Chapter 18 Classification The diversity of life

Why is it necessary to classify? 1.5 million species on the planet so all creatures must be organized with a universal system. We call this taxonomy. Scientists cannot use common names because they change depending on where you live. For example: cougar, panther, puma, mountain lion all represent the same animal. It has a scientific name – Felis concolor

Scientific Names Carolus Linneaus – Swedish botanist who began the modern naming system. Developed a two word naming system called binomial nomenclature (latin) 2 name naming system Scientific names are Descriptive In Latin 2 words – capitalize the first letter of the first word and lowercase everything else. First word is Genus second word is species Ursus maritimus

Examples scientific name = genus + species Homo sapien Canis familiarius Felis domesticus Drosophilia melanogaster Human Dog Cat Fruit fly

Classification System We organize all life on Earth into 9 levels. Each level is called a taxon. Domain is the largest – 3 large groups (see below) Species is the smallest

Classification Levels Example: Grizzly bear

Here’s how to memorize it Kings = Kingdom Play = Phylum Chess = Class On = Order Fine = Family Grain = Genus Sand = Species

Human Taxonomy Levels

Changing Number of Kingdoms History of Kingdoms: 1700’s - 2 kingdoms –Plants and Animals 1800’s – 3 kingdoms – Plants, Animals, Protists (pond water critters) 1950’s – 5 kingdoms – Monera (bacteria), Protists, Fungi, Plants and Animals 1990’s – Eubacteria, Archaebacteria, Protists, Fungi, Plants and Animals.

Section 18-3 Kingdoms and Domains Shown below are the three domains and the 6 modern kingdoms we use today.

Autotroph v. Heterotroph Autotroph = Create their own food through photosynthesis Heterotroph = Receive their food through outside resources. They can absorb them or consume them.

Domain: Bacteria and Archaea 1. Kingdom: Bacteria unicellular prokaryotic cell wall contains a special molecule called peptidoglycan. 2. Kingdom: Archaebacteria Live in extreme environments Cell wall lacks peptidoglycan

Domain Eukarya 3. Kingdom Protista Eukaryotic organisms (most are one celled) Shows the greatest variety of organisms Photosynthetic or heterotrophic Amoebas, Paramecium, slime molds

Domain Eukarya 4. Kingdom Fungi Absorptive heterotrophs – absorb nutrients through their bodies Feed on dead or decaying organic matter Many are multicellular Yeast is unicellular

Domain Eukarya 5. Kingdom Plantae Multicellular Autotrophs (do photosynthesis) Cellulose in cell wall

Domain Eukarya 6. Kingdom Animalia Multicellular Heterotrophic Eukaryotic Invertebrates and Vertebrates

Cladogram & Dichotomous Keys Cladagram: Diagram that shows evolutionary relationships among organisms based on shared derived characters. Dichotomous Key: A “field guide” to help identify unknown organisms/objects Based on physical traits Rules: Only 2 options at a time All items still in consideration must fit in one of the two options No “grey-areas”

Let’s practice dichotomous keys The next slide, I will show you our organisms/objects For our example, we will use 8 nuts & bolts – keep in mind what they look like. Normally, we would give each organism/object a scientific name (Genus species). When you practice in class, you will make these up, but make them latin sounding, so add “us” or “is” at the end of the word.

Instead of Latin names, I have given them #’s to make this a bit easier to do on PowerPoint!!! Again, when you do this in class, you will make-up a Latin sounding scientific name (Genus species)

Construct a Branching Chart first to ultimately make a dichotomous key Species #1 6 sided Species #4 Rounded head Has a hole Species #6 4 sided Sharp, pointed tip Species #7 Not rounded head 8 nuts & bolts With threading Species #2 Not a flat head Without a hole Species #5 No sharp, pointed tip Body length twice the width of head Species #8 Flat head Without threading Species #3 Body length NOT twice the width of head

First step is to number and letter our branching chart. Now we are ready to construct a dichotomous key from our branching chart. First step is to number and letter our branching chart. Every center horizontal line gets a number Every choice gets a letter “a” or “b”

a a a b a b a a b b a b b b Species #1 6 sided Species #4 2 Species #6 Rounded head Has a hole b Species #6 4 sided 5 a Sharp, pointed tip b Species #7 1 Not rounded head 8 nuts & bolts 4 a With threading a Species #2 b Not a flat head 3 b Without a hole Species #5 6 a No sharp, pointed tip Body length twice the width of head b b 7 Species #8 Flat head Without threading b Species #3 Body length NOT twice the width of head

Finally you write the dichotomous key by coping everything straight from the branching chart. 1a. With a hole Go to question 2 1b. Without a hole Go to question 3 2a. 6 sided Species #1 2b. 4 sided Species #6 3a. With threading Go to question 4 3b. Without threading Species #8 4a. Sharp, pointed tip Go to question 5 4b. No sharp, pointed tip Go to question 6 5a. Rounded head Species #4 5b. No rounded head Species #7 6a. Not a flat head Species #2 6b. Flat head Go to question 7 7a. Body length twice the width of head Species #5 7b. Body length NOT twice the width of head Species #3

We could also construct a Cladogram based on our nuts & bolts…