Taxonomic hierarchy is the process of arranging various groups, class and other categories into successive levels of the biological classification in a sequence either in a decreasing or increasing order from kingdom to species and vice versa. Each of this level or hierarchy is called as the taxonomic category or rank. In this system of classification, Kingdom is always ranked high followed by division, class, order, family, genus, and species which is always ranked the lowest in the Hierarchy.
Taxonomic Hierarchy Categories were introduced by Linnaeus, therefore it is also known as a Linnaean hierarchy.
Let’s understand this concept with an example. Consider birds; they are a group of organisms which show common characteristics like feathers and flight. Thus, based on the common characteristics, they can be classified into a taxonomic category.
The study of taxonomy has led to the taxonomic categories – Kingdom, phylum, class, order, family, genus, and species. Now let us see how all the organisms are classified into the hierarchy.
It is the lowest level of classification and shows the high level of similarities among the organisms. One species can be distinguished from other closely related species based on distinct differences in morphology. Let us look at an example; Plasmodium vivax and Plasmodium falciparum – Both are malaria-causing parasites but have different effects on a patient. Plasmodium is the name of the genus and has a number of species which show distinct morphological characteristics.
This taxonomic group comprises several species which have similar characteristics but different from that of species from another genus. Considering the same example of Plasmodium, it is a genius with multiple species which are similar to each other and differs from the species of another genus.
This category of taxonomy includes various genus which shares some resemblance among themselves. However, the number of similarities decrease compared to species and genus. For example, the genus of tiger, leopard, lion, i.e., Panthera and the genus of cats i.e., Felis are grouped together in the family Felidae.
The classification which begins with the order has fewer comparisons as an effect, they are grouped based on aggregates of characteristics. A group of families showing somewhat few similarities forms an order. For example, the order of carnivores i.e., Carnivore includes families like Felidae and Canidae.
A group of Orders which share a few similarities forms a Class. For example- Orders of primates and carnivores are grouped together in the Class of mammals.
This is the next level of classification was along a number of Classes are clubbed up to form one Phylum. Example – aves, fishes, reptiles, mammals, and amphibians combined to form the phylum of Vertebrates or Chordata.
This is the highest level of classification. We have Kingdoms like Plantae, Animalia, Fungi, Protista, and Monera.
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