Meaning of Phylogeny (What is it, Concept and Definition)

What is Phylogeny?

Phylogeny is a branch of biology that is responsible for studying the origin and evolution of living things.

Phylogeny is used to establish relationships between organisms based on their DNA, RNA, anatomy, embryology, morphology, and other biological data of interest. The information obtained helps to better understand the evolution of the different species, their similarities, differences, relationships, and their role in the phylogenetic tree of life.

Phylogeny is a word composed of the Greek terms phylon (race, group, tribe), gen (generate), and ía (quality). It refers to the study of the origins of a species or group.

The word was coined by the German naturalist and philosopher Ernst Haeckel at the end of the 19th century, as part of his research based on Darwinian theory.

Phylogeny development

Charles Darwin, the creator of the evolutionary theory, was the first person to propose a classification system for living beings according to their origin.

This classification was reflected in his book The Origin of Species with the illustration of a tree whose trunk refers to the common origin of living beings. From there, a series of branches emerge that represent the different species known until then.

For this reason, this type of scheme is also known as the tree of life or phylogenetic tree.

It was in 1966 when the German biologist Willi Hennig laid the foundations for phylogenetic analysis and created phylogenetic systematics, from which two branches emerged, Hennigian systematics and cladistic systematics, or cladism. Each of them defends the idea of ​​studying the species according to different parameters.

Cladist phylogenetic system

It deals with studying monophyletic groups, that is, groups of species that have a common ancestor. For cladists, phylogeny should only be analyzed from monophyletic groups, also known as clades.

An example of a monophyletic group is birds and reptiles since until now, it is believed that they come from a common ancestor.

Hennigian phylogenetic system

Study paraphyletic groups, which are groups of species with a common ancestor and some common descendants. As it excludes some elements, it is not considered a natural group, but a group created for methodological purposes.

An example of a paraphyletic group is the current reptiles, whose classification considers birds as another group descended from a common ancestor.

Hennigian systematics also studies polyphyletic groups, which are groups of species in which the most recent common ancestor is not considered. It is also an artificial group, created from the union of branches that are scattered in the phylogenetic tree.

An example of a polyphyletic group is the warm-blooded vertebrates, which in this case would include birds and mammals, without considering their common ancestor.

In short, cladistic systematics is responsible for studying monophyletic groups, and Hennigian systematics studies non-monophyletic groups (paraphyletic and polyphyletic).

Phylogeny and taxonomy

Both phylogeny and taxonomy have the same goal, which is the classification of living things. However, phylogeny considers the origin, descent, and common characteristics between species.

For its part, taxonomy is responsible for identifying and organizing living beings in a hierarchical way. The main category is the domain, and the last one is the species, as shown below:

• domain.
• Kingdom.
• Filo or division.
• Class.
• Order.
• Family.
• Gender.
• Species.

 

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