Question

Define phylogeny.

Answer 1

Hint: It is a study to which relates the origin of organisms. Organisms present today, which may be extremely different from one another, may have been raised from the same ancestors.

Complete Answer:
The study of relationships among various groups of organisms and their evolutionary development is called Phylogeny.

Phylogeny trace the evolutionary history of all living organisms on the planet. It is built on the basis of phylogenetic hypothesis according to which a common ancestry is shared by all living organisms. The phylogenetic trees are used to depict the relationship among the organisms. Such relationships can be determined observing characteristics shared among organisms, comparison of genetic and anatomical similarities can indicate the relationships of these organisms.

Analysis of DNA and protein structure determines the molecular phylogeny. The genetic relationships among different organisms is determined using molecular phylogeny. Biochemical structures, such as DNA and proteins which are similar among organisms, are then used to develop a phylogenetic tree. It is all based on inherited shared traits.

A phylogenetic tree is also called cladogram. It is a schematic diagram. It is a visual illustration of predicted evolutionary relationships among related taxa. Assumptions of cladistics, or phylogenetic systematics are used to plot phylogenetic trees. Cladistics is a classification system. On the basis of shared traits, or synapomorphies, as determined by anatomical, genetic, and molecular analysis, the tree is categorized.

The hypothesis of cladistics includes:
- All organisms are descendants of a common ancestor.
- When existing populations split into two groups, new organisms develop.
- Over time, changes in characteristics are observed in lineages.

Note: The shared traits among different organisms determine the phylogenetic tree structure. It has tree-like branching that represents diverging taxa occurring from a common ancestor. It includes nodes, branches, clades and taxa.