Phylogenetic Tree

What is the Phylogenetic Tree?

It is defined as a diagrammatic representation of evolutionary relationships among living organisms. This diagrammatic representation represents how different species evolved from a series of common ancestors.

The phylogenetic tree can also be defined as the two-dimensional graph representing the evolutionary relationship between an organism from various other organisms.

The phylogenetic tree is also called the “Tree of Life” or “Dendrogram” The idea of a phylogenetic tree arose from an ancient concept of a ladder-like progression from moderate to powerful forms of life. The term Phylogenetic or Phylogeny is derived from the ancient Greek word, which refers to race, origin or lineage.

Construction of the Phylogenetic tree

There are two different methods based on which the phylogenetic tree is constructed.

  • Character-based method

This method is based directly on the sequence characters, therefore it is also called the discrete method. The character-based method uses the aligned characters for constructing the phylogenetic tree.

These aligned characters include either the DNA or protein sequences during the tree inference. The two most popular character-based methods are:

  1. Maximum parsimony.
  2. Maximum likelihood.
  • Distance-based method

This method is based on the amount of the distance or the dissimilarity between the two aligned sequences. In this method of constructing the phylogenetic tree,

the sequence data is transformed into pairwise distances and then the matrix is

used for building a tree.

Steps for preparing the Phylogenetic Tree

Selection of an organism or a gene family

Selection of appropriate molecular markers

Amplification

Sequencing

Assembly

Alignment

Evolutionary model

Phylogenetic Analysis

Construction of a Tree

Evolution of a Phylogenetic Tree

Types of Phylogenetic Trees

1. Rooted tree

Make the inference about the most common ancestor of the leaves or branches of the tree.

Rooted Phylogenetic Tree

2. Un-rooted tree

Make an illustration about the leaves or branches and do not make any assumption regarding the most common ancestor

Un-Rooted Phylogenetic Tree

3. Bifurcating tree

This tree has a maximum of two descendants arising from each of the interior nodes.

The Bifurcating Phylogenetic Tree

4. The multifurcating tree

This tree has multiple descendants arising from each of the interior nodes.

The Multifurcating Phylogenetic Tree

Importance of Phylogenetic Tree

It is the fundamental tool to derive their most-useful evidence from the fields of anatomy, embryology, palaeontology and molecular genetics. Other significances of the phylogenetic tree are:

  1. Used in the search for a new species.
  2. Used to study evolutionary histories.
  3. To study how the species were spread geographically.
  4. To study the common ancestors of extant and extinct species.
  5. It is used to identify the most recent common ancestors and to recognize how closely related species are.
  6. To relate the milestones of the evolution of major life forms to the tree of life.
  7. To represent evolutionary relationships between organisms that are believed to have some common ancestry.
  8. With the help of the phylogenetic tree, the infectious microbes can be traced along with their evolutionary histories.

This article concludes an introduction to phylogenetic trees, their types, and their importance. To know more about the phylogenetic tree, other related topics and important questions, keep visiting our website at BYJU’S Biology.

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