Dispersal-range size moderators in animals vs. plants
Our results confirmed our hypothesis that a positive dispersal-range size relationship is less common for endotherms than for ectotherms (Table 1, Fig. 3, Table S2 Supple. Mat.), possibly because endotherms are less affected by niche limitation than ectotherms due to broad thermal tolerances, allowing them to attain and persist in larger ranges more easily. Indeed, the ‘thermal plasticity hypothesis’ proposes that high metabolic rates increase thermal tolerance, and the ‘energy constraint hypothesis’ that due to higher and sustained levels of energy requirements, organisms with high metabolic rates need to forage farther and with lower densities, resulting in larger home ranges and range sizes (Pie et al. 2021). Even though endo- and ectotherms might not differ in the dispersal capacities required during the transfer phase of dispersal, endothermy might have an advantage during settlement and establishment (the third phase of dispersal). If endothermy has allowed species to attain range sizes that are larger than predicted by their dispersal ability only, this might explain why we find fewer positive relationships between dispersal and range size. Note that a model including latitude instead of temperature regulation has a similarly good model fit (Table S1, S2 Suppl. Mat).