Question

How are phylogenetic trees read?

Answer 1

The study of evolutionary relationships between the organisms and their evolutionary development is called Phylogeny. The diagram that represents the evolutionary relationship between the organisms is called the phylogenetic tree.

Complete answer:
The branch of systematics- that deals with the study of evolutionary history and relation between various organisms is called Phylogeny. Haeckel gave the term phylogeny and also the concept of phylogenetic trees. It develops a better understanding of the evolution of genes and genomes, and species. The relationship between organisms can be studied through a branching diagram called a phylogenetic tree.

A phylogenetic tree shows the- evolutionary relationship of a group of organisms that have arisen from a common ancestor. The pattern of branching explains the relationship between different organisms and also their origin from a common ancestor. The similarities and differences in the physical and genetic characteristics of the organisms- are the basis of their study. The features of a set of species are studied.

The phylogenetic trees can be made in different shapes and styles. The species to be studied are usually placed at the branches of the tree. The branches of the trees are the tip of the lines. The point of the branch is also called the internal node. It indicates the divergence point from where one group is divided into two sub-groups. The individual or individuals present at the internal node is the most common ancestor of the species present at the- tips of the branches. So, all the branch points will have their most common ancestor present there. The horizontal/ vertical/ diagonal line of the phylogeny tree indicates a series of ancestors. The root of the phylogeny tree is the point from where the tree began, or the oldest ancestor originated. As we go from the root to the branch points and the branch tips, we move forward in time.

The relationship between the two species is determined by their most common ancestor. They are more related if their ancestor is recent and less related if their ancestor is a little ancient. To find the most common ancestor, we look for the point of convergence of the two lines of those species. The pattern of branches speaks about the evolutionary relationship between the organisms and not the length of the branches. Also, the relationship between organisms is not changing if the branches are rotated along with their branch point. The more number of branches in a tree indicates that more lineages have occurred in these specific sets of species.

The phylogenetic trees do not rank organisms and give us the evolutionary history of the organisms. However, these are hypothetical facts and do not speak about the time of evolution. The evolution of one organism cannot be related to the evolution of another organism.
Note: The phylogenetic trees are often associated with cladogram. A cladogram is a diagram that shows the hypothetical evolutionary relationship between organisms. While phylogenetic trees give actual data of the evolutionary histories, a cladogram only provides the hypothetical or assumed data.