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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?