Cladogenesis
Encyclopedia
Cladogenesis is an evolutionary splitting event in a species in which each branch and its smaller branches forms a "clade
", an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of sister species
. This event usually occurs when a few organisms end up in new, often distant areas or when environmental changes cause several extinctions, opening up ecological niches for the survivors. An example of cladogenesis today is the Hawaiian archipelago
, to which stray organisms traveled across the ocean via ocean currents and winds. Most of the species on the islands are not found anywhere else on Earth due to evolutionary divergence.
Cladogenesis is often contrasted with anagenesis
, in which gradual changes in an ancestral species
lead to its eventual "replacement" by a novel form (i.e., there is no "splitting" of the phylogenetic tree
).
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
", an evolutionary mechanism and a process of adaptive evolution that leads to the development of a greater variety of sister species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. This event usually occurs when a few organisms end up in new, often distant areas or when environmental changes cause several extinctions, opening up ecological niches for the survivors. An example of cladogenesis today is the Hawaiian archipelago
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
, to which stray organisms traveled across the ocean via ocean currents and winds. Most of the species on the islands are not found anywhere else on Earth due to evolutionary divergence.
Cladogenesis is often contrasted with anagenesis
Anagenesis
Anagenesis, also known as "phyletic change," is the evolution of species involving an entire population rather than a branching event, as in cladogenesis. When enough mutations have occurred and become stable in a population so that it is significantly differentiated from an ancestral population,...
, in which gradual changes in an ancestral species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
lead to its eventual "replacement" by a novel form (i.e., there is no "splitting" of the phylogenetic tree
Phylogenetic tree
A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical and/or genetic characteristics...
).