1. Taxonomy
Bio 250

2. History of Taxonomy Aristotle
Taxonomy – the branch of biology which names and groups organisms according to their characteristics
Aristotle
First person to put organisms in
groups.
- Grouped animals into land, air
or water dwellers.
At first, Aristotle’s system seemed adequate.
When many new organisms were discovered,
scientists began having problems. More groups
were needed. Common names were different from
place to place and caused confusion and did not
describe the organism.

3. History of taxonomy cont.
Linnaeus created a new system of grouping organisms.
Based on their morphology (structure)
Created 7 levels of classification
Also created a two-part naming
system called Binomial
Nomenclature.
Linnaeus

4. The 7 Levels of Classification
Linnaeus devised seven levels of organization.
Kingdom: the largest group of living things.
Phylum: The largest group within a kingdom.
Class: The largest group within a phylum.
Order: The largest group within a class.
Family: Largest group in an order.
Genus: Largest group in a family.
Species: Smallest group of living things.

5. Wait.. What were those again?
No Looking!
Kingdom
Phylum
Class
Order
Family
Genus
Species

6. Binomial Nomenclature
The species name, also called the scientific name of an organism has two parts.
The Genus name
The species identifier
The Genus name is capitalized, the species name is lower case and both are underlined or written in italics (typing only)
Thus, our scientific name is written as such Homo sapiens or Homo sapiens.
The full scientific name of a species will contain the
the names of each classification group the organism is
in.
For Humans:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Primata
Family: Hominidae
Genus: Homo
species: sapiens

7. The Six Kindoms
All life on Earth has been divided into six different kingdoms.
Kingdom Archaebacteria
Unicellular prokaryotes
Cell membranes are different from other bacteria.
Many live in harsh environments.
Kingdom Eubacteria:
These are the ones which affect you: tooth decay, food poisoning, disease, create food products like yogurt.

8. The Six Kingdoms cont. Kingdom Protista
The catch-all Kingdom. If it’s eukaryotic and not a plant, animal or fungus, it’s in here.
Mostly unicellular but do have some multicellular species.
Some are plantlike and some are animalike.

9. The Six Kingdoms cont. Kingdom Fungi
Multicellular, eukaryotic, heterotrophic
Absorb nutrients – digest outside their body
Includes mushrooms, puffballs, rusts, smuts, mildews, and molds

10. The Six Kingdoms cont. Kingdom Plantae
Multicellular, eukaryotic, autotrophic
Make their own food through photosynthesis
Include mosses, ferns, conifers, and flowering plants

11. The Six Kingdoms cont. Kingdom Animalia
Eukaryotic, heterotrophic, multicellular
Can move around in their environment
Insects, mammals, reptiles, amphibians, fish, birds, worms

12. The 3 Domain System
Scientists have added another classification group ABOVE the level of Kingdom
Molecular biology has shown that all organisms naturally fall into 3 large groups which are called Domains
Domain Bacteria
Contains the Kingdom Eubacteria
Domain Archae
Contains the Kingdom Archaebacteria
Domain Eukarya
Contains all Kingdoms with Eukaryotic cells
Protista, Fungi, Plantae, Animalia

13. based upon specific traits.
Taxonomy
So how do we put all
these organisms into
groups?
Today, scientists use
either Systematics or
Cladistics to put
organisms into groups
based upon specific traits.
Systematics – Organizes the diversity of living things in the context of evolution.
Creates a Phylogenetic Tree – A family tree which shows the evolutionary relationships thought to exist among groups of organisms.
A phylogenetic tree represents a hypothesis.
Scientists use morphology (structure), patterns of embryological development, similarity in DNA and proteins to construct phylogenetic trees.

14. Taxonomy cont.
Cladistics – uses certain features of organisms called shared derived characters to establish evolutionary relationships.
Derived Characters – are features that apparently evolved only within the group under consideration.
Ex: If you’re studying birds, a derived character may be feathers.
Scientists believe that if a group shares a character not shared with any other group, then they likely inherited it from a common ancestor.
Cladogram – Ancestry diagram made by means of cladistics.