Topic 04 History of Plant Systematics &...

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Topic 04History of Plant Systematics & Classification

I. Primer on ClassificationA. Definition

‐process of organizing thoughts and ideas about the world around us.



B. Primary Operations1. Grouping & Ranking

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DA BC DAB

DAB

CDB

C

DA B CE

EE

Grouping results in a horizontal or coordinate arrangement of objects or organisms.

objects or organisms.

DA BC DAB

DAB

CDB

C

DA B CE

EE

DA B

CD

AB

DA B C

D

B C DA B

C

Group CGroup B Group DGroup A

EEE

E

Group E

objects ororganisms.

Groups ofobjects ororganisms


DA B

CD

AB

DA B C

D

B C DA B

C


EEE

E

Group E


groups have equal ranks or importance (e.g. species or genera, etc.)

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Genus 3Genus 2Genus 1

Family 2Family 1

Order

DA B

CD

AB

DA B C

D

B C DA B

C


EEE

E

Group E

Ranking results in a vertical or hierarchical arrangement of those groups.



B. Primary Operations1. Grouping & Ranking2. Universally found

‐from folk taxonomies to scientific classifications



B. Primary Operations1. Grouping & Ranking2. Universally Found

C. Artificial vs. Natural Systems

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C. Artificial vs. Natural Systems1. AS have little basis in reality





a. a priori decisions about which chars are used at 1st, 2nd, 3rd – order ranks, etc.

e.g. the number of legs

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e.g. the number of legs

Tetrapods

Bipods

Tripods





a. a priori decisions about which chars are used at 1st, 2nd, 3rd – order ranks, etc.

b. Groups easy to recognizec. Little predictive powerd. Of limited utility




C. Artificial vs. Natural Systems1. AS have little basis in reality2. NS: meant to recognize “real” groups

a. a posteriori reasoning

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Group A

Group B

Group C

Group D

I. Primer on Classification

.2. NS: meant to recognize “real” groups

a. a posteriori reasoningb. Groups may be harder to recognize b/c no one character

used to delimit eachb. But have greater predictive power

II. The Early Days

Given name: Tyrtamus

Nicknames:

‘Theophrastus’ by Aristotle(theos, god, phrasis, declare or tell)

‘Father of Botany’ by Linnaeus

A. Theophrastus (ca. 371‐287 BC)

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II. The Early DaysA. Theophrastus (ca. 371‐287 BC)

Important Works: • De Historia Plantarum• De Causis Plantarum

(only Latin translations remain)

Characteristics:• Empirical approach to biology of plants• Primary subdivision based on habit• Subsidiary grps based on other chars• Fundamentally an AS.

Significance: • First systematic treatment of plants

II. The Early DaysA. TheophrastusB. Herbalists

1. Herbals

Characteristics: • Utilitarian compendiums of medicinal or useful plants where they grew,

what they look like, and how to use them• Artificial systems (primary subdivisions based on habit or use)

Significance:• Partial floras• Elements of modern floras: names of plants, where they grow, what

they look like (incl. illustrations)


1. Herbals2. Dioscorides (40‐90 AD)

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1. Herbals2. Dioscorides (40‐90 AD)

Important Work:• De Materia Medica

Characteristics: • Medicinal plants (ca. 600 spp)

of Roman Empire• Used Theophrastus’s system

Significance:• Partial Mediterranean flora• Promoted importance of knowing

plants and their names• Elements of modern floras:

names of plants, where they grow, what they look like (incl. illustrations)

• Used ca. 1500 yrs

De Materia Medica – Arabic translation from Spain (12-13th Century)Photo courtesy of PHGCOM.

Dill (anti-gas, indigestion soother) Cumin (parasites)

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1. Herbals2. Dioscorides (40‐90 AD)3. Others (15th‐17th century)

Important Works:• Various

Characteristics: • Utilitarian, partial floras.• Printed (printing press invented in 1440).

Significance:• Renaissance in botany ushered in by Age of Exploration• Widely and more economically distributed.• Herbals were repository for this information.


1. Herbals2. Dioscorides (40‐90 AD)3. Others (15th‐17th century)4. De La Cruz ( ? ‐ 1552 ‐ ?)

Martin de la Cruz• Aztec physician/botanist in Mexico (Spain)

Important Works:• Badianus Manuscript (translated from Nahuatl to Latin by Badiano)

Characteristics: • 250 medicinal spp of Aztec (Nahua)• Rediscovered in Vatican library in 1929, returned by Pope John Paul II in

1990.

Significance:• Earliest systematic record of Mexican (New World) flora, including

Nahuatl names and uses.

(Calliandra anomala; stalky cornsilk flower; Tlacoxiloxochitl)

For persistent cough.

-Drink juice of the root.-Mix some of juice with honey and smear on throat.

-Fls of this plus water were said to improve eyesight and heal ulcers.

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(Mixture including Pinus sp.)

For lightening strike.

-Drink made from lvs of a pine and other species.

(thistle, pepper)

For “Black Blood” (depression).

-Grind, cook in water. Add pearl, wolf’s liver and wine. Drink. Dance.

(Urtica chichicaztli; water-nettle)

For nose bleeds (Atzitzicaztli)

-Grind juice w/ salt in urine, milk. -Pour into nose to stop flow of blood.

