CHAPTER 12
SYSTEMICS:
THE SCIENCE OF
BIOLOGICAL DIVERSITY
8 pts
TAXONOMY AND
HIERARCHIAL
CLASSIFICATION
Taxonomy: The science of discovering,
describing, naming and classifying organisms
Blanketflower, Indian Blanket
Gaillardia species, hybrids and cultivars
TAXONOMY
Taxonomy is not static, it is constantly being revised
and relearned by each generation
Englerian System, 1887
Monocotyledonae
Dicotyledonae
Amentiferae
Polypetalae
Ranales
Centrospermae
Gamopetalae
Cronquist System, 1988
Magnoliopsida (Dicots)
Magnoliidae
Hamamelidae
Caryophyllidae
Dilleniidae
Rosidae
Asteridae
Liliopsida (Monocots)
APG Classification, 1998
Basal Angiosperms
Monocots
Eudicots
Core Eudicots
Caryophylliales
Rosids
Eurosids I
Eurosids II
Asterids
Euasterids I
Euasterids II
TAXONOMY
To a certain extent, we are all taxonomists
1. Edible plants vs medicinal plants vs ornamentals for example
2. Classification can depend on religious or ethnic views, or can
be science-based (morphology, DNA sequencing of genes)
PHILOSOPHICAL CONCEPTS
Early classification systems
were “artificial classification
systems” (did not reflect
biological relationships)
Euphorbia (spurge family)
Echinocereus (Cactus)
Hoodia (Milkweed)
All have C3 photosynthesis
HISTORY OF CLASSIFICATION
1.
The most important of these was De
Materia Medica, 1st century AD by
Greek physician Dioscorides
2.
Classified 600 medicinal plants
designed to improve medical services
to the Roman Empire.
3.
Book became the principal book on
plant classification for nearly 1,500
years.
4.
Book became the basis for herbals
HISTORY OF CLASSIFICATION
Herbals: books which document the supposed medicinal
properties of plants
1. Contains: much folklore
2. Doctrine of signatures (defined): Herbals gave rise to the
Doctrine of signatures which holds that if a plant part
resembled a part of the human body, it would be useful in
treating ailments of that part.
HISTORY OF CLASSIFICATION
Walnut meats which contain
something that looks like tiny brains
was used to treat brain disease.
Hepatica leaves which look like
the lobes of liver was used to treat
liver ailments
“If a man be anointed with the juice of the herb Rue, the
poison of wolf’s bane, mushrooms, or toadstools, the biting of
serpents, stinging of scorpions, spiders, bees, hornets and
wasps will not hurt him”
John Gerard, The Herball, 1597
Ruta graveolens or Rue
http://www.desert-tropicals.com
/Plants/Rutaceae/Ruta_graveolens.html
The pith of the [Elder] branches when cut in round flat
shapes, is dipped in oil, lighted and then put to float in a
glass of water; its light on Christmas eve is thought to
reveal all the witches and sorcerers in the neighborhood.
Richard Folkard, Plant lore, Legends and Lyrics
HISTORY OF CLASSIFICATION
15th century issued in a great era of plant
exploration and an expansion of plant classification
Carl Linnaeus
1707 - 1778
Young Swedish Botanist,
Zoologist, Physician, and
Creationist.
Laid the foundation of modern
taxonomy creating a hierarchical
classification among plants and
popularizing the use of binomial
nomenclature to name a ‘species’.
His Species Plantarum published
in 1753 is the starting point for
modern nomenclature
HISTORY OF CLASSIFICATION
Artificial classification system (not based on
evolutionary/genetic relatedness)
•based primarily on stamen structure and number
•Linneaus’ scheme placed cherries and cacti together
because they had many stamens per flower. We would
classify cacti with cacti and cherries with other fruit trees
•significantly simplified the descriptive classification
scheme of the day
eg. The Latin description for peppermint was Mentha
floribus capitatus, foliis lanceolatis serratis subpetiolatis
or Mentha with flowers in a head, leaves lance shaped,
saw toothed with very short petioles
HISTORY OF CLASSIFICATION
1753, Carolus Linneaus formalized
a 2 name system for classification
of plants (introduced by earlier
botanists), a system still used
today
Linnaea borealis (twinflower)
HISTORY OF CLASSIFICATION
Binomial system of nomenclature published 1753
Species Plantarus
Genus and Species: Linnaea borealis L
Language used: Latin
• After the binomial name, there is often an abbreviation of
the name of the person who did the classification or the
authority. L is used for Linnaeus.
• If someone has reclassified the plant, the first name will be
in parenthesis and a second name will be added
Carl Linnaeus’ Country Home in Hammarby
After the devastating fire in 1769 destroyed most of Uppsula
except his Garden house, Linnaeus had this stone building
(without a heat source) build in 1769 where he kept all his
collections of dried plants, insects and stones and held lectures.
Carl Linnaeus’ Country Home
Herbarium Cabinet
Student benches
Linnaeus lecture podium “Studying Horse’
PHILOSOPHICAL CONCEPTS
For Linneaus and his successors,
the prevailing belief was the
recognition of God-given
relationships
No concept of change and no
concept of extinction
Jean-Baptiste Lamarck (1744-1829) formulated new ideas about
the relationships between animals, and then about the
transmutation of species into new ones.
Statue of Lamarck in the Jardin des Plantes, Paris.
The inscription reads, "Fondateur de la doctrine de
l'évolution" (Originator of the doctrine of evolution)
Lamarck developed two laws to explain evolution: the law of use
and disuse, and the law of inheritance of acquired characteristics.
