2006-2007

Classification

Chapter 18

What is Classification?

• System to organize ALL living things into groups with biological meaning.

•Taxonomy: The study of classification.

Assigning a Name

Problem: Common names can vary among languages. Common name is misleading. Descriptions are too long to be a name.

ex: Mountain Lion or Puma or Cougarex: Starfish, dragonflyex:“Oak with deeply divided leaves that have no

hairs on their undersides and no teeth around their edges.”

Solution: Latinized and Greek words are commonly used to avoid any language issues. Reduce the number of words to a two part name.

Carolus Linnaeus• The Linnean system where each

species has a 2 part (scientific) name:

BIONOMIAL NOMENCLATURE• genus• Species

(Genus is 1st word, species is 2nd)

Homo sapiens• means “wise man”• perhaps in a show of hope &

optimism

Genus groupings

• Classify organisms into broader groups• Species that are closely related are

grouped into the same genus– Leopard Panthera pardus– African lion Panthera leo– Tiger Panthera tigris

Classification System

• Linnaeus’ hierarchical system:Kingdom

general

Phylum

Class

Order

Family

Genus

Species specific

((KKings ings pplay lay cchess hess oon n ffine ine ggold old ssquares)quares)

Taxons

Kingdoms and Domains

Modern groups are six kingdoms: Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia

Domains – newest, largest inclusive category developed from comparing r-RNA subunits. Bacteria, Archaea, Eukarya

So…, classification sequence is now:D, K, P, C, O, F, G, S

Cladogram comparing Domains

Regents Biology

Bacteria&

Archaebacteria

Classification 6 Kingdom system

Prokaryotes No separate organelles in their cells Bacteria Archaebacteria

Eukaryotes Separate organelles

in their cells Protists Plants Fungi Animals

Prokaryote

Eukaryote

DOMAIN

KINGDOM

CELL TYPE

CELL STRUCTURES

NUMBER OF CELLS

MODE OF NUTRITION

EXAMPLES

Bacteria

Eubacteria

Prokaryote

Cell walls with peptidoglycan

Unicellular

Autotroph or heterotroph

Streptococcus, Escherichia coli

Archaea

Archaebacteria

Prokaryote

Cell walls without peptidoglycan

Unicellular

Autotroph or heterotroph

Methanogens, halophiles

Protista

Eukaryote

Cell walls of cellulose in some; some have chloroplasts

Most unicellular; some colonial; some multicellular

Autotroph or heterotroph

Amoeba, Paramecium, slime molds, giant kelp

Fungi

Eukaryote

Cell walls of chitin

Most multicellular; some unicellular

Heterotroph

Mushrooms, yeasts

Plantae

Eukaryote

Cell walls of cellulose; chloroplasts

Multicellular

Autotroph

Mosses, ferns, flowering plants

Animalia

Eukaryote

No cell walls or chloroplasts

Multicellular

Heterotroph

Sponges, worms, insects, fishes, mammals

Eukarya

Classification of Living Things

Section 18-3

Figure 18-12 Key Characteristics of Kingdoms and DomainsTaxon Characteristics

Regents Biology

Organizing systems Making sense out of the differences

Eastern gray squirrelSciurus carolinensis

Regents Biology

Organizing the world of organsims The Tree of Life

organize creatures by structure & function how they are built how they live

organize them into groups of closely related creatures

Modern Classification

• Just using appearance is not enough.• New system uses:

1. Fossils 2. Dissections/comparative anatomy3. Molecular similarities/DNA/enzymes4. Evolutionary similarities or developmental milestonesEx: amniotic sac, jaws, endothermic

Cladistics

• Classifying organisms according to the order that they diverged from a common ancestor.1. Ancestral characters – found in all groups

2. Derived characters – found in some groups

ex: backbone is an ancestral trait found in all birds and mammals

ex: hair is a derived trait found in only mammals

Vertebrate Cladogram

Which organisms are more closely related? -Perch and pigeon-Pigeon and chimp

Which organisms share the trait of claws/nails?

Which organism doesn’t have any of the traits?

What are the Derived Traits in this cladogram?

What could the ancestral trait be?