Taxonomy and Phylogeny
SB3. Students will derive the relationship between single-celled
and multi-celled organisms and the increasing complexity of
systems.
b. Compare how structures and function vary between the six kingdoms
(archaebacteria, eubacteria, protists, fungi, plants, and animals).
c. Examine the evolutionary basis of modern classification systems.
Taxonomy
Taxonomy is the science of classification and
nomenclature, especially of organisms
How do scientists classify organisms?
•by their morphology– how they look
•by their phylogeny– their evolutionary relationships
•by their DNA
In a lot of ways, classification is like sorting
the organisms.
Autotrophs
heterotrophs
Cell wall
No cell wall
History of Taxonomy
• Aristotle (350 BC)
– 2 groups: plants and animals; vertebrates and
invertebrates
• Carl Linnaeus (1735)
– Developed the hierarchy of classification
– Developed a standardized binomial
nomenclature
Hierarchy of Classification
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Kingdom
Phylum
Class
Order
Family
Genus
Species
General, Inclusive
Specific, Exclusive
“Kings Play Chess on Fluffy Green Sofas”
How was life grouped?
• Plantae and Animalia (1735)
• Plantae, Animalia, and Protista (1866)
• Plantae, Animalia, Protista and Monera
(1938)
• Plantae, Animalia, Protista, Monera, and
Fungi (1969)
• Plantae, Animalia, Protista, Eubacteria,
Archaebacteria, and Fungi (1977)
How is life grouped now?
• Domains Bacteria, Archaea, Eukaryota
(1990) now incorporate the kingdoms
• Bacteria (Eubacteria)
• Archaea (Archaebacteria)
• Eukaryota
– Protista
– Fungi
– Plantae
– Animalia
An example…
• In the ONE Kingdom Animalia…
– There are over 7,700,000 different kinds of
animals
• So the kingdom is subdivided into at least
30 phyla
– The largest phylum is Arthropoda, which
contains ~85% of all animals
• So the phylum is subdivided into ~15
classes
– The largest class is Insecta, which includes
over 5 million different creatures
An example…
• So the class is divided into ~34 orders
– The largest order is Coleoptera (beetles),
which includes 25% of all animal types
• So the order is divided into ~170 families
– One of the families, Coccinellidae (lady
beetles), includes about 5000 types
• So the family is divided into ~360 genera
– One genus, called Coccinella, includes about
6000 different types, or species
– Coccinella septempunctata
Kingdom
Phylum
Class
Order
Family
Genus
Species
Animalia
Arthropoda
Insecta
Hymenoptera
Apidae
Apis
mellifera
What organism do you think this might be?
Kingdom
Phylum
Class
Order
Family
Genus
Species
Animalia
Chordata
Mammalia
Primates
Hominidae
Homo
sapiens
What organism do you think this might be?
Writing a scientific name
• Always use genus & species names.
• Must be underlined (in books they’re in italics)
• Genus name is capitalized, species name is not!
Examples:
Homo sapiens
Escherichia coli
Pinus aristata
Canis lupus
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Panthera leo
Panthera tigris
Panthera pardus
Canis lupus (and Canis domestica)
Pan troglodytes
Ovis aries
Rattus norvegicus ; Rattus rattus
Perca fluviatalis
Carcharodon carcharias
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Boa constrictor
Gorilla
Giraffus
Hippopotamus amphibius
Bison bison
Equus zebra
Tyrannosaurus rex
Elephas maximus
What makes a species?
• Look similar, have similar traits, and
similar habitats.
• Can interbreed and produce fertile
offspring.
Housecat
Mountain Lion
Kingdom
Animalia
Animalia
Phylum
Chordata
Chordata
Class
Mammalia
Mammalia
Order
Carnivora
Carnivora
Family
Felidae
Felidae
Genus
Felis
Felis
Species
domesticus
concolor
Sometimes hybrids can form.
• A hybrid is a cross between two very
similar organisms– in all the same groups
except for species.
• Example: horse + donkey = mule
• Mules cannot produce their own offspring.
The Phylogenetic Tree of Life
Cladistics
• Cladistics is a method of classifying
organisms based on shared characteristics
that can be traced to common ancestors
Cladistics
• Here is an example of a cladogram for
vertebrates
Cladistics
• Let’s see how to put one together…
https://www.youtube.com/watch?v=46L_2RI1k3k
Archaea
• Prokaryotes
• Ancient bacteria
Able to survive harsh environments
Thermoacidophiles: heat & acid
Methanogens: methane
halophiles: salt
Bacteria
• Prokaryotes
• Typical bacteria
Protista (every living thing that is NOT a
bacterium, fungus, plant, or animal)
Protists are classified according to how they
acquire nutrients:
• animal-like: heterotrophic,
predatory
• plant-like: photosynthetic
• fungus-like: heterotrophic, absorptive
Fungi– heterotrophic, cell walls of
chitin, uni- & multicellular
yeast
Plantae– autotrophic, cell walls of
cellulose, most are multicellular
Animalia– all multicellular,
heterotrophic, no cell walls