systems of classification order from chaos when you need a new pair of shoes, what do you do? you...

Systems of Classification

Order From Chaos

• When you need a new pair of shoes, what do you do? You probably walk confidently into a shoe store, past the tens or hundreds of pairs of shoes you don’t want and straight to the kind you do want. How do you find them? Shoes are organized in the store in categories. People organize objects by grouping similar objects together.

Section 18-1

Interest Grabber

Go to Section:


1.Consider the task facing early biologists who attempted to organize living things. How might they have begun?

2.Suppose that you have been given a green plant, stringy brown seaweed, a rabbit, a mushroom, a worm, and a grasshopper. You’ve been asked to organize these things into categories that make sense. How would you do it?

3.Decide on your categories and write each on a sheet of paper. Next to each category, write the defining characteristics of that category. Then, write in the organisms that fall into each category.

Section 18-1

Go to Section:


• 18–1 Finding Order in DiversityA. Why Classify?

B. Assigning Scientific Names1. Early Efforts at Naming

Organisms

2. Binomial Nomenclature

C. Linnaeus’s System of Classification

Section 18-1

Section Outline

Go to Section:


KEY CONCEPT Organisms can be classified based on physical similarities.


What is the purpose of classification?

**Taxonomy:

The study of classification and giving each organism a unique name.

Why not use common names?

Binomial Nomenclature:

The 2-part scientific name each species is given.

Genus:

A group of closely related species.

Taxon: A group or level of organization


Classification• grouping of objects based on similarities (clothes,

dishes, etc.)

Humans like to organize their world so early on we grouped or classified everything we saw.

.


Systematics

• classification system that groups organisms according to evolutionary relationships– Based on common descent (idea that any two

organisms can trace back to a common ancestor)– identifies species, determines their relationships to

known organisms, and gives them names.


1. Organize huge amounts of information

~1.5 million species named

A MINIMUM of 10 million different kinds of organisms expected


2. Accurate identification of existing and new species

http://www.igreens.org.uk/archeopteryx_solnhofen3.jpg

http://extra.listverse.com/amazon/edge/echidna.jpghttp://www.show.me.uk/dbimages/chunked_image/2007_0538.jpg


3. Consistent names for communication

• Cougar, mountain lion, snow cat, screaming cat, panther, puma

• 30+ common names


Scientific names help scientists to communicate. – Some species have very similar common names.– Some species have many common names.


4. Demonstrates relationships between organisms


5. Make hypotheses about life

http://www.mc.maricopa.edu/dept/d10/asb/origins/hominid_journey/central.html


SPECIES = Group of similar organisms that can mate and produce offspring

Number of species of living organisms in the world? Probably a minimum of 10 million different organisms.

HOW can we group and name these organisms?

Classify = to organize things into GROUPS based upon

HOW do grocery stores classify different things?

HOW do department stores classify different things?


Problem with common names

1) Names are not the same in all languages

2) Names in different countries mean different things - corn in England means callus

NEED a system of classification that is understood by ALL scientists throughout the world = Binomial Nomenclature (understood by everyone in the world)


History of ClassificationAristotle

(Greek philosopher 384-322 B.C.)

• developed the first accepted system of biological classification

•Grouped organisms by how they looked

http://westernparadigm.files.wordpress.com/2008/10/aristotle.jpg


Aristotle

PROBLEMS:•Birds, bats, and flying insects together even though little in common besides ability to fly.• Very few groups - as more organisms discovered , many did not fit easily into Aristotle’s groups.

BUT Many centuries passed before Aristotle’s system was replaced.


Linnaeus developed the scientific naming system still used today.

**Taxonomy is the science of naming and classifying organisms.

A taxon is a group of organisms in a classification system.

White oak:Quercus alba


History of ClassificationCarolus Linnaeus (Carl von Linné)

(Swedish Botanist 1707-1778)"Father of Modern Classification"

2. Hierarchical Classification

Organisms organized into groups of increasing inclusiveness by morphology

1.** Binomial NomenclatureDeveloped a naming system for giving each group a unique two part scientific name


Binomial nomenclature is a two-part scientific naming system.

– **uses Latin words – scientific names always written in italics – **two parts are the genus name and species descriptor


A genus includes one or more physically similar species.– Species in the same genus are thought to be closely

related.– Genus name is always capitalized.

A species descriptor is the second part of a scientific name.– always lowercase– always follows genus

name; never written alone

Tyto alba

Systems of ClassificationBinomial Nomenclature Linnaeus

Bi (two) nomial (name)

1. First part of name = genus

– first letter ALWAYS capitalized2. Second part of name = specific or species name

– first letter NEVER capitalized3. Both words UNDERLINED or in ITALICS

4. LATIN based


Every species has a unique two part scientific name.

