Chapter 15

Classification Systems

15-1 Why Classify?

 Why are classification systems useful?

 What are some characteristics of a good classification system?

Why classify?

 Over 2.5 million kinds of species scientists have classified  May be another 10 million or so unknown species still out there  No one can keep track of these organisms by their names alone

http://www.answers.com/topic/biodiversity

 Only way to study these organisms is divide them into smaller groups  We have systems of biological classification that name and order organisms in a logical manner  These systems have two important features

 1. Assign a universally accepted name to each organism…Why?

 So scientists in other countries can know they are discussing the same organism  2. They place organisms into groups that have real biological meaning…Why?

 So they are in useful groups where they can expect the members to share important traits

Dichotomous key style

http://www.scholarsjunction.com/Taxonomy.aspx

15-2 Biological Classification

One problem was that the names were too long and based off of physical characteristics of a species

http://image.tutorvista.com/content/feed/tvcs/binomial-nomenclature-examples.jpeg

Secondly, it was difficult to standardize names of organisms because different scientists chose different characteristics to describe

http://fstoppers.com/wp-content/uploads/2013/05/photoshop-animals-together-new-species-18.jpg

Carolus Linnaeus

http://upload.wikimedia.org/wikipedia/commons/6/68/Carl_von_Linn%C3%A9.jpg

Linnaeus Video

Binomial nomenclature

http://bio1151.nicerweb.com/Locked/media/ch26/26_04CarnivoraPhylogeny-L.jpg

You give a two-part scientific name to the organism. The first name is the genus name and the second name is the species name

http://images.tutorvista.com/content/modern-classification/human-being-and-hibiscus-systematic-position.jpeg

They belong to that certain group

http://www.glencoe.com/qe/images/b136/q4322/ch17_0_b.gif

Their body structures they shared, taxa

http://www.bio.miami.edu/~cmallery/150/physiol/c34x2chordates.jpg

Taxonomy-The science of naming organisms and assigning them to these groups is called taxonomy

http://cristinahenryclassification.weebly.com/uploads/1/1/0/2/11023925/8677203_orig.jpg

Species-A population of organisms that share similar characteristics and that can breed with one another.

http://www.glacierbayalaska.com/wp-content/uploads/2010/12/alaska-fish-species.jpg

Kingdom, Phylum, Class, Order, Family, Genus, Species

http://www.biologycorner.com/resources/orca_taxonomy.gif

15-3 Taxonomy Today

 How do taxa show evolutionary relationships among different organisms?

 How do modern scientific techniques contribute to the classification of organisms?

Taxonomy Today

 Throughout the many years since Linnaeus, biological taxonomy has changed  Species is the only level that has a clear biological identity (share common gene pool)  Above species there can be many variations because different scientists believe that some characteristics are more important than others  This causes organisms to be moved between taxa quite a bit

http://www.nature.com/nature/journal/v438/n7069/fig_tab/nature04338_F10.html

Taxonomy and Evolutionary Relationships

 Taxonomists tend to group organisms in ways that show evolutionary relationships  They identify and study homologous structures, embryos and well-preserved fossils  Species shown to be closely related are classified together  Which structures are most important is up for debate

Biochemical Taxonomy

 All forms of life share organic molecules that are almost, but not exactly, identical from species to species  Taxonomists use this as a way to classify as well  All forms of life use DNA which carries a common genetic code

http://secularpsychedelic.webs.com/apps/photos/photo?photoid=122401939

 Genes in many different organisms resemble one another due to the theory of common descent  Similar genes direct the synthesis of similar proteins  Cytochrome c is a protein used by almost every organism but it is slightly different between species  They than compare the DNA sequences for cytochrome c between two species to see relation

http://en.wikipedia.org/wiki/Cytochrome_c

Cytochrome c

15-4 The Six-Kingdom System

 Linnaeus started with two kingdoms (vegetabile & animalia) and it is increased since then to 5/6  This increased by discoveries of such different organisms  There are three domains Bacteria, Archaea, & Eukarya  Make up six kingdoms bacteria, archaea, protista, plantae, fungi, animalia

http://www.bioedonline.org/slides/slide01.cfm?q=%22archaebacteria%22&dpg=1

Bacteria

 Prokaryotic  Some are aerobic and some are anaerobic  Some are autotrophic and some are heterotrophic  More abundant than any other organism (more abundant on your body than there are people in the world

http://cires.colorado.edu/news/press/2009/bodyBacteria.html

Bacteria

Archaea

 More ancient than bacteria but more closely related to eukaryote ancestors  Live an extreme environments (boiling hot springs, salty lakes, thermal vents, and in anaerobic conditions)

http://www.microbiologyonline.org.uk/about-microbiology/introducing-microbes/archaea

Protista

 Contains all the single-celled eukaryotic organisms  There are animallike protists, plantlike protists, and funguslike protists  Scientists believe that evolution came from these protists

Amoeba

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/protists/protists.htm

Fungi

 Build cell walls that do not contain cellulose  Heterotrophic and do not photosynthesize  Do not always have separate cells divided by complete cell walls

http://www.botanicalgarden.ubc.ca/potd/2006/10/fungus_diversity.php

Plantae

 Muticellular, have cell walls that contain cellulose, and are autotrophic  Includes all plants such as flowing plants, mosses, and ferns  Also includes multicellular algae

http://en.wikipedia.org/wiki/Plant

 Multicellular  Heterotrophic,

Animalia

 Have cell membranes without cell walls

http://en.wikipedia.org/wiki/Animal