Chapter 17 Classification of Organisms Section 1 Biodiversity Be Able To: Relate biodiversity to biological classification. Explain why naturalists replaced Aristotle’s classification system. Identify the main criterion that Linnaeus used to classify organisms. List the common levels of modern classification from general to specific. Key terms: Pg 337.

Early Systems of Classification TaxonomyTaxonomy is the science that groups organisms according to their characteristics and evolutionary history. Aristotle: Plants or animals Land dwellers, water dwellers or air dwellers Common names varied and did not accurately describe the species.

Linnaeus’s System morphologyGrouped organisms by their morphology (form and structure). Hierarchy of seven levels. –Kingdom –Phylum (animal) Division (plant) –Class –Order –Family –Genus –Species

Binomial Nomenclature Species name or scientific name consists of the genus and species identifier, usually a descriptive word. Binomial nomenclature is a two- part naming system. Varieties are subsets of a plant species. Subspecies are animal species that occur in different areas. Phylogeny is the evolutionary history of an organism.

Are these scientific names written correctly? canis Familiaris Felis domesticus canis lupus Vulpes P. deltoides Cercis C. Carya Illinoensis Dog Cat Wolf Fox Cottonwood (Populus) Red bud (canadensis) Pecan

Chapter 17 Classification of Organisms Section 17-2 Systematics Be Able To: Identify the kinds of evidence that modern biologists use in classifying organisms. Explain what information a phylogenetic diagram displays. State the criteria used in cladistic analysis. Describe how a cladogram is made. Discuss how proteins and chromosomes are used to classify organisms. Explain cladistic taxonomy and identify one conclusion that is in conflict with classical taxonomy. Key Terms: Pg 341.

Phylogentics Systematics organizes the diversity of living things in the context of evolution. Phylogenic tree is a family tree that show the evolutionary relationships thought to exist among groups of organisms. Fossil record – is it a complete record? Morphology – if there is a greater number of homologous morphological features between organisms it could mean they are more closely related.

CAN YOU SEEN A COMMON PATTERN?

Cladistics System of phylogenic classification using shared derived characteristics. A derived character is a feature that evolved within the group under consideration (example feathers). shared characterA shared character is a feature that all members of a group have in common (ie feathers in birds). Cladograms are diagrams that are used to show evolutionary relationships among organisms. cladeA clade is a group of organisms including an ancestor and all of their descendants. What is the shared character for all the animals in this cladogram? What is the derived character that separated turtles from all of the other clades in evolutionary order?

Constructing a Cladogram Cladistic analysisCladistic analysis is comparative. An out-group is an organism that is distantly related to the other organisms, it is a starting point. A table of organisms and their characteristics is the start of creating a cladogram. Organisms with a derived trait score a 1 and those without score a 0. Look for the organism that has fewer traits in common, this is the out-group in the cladogram. The table will reveal derived characters shared by most group.

Molecular Evidence for Evolutionary Evidence Taxonomists compare macromolecules such as DNA and RNA. “Molecular clock” model: Differences in amino acid sequences for homologous proteins indicate how long the species shared an ancestor. Chimps are genetically very similar to humans - 5 millions years