Abstract:

Aims: The variation of species distribution ranges along environmental gradients has long been an important topic in macroecology and biogeography. Rapoport’s rule was initially proposed as a hypothesis concerning the relationship between the latitudinal position of species distributions and their latitudinal range size. In 1996, Stevens provided a broad definition of Rapoport’s rule, stating that the geographic range size of species gradually increases with the rise of a biogeographic gradient (such as latitude, elevation, water depth, etc.). Currently, there is relatively limited research examining the applicability of Rapoport's rule to latitudinal range breadth of Chinese birds, particularly in terms of comparisons across different taxonomic categories and traits. 

Methods: We used distribution and trait data of Chinese birds, and applied four commonly used methods to test whether the latitudinal patterns of species range size of Chinese birds support Rapoport’s rule across three dimensions: taxonomic categories, feeding habits and body mass. 

Results: The results showed that: (1) At different taxonomic levels (family, genus and species), higher taxonomic levels exhibited stronger support for Rapoport’s rule (the R² values for Stevens’s method, Pagel’s method and Cross-species method were all greater than 0.5). (2) Among different feeding habits, species range size variation of herbivorous birds exhibited the least support for Rapoport’s rule (Cross-species method: R² = 0.24). (3) Under the criteria of different body mass, small-bodied birds showed the strongest support for Rapoport’s rule (Cross-species method: R² = 0.42). 

Conclusion: This study found that birds with different dimensions show varying applicability to Rapoport’s rule. The stronger applicability of small-bodied birds to Rapoport’s rule may be due to their weaker competitive abilities, rapid growth rates and better adaptability to changing environment; the lower applicability of herbivorous birds may be related to their correlation with the distribution of plant species. This study discussed the potential reasons for these differences, which helps to understand the formation and maintenance of biodiversity distribution patterns at a macro scale.

Key words: birds, body mass, feeding habit, Rapoport’s rule, taxonomic category