Phylogenetics

In biology, phylogenetics ( /faɪlɵdʒɪˈnɛtɪks/) is the study of evolutionary relationships among groups of organisms (e.g. species, populations), which are discovered through molecular sequencing data and morphological data matrices. The term phylogenetics derives from the Greek terms phylé (φυλή) and phylon (φῦλον), denoting "tribe","clan", "race" and the adjectival form, genetikós (γενετικός), of the word genesis (γένεσις) "origin," "source," "birth". The result of phylogenetic studies is a hypothesis about the evolutionary history of taxonomic groups: their phylogeny.

Evolution is regarded as a branching process, whereby populations are altered over time and may split into separate branches, hybridize together, or terminate by extinction. This may be visualized in a phylogenetic tree, a hypothesis of the order in which evolutionary events are assumed to have occurred.

Phylogenetic analyses have become essential in researching the evolutionary tree of life. The overall goal of National Science Foundation's Assembling the Tree of Life activity (AToL) is to resolve evolutionary relationships for large groups of organisms throughout the history of life, with the research often involving large teams working across institutions and disciplines. Investigators are typically supported for projects in data acquisition, analysis, algorithm development and dissemination in computational phylogenetics and phyloinformatics. For example, RedToL aims at reconstructing the Red Algal Tree of Life.

Taxonomy, the classification, identification, and naming of organisms, is usually richly informed by phylogenetics, but remains methodologically and logically distinct. The degree to which taxonomy depends on phylogenies differs between schools of taxonomy: numerical taxonomy ignored phylogeny altogether, trying to represent the similarity between organisms instead; phylogenetic systematics tries to reproduce phylogeny in its classification without loss of information; evolutionary taxonomy tries to find a compromise between them in order to represent stages of evolution.