Classification of Living Things

Non-Science Example of Classification The item in this picture is Automobile: Truck, Car, or SUV? Car Made by? Ford Type of Ford car? Mustang -Was made in what year? 2002 -Is it Convertible? No -Color? Silver Car Lot Example Scenario

Classification: Goes from General to Specific Automobile – Biggest Car Ford Mustang 2002 -Non Convertible -Silver - Specific

Classification Classify – to group things together based on similarities Why Classify? To make organisms easier to identify To make organisms easier to compare How do we classify? Compare Traits – features or characteristics of an organisms

Little Known Fact: There are over ___1.5 Million_____; and more are discovered each year. What do we classify? Somewhere between 2 and 100 million have yet to be discovered. Classification serves as an organization system for all the existing and new organisms The Science of Classification is called Taxonomy

Early Classification – Aristotle 384-322 B.C. 2 Groups: Plants and Animals Plants – Green, Non Mobile Animals – Not Green, Mobile Something that moves and is green would fit into both categories

How would you classify this using the Plant/Animal system? Praying Mantis Green but.. Mobile Aristotle’s Grouping of life not specific enough

Updating the Classification Process: Tools Used to Classify Organisms 1. Comparative Anatomy Compares Physical Structures, Traits 2. Biochemistry – DNA and RNA 3. Embryology – Developing Embryos 4. Molecular Basis – Cellular Structure 5. Phylogeny Related Organisms with common ancestors, Derived Characters

Linnaeus Divisions Still Used in Modern Classification 1. Kingdom – largest group 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species (Most Closely Related) We have now added DOMAIN which is bigger then Kingdom Do not write this slide

Mnemonic Device – To help remember categories and order Domain - Did Kingdom - King Phylum - Phillip Class – Came Order – Over Family - From Genus - Great Species - Spain

Taxons Within each category, a particular group is called a Taxon Many Taxons for each category Ex: Mammalia is the Taxon for the Class category in Humans Ex: Homo is the Taxon for the Genus category in Humans Carnivora is the Taxon for the Order category in Lions

From Kingdom to Species

Example Classification Lion 1. Kingdom – Animalia (all Animals) 2. Phylum – Chordata (All vertebrate animals) 3. Class – Mammalia (All Mammals – mammary glands) 4. Order – Carnivora (Meat eaters) 5. Family – Felidae (includes all Cats) 6. Genus – Panthera (Includes all roaring Cats) 7. Species – leo (Lions)

Which two animals are most closely related? At what taxon do they diverge?

Linnaeus Introduced Scientific Naming Binomial Nomenclature is the 2 word scientific name of an organism Uses Genus and Species Genus is capitalized, not species, all italicized In writing the name, can’t italicize, so underline Homo sapien (Genus and species of Human) Panthera leo (Genus and species of Lion) Used Latin – Felis concolor or Felis concolor

Practice Scientific name for…. Humans? Squirrel? Gorilla? Katydid?

If we find things we don't know and we want to know what they are what should we do? We use something’s characteristics in a similar way using…

Dichotomous Keys A dichotomous key is a tool that allows the user to determine the identity of items in the natural world based on the items characteristics "Dichotomous" means “divided into two parts” Greek origin Dichotomous keys always give two distinct choices in each step, often they are opposites ex) Black/white antennae present/antennae not present pointed/rounded

Here are creatures we don’t know! How to use a Dichotomous Key? Here are creatures we don’t know! 19

How to use a Dichotomous Key? Choose only one creature at a time. 20

Decide which statement is true How to use a Dichotomous Key? Read steps 1a and 1b Decide which statement is true 1b is true

Then follow the directions after that step. How to use a Dichotomous Key? Then follow the directions after that step. Go to step 5!

At choice 5, you make another dichotomous choice How to use a Dichotomous Key? At choice 5, you make another dichotomous choice 5a is true Go to step 6!

C How to use a Dichotomous Key? Keep going until you come to a step that gives you the creature’s name. 6 a. The creature has one antennae Go to Step 7. C

How to use a Dichotomous Key? Choose a new creature and start at step 1a and 1b again. Continue until you find the creature’s name. C Where do you start Again?

Then, find the names of all the creatures 26

1. a. wings covered by an exoskeleton – go to step 2 b. wings freely observed – Go to step 3 2. a. body has a round shape ……….ladybug, a red beetle with black spots b. body has an elongated shape ……….grasshopper, a green insect that hops 3. a. wings point out from the side of the body ……….dragonfly, an insect that is 10- 15 cm long and lives in marshes b. wings point to the posterior of the body ……….housefly, a flying insect with red eyes and an annoying buzz

What if I needed to make a key: - Use constant characteristics rather than variable ones. (Flowers change with the seasons) - Use measurements rather than terms like "large" and "small". Make the choice a positive one - something "is" instead of "is not". - Ex: snake ears are internal only If possible, start both choices of a pair with the same word or item. - the body is “round” vs the body is “square” - Finish the dichotomous key with a full description of the organism

Dichotomous key Another Example of a dichotomous key…

Dichotomous key the dichotomous key can also be expressed in a diagram form

Cladograms (Phylogenetic Trees) Show relationships between organisms. All organisms have at least one thing in common in order to be on the same tree, each branch shows how they differ from those before them, these are the derived characteristics. You read from the “roots” forward.

EXAMPLES

Practice Which organism is the first to have lungs? How many have fur? Which organism contains none of the identified derived characteristics?