Classification 1 Why Classify Classification is the arrangement

Classification 1

Why Classify? • Classification is the arrangement of organisms into orderly groups based on their similarities in DNA. Life is so diverse, that scientists use classification to group organisms in a logical way. • 2

Taxonomy The science of classification is known as taxonomy. Taxonomists are scientists that identify & name organisms 3

Why does it matter? What is this? 4

Cougar? Mountain Lion? Panther? Puma? Felis concolor For many species, there are regional differences in their common name. 5

Assigning Scientific Names • To eliminate confusion, 18 th century scientists agreed to a single name for each organism. • The languages that were chosen to use were Greek and Latin because they were widely understood. 6

Early Attempts at Naming • The first attempts at naming were descriptions of physical characteristics. • But they were WAY TO LONG and still caused confusion. 7

Example: name this in 10 words: Oak with rounded edges three fingered top and narrow bottom 8

Binomial Nomenclature is the system still used today in which a species is given a two-part scientific name. RULES: 1) Written in italics 2) 1 st word capitalized 3) 2 nd word is lower case 9

What does each word stand for? 1 st Word- Genus- group of closely related species. 2 nd Word- Species Specificimportant trait or reflection of habitat. 10

Example: Polar Bear Scientific Name: Ursus maritimus Ursus = genus the polar belongs to maritimus = Latin for “sea” 11

Carolus Linnaeus 1707 – 1778 • 18 th century taxonomist • Classified • organisms by their structure Developed naming system still used today 12

Linnaeus’s system of classification includes seven Taxa (levels) (singular - taxon). They are (from largest to smallest): Kingdom Phylum Class Order Family Genus Species 13

King Phillip Came Over For Good Spaghetti 14

Example: Polar Bear Kingdom- Animalia Phylum- Chordata Class- Mammalia Order- Carnivora Family- Ursidae Genus- Ursus Species- maritimus 15

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1) 2) 3) 4) 5) Read pg. 449 in your text. Then answer the following questions: What would NOT share a kingdom with a polar bear? Name one animal that shares a phylum with the polar bear. Name one animal that shares a class with the polar bear. Name one animal that shares an order with the polar bear. Name one animal that shares a family with the polar bear. 17

18 -2 Modern Evolutionary Classification Q: What was the problem with Linnaeus’s system of classification? A: Which similarities and differences were most important when classifying? Example: Dolphins- what is more important? Live in water with fins or breathe air and feed their young with milk? A better system was developed based on Darwin’s ideas of descent with modification. 18

Evolutionary Classification Phylogeny- study of evolutionary relationships among organisms. Biologists now place organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities. This strategy is called evolutionary classification. 19

The larger the level of the taxon, the farther back in time is the common ancestor of all organisms in that taxon. Share a common ancestor further back in time. Therefore, more differences. Share a common ancestor more recently. Therefore, more similarities. 20

Classification Using Cladograms Derived Characters-characteristics that appear in recent parts of the lineage as a result of evolution/adaptations over time, that don’t appear in older parts of the lineage. Derived characters can be used to construct a cladogram- a diagram that shows evolutionary relationships among a group of organisms. Derived characters are the point at which one organism breaks from another on a cladogram. 21

Example Cladogram Derived characters appear on the branch in the evolutionary order they first appeared. Outgroup Examples: jaws, lungs, claws/nails, feathers, fur, mammary glands Questions: What characteristics do both lizards and pigeons share? _________________ What two characteristics appeared around the same time? ___________________ 22

Making a Cladogram Step 1: Create a table Perch Lizard Chimp Hagfish Salamander Pigeon Mouse Fur, Mammary glands Lungs Jaws Claws/ Nails Feathers Step 2: Mark derived Characters and total them 23

Step 3: Create Cladogram from Data • The organism with the least amount of checked derived characters is the first to evolve, etc. • The derived character with the most amount of checked organisms is the first to evolve, etc. 24

Similarities in DNA Help Classify • The genes of many organisms show important similarities at the molecular level. • Similarities in DNA are used to classify organisms and show if there is a common ancestor. • The more DNA there is in common, the more recent they shared a common ancestor. 25

Even organisms as different as a multicellular organism (like a human) and a unicellular organism (like yeast) can have similarities in their genes! The study of these genes can help determine if there is any degree of relatedness. (common ancestor? ) 26

A molecular clock is a model that uses DNA comparisons to estimate the length of time two species have been evolving independently. It shows when new mutations occur in the DNA. 27

18 -3: Kingdoms and Domains There are 3 Domains that scientists have created that are broader categories than kingdoms. The 3 Domains are: 1) Eukarya 2) Bacteria 3) Archaea Each Kingdom fits into these domains. 28

Domain 1: Bacteria • Contains the Kingdom Eubacteria. • Cell Type: prokaryotic • Cell Structures: cell walls with peptidoglycan • Number of Cells: unicellular • Mode of Nutrition: autotroph or heterotroph 29

Domain 2: Archaea • Contains the Kingdom Archaebacteria. • Cell Type: prokaryotic • Cell Structures: cell walls without peptidoglycan • Number of Cells: unicellular • Mode of Nutrition: autotroph or heterotroph 30

Domain 3: Eukarya • Contains the Kingdoms Protista, Fungi, Plantae, Animalia • Each kingdom must be broken down separately to describe differences in this domain. 31

Kingdom Protista Cell Type: Eukaryote Cell Structures: Cell walls with cellulose; chloroplasts Number of Cells: most unicellular Nutrition: Autotroph or heterotroph 32

Kingdom Fungi Cell Type: Eukaryote Cell Structures: Cell walls with chitin Number of Cells: most multicellular Nutrition: heterotroph 33

Kingdom Plantae Cell Type: Eukaryote Cell Structures: Cell walls with cellulose; chloroplasts Number of Cells: multicellular Nutrition: Autotroph 34

Kingdom Animalia Cell Type: Eukaryote Cell Structures: No cell wall, no chloroplasts Number of Cells: multicellular Nutrition: Heterotroph 35

Domain Classification Table Eukarya Bacteria Archaea Kingdom Cell Type Cell Structures Number of Cells Nutrition Examples 36

Dichotomous Keying • Used to identify organisms • Characteristics given in pairs that are “opposites” • Read both characteristics and either go to another set of characteristics OR identify the organism 37

Turn to pages 462 -463 in Textbook 38

Example of Dichotomous Key 1 a 1 b 2 a 2 b 3 a 3 b 4 a 4 b Tentacles present – Go to 2 Tentacles absent – Go to 4 Eight Tentacles – Octopus More than 8 tentacles – Go to 3 Tentacles hang down – Go to 4 Tentacles upright–Sea Anemone Balloon-shaped body–Jellyfish Body NOT balloon-shaped. Go to 5 39

Creating a Dichotomous Key 40

1) Brainstorm characteristics of the items: Long and tubular For writing Short non-tubular Not for writing Plastic has a cap Not plastic no cap Green and gray Blue and clear Black and silver Silver 41

2) Make a spider key 2 Main groups Further breakdown 42

3) Using your spider key as a guide, construct your dichotomous key. When something can no longer be divided, name it! 43

Let’s practice! 44