Data for: Allometry reveals trade-offs between Bergmann’s and Allen’s rules, and different avian adaptive strategies for thermoregulation

Animals tend to decrease in body size (Bergmann’s rule) and elongate appendages (Allen’s rule) in warm climates. However, it is unknown whether these patterns depend on each other or constitute independent responses to thermal environment. Here, based on a global phylogenetic comparative analysis across 99.7% of the world’s bird species, we show that the way in which the relative length of unfeathered appendages co-varies with temperature depends on body size and vice versa. First, the larger the body, the greater the increase in beak length with temperature. Second, the temperature-based increase in tarsus length is apparent only in larger birds, whereas in smaller birds, tarsus length decreases with temperature. Third, body size and the length of beak and tarsus interact each other to predict the species’ temperature preferences. These findings suggest that the animals’ body size and shape are products of an evolutionary compromise that reflects distinct alternative thermoregulatory a..., BirdTherm.xlsx
The data was obtained by using sf (version 1.0-8)1 and raster (version 3.5-15)2 R packages. As input, we used global raster layers of temperatures World Clim (version 2.1)3. These rasters had a resolution of 30” and were consist of monthly averages from a period of 58 years (1960-2018). The temperature metrics have been calculated within polygons of species ranges available in form of multi-polygon vector layers extracted from the BirdLife International database (version 2020.1)4.
First, we excluded polygons identified as uncertain species presence, uncertain season of presence, non-native presence or species extinct in a region, leaving us with 9,962 species (out of 9,993 species) with complete geographic data.
Second, having polygons with only a certain, native and extant species presence we grouped them by the species (according to the phylogenetic taxonomy5) and the season of presence (either breeding season, winter or year-round presence) and then we aggregated them ..., This data is available through excel and R (or R Studio).