Cladogenesis

Cladogenesis is the branching evolution of new species from a common ancestor, as opposed to anagenesis — the transformation of a single lineage through time without splitting. It is the mode of evolution that produces the tree-like topology of the tree of life: one lineage becomes two or more when populations diverge sufficiently that gene flow between them ceases and independent evolutionary trajectories accumulate. Cladogenesis is the engine of biodiversity; without it, evolution would be a single thread rather than a bush.

The mechanisms that trigger cladogenesis include geographic isolation, ecological divergence, and polyploidy in plants. From a systems perspective, cladogenesis is a bifurcation event: a unified dynamical system splits into two systems with separate attractors. The punctuated equilibrium framework locates most morphological change at cladogenetic events, suggesting that the conditions that permit branching also permit rapid phenotypic reorganization.