 0.01 | |
| Age at sexual maturity | |||||||
| Continuous latitude | 20.2 | -28.82 | 79.24 | 68.52 | 0.00 | 0.57 | |
| Bioclimate - temp | 37.7 | -19.46 | 92.49 | 69.13 | 0.62 | 0.42 | |
| Bioclimate - rain | 31.6 | -22.86 | 99.50 | 76.08 | 7.56 | 0.01 | |
| Categorical latitude | 32.2 | -22.62 | 104.54 | 79.42 | 10.91 | 0.00 | |
| Adult survival | |||||||
| Bioclimate - temp | 16.7 | 14.16 | -10.39 | -16.31 | 0.00 | 0.85 | |
| Continuous latitude | 6.7 | 12.09 | -6.27 | -12.19 | 4.12 | 0.11 | |
| Bioclimate - rain | 1.4 | 11.09 | -4.26 | -10.18 | 6.13 | 0.04 | |
| Categorical latitude | 23.8 | 15.77 | 7.28 | 0.73 | 17.04 | 0.00 | |
a Models used to predict natural history traits. Each model contained Family as a random effect (smooth term with “re” basis) and body size (log transformed carapace length) as a parametric (not smooth) effect. Continuous latitude included median latitude from all records (S1 Table). Categorical latitude included four latitudinal classes: Temperate (species with latitudinal median and range within temperate zone), “Temp-Trop” (species with latitudinal median within temperate and range overlapping tropical zone/s), “Trop-Temp” (species with latitudinal median within tropical and range overlapping temperate zone/s), Tropical (species with latitudinal median and range within tropical zone). Bioclimate—temp included Mean Temperature of Warmest Quarter (WorldClim: bio10). Bioclimate—rain included Precipitation of Driest Quarter (WorldClim: bio17). Coefficients for individual variables in all models are presented in Table 2.
b Akaike weights (Wi) from largest to smallest. Predictions for each trait were obtained using variables from the 95% confidence subset of models, obtained by first ordering all models in the set by decreasing Akaike weight (Wi), and then sequentially summing the model Wi's in rank order.