Question

How can a phylogenetic tree are used to make predictions?

Answer 1

Hint: Edward Hitchcock in $1840$ gave the first phylogenetic tree which was published in Elemental Geology. This diagram included the paleontological and geographical relations. Phylogenetic trees use data like characters of organisms, their physical features and genetic features, etc. The word phylon means lineage, race and word genesis means origin or source.

Complete answer:
A phylogenetic tree had been used by scientists since early times to calculate the evolutionary aspects between different species present on earth.
A phylogenetic tree helps to trace the evolutionary path from a common ancestor to their descendants.
The tree gives relationships among different organisms hypothetically using different kinds of data like characters of homology, physical and genetic characters, etc.
The data further constructs a tree with branches, nodes, internodes and a root. Branches denote the division of a taxon. Nodes symbolize a common ancestor between two taxa.
Internodes show the path of evolution and the taxa or species resulting in those taxa.
If all of the organisms are connected to each other, there will be a root ancestor through which every other species diversified and eventually developed into a species of their own. This type of tree is called a “Rooted tree”.
But if there is no root ancestor, the tree is called an “Unrooted” tree.
If a species is altogether different from the rest of the species in the phylogenetic trees, this group of species is called an “Outgroup”.
The branches of a phylogenetic tree do not represent time. Phylogenetic branches show that all of the species grew together at some point of time and due to speciation, different types of species built through existing ones.
The biggest use of phylogenetic trees is depicting or predicting relations between species. For instance, if antidote “a” is used to cure a disease, caused by a species A. Another species B causes a disease for which no antidote is available. Now, if species A and species B are closely related, then we can test species B for the chemical which is responsible for causing the disease and use the same antidote, we used for curing the disease by species A.
This relation between species is tested by Phylogenetic trees.
Also, phylogenetic trees are used to predict the path of evolution and possible patterns are found in their evolution to depict any further evolution taking place in those species.

Note: Phylogenetic trees give hypothetical knowledge and do not show correct analysis always. Phylogenetic trees are hypothetical as one cannot go back to confirm the proposed relationships. Trees represent relationships ranging from the entire history of life on earth and down to individuals in a population.