Diversity of Living Organisms - Taxonomy and Systematics

Taxonomy is the branch of science dealing with the identification, nomenclature, and classification of organisms based on internal and external structures, including $cellular$ organization, $biochemical$ compositions, and ecological information.

Systematics is the study of the diversity of organisms and all their comparative and evolutionary relationships ($phylogeny$). It is often represented as $Systematics = Taxonomy + Phylogeny$.

Binomial Nomenclature, introduced by Carolus Linnaeus, assigns every organism a two-part scientific name. The first part is the $Genus$ (capitalized) and the second is the $specific\ epithet$ (lowercase). Both are printed in italics or underlined separately when handwritten, e.g., $Homo\ sapiens$.

The Taxonomic Hierarchy follows a specific descending order: $Kingdom \rightarrow Phylum/Division \rightarrow Class \rightarrow Order \rightarrow Family \rightarrow Genus \rightarrow Species$. $Species$ is the basic unit of classification.

The Biological Species Concept, proposed by Ernst Mayr, defines a species as a group of potentially interbreeding natural populations that are reproductively isolated from other such groups.

Taxonomical Aids include the $Herbarium$ (storehouse of dried plant specimens), $Botanical\ Gardens$ (living plant collections), $Museums$ (preserved plant and animal specimens), $Zoological\ Parks$ (wild animals in protected environments), and $Keys$ (analytical tools based on contrasting characters called couplets).

Three Domains of Life, proposed by Carl Woese in $1990$, classify life into $Archaea$, $Bacteria$, and $Eukarya$ based on the $16S\ rRNA$ sequences.