Transcript Chapter 13
Chapter 13
Lecture Outline
Plant Names and
Classification
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Outline
Introduction
Development of the Binomial System of
Nomenclature
• Linnaeus
• The International Code of Botanical Nomenclature
Development of the Kingdom Concept
Classification of Major Groups
The Species Concept
Introduction
All living organisms given two-word Latin
scientific name = species name.
• Only one correct scientific name for a species.
• Many common names may be given to same
species.
–
Dicentra cucullaria - Many common names:
Dutchman’s breeches, little-boy’s breeches,
monkshood, boys-and-girls, soldier’s cap, white
hearts,…, plus others in different languages
• Or one common name may be applied to a
number of different species.
–
Monkshood is common name for Dicentra cucullaria and
for Aconitum species, which is in a different family.
Development of the Binomial System of
Nomenclature
First attempt to organize and classify plants
by Theophrastus in 4th century B.C.
• Classified nearly 500 plants by leaf characteristics
13th century - Distinction made between
monocots and dicots.
Beginning of 18th century - Details of fruit and
flower structure, in addition to form and habit,
used in classification schemes.
• Latin phrase name given to plants and animals.
–
First word of phrase indicated genus (plural: genera).
Development of the Binomial System of
Nomenclature
Carolus Linnaeus (1707–1778) - Established
Binomial System of Nomenclature
• Published Species
Plantarum, 1753
• Changed the Latin
phrases to reflect
relationships and
placed one to many
species in each
genus
–
Abbreviated names to
two parts (binomials)
Development of the Binomial System of
Nomenclature
Binomial System
of Nomenclature
• All species named
according to this
system, which
includes authority
for species name.
–
Spearmint:
Mentha spicata L.
The International Code of Botanical
Nomenclature
Book that standardizes rules governing the
naming and classification of plants
• Agreed that Linnaeus is starting point for names
• Rules revised and expanded at periodic international
botanical congresses.
• Has English, French and German translations
• Requires two steps to officially recognize new plant
species:
–
Latin description of plant must be published in a journal or
other public publication.
–
Author must designate type specimen that is deposited in a
herbarium.
Development of the Kingdom Concept
When classification schemes first developed,
organisms placed in either Plant Kingdom or
Animal Kingdom.
• The distinction works well for complex animals,
but not for simpler organisms.
Hogg and Haeckel proposed a third kingdom
in 1860’s.
• All organisms that did not develop complex
tissues were placed in Kingdom Protoctista.
Development of the Kingdom Concept
In 1938, Copeland assigned single-celled,
prokaryotic organisms to Kingdom Monera,
leaving algae, fungi and single-celled
eukaryotic organisms in Protoctista.
In 1969, Whittaker developed five-kingdom
system.
• Split Fungi from Kingdom Protista
In 1980s, Woese argued Monera should be
split into Archaea and Bacteria, resulting in
six kingdoms:
• Archaea, Bacteria, Protista, Fungi, Plantae, Animalia
Classification of Major Groups
Genera grouped into families.
• Families grouped into orders.
– Orders grouped into classes.
o Classes grouped into phyla (divisions).
« Phyla grouped into kingdoms.
Example: onion
Kingdom: Plantae
Phylum:
Magnoliophyta
Class:
Liliopsida
Order:
Liliales
Family:
Liliaceae
Genus:
Allium
Species: Allium cepa L.
Classification of
Major Groups
3 domains (superkingdoms): Bacteria,
Archaea, Eukarya
Depending on the
classification system,
between 12 and 30 plant
phyla recognized.
In-between categories,
such as subphylum,
subclass, and suborders
used; and species
sometimes further
divided into subspecies,
varieties and forms.
Classification of Major Groups
Second part of species name = specific epithet.
• Specific epithet followed by author(s) who named
the plant.
Taxonomists specialize in identifying, naming,
and classifying organisms.
Systematists incorporate evolutionary
processes to sort out natural relationships.
Dichotomous keys help identify organisms.
• Choose features from paired statements that most
closely apply to organism
The Species Concept
Morphological species concept - A species
is defined by morphology.
Interbreeding species concept - A species is
a population capable of interbreeding and is
reproductively isolated from other groups.
Ecological species concept - A species is a
group of related individuals that occupy a
unique ecological niche.
The Species Concept
Cladistic species concept - A species is
determined by phylogenetic history.
• Individuals with common evolutionary background
considered to be a species.
–
Cladistic methods used to determine evolutionary
history.
o
Examines natural relationships among organisms,
based on shared features.
o
Relationships portrayed on cladograms.
o
The value or form of a feature referred to as a
character state.
o
Hypotheses made about which state is ancestral.
The Species Concept
In trying to choose the best cladograms,
taxonomists use principle of parsimony.
• Occam’s razor - “One should not make more
assumptions than the minimum needed to explain
anything.”
Best cladogram is interpreted as that which
requires fewest evolutionary changes in taxa
involved.
The Species Concept
Eclectic species concept - Single criterion
not sufficient to identify species.
• Morphological, geographical, biological and
ecological criteria must be used when defining
species.
Nominalistic species concept - Species do
not exist.
• Evolutionary unit of importance is local
interbreeding population.
Review
Introduction
Development of the Binomial System of
Nomenclature
• Linnaeus
• The International Code of Botanical Nomenclature
Development of the Kingdom Concept
Classification of Major Groups
The Species Concept