•Panthera leo is the scientific name for an African lion

•Panthera (beasts) is the genus name

• leo (lion) is the specific name

Systems of ClassificationBinomial Nomenclature - more • Two different organisms cannot be given the same binomial name – (may have same first name = same genus or

same second name if in different genera)• Names usually have clues: often

• Describes the appearance (Tyrannosaurus rex – tyrant/lizard king)

• Describes the distribution (carolinensis – from North/South Carolina)

• Describes the discoverer or famous scientist (darwinii)


Sugar Maple – Acer saccharum


Brown Bear (Grizzly Bear) – Ursus arctos


Great White Shark – Carcharodon carcharias


Checkpoint

1. What is systematics and why is it important?

2. Who is Carl Linnaeus?

3. Write the species name of humans according to Binomial nomenclature.

4. What is a species?

5. What is a genus?

28ANY QUESTIONS?


Linnaean System is Hierarchal.

Larger groups are more inclusive and smaller groups are more specific.

• For example, the phylum Chordata includes both lions and lionfish, but the genus Panthera includes only lions & other large cats – no fish!

Systems of ClassificationHierarchical Classification

•Kingdom•Phylum•Class•Order•Family•Genus•Species

Kids Playing Chicken OnFreeways Get Squashed.

There were 7 Levels of Biological Classification when I learned them.


**Linnaeus’ classification system has seven levels.

• Each level is included in the level above it.

• **Levels get increasingly specific from kingdom to species.


The Linnaean classification system has limitations.

Linnaeus taxonomy doesn’t account for molecular evidence.– **The technology didn’t exist during Linneaus’ time.– Linnaean system based only on physical similarities.


Physical similarities are not always the result of close relationships. Sometimes siiliarities are due to environment

Genetic similarities more accurately show evolutionary relationships.


How does it work?• Each grouping is a taxon (pl. taxa) = group of

animals defined by a shared set of traits• Every living thing that we know of fits into one of

the six kingdoms• **Each level gets more specific as fewer

organisms fit into each successive group (taxa)


Panthera leo

Panthera pardus Panthera tigris

Felis catus Lynx candensis Acinonyx jubatus

Felidae – the Cat Family


Checkpoint

1. List the hierarchy of classification from kingdom to species.

2. What is a taxon (plural taxa)?

3. Are there more species in an order or in a class?

36ANY QUESTIONS?


One Big Family?

• How can you determine if one organism is closely related to another? It may seem easy, but it isn’t, and looks are often deceiving. For example, roses and orchids are both flowering plants, but roses grow on bushes or vines and have thorns. Many orchids don’t even grow in soil—they can grow in trees! Rose and orchid blossoms look very different, and roses and orchids cannot produce hybrids, or offspring of crosses between parents with different traits.

Section 18-2Interest Grabber

Go to Section:


• 1. Do you think roses and orchids are closely related? Explain your answer.

• 2. Now, apply the same logic to dogs. Different breeds of dogs—such as a Labrador retriever and a collie—can breed and produce offspring. So what is the difference between the rose-orchid combination and the Lab-collie combination?

• 3. What defines a species? Is appearance important? What other factors might be considered?

Section 18-2Interest Grabber continued

Go to Section:


• 18–2 Modern Evolutionary ClassificationA. Problems With Traditional

Classification

B. Evolutionary Classification

C. Classification Using Cladograms

D. Similarities in DNA and RNA

E. Molecular Clocks

Section 18-2

Go to Section:


KEY CONCEPT Modern classification is based on evolutionary relationships.


Evolutionary Classification:

Classification based on lines of evolutionary descent or history.

Derived characteristics:

Recent adapted characteristics not found in older members of the same descent line.

Cladogram:

Diagram that shows evolutionary relationships among a group of organisms.

**Molecular Clock:

A model that shows how long two species have been evolving independently.


Cladistics is classification based on common ancestry.

**Phylogeny is the evolutionary history for a group of species.– evidence from living species, fossil record, and

molecular data– **shown with branching tree diagrams


**Cladistics is a common method to make evolutionary trees.

– classification based on common ancestry– species placed in order that they descended from

common ancestor


DNA studies have shown that at the molecular level many species show important similarities.

The genes allow scientists to trace genetic history for an organism.

Classification Systems TODAY - Based on SIMILARITIES that reflect Genetic RELATIONSHIPS: Scientists today use> DNA sequencing> Amino acid sequencing> Radioactive dating/fossil record> Similarities in embryological development> Homologous and vestigial structures

Systems of ClassificationEvolutionary Classification

Phylogeny – study of how living and extinct organisms are related

goal: classify organisms according to common ancestry rather than similarities and differences

Members of same genus share a more recent ancestor to each other than to other species in their order.

