1. Scientists develop systems for classifying living things.
Notes 2.1
Scientists develop systems for classifying living things.

2. Scientists classify millions of species.
Until the 1600s, scientists classified organisms according to their appearance.
The invention of the microscope allowed scientists to see structures and organisms that were not visible before.

3. Classification and Taxonomy
Classification: the process of arranging organisms into groups based on similarities
Taxonomy: the science of naming and classifying organisms
The purpose of classification and taxonomy is to make information easier to find and understand.

4. Classification and Taxonomy
Until 1700s scientists could not agree on a system
Both overly long Latin scientific names and common names can be confusing.

5. Using Classification
Scientists use similarities and differences among species, including appearance, biology, and genetics.
The more characteristics 2 organisms share, the more similar their scientific names should be in the classification system.
See examples on page 45B.

6. Taxonomists study biological relationships.
Taxonomists: the scientists who classify and name organisms based on their similarities and differences.
Taxon: a group of organisms that share certain traits
Taxons can be broad (animal) or more specific (cat).
A single species found in a fossil record can be the ancestor of many species on Earth today.

7. Taxonomists study biological relationships (continued)
In order to classify organisms, scientists compare a variety of traits.
Trait: a characteristic or behavior
If 2 organisms share a trait, taxonomists try to determine if they share that trait because they share an ancestor.

8. Continued
Page 47B—the seahorse shares more traits with a leafy sea dragon than the sargassum seaweed or sargassum fish.
Taxonomists take evidence and try to reconstruct the evolution of a species.
Then they place the species in the classification system.

9. Physical Evidence Primary devices used—eyes and measuring devices
Collect samples and note characteristics—size, color, weight, how obtain energy, internal structures, outward appearance
Individuals of a species have many similarites and some differences.

10. Physical Evidence
Skeletons, shells, and other hard parts of organisms fossilize more easily.
Scientists observe and measure this evidence.
They also compare bones.
All this physical evidence helps scientists see that all living organisms are related by evolution.
Those most closely related share a more recent ancestor.

11. Genetic Evidence
Scientists can compare the components of a gene from one organism with the components of the same gene from another organism.
Genetic evidence usually supports physical evidence.
See p. 49B—Red pandas are more closely related to raccoons than Giant Pandas

12. Review Questions 49B
1. Classification allows taxonomists to organize a great deal of data so that it is easier to find and understand.

13. Number 2
Taxonomists study biological relationships to discover how one species evolved as compared with another species.

14. Number 3
Scientists look at DNA and compare genes of organisms.

15. Number 4
Having a universal naming system allows people speaking different languages to refer to all organisms the same way. It’s easier to understand.

16. Number 5
A marbled godwit would have marbled feathers, wings, feet, and a beak.

17. Number 6
Compare physical traits, such as color, size, weight and how they get energy. Analyze bones; compare to fossils; compare DNA.

18. Quiz Fill-in Terms
Classification Evolution physical System taxons Taxonomy Traits genetic

19. Extended Response
Explain how scientists may use physical and genetic evidence to determine how closely related two species of birds are.
Quiz Wednesday!