Systematics Quick Kit: 17 flashcards

Systematics is the study of kinds and diversity of organisms and their comparative and evolutionary relationship.

Taxonomy comes from Greek words 'taxis' (arrangement) and 'nomos' (law). The term was first introduced by A. P. de Candolle, a Swiss botanist.

Artificial classification uses few easily observable, non-evolutionary features (e.g., Linnaeus). Natural classification uses objectively significant features (e.g., Bentham and Hooker). Phylogenetic classification is based on evolutionary descent (e.g., Engler and Prantl).

A taxon is a taxonomic group of any rank in the classification system. Example: Angiospermae, Dicotyledonae, or Malvaceae.

Archaea (prokaryotic), Bacteria (prokaryotic), and Eukarya (eukaryotic).

Archaea have cell walls without peptidoglycan, while Bacteria have cell walls containing peptidoglycan.

Chemotaxonomy is classification based on chemical constituents of organisms. Example: Classification of plants based on alkaloids and terpenes (proposed by Alston).

Numerical taxonomy (also called taxometrics or Adansonian classification) uses quantitative analysis of many observable characters (usually >100) to classify organisms. It was first proposed by R. Sokal and P. Sneath in 1963.

A cladogram is a branching diagram that represents a hypothetical relationship among organisms, showing their common ancestors and evolutionary relationships.

Phylogeny is the evolutionary relationship of organisms. Examples: Woese's three-domain system and Whittaker's five-kingdom system.

DNA barcoding is a method to identify species based on a short DNA sequence from a tiny tissue sample. Steps: (a) collect DNA barcode data of known species, (b) match the unknown sample's barcode against the library.

Kingdom, division/phylum, class, order, family, genus, species.

An order is a group of closely related families, while a class is a group of closely related orders. Class is a higher rank than order.

Species is the lowest natural taxonomic unit, a group of organisms that can interbreed to produce fertile offspring. Example: Genus Panthera includes tiger, lion, and leopard.

Binomial nomenclature is the system of naming organisms with two words: genus and species. It was introduced by Linnaeus. Example: Solanum tuberosum (Solanum = genus, tuberosum = species).

Kingdom: Plantae, Division: Angiospermae, Class: Dicotyledonae, Order: Malvales, Family: Malvaceae, Genus: Hibiscus, Species: rosa-sinensis.

Sub-categories (like sub-order, sub-family) are added to place organisms in a more scientific and precise manner, especially when the main categories are too broad.