Lesson 5 - Biology 2

• Systematics - the study of the kinds and diversity of organisms and of any and all relationships among them.
• Systematists - use data ranging from fossils to molecules and genes to infer evolutionary relationships. This information enables biologists to construct a comprehensive tree of life that will continue to be refined as additional data are collected.
• Lines of evidence to infer evolutionary relationships

  • Fossil evidence
  • Homologies
  • Embryology/Developmental biology
  • Biogeography
  • Molecular clocks help track evolutionary time
• Taxonomy - a major part of systematics that includes description, identification, nomenclature and classification
• Systematics


  Connecting classification to phylogeny
• Phylogeny


  The evolutionary history of a species or a group of related species
• Classification


  Method of grouping organisms; arranging entities into some type of order to provide a system for cataloguing and expressing relationships between these entities
• Hierarchy


  A system of organizing groups into ranks according to status; putting groups at various levels according to importance or power
• Nomenclature


  The formal naming of taxa according to some standardized system. For plants, fungi, and algae, rules for naming are provided by the International Code of Botanical Nomenclature. For animals, rules on naming are based on the International Code of Zoological Nomenclature.
• Identification


  The process of associating an unknown taxon with a known one
• Description


  The assignment of features or attributes (characters) to a taxon
• Taxonomy


  The theory and practice of classifying organisms.
• Emperor Shen Nung of China (around 3000BC) - have classified plants based on practical uses—for food, as herbal medicine, for shelter and others.
• Linnaeus method was also known as?

  Linnaeus’ system of classification or the Linnaean taxonomy.
• taxonomic system was devised by Carolus Linnaeus (1707-1778)
• In 1981, a category higher than a kingdom, called domain, was proposed by Carl Woese.
• Animalia - Organisms that are able to move on their own
• Chordata - Animals with a backbone
• Mammalia - Chordates with fur or hair and milk glands
• Primates - Mammals with grasping fingers
• Hominidae - Primates with relatively flat faces and three-dimensional vision
• Homo - Hominids with upright position and large brain
• sapiens - Members if the genus Homo with a high forehead and notably thin skull bones
• Binomial Nomenclature - refers to the practice of assigning scientific names that consists of two parts.
• Binomial comes from the words “bi” meaning “two” and “nomen” meaning “name”.
• Nomenclature refers to the practice of assigning scientific names.
• dichotomous key is a tool that helps identify unknown organisms to some taxonomic level
• Dichotomous means, "divided into two parts."
• Cladistics studies relationships between taxa using shared derived characters.
• Phylogeny


  The evolutionary relationships among organisms
• Cladogram


  A phylogenetic tree that shows relationship of taxa based on shared derived characters
• Character


  Any trait of an organism that can be described or measured
• Character state


  Describes the character. A particular character can have several character states.
• Homologous characters


  Characters having similar structures because these were derived from a common ancestor
• Analogous characters


  Characters that have separate evolutionary origins, but are superficially similar because they perform the same function. It is the result of convergent evolution.
• phylogenetic trees - used to illustrate evolutionary relationships among organisms
• Clade


  A group of taxa consisting of an ancestor and all of its descendant taxa