1. Modern Taxonomy Reflects Evolutionary History Section 15.4

2. Taxonomy Identification, naming, & classification of species Identification, naming, & classification of species Common names don’t always work well, because they have different meanings in different areas. Common names don’t always work well, because they have different meanings in different areas. For example, a tortoise might be called a gopher in Florida, but in Kansas, "gopher" might refer to either a ground squirrel or a pocket gopher. For example, a tortoise might be called a gopher in Florida, but in Kansas, "gopher" might refer to either a ground squirrel or a pocket gopher. Goals: Goals: assign universal scientific name to each known species. assign universal scientific name to each known species. Place groups of species into larger groups of related species. Place groups of species into larger groups of related species.

3. Linnean System of Classification Swedish botanist Carolus Linnaeus Swedish botanist Carolus Linnaeus System has 2 main characteristics System has 2 main characteristics 2 part latin name for each species (binomial). The 1 st part is the Genus name, the 2 nd part is the species name. 2 part latin name for each species (binomial). The 1 st part is the Genus name, the 2 nd part is the species name. Genus is capitalized, species is lower case Genus is capitalized, species is lower case The whole name is in italics The whole name is in italics Ex. African lion (Panthera leo) Ex. African lion (Panthera leo) Hierarchy of species into broader and broader groups Hierarchy of species into broader and broader groups KPCOFGS or SGFOCPK KPCOFGS or SGFOCPK Lg  SmSm  Lg Lg  SmSm  Lg

5. Phylogenic Trees (Cladograms) Phylogenic Trees (Cladograms) In a phylogenetic tree, each branch point represents a common ancestor of the species above that point. In this diagram, the branches are labeled to reinforce how taxonomy reflects the branching pattern of evolution.

6. Homologous structures are one of the best clues to assess how closely organisms are related. Homologous structures are one of the best clues to assess how closely organisms are related. Not all similar structures are inherited from a common ancestor. Not all similar structures are inherited from a common ancestor. Convergent evolution is a process in which unrelated species from similar environments have adaptations that seem very similar. Convergent evolution is a process in which unrelated species from similar environments have adaptations that seem very similar. Similar adaptations that result from convergent evolution are called analogous structures. Similar adaptations that result from convergent evolution are called analogous structures. For example, the wings of insects and those of birds are analogous, not homologous, flight equipment—they evolved independently. And, they are built from entirely different structures. There is no evidence that insects and birds shared a common winged ancestor. For example, the wings of insects and those of birds are analogous, not homologous, flight equipment—they evolved independently. And, they are built from entirely different structures. There is no evidence that insects and birds shared a common winged ancestor.

7. Cladistics This cladogram shows how derived characters can be used to identify clades among certain vertebrates (animals with backbones). All the species shown here share a common ancestor that had a backbone. (Each clade is actually defined by several derived characters, not just one.) This cladogram shows how derived characters can be used to identify clades among certain vertebrates (animals with backbones). All the species shown here share a common ancestor that had a backbone. (Each clade is actually defined by several derived characters, not just one.)

8. The key rule in cladistics is that all of the organisms of a particular clade must share homologous structures that do not occur outside the clade. The key rule in cladistics is that all of the organisms of a particular clade must share homologous structures that do not occur outside the clade. These unique features that unite the organisms as a clade are called derived characters. These unique features that unite the organisms as a clade are called derived characters. A phylogenetic diagram that specifies the derived characters of clades is called a cladogram. A phylogenetic diagram that specifies the derived characters of clades is called a cladogram. For example, compare the animals in the cladogram in Figure 15-30. The horse, wolf, leopard, and house cat all have hair. This derived character unites a clade that doesn't include the turtle. For example, compare the animals in the cladogram in Figure 15-30. The horse, wolf, leopard, and house cat all have hair. This derived character unites a clade that doesn't include the turtle.

9. Comparing Classification Schemes Two- and Three-Kingdom Schemes - Linnaeus divided all known forms of life between the plant and animal kingdoms. Two- and Three-Kingdom Schemes - Linnaeus divided all known forms of life between the plant and animal kingdoms. A Five-Kingdom Scheme A Five-Kingdom Scheme Three Domains - This newer scheme recognizes three basic groups: two domains of prokaryotes—the Bacteria and the Archaea—and one domain of eukaryotes, the Eukarya. Three Domains - This newer scheme recognizes three basic groups: two domains of prokaryotes—the Bacteria and the Archaea—and one domain of eukaryotes, the Eukarya.

10. For many years, most biologists classified organisms according to a five- kingdom system. Based on molecular data, however, many biologists now prefer a three- domain classification. Within each domain there are multiple kingdoms (only listed here for Eukarya). For many years, most biologists classified organisms according to a five- kingdom system. Based on molecular data, however, many biologists now prefer a three- domain classification. Within each domain there are multiple kingdoms (only listed here for Eukarya).