Phylogeny
In biology, phylogeny (also known as taxonomy) is the evolutionary history and relationships among individuals or taxa (e.g., species, genera, families) within a given species or organismal group. The term has two related meanings. It may refer to the "structure" of a taxonomic hierarchy, or to the inferred evolutionary history of a group of organisms. The first definition of phylogeny was introduced by Carl Linnaeus in the first edition of his Systema Naturae in 1758. The second meaning was introduced by Haeckel in 1866. The approach was later adopted by Georges Cuvier in 1812. The hypothetical common ancestor (or "last common ancestor") of all living organisms is the point at which the various lineages diverged—that is, the point at which evolutionary history began to diverge from the fossil record. In other words, the point where the cladogenesis (the branching of lineages) occurred. It has also been suggested that common descent might have been in the "very early" stage at the beginning of the Cambrian period, as well as the "mid-late" stage at the beginning of the Paleozoic era (a period of 540 million years). The cladistic school of thought (which maintains that the divergence of lineages occurred in a branching pattern of species, genera, families, etc.) is as old as the science itself. Indeed, it was Linnaeus' idea to classify the living organisms according to their assumed relationships to the last common ancestor of all living organisms. This is now referred to as the Linnaean taxonomy. In the first edition of his "Systema Naturae" (1758), Linnaeus carried the three great branches of the tree of life (animals, plants, and minerals) with the last common ancestor at its root. This was referred to as the "law of priority" or "law of consanguinity". The German botanist Peter Mährholz is considered the founder of the modern cladistic method. He proposed a set of rules for determining evolutionary relationships called taxonomic hierarchy. A basic definition of his "taxonomic hierarchy" was that "each term should be unique, and each higher term should contain a lower term in its definition, and that each term should be related to the next lower term and its lowest common ancestor". Mährholz's "taxonomic hierarchy" was later extended by Carl Linnaeus to include not only plants and animals, but also minerals. Linnaeus's system of binomial nomenclature was already in place, and it was soon widely adopted around the world. Most modern-day biological classification, and thus the concept of phylogeny itself, was originally developed by Carl Linnaeus in the 19th century. The term phylogeny was first used in 1866 by Haeckel, who developed a classification of the plant and animal kingdoms that was based on the evolutionary hypothesis of the transmutation of species. In 1869, Haeckel published a phylogenetic classification of the animal kingdom, and in 1871 the first edition of his "Generelle Morphologie" which included a living animal and plant phylogeny. This was an ancestor of modern phylogenetics, developed by William Kingdon Clifford in 1876. The term "phylogeny", in the context of a branching tree diagram, was coined by Willi Hennig in a series of publications from 1957 to 1966, influenced by the work of Erich Jantsch. Phylogenetic taxonomy was developed by Ernst Mayr in the early 1940s. It uses a branching pattern of evolution to define taxa, grouping organisms according to common descent. This branching pattern is depicted in a tree diagram. This system of classification has become widely used globally for numerous groups of organisms. Mayr's original use of phylogenetic taxonomy was mainly on bird species of the world. The first formal definition of phylogenetic nomenclature was presented in 1997 by K.J. Parker et al. and modified by T.W. Clouse in 2002. The formal definition of a phylogenetic nomenclature is a hierarchical system that represents a tree-like branching pattern of evolution. The hierarchical structure of the system is defined as follows: Phylogenetic nomenclature is based on the phylogenetic tree concept, which is a branching pattern of evolutionary history of a group of organisms. Phylogenetic nomenclature is a system of nomenclature which describes taxa in terms of their evolutionary relationships. This is commonly represented in a tree diagram. The main objective of phylogenetic nomenclature is to provide a unique name for every taxon, in a system that is consistent with current evolutionary theory. The
