The fractal dimension of the tree of life

The structure pattern of the tree of life clues on the key ecological issues; hence knowing the fractal dimension is the fundamental question in understanding the tree of life. Yet the fractal dimension of the tree of life remains unclear since the scale of the tree of life has hypergrown in recent years. Here we show that the tree of life displays a consistent power-law rules for inter- and intra-taxonomic levels. The values of fractal dimension for both inter- and intra-taxonomic levels were different among different kingdoms. The distribution of taxa size is governed by fractal diversity but skewed by overdominating taxa with low frequency; the proportion of subtaxa in taxa with small and large sizes was greater than in taxa with intermediate size. Our results suggest that the abundance of subtaxa in taxa with small and large sizes can be predicted with fractal dimension for the accumulating taxa abundance rather than the taxa abundance. These results emphasize the need for further theoretical studies, as well as predictive modelling, to interpret the different fractal dimension for different taxonomic groups.