Classification and Identification What is it? Why do we use it?

What is Classification? Since before Roman times, scientists and naturalists have investigated the world around them. As they discovered new organisms, they realized that they needed to come up with a system to keep everything in order. This system helped these scientists to categorize or classify life.

Who came up with this system? In the mid-eighteenth century, a Swedish biologist, named Carolus Linnaeus came up with a system of names to catalog life’s diverstiy. He came up with Binomial Nomenclature. What is this? A system that uses two names - genus and species – to identify each individual.

What is a Genus and Species? Organisms can be broken up into different groups (taxonomic groups), which have shared characteristics. What are these groups?? Biologists recognize several major groups beyond genus and species. Let’s look at the common dog.

The Taxonomic Groups Kingdom – Animalia – meaning it is in the group of animals Phylum – Chordata – meaning it has a backbone Class – Mammalia – meaning it is part of the mammals group Order - Carnivora - means that it is a carnivore (eats meat) Family – Canidae - meaning it has canines Genus – Canis - It’s a type of dog Species – familiaris (tail turns to the right) – it the actual dog species.

But what does this mean? All life is categorized into Six major Kingdoms. Monera (Eubacteria) – single celled bacteria Archaebacteria – single celled bacteria living in extreme environments Protista – single celled eukaryotes Fungi – multicelled heterotrophs (mushrooms) Plantae – multicelled autotrophs (algae, ferns, flowering plants) Animlia – multicellular heterotrophs (lack cellulose and have movement) From there, each individual is then classified into Phyla, Classes, Orders, Families, Genuses, and Species based on their specific characteristics. (We will take a look more closely later)

Classification of Living Things Learning About The Kingdoms Of Life

What is Classification? The organization of objects using characteristics & attributes

Biological Classification Systems that name & organize living things in a meaningful way AKA taxonomy

Modern System (post-Linnaeus) 2 functions 1 groups organisms according to basic characteristics 2 gives unique name to each organism

Think of it like this… Kingdom Phylum Class Order Family Genus Species

How are relationships determined? Structural similarities Shared physical structures Breeding behaviors – species may look alike but… Make different sounds, or breed at a different time Geographical distribution South American Finches vs. Galapagos finches Chromosome comparisons Number and structure of chromosomes as seen during meiosis and mitosis Biochemistry Similar DNA sequences, and therefore similar proteins More inherited nucleotide sequences = closely related species

Modeling

1.  Start with a list of taxa that are to be fit into the cladogram (the ingroup) and their derived characters.  Choose an outgroup; a taxa that shares a primitive character with the ingroup, but exhibits none of the derived characters.     

2. Fill in a character table that will be used to make the cladogram 2.  Fill in a character table that will be used to make the cladogram.  The taxon with the least number of derived characters should be the first row.  The taxon with the greatest number of derived characters should be the last row.  The character that is seen in the greatest number of taxa should be the first column.  The character that is exhibited in the least number of taxa should be the last column.  Use ones and zeroes to represent presence (1) or absence (0) of specific characters in specific species.   

3. Build the cladogram step-by-step 3. Build the cladogram step-by-step.  Start with the first character (first column).  The outgroup is the only taxon that doesn't exhibit the first character.  Separate it from the other taxa on the cladogram.  Remember, the outgroup shares a common ancestor with the ingroup.  Also, each split in the cladogram marks a separate evolutionary event.             

4.  By looking at the completed cladogram, we can see which species are most closely or distantly related.  In this example, humans are more closely related to chimpanzees, than to any other taxon on the cladogram. 

Terms to Know Autotrophs make own food Heterotrophs get food from another source Photosynthesis using the sun’s energy to make own food Prokaryotic nucleus not enclosed; DNA flows freely in cell Eukaryotic has an enclosed nucleus (where DNA is stored) Locomotion means of movement; transportation

Terms to Know Sessile non- moving; stationary Motile mobile; ability to move Taxonomy another word for classification Nucleus cell structure that contains DNA for reproduction; enclosed with a membrane