The influence of wing morphology upon intraspecific divergence in birds: A global study of subspecies richness

Since the time of Darwin, subspecies have been recognized as an initial stage in the evolution of species. However, the impact of dispersal on subspecies richness in birds globally has received little attention, despite dispersal being a key factor in determining the rate of evolution and playing a significant role in evolutionary divergence. Therefore, it is important to conduct a comprehensive study to address this issue. In this study, we aimed to assess the association between subspecies richness (measured by the number of subspecies) and dispersal ability (measured by the hand-wing index) on a global scale, using a dataset of over 7000 bird species. Our results revealed a negative correlation between dispersal ability and the number of subspecies, without any quadratic correlation. The wing is a crucial phenotypic trait for birds, and the concept of subspecies is important in speciation theory and conservation biology. Therefore, our findings not only enhance our understanding of the association between avian morphological traits and evolutionary divergence but also have implications for the conservation of avian species diversity.