Table 1.
Effects of potential drivers of native and exotic bee abundance and richness. Dash indicates that the predictor was not included in the best model (determined by AICc). %DE, per cent of null deviance explained; DF, degrees of freedom; ΔAICc, difference in AICc between full model and the best-fitting model, which omits non-significant predictors. Significance codes are indicated by asterisk. Italic text represents significant predictors at p < 0.05.
| predictors of interest |
covariates |
||||||||
|---|---|---|---|---|---|---|---|---|---|
| response variable | urbanization (β ± s.e.) | proximity to international port of entry (β ± s.e.) | proportional richness of exotic plants (β ± s.e.) | proportional bloom cover of exotic plants (β ± s.e.) | total plant richness (β ± s.e.) | year (β ± s.e.) | %DE | DF | ΔAICc |
| (a) GLMs | |||||||||
| abundance | |||||||||
| non-honeybee exotic | 0.80 ± 0.21*** | –0.11 ± 0.21 | — | — | — | 1.03 ± 0.28*** | 52.2 | 37 | 2.35 |
| proportion non-honeybee exotic | 0.98 ± 0.09*** | –0.34 ± 0.09*** | — | — | — | — | 63.6 | 38 | 0.00 |
| honeybee | 0.10 ± 0.42 | –0.31 ± 0.41 | — | — | — | — | 0.0 | 38 | 3.52 |
| Hylaeus hyalinatus | 0.70 ± 0.29* | 0.53 ± 0.32 | — | — | — | — | 46.8 | 38 | 0.34 |
| H. leptocephalus | 2.07 ± 0.52*** | –0.84 ± 0.51 | — | — | — | — | 55.6 | 38 | 0.35 |
| Anthidium manicatum | 1.19 ± 0.59* | –0.07 ± 0.62 | — | — | — | — | 24.8 | 38 | 2.45 |
| Megachile rotundata | 1.51 ± 0.45*** | –0.61 ± 0.45 | — | — | — | — | 38.6 | 38 | 0.69 |
| exotic cavity-nesting | 0.81 ± 0.21*** | 0.05 ± 0.21 | — | — | — | 1.66 ± 0.27*** | 68.4 | 37 | 2.55 |
| native overall | –0.35 ± 0.25 | — | — | — | — | 0.37 ± 0.14** | 17.6 | 38 | 0.58 |
| native cavity-nesting | 0.27 ± 0.14 | — | — | — | — | 2.92 ± 0.33*** | 73.7 | 38 | 0.35 |
| native non-cavity-nesting | –0.01 ± 0.07 | — | — | — | — | 0.30 ± 0.14* | 9.7 | 38 | 2.42 |
| richness | |||||||||
| exotic | 0.42 ± 0.16* | –0.11 ± 0.16 | — | — | — | 0.78 ± 0.21*** | 42.4 | 37 | 2.01 |
| proportion exotic | 0.49 ± 0.16** | 0.19 ± 0.16 | — | — | — | — | 30.5 | 38 | 0.95 |
| exotic cavity-nesting | 0.59 ± 0.22** | –0.10 ± 0.21 | — | — | — | 1.26 ± 0.27*** | 55.4 | 37 | 2.24 |
| native overall | –0.18 ± 0.16 | — | — | — | — | 0.34 ± 0.09*** | 27.6 | 38 | 1.24 |
| native cavity-nesting | 0.11 ± 0.11 | — | — | — | — | 2.24 ± 0.30*** | 70.0 | 38 | 1.30 |
| native non-cavity-nesting | –0.02 ± 0.04 | — | — | — | — | 0.26 ± 0.09** | 17.6 | 38 | 2.20 |
| total | –0.04 ± 0.16 | — | — | — | — | 0.40 ± 0.09 | 33.8 | 38 | 2.39 |
| (b) GLMMs | |||||||||
| non-honeybee exotic abundance | 0.66 ± 0.13*** | — | 0.11 ± 0.14 | 0.01 ± 0.11 | 0.39 ± 0.08*** | 0.76 ± 0.29** | 10.4 | 106 | 3.59 |
| H. hyalinatus abundance | 1.02 ± 0.20*** | — | –0.23 ± 0.24 | 0.09 ± 0.21 | 0.59 ± 0.13*** | — | 15.5 | 107 | 3.48 |
| H. leptocephalus abundance | 1.59 ± 0.40*** | — | 0.13 ± 0.40 | –0.02 ± 0.31 | — | — | 9.8 | 108 | 4.22 |
| A. manicatum abundance | 0.84 ± 0.42* | — | –0.27 ± 0.50 | 0.34 ± 0.39 | 0.75 ± 0.28** | — | 10.8 | 107 | 3.60 |
| M. rotundata abundance | 1.01 ± 0.32** | — | 0.08 ± 0.41 | 0.15 ± 0.35 | — | — | 7.4 | 108 | 3.89 |
| non-honeybee exotic richness | 0.39 ± 0.09*** | — | 0.11 ± 0.15 | –0.23 ± 0.13 | 0.25 ± 0.10* | 0.71 ± 0.21*** | 11.6 | 106 | 1.30 |
*p < 0.05; **p < 0.01; ***p < 0.001.