CLASSIFICATION OF ORGANISMS

1. CLASSIFICATION OF ORGANISMS

2. Biologists have classified nearly 2 million species • Estimates range from 13 million to 40+ million • The science of describing, naming, classifying organisms is called taxonomy • Any particular group within a taxonomic system is called a taxon

15. Species Concept • Species can interbreed to produce fertile offspring • Variations in a population include individual variations, geographic variations, and variations in form (polymorphisms) • Species: a population of individuals that interbreed and produce fertile offspring under natural conditions

18. Taxonomists use structure, function, biochemistry, behavior, genetic systems, evolutionary history to classify organisms • Homologies are similarities and can either be structural or chemical

19. HOMOLOGOUS STRUCTURE • Similar features that originate in a shared ancestor (derive from same embryonic structure) • Can result from modifications that change an original feature to 2 extremely different types (wing and arm)

22. Modern Version • Domain - 3 • Kingdom - 6 • Phylum – 30 – 89 (??) • Class • Order - Family - Genus - Species

23. Human Classification • Kingdom: Animalia (common phyla) • Phylum: Chordata (common class) • Class: Mammalia (similar order, common characteristics) • Order: Primates (similar family, distinctive anatomy and way of life) • Family: Hominidae (similar genera) • Genus: Homo (sp w/ similar characteristics) • Species: sapiens • (Homo sapiens = wise man) (Greek homo = same; Latin homo = man, from the Earth)

24. 6 Kingdoms • Eubacteria • Archaebacteria • Protista • Fungi • Plantae • Animalia

25. The 6 kingdoms • Prokaryotes (Used to be 1 kingdom, Monera) • Archaebacteria • Eubacteria • Eukaryotes • Fungi • Protista • Animal • Plantae

26. Overview of the 6 kingdoms • Archaebacteria • Unicellular • Live in extreme environments • Prokaryotic • Eubacteria • Unicellular • Prokaryotic • “Common bacteria”

27. Overview of the 6 kingdoms • Protista • Eukaryotic • Unicellular or colonial • Lots of different life styles • Fungi • Cell walls made of chitin • Eukaryotic • Multicellular • External heterotrophs

28. Overview of the 6 kingdoms • Plantae • Eukaryotic & Multicellular • Cell walls made of cellulose • Autotrophic • Animalia • Eukaryotic & Multicellular • No cell walls • Internal heterotrophs

35. Prokaryotes vs. Eukaryotes • Cell structure is extremely important in categorizing • Prokaryotes are single-celled organisms that have no nucleus or other membrane-bound organelle (found in Domain Bacteria and Archaea) • Eukaryotes are cells that have a nucleus and other membrane-bound organelles

40. Taxonomy • Science of grouping organisms • Aristotle grouped organisms into 2 categories: plants and animals • In the 1730’s Carl Linne (Carolus Linnaeus) developed a system of taxonomy called binomial nomenclature

41. Carolus Linneaus (Carl Linne) • Devised taxonomic system using hierarchal categories, and devised binomial nomenclature to identify species; • Physalis amno ramosissime ramis angulosis glabris foliis dentoserratis was changed to Physalis angulata (ground cherry) • Homo sapiens, Chaos chaos,

42. Chaos chaos • The Pelomyxa or Chaos chaos is a very large protozoan and belongs to the Phyllum Sarcodina.  

43. Binomial nomenclature • Names usually describe organism, location; can be used to honor scientist or friend (or in some cases to insult individuals)

44. Phylogeny • Phylogeny is the evolutionary history of a species (or taxon) • Morphology, embryonic development, genetics, and fossil evidence all used to build phylogenetic trees • Use of dichotomous key (written set of choices)

45. Cladistics • Phylogenetic analysis that uses shared characters and derived characters • Shared characters are features that all members of a group have in common (all mammals have mammary glands / all birds have feathers) • Derived characters are those features that evolved only within the group under consideration (only animals (living/fossil) with feathers are birds)