Phylogeny

Phylogeny is the study of the evolutionary history and relationships among individuals or groups of organisms. These relationships are discovered through phylogenetic inference methods that evaluate observed hereditary patterns. The result of these analyses is a phylogenetic tree showing the relationships among various biological species or other entities that are believed to have a common ancestor.

History

The idea of a "tree of life" arose from ancient notions of a ladder-like progression from lower into higher forms of life (early cladistics). Charles Darwin also used the concept of a tree of life in the context of his theory of evolution.

Terminology

In a phylogenetic tree, each node with descendants represents the inferred most recent common ancestor of the descendants, and the edge lengths in some trees may be interpreted as time estimates. Each node is called a taxonomic unit. Internal nodes are generally called hypothetical taxonomic unit (HTUs) as they cannot be directly observed.

Phylogenetic Analysis

Phylogenetic analysis can be used to understand evolutionary relationships within groups of organisms, under the assumption that all organisms on Earth are genetically related. Phylogenetic analysis has been used for a broad range of applications, such as understanding the origin and spread of HIV and other viral epidemics.

See also

• Cladistics
• Evolution
• Phylogenetic tree
• Phylogenetic network

References

Phylogeny Resources
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