Transcript Taxonomy - Austin Community College

Taxonomy
BIOL 1407
What is taxonomy?
• Naming and classification of organisms
• Traditionally based on system
developed by Carolus Linnaeus
Two Components to Linnaean
System
• Idea of binomial nomenclature – naming
organisms
• Idea of hierarchy – classifying
organisms into groups
Binomial Nomenclature
• Idea is that each species is assigned a
unique name
• Name has two parts: a genus name
and a specific epithet
• Together, the two words make up the
scientific name of the species
Binomial Nomenclature
• Allows clear communication between
different researchers
• Prevents confusion that can occur from
use of common names
Example
• Scientific Name:
Yucca filamentosa
• Common Names:
Bear grass, Adam’s
needle, Weak-leaf
yucca
•
Picture Credit: Larry Allain @ USDANRCS PLANTS Database
Scientific Names: General Guidelines
• Scientific names are based on Latin.
• Scientific names are always italicized
(when printed) or underlined (when
hand-written)
• Modern scientific names follow
international guidelines
Scientific Names: General Guidelines
• Different species with the same genus
name are considered to be more closely
related to each other than to other
species.
• Genus name is always capitalized;
specific epithet is always lower-case.
Example
•
•
•
•
•
Panthera leo – lion
Panthera onca – jaguar
Panthera pardus – leopard
Uncia uncia – snow leopard
Lions, jaguars and leopards are more
closely related to each other than to
snow leopards.
Scientific Names: General Guidelines
• Some scientific names,
especially older ones,
include the name of the
person who discovered or
described the species.
• Example: The Tibetan
antelope Pantholops
hodgsonii was named for the
19th century British naturalist
who discovered it, Brian
Houghton Hodgson.
•
Picture Credit: Rhett A. Butler, mongabay.com
General Naming Guidelines
• Other scientific names
refer to a region, such
as Didelphis virginiana
(Virginia opossum)
•
Picture Credit: Alden M. Johnson @
California Academy of Sciences
General Naming Guidelines
• Scientific names often
include some feature or
trait of the species. The
specific epithet for the
hairy bush clover,
Lespedeza hirta, refers
to its “hairy” stem.
•
Picture Credit: Tom Barnes, University of
Kentucky
Scientific Names
Poison Arrow Frog
Dendrobates
azureus
“Blue Tree-Walker”
•
Picture Credit: Jessie Cohen,
Courtesy of Smithsonian National
Zoo @ nationalzoo.si.edu
Scientific Names
Giant Anteater
Myrmecophaga
tridactyla
“Eater of ants,
with three
fingers”
Picture Credit: Courtesy of
Smithsonian National Zoo @
nationalzoo.si.edu
Taxonomic Hierarchy
• Linnaeus classified organisms into
groups, based on shared characteristics.
• There were different levels of groups.
• Each level nests within the group above.
• In his system, the Kingdom was the most
inclusive. Successive groups contain
fewer and fewer organisms.
Linnaean Hierarchy
• Kingdom (most
general)
• Phylum
• Class
• Order
• Family
• Genus
• Species (unique)
Two Kingdom System
• Linnaeus classified organisms into two
kingdoms: Plantae and Animalia
• Plants, fungi, photosynthetic protists
were all included into Plantae
• Animals, heterotrophic protists (such as
Amoeba) were included into Animalia
• This system was revised several times.
Five Kingdom System
• Proposed by Whittaker in 1968
• Kingdom Monera – prokaryotes
• Kingdom Protista – protists (eukaryotes
that were not plants or animals or fungi)
• Kingdom Plantae – plants
• Kingdom Fungi – fungi
• Kingdom Animalia – animals
Five
Kingdom
Classification
Scheme
Research by Carl Woese
• Research done by Carl Woese in the
1980s with rRNA comparisons showed
that all prokaryotes are not closely
related.
• Prokaryotes are divided into two groups:
true bacteria and archaeans (formerly
called archaebacteria)
rRNA Comparisons
• Based on rRNA, plants, animals and
fungi share more similarities with each
other than with bacteria or archaeans
• All eukaryotes share more similarities
with each other than with prokaryotes
• Archaeans share more similarities with
eukaryotes than with bacteria
Domains
• Based on rRNA studies, Woese
proposed a Three Domain System
• Domain Bacteria – “true” bacteria
(prokaryotes)
• Domain Archaea – archaeans
(prokaryotes)
• Domain Eukarya – eukaryotes
Modern Taxonomic Hierarchy
• Domains are the highest level (most
inclusive), above Kingdoms.
• Kingdom Monera is no longer used.
• Kingdom Protista is no longer used.
• Kingdoms Plantae, Fungi and Animalia
are still in use.
Modern Taxonomy
• Modern taxonomy is in a state of flux.
• As genomes are sequenced for different
organisms, evolutionary relationships
often become more clear. Taxonomy
should reflect those relationships.
• Expect major changes in taxonomy over
the next several years.
Three Domains
Three
Domains
Modern Taxonomic Hierarchy
Modern
Taxonomic
Hierarchy
Example: Giant Anteater
Myrmecophaga tridactyla
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Xenarthra
Family:
Myrmecophagidae
Genus: Myrmecophaga
Species:
Myrmecophaga
tridactyla
Categories and Taxa
• In this hierarch of classification, the different
levels are categories.
• A named group at a level is called a taxon
(plural = taxa).
• The giant anteater is in Class Mammalia.
Class is the category; Mammalia is the taxon.
• The giant anteater is in Family
Myrmecophagidae. Family is the category;
Myrmecophagidae is the taxon.
The End
Unless otherwise specified, all images in this presentation came from:
Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.