Transcript Biology - Earth science

CHAPTER 18
Natural selection has led to great diversity.
• 1.5 million species so far
• 2–100 million yet to be discovered
Classification is a way to group species in
a logical manner.
Taxonomy, a system to classify
organisms. Each organism is given a
biologically significant name (that deals
with their characteristics).
Why Assign Scientific Names?
Common names vary
The cougar is also known as the puma,
mountain lion, mountain cat, catamount
and panther.
Carolus Linneaus developed a naming
system called binomial nomenclature.
In binomial nomenclature, each species is
assigned a two-part scientific name.
The scientific name is italicized.
Linnaeus's not only named species, he also
grouped them into categories (taxa).
Latin and Greek, are used
for scientific names.
The first part = genus name (Capitalized).
A genus is a group of closely related
species.
The second part = species name (lowercase).
The species name often describes an
important trait or where the organism lives.
Linnaeus’s seven levels of
classification are—from largest to
smallest—
•Kingdom - largest
•Phylum
•Class
•Order
•Family
•Genus
•Species – most specific
King Phillip Could Only
Find Green Socks
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Species = smallest, most specific category. It
includes organisms that can breed together and
produce fertile offspring.
A genus contains closely related species
that cannot breed successfully.
Grizzly
bear
Black
bear
Genera that share many characteristics are
grouped in a larger category, the family.
Grizzly
bear
Black
bear
Giant
panda
An order is a broad category composed of
similar families.
Grizzly
bear
Black
bear
Giant
panda
Red
fox
The next larger category, the class, is
composed of similar orders.
Grizzly
bear
Black
bear
Giant
panda
Class Mammalia
Red
fox
Abert
squirrel
Several different classes make up a
phylum.
Grizzly
bear
Black
bear
Giant
panda
PHYLUM
Red
fox
Chordata
Abert
squirrel
Coral
snake
The kingdom is the largest and most
inclusive of Linnaeus's taxonomic
categories.
Grizzly
bear
Black
bear
Giant
panda
Red
fox
Abert
squirrel
KINGDOM Animalia
Coral
snake
Sea
star
Grizzly Black Giant
bear
bear panda
Coral Sea
Red Abert
fox squirrel snake star
Linnaeus grouped species into larger taxa
according to visible similarities and
differences.
Now we group organisms based on
evolutionary descent (or phylogeny) not
just physical similarities.
Grouping organisms based on
evolutionary history is called evolutionary
classification.
Phylogeny is the study of evolutionary
relationships among organisms.
18-2 Modern Evolutionary
Classification
•Cladistic analysis considers only
new characteristics that arise
(called derived characters).
• Characteristics that appear in recent parts
of a lineage (line) but not in its older
members are called derived characters.
Derived characters can be used to construct a
cladogram, a diagram that shows the
evolutionary relationships among a group of
organisms.
Cladograms help scientists understand
how one lineage branched from another in
the course of evolution.
Barnacles and crabs share an evolutionary
ancestor that is more recent than the
ancestor that barnacles and limpets share.
Crustaceans
Crab
Mollusk
Barnacle
Limpet
Molted external skeleton
Segmentation
Tiny free-swimming larva
DNA Evidence
• DNA evidence shows evolutionary
relationships of species.
•The more similar the DNA of two
species, the more recently they
shared a common ancestor, and
the more closely they are related
in evolutionary terms.
• The more two species have diverged from
each other, the less similar their DNA is.
Molecular Clocks
• A molecular clock uses DNA
comparisons to estimate the length of
time that two species have been
evolving independently.
Molecular Clocks
A gene in an
ancestral species
2 mutations
new
mutation
Species
A
2 mutations
new
new
mutation mutation
Species
B
Species
C
A molecular clock relies on mutations to
mark time.
Comparing sequences in two species
shows how dissimilar the genes are, and
shows when they shared a common
ancestor.
The Tree of Life Evolves
• Classification systems change with new
discoveries.
• Linnaeus classified organisms into two
kingdoms—animals and plants.
Then new differences called for a 5 kingdom
system:
• Monera
• Protista
• Fungi
• Plantae
• Animalia
Now we have a Six Kingdom System
• Recently, biologists recognized that
Monera were composed of two distinct
groups: Eubacteria and Archaebacteria.
The six-kingdom system of classification
includes:
•Eubacteria
•Archaebacteria
•Protista
•Fungi
•Plantae
•Animalia
Changing Number of Kingdoms
Names of Kingdoms
Introduced
1700’s
Late 1800’s
1950’s
1990’s
Plantae
Plantae
Protista
Monera
Eubacteria
Archaebacteria
Animalia
Animalia
Protista
Fungi
Plantae
Animalia
Protista
Fungi
Plantae
Animalia
The Three-Domain System
•Molecular analyses have given
rise to the three-domain system
of taxonomy that is now recognized
by many scientists.
• The domain is a more inclusive category
than any other—larger than a kingdom.
The three domains are:
•Eukarya, which is composed of
protists, fungi, plants, and animals.
