Diversification rates are the rates at which new species form (the Speciation rate, λ) and living species go extinct (the extinction rate, μ). Diversification rates can be estimated from fossils, data on the species diversity of clades and their ages, or phylogenetic trees. Diversification rates are typically reported on a per-lineage basis (e.g. speciation rate per lineage per unit of time), and refer to the diversification dynamics expected under a birth–death process.
A broad range of studies have demonstrated that diversification rates can vary tremendously both through time and across the tree of life. Current research efforts are focused on predicting diversification rates based on aspects of species or their environment. Diversification rates are also subject to various survivorship biases such as the "Push of the past"
