Evolutionary Classification: Understanding Life's Tree

1. Scientific Classification

2. CLASSIFICATION • Defn. The grouping of organisms by similarities • TAXONOMY: the branch of biology concerned with the grouping and naming of organisms; the study of classification

3. Taxonomy • Organisms are classified into a hierarchy of groups and subgroups based on similarities that reflect their relationships over a period of time.

4. Cladogram or Phylogenic Tree • A branching, treelike diagram in which the endpoints of the branches represent specific species of organisms. • It is used to illustrate relationships and show points at which various species have diverged from common ancestral forms.

5. What is wrong with this picture? Think-Pair-Share: Why was Aristotle’s system flawed? Why does it not “work”?

6. HISTORY: • Aristotle- developed the 1st method of classification • He divided all living things into 2 major groups • 1. Plants • classified by size and structure • 2. Animals • classified by habitat (where they lived)

7. HISTORY: Aristotle • Problems with his system: • Frogs live in both water and on land

8. HISTORY: Aristotle • Problems with his system: • Bats, birds and flying insects were grouped together

9. HISTORY: • Carolus Linnaeus- developed the modern system of classification • Father of Taxonomy

10. MODERN CLASSIFICATION SYSTEM Organisms are grouped together on the basis of: 1. Similarity in structure Panthera leo Felis rufus Felis domesticus

11. 2. Similarity in genetic makeup (biochemistry) • Similarities among organisms on the structural and metabolic levels are reflected in the large degree of similarity in proteins and nucleic acids of different organisms. • Diversity is the product of variations in these molecules.

12. 3. Similarity of embryonic development

13. 4. Similarity in evolutionary history • Phylogeny: the evolutionary history of a species based on comparing relationships between species using the fossil record

14. 5. Similarity in behavior

15. Check for Understanding: With your partner, develop 2 possible explanations as to why the modern system of classification is “better” and easier to use than the original system of classification. TIME: 2 minutes

16. Classification is based on close evolutionary relationships of organisms. • Organisms classified in the same taxa (pl.)(taxon, sing.) share a common ancestry. They have evolved from the same common ancestral organism.

17. Evolutionary Relationships

18. Levels of Classification • Domain- highest level; bacteria, archaea & Eukarya • Kingdom – 6 Kingdoms • Phylum (sing.) • Phyla (pl.)(Plants don’t have phyla, they have divisions.) • Class • Order • Family • Genus • Species These two taxa make up the scientific name.

19. Binomial Nomenclature • This system was developed by Linnaeus • Binomial nomenclature is a standard way of identifying a species with a scientific two-word name. • The first word is the genus name and the second the species name.

20. Binomial Nomenclature • Scientific name - 2 Latin names • Genus and species • Capitalize the first letter of the genus • Do NOT capitalize the species • ALWAYS underline or use italics Ex. Homo sapiens

21. Binomial Nomenclature Scientific Name: Pinus virginianis Common Name: Virginia Pine

22. What defines a “Species”? • organisms that belong to the same species can mate AND produce FERTILE offspring.

23. Why use scientific names? • Common names do not indicate how organisms are related or classified. • Common names can be misleading. (e.g., seahorse, weeping willow) • Organisms with more than one common name leads to mass confusion.

24. Why Latin? • Latin is no longer spoken, and therefore, does not change as spoken languages do. • So, scientific names remain the same forever.