•Bacteria, which corresponds to
the kingdom Eubacteria (true
bacteria).
•Archaea, which corresponds to
the kingdom Archaebacteria.
Modern classification is a rapidly changing
science.
As new information is gained about
organisms in the domains Bacteria and
Archaea, they may be subdivided into
additional kingdoms.
Size Comparison of Select Organisms
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Domain Bacteria
• Members of the domain Bacteria are
unicellular prokaryotes.
• Their cells have thick, rigid cell walls
that surround a cell membrane.
• Their cell walls contain peptidoglycan.
Bacteria
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Domain Bacteria
The domain
Bacteria
corresponds to
the kingdom
Eubacteria.
Domain Archaea
Domain Archaea
• Members of the domain Archaea are
unicellular prokaryotes.
•Archaea live in extreme
environments.
• Their cell walls lack peptidoglycan, and
their cell membranes contain unusual
lipids not found in any other organism.
Domain Archaea
The domain
Archaea
corresponds to
the kingdom
Archaebacteria.
Domain Eukarya
•The domain Eukarya consists of
organisms that have a nucleus.
•Eukarya includes the kingdoms
•Protista
•Fungi
•Plantae
•Animalia
Domain Eukarya
Domain Eukarya
Protista
• The kingdom Protista is composed of
eukaryotic organisms that cannot be
classified as animals, plants, or fungi.
• Its members display the greatest variety.
• They can be unicellular or multicellular;
photosynthetic or heterotrophic; and
can share characteristics with plants,
fungi, or animals.
Common Protista
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Fungi
•Members of the kingdom Fungi
are heterotrophs with cell walls
that contain chitin.
• Most fungi feed on dead or decaying
organic matter by secreting digestive
enzymes into it and absorbing small
food molecules into their bodies.
• They can be either multicellular
(mushrooms) or unicellular (yeasts).
FUNGI
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Domain Eukarya
Plantae
• Members of the kingdom Plantae are
multicellular, photosynthetic autotrophs.
• Plants are nonmotile—they cannot move
from place to place.
• Plants have cell walls that contain
cellulose.
• The plant kingdom includes conebearing and flowering plants as well as
mosses and ferns.
Plant Kingdom
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Domain Eukarya
Animalia
• Members of the kingdom Animalia are
multicellular and heterotrophic.
• The cells of animals do not have cell
walls.
• Most animals can move about.
• There is great diversity within the animal
kingdom, and many species exist in
nearly every part of the planet.
Animal Kingdom
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Which statement about classification is true?
a. Biologists use regional names for
organisms.
b. Biologists use a common classification
system based on similarities that have
scientific significance.
c. Biologists have identified and named
most species found on Earth
d. Taxonomy uses a combination of
common and scientific names to make the
system more useful.
Linnaeus's two-word naming system is
called
a. binomial nomenclature.
b. taxonomy.
c. trinomial nomenclature.
d. classification.
Several different classes make up a(an)
a. family.
b. species.
c. kingdom.
d. phylum.
A group of closely related species is
a(an)
a. class.
b. genus.
c. family.
d. order.
Which of the following lists the terms in
order from the group with the most
species to the group with the least?
a. order, phylum, family, genus
b. family, genus, order, phylum
c. phylum, class, order, family
d. genus, family, order, phylum
Grouping organisms together based on
their evolutionary history is called
a. evolutionary classification.
b. traditional classification.
c. cladogram classification.
d. taxonomic classification.
Traditional classification groups
organisms together based on
a. derived characters.
b. similarities in appearance.
c. DNA and RNA similarities.
d. molecular clocks.
In an evolutionary classification
system, the higher the taxon level,
a. the more similar the members of the
taxon become.
b. the more common ancestors would
be found in recent time.
c. the fewer the number of species in
the taxon.
d. the farther back in time the common
ancestors would be.
Classifying organisms using a
cladogram depends on identifying
a. external and internal structural
similarities.
b. new characteristics that have
appeared most recently as lineages
evolve.
c. characteristics that have been
present in the group for the longest
time.
d. individual variations within the
group.
To compare traits of very different
organisms, you would use
a. anatomical similarities.
b. anatomical differences.
c. DNA and RNA.
d. proteins and carbohydrates.
Organisms whose cell walls contain
peptidoglycan belong in the kingdom
a. Fungi.
b. Eubacteria.
c. Plantae.
d. Archaebacteria.
Multicellular organisms with no cell
walls or chloroplasts are members of
the kingdom
a. Animalia.
b. Protista.
c. Plantae.
d. Fungi.
Organisms that have cell walls
containing cellulose are found in
a. Eubacteria and Plantae.
b. Fungi and Plantae.
c. Plantae and Protista.
d. Plantae only.
Molecular analyses have given rise to a
new taxonomic classification that
includes
a. three domains.
b. seven kingdoms.
c. two domains.
d. five kingdoms.
Which of the following contain more
than one kingdom?
a. only Archaea
b. only Bacteria
c. only Eukarya
d. both Eukarya and Archaea