Transcript Classification of Organisms

Classification of Organisms
Classification of Organisms
• The study of the kinds and diversity of
organisms and their evolutionary relationships
is called systematics or taxonomy
▫ Taxonomy is the work involved in the original
description of a species.
▫ Systematics is the assigning of species into
evolutionary groups.
Father of Modern Classification
• The modern classification system originated with
the work of Carolus Linnaeus
▫ he recognized the different species could be grouped
into broader categories based on shared
characteristics
▫ any grouping of animals that shares a particular set
of characteristics forms an assemblage called a
taxon
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CLASSIFICATION
• OBSERVATION:
• Many kinds of organisms:
• Some similar to each other.
▫ wood frog,
▫ leopard frog,
▫ bull frog
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CLASSIFICATION
• Others less similar
▫ fish,
▫ frogs,
▫ snakes
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CLASSIFICATION
• Others very dissimilar
▫ people,
▫ pine trees,
▫ protozoans
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CLASSIFICATION
• Why are some kinds similar and others
NOT similar?
 Question to be answered later?
• How can we make sense of (explain) this
diversity?
• How can we organize what we know about
these organisms?
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Answer: CLASSIFY
• Similar “types” (species) grouped together,
separated from other species.
• Then, group similar groups together,
• etc.
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CLASSIFICATION
• Species = kind of organism
▫ fundamental unit in evolution and ecology
▫ more precise definition soon
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CLASSIFICATION
• Necessary? YES !!
~ 1 million species of plants,
5-10 million species of animals
+ fungi, protists, bacteria
no good estimates of numbers of species
• Human mind needs to organize information.
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CLASSIFICATION
• Classification system organizes biological
knowledge.
• Classification itself is HYPOTHESIS about
relationships, similarity because of common
ancestry.
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HYPOTHESIS of relationship
Modern taxonomists use 7 taxa:
• kingdom, phylum, class, order, family, genus
and species
▫ as taxa increase organisms get more specific
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CLASSIFICATION = Sequence of levels.
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Linnaean system, from Carolus Linnaeus, 1740's
Kingdom
Phylum
Class
Order
Family
Genus
Species
King Phil called old fat George stupid.
Kingdoms and Domains
The three-domain system
Bacteria
Archaea
Eukarya
The six-kingdom system
Bacteria
Archaea
Protista
Plantae
Fungi
Animalia
Plantae
Fungi
Animalia
The traditional five-kingdom system
Monera
Protista
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CLASSIFICATION
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Woese, 1985
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Did King Phil call old fat George stupid ?
Kingdoms of Life
• In 1969, Robert H. Whitaker classified kingdoms
based on cellular organization and mode of
nutrition
▫ this lead to the formation of the 5 kingdoms
5 Kingdoms of Classification:
Monera: comprised of bacteria and cyanobacteria
• distinguished by being single cell prokaryotes
Protista: comprised of Amoeba, Paramecium etc….
• distinguished by being single celled eukaryotes
Plantae: multi-cellular photosynthetic eukaryotes
• plants have cell walls and are non-motile
5 Kingdoms of Classification:
Fungi: multi-cellular heterotrophic eukaryotes
• fungi have cell walls and usually non-motile
• digest organic matter extra-cellularly (outside of
cell) and absorb the breakdown products
Animalia: multi-cellular heterotrophic
eukaryotes
• animal cells lack a cell wall and usually motile
• feed by ingesting other organisms or parts of
other organisms
Monera
prokaryote
single-cell
Protista
eukaryote
multi-cell
Plantae
eukaryote
multi-cell
autotrophic
Fungi
eukaryote
multi-cell
heterotrophic,
external digestion
Animalia
eukaryote
multi-cell
heterotrophic,
internal digestion
DOMAINS???
• Many taxonomists have pushed the idea that the
five kingdom system isn’t enough
▫ they feel that organisms share too much
similarities and need to be grouped otherwise
• the push has led to the addition of 3 domains
3 Domains
1. Archae: bacteria that live in extreme
conditions
2. Eubacteria: “true bacteria”
3. Eukarya: all eukaryotic organisms
Taxonomic Diagrams
Mammals
Turtles
Lizards and
Snakes
Crocodiles
Phylogenetic
Tree
BioEd Online
Birds
Mammals
Turtles
Lizards and
Snakes
Crocodiles
Cladogram
Birds
Binomial Nomenclature:
• when a species is talked about only the genus and
species names are used
▫ this is called the scientific name
▫ unique to each type of organism
• Required by the International Code of
Zoological Nomenclature
Writing Scientific Names
• the genus names is always capitalized
• both names are either italicized or underlined
▫ leave a space in the underline between names
ex. Homo sapien
Felis leo
Quercus rubra
Ursus americanus
American Black Bear
Often Latin names contain clues about the type of organism being described.
Canis domesticus :And closely related organisms are often in the same genus, also giving clues about
their names
Canis lupus: Some names are given after the discoverer, or the discovery location, or even a Latinized
descriptive term in English
Conclusion
The classification system for organisms
have been around for a long time. It has
endured several changes and is quite
complex. Without it modern biology could
not exist, much in the same way that
a grocery store would go out of business
if it did not have a classification system.