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CHAPTER 17
Taxonomy
Early Classification
Aristotle’s System
• Developed BCE, 1st common classification system
• Classified organisms as either animals or plants
• Animals divided:
• Presence or absence of “red blood”
• By habitat & morphology
• Plants classified by avg. size and structure
Linnaeus’s System
• 1st formal taxonomy system
• Hierarchical classification
Perching bird
Bird of prey
Wading bird
Binomial Nomenclature (Linnaeus)
• 2 part naming
• 1st Genus (capitalized)
• 2nd specific epithet (species)
• Homo sapien, Canis lupus
• Italicize in print, underline if handwritten
• After 1st instance abbreviate Genus (H. sapien)
Why use scientific names?
• Vary too much, too inaccurate
• Language, region, misnomers like catfish…
Ursus americanus
American black bear
The thing that ate Uncle Ned
un ours noir
Taxonomic Categories
• Nested hierarchy
• Like Russian nesting dolls
Taxa = group or organisms
• Genus
• Closely related species, have common ancestor
• Family
• Closely related/similar Genera
• Order
• Closely related/similar Families
• Class
• Closely related/similar Orders
• Phylum
• Closely related/similar Classes
• Kingdom
• Closely related/similar Phyla
17-2 Modern Classification
• Typological species concept
• AKA morphological
• Uses physical characters of specimens
• Older, still good for fossils/asexual organisms
• Assumes species are physically distinct
Biological Species Concept
• A species is a group of organisms that is able to
interbreed and produce fertile offspring in a
natural setting
Phylogenetic Species Concept
• Phylogeny = evolutionary history
• A species is a cluster of organisms that is distinct
from other clusters and shows evidence of a
pattern of ancestry and descent
Review
Characters
• Morphological or biochemical markers
• Used to find/track evolutionary history
• Shared character = homologous (related)
or analogous (unrelated)
• Shared DNA/Protein = more related
Haliaeetus
leucocephalus
• Ex: birds and dinosaurs
• Hollow bones
• Similar shoulder/wrist/leg structure
• Some dinosaurs had feathers
Oviraptor
philoceratops
Finding Shared Ancestry
• Chimps, gorillas and orangutan have similar
chromosomes and DNA; are closely related
Molecular Clock
• Uses mutation in
Nucleotides/Amino acids
• More mutations = more distantly
related
• Rate of mutation can give a
timeline
• Rate affected by:
• Mutation type
• Mutation location (in DNA)
• Protein coded for, etc.
Cladistics
• Reconstruct phylogeny using characters
• Ancestral characters shared by all group members
• Derived characters separates out new groups
within the clade (not everyone has it)
• Represented visually by cladogram
• More shared derived characters more recent
common ancestor
Cladogram
17-3 Grouping Species
 The broadest category = domain
 Most accepted classification system has 6
kingdoms and 3 domains.
 3 domains are Bacteria, Archaea, and Eukarya
 6 kingdoms are Bacteria, Archaea, Protists,
Fungi, Plantae, and Animalia.
Domain Bacteria
 Eubacteria are prokaryotes
whose cell walls contain
peptidoglycan.
 Eubacteria are a diverse
group that can survive in
many different environments.
Classifying Using
Biotechnology
Domain Archaea
 Archaea are thought to be more ancient than
bacteria and yet more closely related to our
eukaryote ancestors.
 Archaea are diverse in shape and nutrition
requirements.
 They are called extremophiles because they
can live in extreme environments.
Domain Eukarya
 All eukaryotes are classified in Domain
Eukarya.
 Domain Eukarya contains Kingdom Protista,
Kingdom Fungi, Kingdom Plantae, and
Kingdom Animalia.
Kingdom Protista
 Protists are eukaryotic organisms that can be
unicellular, colonial,
or multicellular.
 Protists are classified
into three different
groups—plantlike,
animal-like, and
funguslike.
Kingdom Fungi
 A fungus is a unicellular or multicellular
eukaryote that absorbs
nutrients from organic
materials in its
environment.
 Member of Kingdom
Fungi are
heterotrophic, lack motility, and have cell walls.
Kingdom Plantae
 Members of Kingdom Plantae form the base
of all terrestrial habitats.
 All plants are
multicellular and have
cell walls composed of
cellulose.
 Most plants are
autotrophs, but some are heterotrophic.
Kingdom Animalia
 All animals are heterotrophic, multicellular
eukaryotes.
 Animal organs often are
organized into complex
organ systems.
 They live in the water,
on land, and in the air.
Viruses—An Exception
 A virus is a nucleic acid surrounded by a
protein coat.
 Viruses do not possess cells, nor are they
cells, and are not considered to be living.
 Because they are nonliving, they usually
are not placed in the biological
classification system.