The higher/larger the taxa, the farther back the common ancestor

Systems of ClassificationEvolutionary Classification

Clade – taxa that include a single common ancestor and all of its descendents living or extinct– Should include all species from that ancestor and

exclude all species NOT from that ancestor

**Cladogram – shows how species are related and branched over time according to shared derived characters– Derived characters - traits passed to members in a

given lineage; homologous


TRADITIONAL CLASSIFICATION

CLADOGRAM

Appendages Conical Shells

Crab Barnacle Limpet Crab Barnacle Limpet

Crustaceans Gastropod

Molted exoskeleton

Segmentation

Tiny free-swimming larva

Section 18-2Traditional Classification Versus Cladogram

Go to Section:


• A cladogram is an evolutionary tree made using cladistics.

– **A clade is a group of species that shares a common ancestor.

– Each species in a clade shares some traits with the ancestor.

– Each species in a clade has traits that have changed.


**Derived characters are traits shared in different degrees by clade members.

– basis of arranging species in cladogram

– more closely related species share more derived characters

– represented on cladogram as hash marks FOUR LIMBS WITH DIGITS

Tetrapoda clade1

Amniota clade2

Reptilia clade3Diapsida clade4

Archosauria clade5

EMBRYO PROTECTED BY AMNIOTIC FLUID

OPENING IN THE SIDE OF THE SKULL

SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW

FEATHERS & TOOTHLESS BEAKS.

SKULL OPENINGS BEHIND THE EYE

DERIVED CHARACTER


FOUR LIMBS WITH DIGITS

**•Nodes represent the most recent common ancestor of a clade.

• Clades can be identified by snipping a branch under a node.

Tetrapoda clade1

Amniota clade2

Reptilia clade3Diapsida clade4

Archosauria clade5

EMBRYO PROTECTED BY AMNIOTIC FLUID

OPENING IN THE SIDE OF THE SKULL

SKULL OPENINGS IN FRONT OF THE EYE AND IN THE JAW

FEATHERS AND TOOTHLESS BEAKS.

SKULL OPENINGS BEHIND THE EYE

NODE

DERIVED CHARACTER

CLADE


Molecular data may confirm classification based on physical similarities.

Molecular data may lead scientists to propose a new classification.

** Molecular evidence reveals species’ relatedness.

DNA is usually given the last word by scientists.


KEY CONCEPT Molecular clocks provide clues to evolutionary history.


Molecular clocks use mutations to estimate evolutionary time.

**Mutations add up at a constant rate in related species.– This rate is the ticking of the molecular clock.– As more time passes, there will be more mutations.

DNA sequence from ahypothetical ancestor

The DNA sequences from twodescendant species show mutationsthat have accumulated (black).

The mutation rate of thissequence equals one mutationper ten million years.

Mutations add up at a fairlyconstant rate in the DNA of species that evolved from a common ancestor.

Ten million years later—one mutation in each lineage

Another ten million years later—one more mutation in each lineage


**Scientists estimate mutation rates by linking molecular data and real time.

– an event known to separate species– the first appearance of a species in fossil record


Different molecules have different mutation rates.– higher rate, better for studying closely related species– lower rate, better for studying distantly related species

**Mitochondrial DNA and ribosomal RNA provide two types of molecular clocks.


**Mitochondrial DNA is used to study closely related species.

grandparents

parents

child

Nuclear DNA is inherited from bothparents, making it more difficult totrace back through generations.

Mitochondrial DNA ispassed down only from the mother of each generation,so it is not subject to recombination.

mitochondrialDNA

nuclear DNA

– mutation rate ten times faster than nuclear DNA– passed down unshuffled from mother to offspring


**Ribosomal RNA is used to study distantly related species.

– many conservative regions– lower mutation rate than most DNA


Dichotomous Keys

• Tool to determine the identity of an organism by going through a series of paired choices

• Dichotomous means "divided in two parts“• each alternative leads to another question until the

item is identified• Keys are identification tools & do not propose an

evolutionary history.


Cladogram- with shared derived characters


Where would you put a hairy, carnivorous animal without retractable claws?


Cladogram

Where would you put an animal with claws but no fur or feathers?


• What are two ways you could you find out?

Are hyenas more closely related to dogs or cats?

http://z.about.com/d/healing/1/0/f/N/gtotem_hyena.jpg


My Way or the Highway

• Categories that are used to organize an assortment of things should be valid. That is, they should be based on real information. However, categories should be useful, too. Suppose that you are taking a survey of traffic. You sit at the side of a busy intersection and record the vehicles you see in one hour.

Section 18-3Interest Grabber

Go to Section:


1. What categories could you use to organize your count of vehicles?

2.Look at your list of categories. Are all of them equally useful?

