Time in this particular style of tree is represented vertically, proceeding from the oldest pictured here at the bottom to the most recent at the top.
![phylogentic tree bioedit phylogentic tree bioedit](https://cloudfront.jove.com/files/ftp_upload/56684/56684fig2.jpg)
The trunk at the base of the tree is actually called the root, and the root node represents the most recent common ancestor of all of the taxa represented on the tree. The nodes are where lineages diverge, representing a speciation event from a common ancestor. In this tree, the vertical branches represent a lineage, which is a taxon, shown at the tip, and all its ancestors. Notice that the tree above tree branches from a single trunk into two branches, the vertical lines, and then the left side branches again. Modified from Terminology of phylogenetic trees The diagram below shows a tree of 3 taxa (singular taxon, a taxonomic unit). The process of new species formation, called speciation, is the starting point for a discussion of biological diversity. Trees that show species help us understand how new species form from common ancestral species. Trees can represent relationships ranging from the entire history of life on earth, down to individuals in a population.
![phylogentic tree bioedit phylogentic tree bioedit](https://www.researchgate.net/profile/Tomislav-Keros/publication/268786897/figure/fig1/AS:295382421655575@1447436065946/Phylogenetic-relationships-of-Croatian-PrV-strains-and-selected-reference-PrV-strains.png)
The image below represents a basic phylogenetic tree, with the living species represented by letters across the top of the diagram.Ī phylogenetic tree is a visual representation of the relationship between different organisms, showing the path through evolutionary time from a common ancestor to different descendants. Tree thinking, or phylogenetic thinking, helps us unravel the branching evolutionary relationships between extant species, while thinking about the passage of time and the ancestors of each of those living species. To decipher this relatedness between the diversity of organisms, both living and extinct, “tree thinking” is invaluable. Image credit: Modified from Eric Gaba, Wikimedia Commons. Phylogenetic tree of life built using ribosomal RNA sequences, after Karl Woese.