1. Chapter 18
Classification

2. Why Classify?
The goal of systematics is to organize living things into groups that have biological meaning
By using a scientific name, biologists can be sure that they are discussing the same organism.
Ex. cougar, puma, panther, and mountain lion can all be used to indicate the same animal— Felis Concolor.

3. Linnaean Classification System
Organizes living things into groups (taxa) that have biological meaning
Linnaeus grouped species according to anatomical similarities and differences
Linnaeus’s classification system includes seven hierarchical taxa: species, genus, family, order, class, phylum, and kingdom.

4. Classification

5. Binomial Nomenclature
Linnaeus developed a two- word naming system in the 1730s= binomial nomenclature
The scientific name is written in italics
The first word begins with a capital letter
The second word is lowercase
EXAMPLE : Genus species
Polar bear = Ursus maritimus

6. Dichotomous Key Used to identify organisms
Consists of paired statements that describe alternative characteristics for an organism.

7. Problems with Traditional Classification
Organisms that look alike are not always the most closely related
Which two are most closely related?
Dolphin wolf shark

8. Evolutionary Classification
Evolutionary classification = groups species into larger categories that reflect lines of evolutionary descent (not overall similarities and differences)
Clade = a group of species that includes a single common ancestor and all descendants of that ancestor—living and extinct.

9. Cladogram
Cladogram = illustrates how groups of organisms are related to one another by showing how evolutionary lines, or lineages, branched off from common ancestors.

10. Derived character = a trait that arose in the most recent common ancestor of a particular lineage and was passed along to its descendants

11. Clade or not a clade????

12. DNA in Classification
Similarities and differences in DNA can be used to develop hypotheses about evolutionary relationships.
Ex. DNA analysis revealed that the giant panda shares a more recent common ancestor with bears than with raccoons. Therefore, the giant panda has been placed in a clade with bears. Red pandas, however, are in a clade with raccoons

13. The 6 Kingdoms

14. The 3 Domains
Genetic analysis shows the two prokaryotic kingdoms are more different from each other, and from eukaryotes
Domain = a larger, more inclusive category than a kingdom.

15. The Tree of Life