The document discusses the evolution of biological classification systems from Linnaeus' initial two kingdom system to the current three domain system. It describes the key features used to classify organisms at different taxonomic levels and explains how modern evolutionary classification is based on phylogeny rather than just physical similarities. The increasing use of DNA evidence and molecular clocks to study evolutionary relationships is also summarized.

2. 18-1 Finding Order in Diversity

18. Red fox Grizzly bear Black bear Giant panda Sea star Coral snake Abert squirrel

19. 18-2 Modern Evolutionary Classification

33. Molecular Clocks new mutation new mutation 2 mutations A B C A gene in an ancestral species Species Species Species new mutation 2 mutations

35. 18-3 Kingdoms and Domains

40. Changing Number of Kingdoms Introduced Names of Kingdoms 1700’s Late 1800’s 1950’s 1990’s Plantae Animalia Protista Plantae Monera Protista Fungi Plantae Eubacteria Archae-bacteria Animalia Animalia Animalia Protista Fungi Plantae

49. Domain Eukarya