Chapter 17 171 The Linnaean System of Classification KEY CONCEPT Organisms can be classified based on physical similarities vocabulary Taxonomy Taxon Binomial nomenclature genus Linnaeus developed the scientific naming system still used today ID: 910962
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Slide1
Classification and Diversity
Chapter 17
Slide217-1 The Linnaean System of Classification
Slide3KEY CONCEPT
Organisms can be classified based on physical similarities.
Slide4vocabulary
Taxonomy
Taxon
Binomial nomenclature
genus
Slide5Linnaeus 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
Slide6Linnaean taxonomy classifies organism based on their physical and structural similarities
Organisms are placed into different levels in a hierarchy
Slide7Binomial nomenclature
is a two-part scientific naming system.
uses Latin words
scientific names always written in italics (underline if written)
two parts are the genus name and species descriptor
Slide8A
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
Slide9Scientific names help scientists to communicate.
Some species have very similar common names.
Some species have many common names.
Slide10Linnaeus’ classification system has seven levels.
Each level is included in the level above it.
Levels get increasingly specific from kingdom to species.
Slide11Slide12The 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.
Slide13Physical similarities are not always the result of close relationships.
Genetic similarities more accurately show evolutionary relationships.
Slide1417-2 Classification Based on Evolutionary Relationships
Slide15KEY CONCEPT
Modern classification is based on evolutionary relationships.
Slide16vocabulary
Phylogeny
Cladistics
Cladogram
Derived character
Slide17Cladistics 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
Slide18Cladistics
is a common method to make evolutionary trees.
classification based on common ancestry
species placed in order that they descended from common ancestor
Slide19A
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.
Slide20Derived 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 clade
1
Amniota clade
2
Reptilia clade
3
Diapsida clade
4
Archosauria clade
5
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
Slide21FOUR 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 clade
1
Amniota clade
2
Reptilia clade
3
Diapsida clade
4
Archosauria clade
5
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
Slide22Molecular evidence reveals species’ relatedness.
Molecular data may confirm classification based on physical similarities.
Molecular data may lead scientists to propose a new classification.
DNA is usually given the last word by scientists.
Slide23Slide24KEY CONCEPT
Molecular clocks provide clues to evolutionary history.
Slide25Molecular 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 ancestorThe DNA sequences from two
descendant species show mutations
that have accumulated (black).
The mutation rate of this
sequence equals one mutation
per ten million years.
Mutations add up at a fairly
constant 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
Slide26Scientists 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
Slide27Different 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.
Slide28Mitochondrial DNA is used to study closely related species.
grandparents
parents
child
Nuclear DNA is inherited from both
parents, making it more difficult to
trace back through generations.
Mitochondrial DNA is
passed down only from
the mother of each generation,so it is not subject to recombination.
mitochondrial
DNA
nuclear DNA
mutation rate ten times faster than nuclear DNA
passed down unshuffled from mother to offspring
Slide29Ribosomal RNA is used to study distantly related species.
many conservative regions
lower mutation rate than most DNA
Slide30Domains and Kingdoms
Slide31KEY CONCEPT
The current tree of life has three domains.
Slide32vocabulary
Bacteria
Archaea
Eukarya
Slide33Classification 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
Slide34Classification 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 Plantae
1866: all single-celled organisms moved to kingdom Protista
Animalia
Protista
Plantae
Slide35Classification 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 Plantae
1938: prokaryotes moved to kingdom Monera
1866: all single-celled organisms moved to kingdom Protista
Animalia
Protista
Plantae
Monera
Slide36Classification 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 Plantae
1938: prokaryotes moved to kingdom Monera
1866: all single-celled organisms moved to kingdom Protista
Monera
1959: fungi moved to own kingdom
Fungi
Protista
Plantae
Animalia
Slide37Classification 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 Plantae
1938: prokaryotes moved to kingdom Monera
1866: all single-celled organisms moved to kingdom Protista
1959: fungi moved to own kingdom
1977: kingdom Monera
split into kingdoms Bacteria and Archaea
Animalia
Protista
Fungi
Plantae
Archea
Bacteria
Slide38The 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 prokaryotesdomain model more clearly shows prokaryotic diversity
Slide39Domain
Bacteria
includes prokaryotes in the kingdom Bacteria.
one of largest groups on Earth
classified by shape, need for oxygen, and diseases caused
Slide40Prokaryotes
unicellular
Anaerobic and aerobic
Some are photosynthetic or chemosynthetic
Reproduce asexuallyAbout 5,000 known species, probably many unknown
Slide41Borrelia burgdorferi
Staphylococcus
Slide42Prokaryotes
Includes aerobic and anaerobic bacteria
Often live in extreme environments like high temperatures, high acidity, or high salt content
Asexual reproduction only
Domain
Archaea
includes prokaryotes in the kingdom Archaea.
cell walls chemically different from bacteria
Slide43fewer species than any other kingdom, less than 100
Three broad groups of
Archaebacteria
Slide44Domain Eukarya includes all eukaryotes
.
kingdom Protista
Slide45Domain Eukarya includes all eukaryotes.
kingdom Protista
kingdom Plantae
Slide46Domain Eukarya includes all eukaryotes.
kingdom Protista
kingdom Plantae
kingdom Fungi
Slide47Domain Eukarya includes all eukaryotes.
kingdom Protista
kingdom Plantae
kingdom Fungi
kingdom Animalia
Slide48Eukaryotic cells
Mostly multi-celled
Producers or consumers
Slide49Protists
Slide50Slide51Slide52Fungi
Slide53Slide54Plants
Slide55Slide56Animals
Slide57Major Phyla (under Animalia) -
Slide58Invertebrates Phyla
Sponges, Cnidarians, flatworms, and round worms
Slide59Sponges
Slide60Cnidarians
Slide61Flatworms
Slide62Roundworms
Slide63Mollusks and Segmented Worms
Slide64Slide65Slide66Arthropods
Slide67Slide68Slide69Echinoderms and Invertebrate Chordates
Slide70Slide71Slide72Vertebrates
Include Fishes, amphibians, reptiles, birds, and mammals
Slide73Fish
Slide74Slide75Amphibians
Slide76Slide77Reptiles
Slide78Slide79Slide80Birds
Slide81Slide82Slide83Mammals
Slide84Slide85Slide86