3. Is there more than one valid and useful way to organize living things?

Section 18-3

Interest Grabber continued

Go to Section:


• Kingdoms and DomainsA.The Tree of Life

Evolves

B.The Three-Domain System

C.Domain Bacteria

D.Domain Archaea

E.Domain Eukarya1. Protista

2. Fungi

3. Plantae

4. Animalia

Section 18-3

Go to Section:


Classification is always a work in progress.

The tree of life shows our most current understanding.

**New discoveries can lead to changes in classification.– Until 1866: only two kingdoms,

Animalia and PlantaeAnimalia

Plantae




New discoveries can lead to changes in classification.– Until 1866: only two kingdoms,

Animalia and Plantae

– 1866: all single-celled organisms moved to kingdom Protista

AnimaliaProtista

Plantae



• The tree of life shows our most current understanding. • New discoveries can lead to changes in classification.

– Until 1866: only two kingdoms,Animalia and Plantae

– 1938: prokaryotes moved to kingdom Monera


AnimaliaProtista

Plantae

Monera


• The tree of life shows our most current understanding. • New discoveries can lead to changes in classification.

– Until 1866: only two kingdoms,Animalia and Plantae




Monera– 1959: fungi moved to own kingdom

Fungi

Protista

Plantae

Animalia



New discoveries can lead to changes in classification.– **Until 1866: only two kingdoms,

Animalia and Plantae




– 1959: fungi moved to own kingdom

– 1977: kingdom Monerasplit into kingdoms Bacteria and Archaea

AnimaliaProtista

Fungi

Plantae

Archea

Bacteria


**rRNA research by Carl Woese revealed two genetically

Different groups of prokaryotes. This resulted in splitting the Kingdom Monera into two kingdoms; Bacteria and Archea.

His findings about the differences lead to the three domain system.


KEY CONCEPT The current tree of life has three domains.


The three domains in the tree of life are Bacteria, Archaea, and Eukarya.

Domains are above the kingdom level. – proposed by Carl Woese based on rRNA studies of

prokaryotes– domain model more clearly shows prokaryotic diversity


**Domain Bacteria includes prokaryotes in the kingdom Bacteria.

– one of largest groups on Earth

– classified by shape, need for oxygen, and diseases caused


– known for living in extreme environments

**Domain Archaea includes prokaryotes in the kingdom Archaea.

– cell walls chemically different from bacteria

– differences discovered by studying RNA


Domain Eukarya includes all eukaryotes.

– kingdom Protista



– kingdom Protista– kingdom Plantae



– kingdom Protista– kingdom Plantae– kingdom Fungi


**Domain Eukarya includes all eukaryotes.

– kingdom Protista– kingdom Plantae– kingdom Fungi– kingdom Animalia


EUKARYA (eukaryotic – one or more cells)

Kingdoms and Domains (underlined)

(extremophiles & unique bacteria)

(true bacteria)

Systems of ClassificationHierarchical Classification

•Domain•Kingdom•Phylum•Class•Order•Family•Genus•Species

Dumb Kids Playing Chicken

On Freeways Get Squashed.

With Domains = 8 levels


**Bacteria and archaea can be difficult to classify.

– transfer genes among themselves outside of reproduction

– blurs the linebetween “species”

– more researchneeded tounderstand prokaryotes

bridge to transfer DNA


Section 18-3Concept Map

are characterized by

such as

and differing which place them in

which coincides withwhich coincides with

which place them in which is subdivided into

Living Things

Kingdom Eubacteria

Kingdom Archaebacteria

Eukaryotic cellsProkaryotic cells

Important characteristics

Cell wall structures

Domain Eukarya

Domain Bacteria

Domain Archaea

Kingdom Plantae

Kingdom Protista

Kingdom Fungi

Kingdom Animalia

Go to Section:


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


Methanogens, halophiles

Protista

Eukaryote

Cell walls of cellulose in some; some have chloroplasts

Most unicellular; some colonial; some multicellular


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 18-3Figure 18-12 Key Characteristics of Kingdoms and Domains

Go to Section:


KingdomsEubacteria

Archaebacteria

Protista

Plantae

Fungi

Animalia

DOMAIN EUKARYA

DOMAIN ARCHAEA

DOMAIN BACTERIA

Section 18-3Figure 18-13 Cladogram of Six Kingdoms and Three Domains

Go to Section:


• What are the three domains of life?


Human Classification

Homework: Complete a full classification list for humans. Include the eight taxa in order and name of each group that humans belong.


Full classification of human

• Domain Eukarya• Kingdom Animalia• Phylum Chordata• Class Mammalia• Order Primates• Family Hominidae• Genus Homo• Species sapien

systems of classification order from chaos when you need a new pair of shoes, what do you do? you...

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