Biological classification or taxonomy is a system that organizes living beings into categories, grouping them according to their common characteristics, as well as by their kinship relationships evolutionary.
Scientific nomenclature is used which facilitates the identification of organisms anywhere in the world.
Through this system, biologists seek to understand biodiversity, describing and naming the different species and organizing them according to the criteria they define.
The Taxonomic Categories
In the biological classification system, categories are used to group organisms according to their similarities.
The basic category is species, which is defined as similar beings that are able to reproduce naturally and generate fertile offspring.
Animals of the same species are grouped under another category, the genus. All that belong to the same genus are grouped into families, which are grouped into orders, which in turn are grouped into classes, grouped into phyla and finally we have the kingdoms.
The eeinos are, therefore, the last category in the hierarchy and they subdivide until reaching the species, the most basic category. So we have:
Kingdom ⇒ Phylum ⇒ Class ⇒ Order ⇒ Family ⇒ Genus ⇒ Species
How are Species Classified?
An animal may be known by several names in different regions, however, to facilitate the identification of animals, scientific nomenclature is adopted internationally.
Linnaeus developed in 1735 the binomial nomenclature, consisting of two names, the first of which is written in capital letters and defines the genus, and the second has a small letter and defines the species.
Scientific names must be written in Latin and highlighted in italics or underlined.
So, for example, the dog's scientific name is familiar kennels. The name Kennels it can also be used alone, indicating only the gender, being, therefore, common to animals that are related, in this case it can be the dog or the wolf (Canis lupus) or the like.
Also read about the characteristics of living beings.
The Realms of Living Beings and Phylogenetic Relationships
Classification of Living Beings in the Five Realms.
The First Classifications: Aristotle and Linnaeus
Aristotle, as far as is known, he was the first to classify living beings. He divided them into two groups: animals and plants, which would have subgroups organized according to the environment in which they lived, being characterized as aerial, terrestrial or aquatic.
Later, several scientists created systems based on what Aristotle had done.
Swedish naturalist Carl von Linnée (1707-1778), better known as Linnaeus, he defined structural and anatomical characteristics as classification criteria.
Linnaeus was a creationist and believed that the number of species was fixed and unchanging, having been defined by God at the time of creation.
Thus, animals were only grouped according to their bodily similarities and plants according to the structure of their flowers and fruits.
Lineu also developed a method for naming species, the binomial nomenclature published in his book Naturae System, which is still accepted today.
Read too: What are living beings?
Emergence of Kingdoms
In 1866, the German biologist Ernst Haeckel (1834-1919) suggested the creation of the Protista and Monera kingdoms, in addition to the already existing kingdoms: Animal and Vegetal.
In 1969, the biologist R.H. Whittaker proposed the division of plants into another group, the Fungi, thus creating the five kingdoms: protist, monera, fungi, Plante and animalia.
From 1977, with studies by C. Woese, there are now 3 domains: Archaea, Eubacteria and Eukarya.
In the first two are distributed prokaryotes (bacteria, protozoa and unicellular algae), and in the other are all eukaryotes (fungi, plants and animals).
Learn more about living beings and non-living beings.
Phylogenetic Relationships
the english naturalist Charles Darwin (1809-1882), contributed to the development of the classification of living beings through his evolutionary theory and the notion of common ancestry that gave rise to current species.
He created "genealogies of living things," diagrams representing the evolutionary kinship relationships between species, which are now called phylogenetic trees.
The way of classifying organisms has changed a lot in recent decades due to the development of areas such as genetics and molecular biology. Kinship relationships are defined not only by external characteristics, but also by genetic and biochemical similarities.
Currently, some scientists have used cladistics to determine the phylogenetic relationships between species. In this way, the evolutionary history of organisms is investigated in order to classify them.
Cladograms are similar to phylogenetic trees, which show kinship relationships. Groups of species that descend from a single common ancestor are called monophyletic and groups that have different ancestors in their origin are polyphyletic.
know more about Phylogeny.
systematics
Systematics is an area of biology that studies biodiversity through a synthetic classification system, called taxonomy. It uses hierarchies to group organisms into groups and subgroups.
Thus, for example, within the group of plants there is a subgroup of plants with fruits and another subgroup of plants without fruits.
The objectives of the systematic are:
- To get to know living beings better and, for this, they are grouped into taxonomic categories or taxa. More than 1.5 million species have been identified and it is believed that there are still many unknown;
- Use taxonomy to identify, describe, name and catalog species;
- Identify the determining processes of biodiversity or biological diversity;
- Investigate the evolutionary kinship relationships between current species and their ancestors, using knowledge from other areas of biology such as genetics and molecular biology.
Test your knowledge with exercises on the classification of living beings.