The law of Inheritance of acquired characteristics: All the acquisitions or losses
wrought by nature on individuals, through the influence of the environment in which
their race has long been placed, and hence through the influence of the predominant use
or permanent disuse of any organ; all these are preserved by reproduction to the new
individuals which arise, provided that the acquired modifications are common to both
sexes, or at least to the individuals which produce the young.
Lamarck saw spontaneous generation as being ongoing, with the simple organisms
thus created being transmuted over time (by his mechanism) becoming more complex
and closer to some notional idea of perfection. As organisms became more complex,
they were replaced with new simple organisms by the Creator.
By the mid 1800’s most
scholars had abandoned
the view that species
were immutable and had
accepted a view of
change over time.
Darwin
The question was
how?
Wallace
Darwin’s careful
observations provided a
natural hypothesis as to
how change could occur.
"Yet in all societies, even those that are most
vicious, the tendency to a virtuous attachment is so
strong that there is a constant effort towards an
increase of population. This constant effort as
constantly tends to subject the lower classes of the
society to distress and to prevent any great
permanent amelioration of their condition".
—Malthus T.R. 1798. An essay on the principle of
population. Chapter II, p18 in Oxford World's
Classics reprint.
The Reverend Thomas Robert Malthus 1766-1834
Thomas Malthus: the rate of growth of a biological
population will always outpace the rate of growth of
the resources in the environment, such as the food
supply leaving the poor in distress.
Evolutionary theory (Darwin and Wallace)
1. There is natural variability within populations and some of
that variability is heritable.
2. Individuals produce more offspring than can survive.
3. Not all the members of a population will be able to survive
and reproduce. Those that do will, on average, be the ones
possessing variations—however slight—that make them
slightly better adapted to the environment
4. Populations adapt locally to an environment (can be
demonstrated ), become reproductively isolated and finally
become new species by gradual accumulation of genetic
differences or by abrupt genetic change. Some become
extinct.
Acceptance
Scientists were the first to accept Darwin’s concepts but since
genes were unknown, there was considerable controversy about
the mechanism
Slowly religious leaders came on board
With the discovery of Chromosomes and Mendel’s work (early
1900’s), a deeper understanding of the mechanisms of selection
resulted in a “new evolutionary synthesis” that included genetics
Rejection
Evolution cannot be correct because it contradicts scriptural
teaching
Natural selection is not a strong enough to mechanism to function
as science says it does
If natural selection is selected as an important biological force,
there is an obligation to have a perverse view of human nature
William Jennings Bryan, 1860-1925 Populist
Politician who worked tirelessly for the
downtrodden. Detested Darwinism because he
feared it “encouraged the exploitation of labor by
justifying selfish competition and discouraging
reform”
MODERN PLANT
CLASSIFICATION
NAMING NEW SPECIES
New species must be anchored by
a “type”
Types and other collections are
stored in collections called
“herbaria” (herbarium)
The University of Tennessee
herbarium (TENN) is located in
Hoskins Library
http://tenn.bio.utk.edu/
THEORETICAL FOUNDATION OF NATURAL
(BIOLOGICAL) CLASSIFICATION
• Organisms exhibit differences between individuals
and groups.
• Some similarities have a genetic/evolutionary basis
• Organisms can be given taxonomic rank by their level
of similarity
• Taxonomic rank reflects real genetic relationships
Thus, all dogs are
classified together
because they have a
common ancestor, the
wolf. Only a few
genes separate big and
small dogs
THE HIERARCHY OF CLASSIFICATION
Linnaea borealis
Genus, species
PHYLOGENETICS
In biology, phylogenetics is the
study of evolutionary relationships
among groups of organisms (e.g.
species, populations), which is
discovered through molecular
sequencing data and morphological
data matrices.
Modern plant classification is being
revised to reflect presumed
evolutionary relationships based on
genetic evidence
Trees depict
evolutionary
relationships
among
vascular plants
Core Eudicots
Papaveraceae (Poppy)
Monocots (Grasses, palms)
Magnoliales (Magnolia)
Austrobaileyales
Ancestor
Nymphales (water lily)
Amborellaceae
Gymnosperms
Ferns
Time
Species 3
Species 2
Present
time
Species 1
RELATIONSHIPS ARE PRESENTED AS TREES
Common
ancestor
(more closely related)
Common
ancestor
(more distantly related)
Species 2
Species 1
Present
time
(AGGTCCGAG)
Species 3
READING PHYLOGENETIC TREES
(AAGTCCCGG)
(AAGTTCCAG)
Time
Common
ancestor
(more closely related)
(AGGTCCGAG)
(AAGTCCCAG)
Common
ancestor
(AAGTCCGAG)
Species 1 AGGTCCGAG
Species 2 AAGTCCCGG
Species 3 AAGTTCCAG
Similarity matrix
Conclusions:
• Species 2 and 3 are
equidistant from 1
• Species 2 and 3 are most
closely related to each other
1
1
2
3
2
3
6/9=.66
6/9=.66
7/9=.77
Species 2
Species 1
(AGGTCCGAG)
Species 3
READING PHYLOGENETIC TREES
(AAGTCCCGG)
Conclusions:
• Species 2 and 3 are
equidistant from 1
• Species 2 and 3 are most
closely related to each other
(AAGTTCCAG)
Common
ancestor
(more closely related)
(AGGTCCGAG)
(AAGTCCCAG)
Common
ancestor
(AAGTCCGAG)
THE MAJOR GROUPS
OF ORGANISMS
THE THREE DOMAINS 0F LIFE
Prokarya
Prokarya
No nucleus
No nucleus
CELLS HAVE NUCLEI = EUKARYOTE
EU = TRUE
KARYOTE = HAVING A NUCLEUS
END