1. Finding Order in Diversity (Ch 18.1)
Unit 5: Evolution

2. Assigning Scientific Names
European scientists in the 18th century agreed to name organisms using Latin or Greek names to the species
Scientific names used to be a description of characteristics of the organism
The scientific names often lead to using dichotomous keys to identify the organisms
Dichotomous Key: used to identify certain types of organisms based off of the visible characteristics of that organism

3. Dichotomous Key

4. Assigning Scientific Names
Binomial Nomenclature
Carl Linnaeus developed a system for naming organisms
binomial nomenclature: each species is assigned a two-part scientific name
Scientific names are in italics and the first word is capitalized and the second word is lowercased
The first word is the genus and the second word is the species name
Example: Ursus maritimus = Polar bear
Genus: group of similar species (Ursus)
It contains 5 other species of bears
Species: a group of individuals capable of interbreeding and producing fertile offspring (maritimus)
It contains only this species

5. Classifying Species into Larger Groups
systematics: the science of naming and grouping organisms
The goal of systematics is to organize living things into groups that have biological meaning
Organisms in a particular group are more similar to one another than organisms of a different group (taxa)
Example: teachers = general group
Biology teachers = specific group

6. The Linnaean Classification System
Linnaeus developed a system for classifying organisms into their taxa
Linnaeus’s original classification system expanded to the seven hierarchical taxa: species, genus, family, order, class, phylum, kingdom
Species: most specific name given to a specific organism
Example: Camel with two bumps (bactrianus)
Genus: groups of similar species that can breed and produce fertile offspring
Example: Camel with two bumps (Camelus)

7. The Linnaean Classification System
Family: Several genera that share many similarities
Example: Camels and Llamas placed in the same family Camelidae
Order: many closely related families
Example: Camels, llamas, deer, and cattle are all placed in the family Artiodactyla
Class: similar orders grouped together
Example: Artiodactyla is placed in the class Mammalia which includes all animals that are warm blooded, have body hair, and produce milk for their young
Phylum: classes that are grouped together because they share important characteristics
Example: Mammalia, Aves, Reptilia, and Amphibia are in the phylum Chordata because they have a nerve chord along their backs
Kingdom: the largest most inclusive group
Example: All multicellular animals are placed in the kingdom Animalia

8. From Species to Kingdom Camelus bactrianus

9. Problems with Traditional Classification
Linnaeus characterized species based on their visible similarities and differences – Which are more important or should be taken into account when classifying?
This is difficult because sometimes organisms may appear to be similar and are not or may appear to be different and are not
Many of Linnaeus’s classifications are valid today, but he worked on his concept before Darwin’s theory of descent with modification – how do we classify organisms based on their evolutionary relationships?
Today, scientists assign species to groups to reflect how closely members of the group are related to one another (evolution)