FBS 21

• Phylogenetic Analysis


  The estimation of evolutionary relationships among taxa
• Phylogeny


  The pattern of genealogical relationships
• Phylogenetic analysis is an example of hypothesis generation
• Taxonomy


  The science of discovering, describing, naming, and classifying species or groups of species

  
• Aspects of Taxonomy


  • Classification
  • Nomenclature
  • Description
  • Identification
• Classification


  The process of grouping things together on the basis of the features they have in common
• Classification is a way of summarising what we know – a kind of filing system
• Anything can be classified (furniture, vehicles, emotions) but here we are referring to biological organisms and specifically plants
• Classification (in its simplest form)


  The placement of plants, animals and objects into groups and categories for a clear understanding, proper study and effective organization
• Classification is the arrangement of a group of plants with particular circumscription by rank and position according to artificial criteria, phenetic similarities, or phylogenetic relationships

  
• Purposes of Classification


  • Organize living things into groups
  • Give organisms names
• Types of Classification Systems


  • Artificial classification
  • Mechanical classification
  • Natural classification
  • Phylogenetic classification
• Classification is based on character correlations and discontinuities of variation, which are necessary for characterizations and delimitation of taxa
• Classification is the ordering of plants into a hierarchy of taxa with the species being the fundamental basic unit, rank or category

  
• Classification results in an orderly arrangement of system designed to express interrelationships in a particular or natural way
• Classification provides a system for efficient and effective information storage
• No character per se is more important than another in classification, but one character may be more significant within a group
• The limits of a taxon cannot usually be defined quantitatively or qualitatively by a single characteristic
• Assignments of natural populations or of population systems to taxa and the hierarchical arrangements of those involve judgment
• Botanical classification aims to be 'natural' in that it tries to express relatedness of plants

  
• Phylogenetic classification aims to reflect evolutionary history, so the plants within a group can be considered to have a common ancestor
• A classification based on relatedness has great power in that it is predictive - if you know the natural group to which a plant belongs you can immediately predict all sorts of other characters for it

  
• Early Plant Classification Systems


  • Folk/tribal classifications based on useful properties
  • Ancient Greek classifications by Theophrastus and Dioscorides

  
• Pre-Linnaean Period (ca. 300 BC - 1700)


  • Ancient Classification Systems based on habit and importance to man
  • Herbalist Classification Systems (c. 1500-1580) based on habit and use to man
  • Mechanical Classification Systems (c. 1580-1700) based on form and other criteria
• Andrea Caesalpino


  Italian, called the first plant taxonomist; first scientist to classify plants primarily according to structural characteristics, such as their fruits and seeds
• Jean Bauhin


  Swiss, provided descriptions and good diagnosis of about 500 plants
• Caspar Bauhin


  Recognized distinction between genera and species as major taxonomic levels; wrote Pinax Theatri Botanici which listed about 6,000 species of plants including their synonyms

  
• J.P. de Tournefort


  Author of the modern genus concept; gave descriptions of 698 genera (10,146 species); classification based on tree/herb, apetalous/petalous/gamopetalous, regular/irregular flowers

  
• J. Ray


  English, produced keys to genera and recognized 18,000 species in his Methodus Historia Plantarum; utilized a large numbers of characters of the flower and vegetative parts
• P. Magnol


  Developed the concept of modern family of plants

  
• R. Camerarius


  Demonstrated sexuality in plants
• Carl Linnaeus


  Swede, the founder of modern taxonomy; developed formal rules that provided consistency for a two-name system in common use called the binomial system of nomenclature
• Linnaeus' Major Works


  • Genera Plantarum (1737)
  • Species Plantarum (1753) - codification of European folk taxonomies; 1350 genera and descriptions of 8,550 species

  
• M. Adanson


  French, rejected artificial classifications; emphasized equal weighing of characters; produced Families des Plantes; considered the "Grand father of Numerical Taxonomy"
• L. de Jussieu


  French, divided plants into three groups; acotyledons, monocotyledons, and dicotyledons; weighed characters in the following order of importance; embryo > sexual parts > fruit = perianth > vegetative characters
• R. Brown


  Recognized the distinctness of gymnosperms from angiosperms; proposed no system of his own
• A.P. De Candolle


  Swiss, first introduced the word "taxonomy" in his book Theorie Elementaire de la Botanique; divided plants into two groups; Cellulares and Vasculares; most important work is Prodromus Systematis Naturalis Regni Vegetabilis
• J. Lindley


  Published first comprehensive natural system in English
• S.L. Endlicher


  Produced Genera Plantarum which covered 6,835 genera of plants, and separated the Thallophyta from Cormophyta
• G. Bentham and J.D. Hooker


  English, produced Genera Plantarum which described 200 families and 7,569 genera of seed plants