Reference Text: Modern Biology Chapter 18 – Section 2 Modern Phylogenetic Taxonomy pgs

Evidence from morphology, the fossil record, embryology and molecular biology is used to organize organisms in systematic taxonomy

Linnaeus focused on morphology or features of an organism when classifying it. Organisms were classified together because they are similar; they are similar because chances are they stem from a common ancestor. Today we know that those features are largely influenced by genes, which are inherited, or passed down from our ancestors. Prairie Dog Cynomys gunnisoni Squirrel Sciurus carolinensis FAMILY SCIURIDAESCIURIDAE

phylogeny Modern Systematic Taxonomists consider several lines of evidence when classifying organisms according to their phylogeny (a.k.a. evolutionary history) Four Types of evidence include: Morphology (homologous structures) Embryological development DNA, RNA, Amino acid sequences Fossil records

PHYLOGENEY The evolutionary relationships between all groups of organisms based on ancestor/descendant relationships. The evolutionary relationships between all groups of organisms based on ancestor/descendant relationships.

Pangolin - Armadillo The Pangolin and armadillo are two animals with no close taxonomic relationship. The morphology Linnaeus followed holds true to phylogeny or evolutionary relationships… in most cases…

Modern Systematic Taxonomists construct a Phylogenetic tree, or family tree to show these relationships. phylogenetic tree A phylogenetic tree shows the evolutionary relationships between different groups of organisms.

Modern Taxonomist consider several lines of evidence when classifying organisms according to their evolutionary history: Four Types of evidence include: Morphology (homologous structures) Morphology (homologous structures) Embryological development Embryological development DNA, RNA, Amino acid sequences DNA, RNA, Amino acid sequences Fossil records Fossil records

9 Homologous Structures (BONES in the FORELIMBS) shows Similarities in the morphology of mammals. copyright cmassengale

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11 EVIDENCE - Similarities in DNA copyright cmassengale

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cladistics. A relatively new system of phylogenetic classification is called cladistics. Based on Derived characteristics: Certain features that evolved only within the group being studied Example: if the group being studied is birds, having feathers is the derived character.

In this approach, ancestry diagrams are made through derived characters analysis. CLADOGRAMS These diagrams called CLADOGRAMS

15 Primate Cladogram copyright cmassengale