Chapter 18 Classification(p.508 - 535)

2013-2014

18.1 Essential QuestionsWhy do scientists classify organisms?

Objectives: Describe the goals of binomial nomenclatureExplain the difference between a common name and a scientific name

2. Which one is it: Puma, Panther, Cougar, Mountain Lion?

1. Which frog below is the green frog?

DO NOW

I. 18.1: Finding Order in Diversity

A. Assigning Scientific Names

1. The problem of common (vernacular) names

a. People in different places use different words to describe the same organism

b. Different organisms from different continents can have the same common name

c. Over 1.3 million organisms described on the planet with an estimated 5-10 million more not described

d. In order to study the diversity of life, scientists needed a universal system

Early Classification

Aristotle •animals classified based on whether they had blood or not•Plants classified based on how they grew

Early Renaissance

Guess the animal being described….

Today: Apis mellifera

2. Binomial Nomenclature

a. 1730’s – Carolus Linnaeus developed the system called binomial nomenclature

Swedish botanist Known as the father of

taxonomy

b. Every species is given a two part name called a scientific name

Scientific names include genus and species

The genus name is always capitalized and goes in front

Species names are written in lowercase and are unique to each species

Heloderma horridum

Genus Species

Scientific names are written in italics Ex: Polar Bear = Ursus maritimus , Brown

Bears are Ursus arctos

Some Genus and species Names You May Already Know

Panthera leo

Tyrannosaurus rex

Boa constrictor

Homo sapiens

3. Classifying Species into Larger Groups

a. Systematics – the science of naming and grouping organisms

b. Organisms that are more similar to one another are placed in similar groups

c. Groups are called taxa (singular taxon)

Analogy:

Kingdom - Country

Phylum - state

Classes – county

Orders – towns

Families – neighborhood

Genus - street

Species – specific house

Kingdom:Animalia

Phylum: Chordata

Class:Mammalia

Order:Primates

Family:Hominidae

Genus:Homo

Species: sapiens

Where do we fit in?

Kingdom:Animalia

Phylum:Chordata

Class:Reptilia

Order:Squamata

Family:Viperidae

Genus:Bothriechis

Species: schlegelii

Kingdom:Animalia

Phylum:Chordata

Class:Reptilia

Order:Squamata

Family:Boidae

Genus:Corallus

Species: caninus

4. Problems with Traditional Classification

a. Linnaeus grouped taxa based on specific traits

b. Many of his groups are still used today

c. The difficulty is deciding which traits should be used to define a group

Ex: Barnacles and Limpets

d. Today we look for evolutionary relationships to group organisms

Activity

Groups of 3-4 individuals Develop a classification system similar to

Linnaeus’s system Create a name for each level of classification in

your system Minimum of 4 levels Group your items according to your system Write down or draw a brief schematic of your

system on a lined sheet of paper

18.1 Essential QuestionsWhy do scientists classify organisms?

Objectives: Describe the goals of binomial nomenclatureIdentify the 7 traditional taxonomic groups

Do Now Questions (Day 2)

1. What is the goal of binomial nomenclature?

2. Who was Carolus Linnaeus?

3. What is a scientific name? Give an example.

4. List from most general to most specific the 7 major classification levels.

18.2 Essential Question How do evolutionary relationships effect how

scientists classify organisms?

Objectives: Describe how to make and interpret a cladogram Explain the use of DNA sequences in

classification

II.  18.2 Modern Evolutionary Classification

A. Evolutionary Classification

1. Common Ancestors

a. Phylogeny – the study of how living and extinct organisms are related

b. Used to groups species into larger taxa

2. Clades

a. Clades- are a group of species that includes a single common ancestor and all of its descendents

b. Includes both living and extinct organisms

c. All clades are monophyletic

Monophyletic group- a group that includes a single common ancestor and all of its descendents

Class Reptilia is not monophyletic, so in evolutionary classification reptiles are not a true group

