Taxonomy and systematics

• Aristotle's Classification System - classified two things: plants and animals.

  One primeval system developed was based on harmful or non-harmful organisms and edible or non-edible plants.
• Linnaean Classification System - Carolus Linnaeus, a swedish doctor and botanist. In 1758, he published the 10th edition of his book, Systema Naturae.

  Linnaeus' Legacy was his naming system called Binomial Nomenclature.
• Modern Classification System - a modern approach to taxonomy is systematics, which focuses on analyzing the diversity of organisms on the context of their natural relationship.

  Phylogenetics is the science that focuses on the evolutionary history of a group of species.
• Phylogenetic tree - like cladograms, they compare organisms based on traits. They are illustrated diagrams showing evolutionary relationships.
• Morphology - comparison of body form and structure.

  Genetics - comparison of DNA and RNA sequences.
• PARTS OF PHYLOGENETIC TREE

  1. Root - a point that represents the position of ancestors of all species of the phylogenetic tree.
  2. Node - a point that connects branches from the phylogenetic tree.
  3. Branch - represents the direction of evolutionary path of each species
  4. Branch length - signifies estimated time period for evolutionary changes.
  5. Clade - clusters of organisms that have been grouped together because of similarities.
• Aristotle: plants were classified based on the size of stem (soft stem-herbs, woody stem-tree, several woody stem-shrubs) and animals were classified based on where they live.
• Taxonomy is a science that deals with classifying, naming, and describing organisms.

  DOMAIN > KINGDOM > PHYLUM > CLASS > ORDER > FAMILY > GENUS > SPECIES
• Functions of taxonomy: Identification and description, nomenclature, and classification
• Identification and description: Modern day taxonomists created comprehensive taxonomic descriptions of all documented organisms on Earth. These were based on their behavior, morphology, and genetic data.

  For plants, taxonomic publications include the 'plant habits.' Plant habit drawing is an illustration of the plants form, appearance, and morphology.
• Nomenclature - thee subfield of taxonomy that deals with the proper naming of organisms. It is a set of rules in properly naming them.
• Classification - taxonomy focuses in organizing organisms based on their genetic, morphological, and evolutionary relatedness. It is based on studying their phylogeny.
• While taxonomy deals with classifying organisms, systematics is a step further by attempting to determine evolutionary history of organisms.
• One of the earliest taxonomic accounts was written by Shen Nong, the father if Chinese medicine. His work, Divine Husbandman's Materia Medica, documented a total of 365 medicinal plants and animals.
• In the middle east, the early Egyptians created illustrations of medicinal plants hand-painted on walls.
• Aristotle is considered one of the most formally trained taxonomists. He introduced the dichotomous concepts: Historia Animalium and Scala Naturae.

  Historia animalium - classified organisms based on their similarities in sturcture and function.

  Scala naturae - organized organisms hierarchically; the Ladder of nature, where humans are on top and followed by animals, plants, and minerals.
• Theophrastus - 'De Historia Plantarum' he described 48 species bthat he grouped according to growth forms.
• Dioscorides - 'De Materia Medica' discovered 600 species and are classified based on their medicinal properties.
• Plinius - 'Naturalis Historia' has 160 volumes. He describe plants and gave them Latin names.
• Caesalpino - regarded as the first taxonomist. 'De Plantis,' his work, contains 1500 species of plants that are classified according to their growth habit, fruit, and seed forms.
• Bauhin Brothers - Wrote Pinix Theatri Botanici in 1623, containing 6000 organisms. Their work recognizes the concept of genera and species as major taxonomic levels.
• John Ray - established the concept of species as ultimate unit of taxonomy. 'Methodus Plantarum Nova' contains 18000 plant species classified according to relatively narrow species concept.
• Joseph Pitton de Tournefort - 'Institutiones Rei Herbariae' classified 9000 species on 628 genera. He emphasized the classification of plants on their genera
• Carolus Linnaeus works: Species Plantarum, Binomial Nomenclature, Systema Naturae, Documentation of species
• On the origin of species (Charles Darwin, 1859)