Abstract: A model of age-dependent birth-death branching tree is developed based on random graph. In this model, biological reproduction processes are described as random graph processes, i.e., a random branching tree. Topological properties of the random branching tree, namely distributions of first-born and last-born age, and the distribution of order statistics of productive ages, are explored. The average size of the connected components in the branching tree is discussed.

Key words: birth-death branching tree, branching process, connected components, degree distribution, random graph