B. Cladograms

1. Traits are carefully selected for use in comparing in evolutionary classification

2. These traits determine where different organisms branched off from a common ancestor

3. Cladogram – a diagram that shows relationships among species and larger taxa

4. Building Cladograms

a. Cladograms look like trees with branches

b. The point where each branch splits off is called a “node” = speciation event

5. Derived Characters

a. Defined- a trait that arose in the most recent common ancestor of an evolutionary line and was passed on to its descendents

b. Ex: having 4 limbs is a derived character in clade Tetrapoda

All tetrapods have 4 limbs

having hair is a derived character for clade Mammalia

all mammals have hair, but having 4 limbs is not a derived character for mammals

If it were only mammals would have this trait

6. Lost Traitsa. Sometimes descendents lose their derived

character

b. Ex: snakes are members of clade Tetrapoda, yet they have no limbs

7. Clades and Traditional Taxonomic Groups

a. Some traditional taxonomic groups are also true clades

Ex: class Mammalia is the same as clade Mammalia

b. Some traditional groups are not true clades

Ex: Birds and Reptiles are placed into separate classes in the traditional system

Reptilia is not a clade without birds since they share common ancestry

Birds belong to 3 clades: Aves, Dinosauria, and Reptilia

C. DNA in Classification

1. Genes as Derived Characters

a. The more similar the genes in two organisms are, the more recently they shared a common ancestor

b. When doing these comparisons, genes and mutations can be used as derived characters

2. New Techniques Redraw Old Trees

a. DNA analysis is making the evolutionary “tree of life” more accurate

The tree of life includes all three domains of life. There are so many taxa that the tree has to be drawn in a circle

b. Ex: DNA evidence has helped to classify Giant Pandas

Red and Giant Pandas share many traits

DNA analysis shows that red pandas share more recent ancestry with raccoons

Giant Pandas share more recent ancestry with bears

Cladogram Construction Link

18.2 Essential Question How do evolutionary relationships effect how

scientists classify organisms?

Objectives: Describe how to make and interpret a cladogram Explain the use of DNA sequences in

classification

Do Now Questions (Day 3)

1. What is the goal of evolutionary classification?

2. What is a cladogram?

3. Give an example of a derived character.

4. How are DNA sequences used in classification?

18.3 Essential Question What are the six kingdoms of life and how

are they arranged into the “tree of life”?

III. 18.3: Building the Tree of Life

A. Changing Ideas about Kingdoms

1. Classification systems will continue to change as long as new evidence is continued to be found.

a. Linnaeus’s system had only 2 kingdoms- plants and animals

b. Technology and greater understanding of evolutionary relationships has lead to today’s system

c. From the late 1800’s until fairly recently, the number of kingdoms had expanded to five

d. Today we have 6 kingdoms

2. Three Domains

a. Genetic studies have shown that there are two major and distinct groups of bacteria

b. Domain- is a larger, more general classification group, just above kingdom

c. The 3 Domains• Bacteria

• Archaea

• Eukarya

B. The Tree of Life

1. Domain Bacteria

a. Kingdom: Eubacteria

b. Basic traits Single celled Prokaryotes- no nucleus Thick cell walls made up of peptidoglycan Live in many environments Some are parasites Some are photosynthetic

2. Domain Archaea

a. Kingdom: Archaebacteria

b. Basic traits Single celled prokaryotes Have unusual cell

membranes Have cell walls made of

different material than bacteria

Live in extreme environments

3. Domain Eukarya

a. Contains all of the kingdoms of organisms that have nucleated cells

b. Kingdom: Protista Very diverse group, but not a true clade Most are single celled organisms Some are multicellular- Ex: brown

algae Some are photosynthetic and others are

heterotrophic

c. Kingdom: Fungi Heterotrophic Most feed on dead

organisms- release enzymes that digest food outside of their “body”, the digested food is then absorbed

Have cell walls made of chitin

Most are multicellular, some are single celled

Ex: yeasts, mushrooms

d. Kingdom: Plantae Are autotrophs =

photosynthetic- can make their own food

Cell wall made up of cellulose

Most are multicellular green algae have

recently been included within this kingdom

Ex: includes all flowers, ferns, and mosses

e. Kingdom: Animalia

Multicellular Do not have cell walls Are heterotrophic Most can move from place to place

Careers that use this “stuff” Zoologist/Taxonomist Nature Show hosts Plant/Animal Breeders Pet Store employees and owners Wine/Beer makers Doctors/Pathologists/Veterinarians Zookeepers Horticulturists Landscapers

18.3 Essential Question What are the six kingdoms of life and how

are they arranged into the “tree of life”?

Do Now Questions (Day 4)

1. Name the 3 domains

2. What are the 6 kingdoms?

3. Which kingdoms include eukaryotes?

4. Which organisms evolved first, fungi or animals?