Table 1.
Climatic characteristics of grid cells. (Characteristics of centres of high species rarity (grid cells containing at least one small-range species) and other cells, in relation to variables associated with the three climatic hypotheses; p-values indicate significance of differences between centres of species rarity and other cells (Kruskal–Wallis tests). Bonferroni-corrected significance levels (15 tests) are indicated as *p<0.05, ***p<0.001. Deviations are calculated as the climate variable in the target cell minus the average value for the same variable in all cells within a 1000 km radius: for example, for WH birds, centres of species rarity have, on average, 99.89 mm less rainfall than the surrounding cells within 1000 km, whereas the other cells have, on average, 3.32 mm more rainfall than the surrounding cells. Negative temperature scores indicate that the target cells are colder than the surrounding areas and positive elevation scores indicate that they are higher.)
| Western Hemisphere birds | European plants | European butterflies | |||||||
|---|---|---|---|---|---|---|---|---|---|
| mean | p | mean | p | mean | p | ||||
| species rarity cells | other cells | species rarity cells | other cells | species rarity cells | other cells | ||||
| climatic rarity | |||||||||
| climatically analogous area (103 km2) | 30.44 | 72.61 | <0.001*** | 27.33 | 58.90 | <0.001*** | 25.06 | 49.15 | <0.001*** |
| distance to the nearest analogous cell (km) | 28.76 | 17.67 | <0.001*** | 15.88 | 12.06 | <0.001*** | 16.05 | 12.88 | <0.001*** |
| mean distance to all analogous cells (km) | 232.86 | 227.11 | 0.211 | 280.24 | 229.27 | <0.001*** | 277.03 | 235.63 | <0.001*** |
| climatic relict | |||||||||
| average deviation within a 1000 km radius: | |||||||||
| elevation (m) | 251.13 | −24.73 | <0.001*** | 72.46 | −40.72 | <0.001*** | 247.98 | −50.14 | <0.001*** |
| mean temperature of the warmest month (°C) | −1.56 | 0.08 | <0.001*** | −0.32 | −0.16 | 0.492 | −1.26 | −0.03 | <0.001*** |
| mean annual temperature (°C) | −1.33 | 0.05 | <0.001*** | 0.10 | 0.23 | 0.894 | −0.95 | 0.43 | <0.001*** |
| mean temperature of the coldest month (°C) | −1.05 | 0.03 | <0.001*** | 1.03 | 0.67 | 0.002* | −0.14 | 1.00 | <0.001*** |
| annual precipitation (mm) | −99.89 | 3.32 | <0.001*** | 96.23 | 26.69 | <0.001*** | 95.25 | 42.58 | <0.001*** |
| number of dry days (d yr−1) | 3.36 | −1.05 | 0.031 | 0.09 | −2.94 | 0.130 | −4.25 | −1.78 | 0.006 |
| climatic buffer | |||||||||
| average range within a 200 km radius: | |||||||||
| mean temperature of the warmest month (°C) | 13.88 | 8.08 | <0.001*** | 10.83 | 7.56 | <0.001*** | 11.65 | 8.30 | <0.001*** |
| mean annual temperature (°C) | 13.39 | 7.67 | <0.001*** | 10.63 | 7.45 | <0.001*** | 11.48 | 8.08 | <0.001*** |
| mean temperature of the coldest month (°C) | 13.52 | 7.77 | <0.001*** | 11.32 | 8.58 | <0.001*** | 12.20 | 8.84 | <0.001*** |
| annual precipitation (mm) | 2298 | 990 | <0.001*** | 951 | 946 | 0.001* | 1007 | 1022 | 0.002* |
| number of dry days (d yr−1) | 89.59 | 54.86 | <0.001*** | 72.15 | 68.53 | <0.001*** | 78.43 | 68.09 | <0.001*** |
| elevational range within a cell (m) | 1461.3 | 531.7 | <0.001*** | 1270.4 | 542.8 | <0.001*** | 1515.5 | 631.2 | <0.001*** |