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III. Pre-Linnaean TaxonomistsA. Caesalpino (1519‐1603)

• Tuscany, Italy• ‘First Taxonomist’

Important Works:• De Plantis Libri• Herbaria (both personal and

commissioned)

Characteristics: • 1500 spp of Italy and region• Principal grps based on habit• Subsidiary groupings by fr, seed, & fl chars

Significance:• Broke free of 1500 yrs of herbalism format• Natural subsidiary groups based on fr,

seed, and fl chars• Created some of the earliest herbaria

III. Pre-Linnaean TaxonomistsB. Ray (1628‐1705)

• British

Important Works:• Synopsis Methodica Stirpium Brittannicarum• Historia Plantarum

Characteristics: • First British flora• Classification of 18,000:

HerbaeImperfectae (Free‐sporing “cryptogams”)Perfectae (Seed Plants)

MonocotyledonsDicotyledons

ArboraeMonocotyledonsDicotyledons

Significance:• Complex mix of artificial and natural groupings• First recognition of cryptogams vs. seed plants, monocots vs. dicots• First to define species (variation within interbreeding populations not

worthy of species distinction)

III. Pre-Linnaean TaxonomistsC. Bauhin & Tournefort

• French• (1656‐1708)

• French‐Swiss• (1560‐1624)

• Both contributed to establishing the genus concept

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• Pinax Theatri Botanici• Shortened polynomials,

flirted with binomials for species

• Listed synonymy


• Institutiones Rei Herbariae• Very explicit about genus

concept and descriptions

IV. Linnaeus A. Carl von Linné (1707‐1778)

• Sweden• aka Carolus Linnaeus • ‘Founder of Modern Taxonomy’

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• Sweden• aka Carolus Linnaeus • ‘Founder of Modern Taxonomy’

Historical Context: • Much old disjunct info,• New info (Age of Exploration,

Microscopy, Herbaria)• Potential to synthesize &

disseminate (herbaria and printing)• Need for easy, rapid way to ID,

classify, and communicate


Important Works:• Systema Naturae (10th ed., 1758)

Important Works:• Species Plantarum (May 1, 1753)

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Characteristics• Starting pt for modern bot nom• 5,490 names (he est. 10K spp)• Binomial


Before: Plantago foliis ovato‐lanceolatis pubescentibus, spica cylindrica, scapo tereti

After: Plantago media

IV. Linnaeus

Polynomial

sp. epithet (for ease of reference)


Characteristics• Starting pt for modern bot nom• 5,490 names (he est. 10K spp)• Binomial• Synonymy


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IV. Linnaeus

Synonyms and source.


Characteristics• Starting pt for modern bot nom• 5,490 names (he est. 10K spp)• Binomial• Synonymy• Nativity


IV. Linnaeus

Nativity

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Characteristics• Starting pt for modern bot nom• 5,490 names (he est. 10K spp)• Binomial• Synonymy• Nativity• Ca. 5,500 spp, ca. 1000 gen, into ca.

100 ord, 24 classes, 1 kingdom



Characteristics• Starting pt for modern bot nom• 5,490 names (he est. 10K spp)• Binomial• Synonymy• Nativity• Ca. 5,500 spp, ca. 1000 gen, into ca.

100 ord, 24 classes, 1 kingdom• Classes and orders were artificial

groupings, called his “Sexual System”.


IV. Linnaeus

Classes based on number (and

arrangement) of stamens

Orders based on number (and

arrangement) of pistils

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Anthropomorphicizing Linnaeus’s Sexual System• The flowers' leaves. . . serve as bridal beds

which the Creator has so gloriously arranged, adorned with such noble bed curtains, and perfumed with so many soft scents that the bridegroom with his bride might there celebrate their nuptials with so much the greater solemnity. . . (L., 1729)




• Class Pentandria, Order Monogynia was described as “5 husbands in the same marriage”

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• Johann Siegesbeck (1686‐1785; St. Petersburg Bot Gard):

o Such “loathsome harlotry as several males with one female would not be permitted in the vegetable kingdom by the Creator!”







o “Who would have thought that bluebells and lilies and onions could be up to such immorality?”







o “Who would have thought that bluebells and lilies and onions could be up to such immorality?”

o “How could so licentious a method be taught to the young without offense?”

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In response, Linnaeus named a foul-smelling weed Siegesbeckia.

V. The French Push for Natural SystemsA. Jussieu (1748‐1836)

• Antoine de J.• Uncle Bernard de J. (Jardin des Plantes)

Important Works:• Genera Plantarum

Significance:• Natural classification• Invented the family

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V. The French Push for Natural SystemsB. Adanson (1727‐1806)

• Extensive fieldwork in Africa• Baobobs (Adansonia L.)

Important Works:• Familles des Plantes

V. The French Push for Natural SystemsB. Adanson (1727‐1806)

• Extensive fieldwork in Africa• Baobobs (Adansonia L.)

Important Works:• Familles des Plantes

Significance:• Natural classification• Compared families

quantitatively, in table format with 65 characters

V. The French Push for Natural SystemsC. Lamarck (1744‐1829)

• Early advocate for evolution• Theory of evolution by

inheritance of acquired traits

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V. The French Push for Natural SystemsC. Lamarck (1744‐1829)

• Early advocate for evolution• Theory of evolution by

inheritance of acquired traits

Important Works:• Flora Francoise

Significance:• Early French flora• Dichotomous‐like key

Darwin (1809-1882)

Origin of Species 1859

VI. Evolutionary Taxonomy

A. Darwin

VI. Evolutionary Taxonomy

B. Engler (1844-1930): Die Natürlichen Pflanzenfamilien

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C. Bessey (1845-1915)

“Bessey’s Dicta”

D. Cronquist (1919-1992)

An Integrated System of Classification of Flowering Plants (1981, 1988)

Evolutionary Taxonomists: Armen Tahktajan& Arthur Cronquist

NYBG ca. 1985

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Cronquist (1919-1992)

An Integrated System of Classification of Flowering Plants (1981, 1988)

VII. Phenetics (Phenetic Approaches to Classification)Recognize taxa based on similarity (overall similarity)

Characteristics of:

1. Many characters used (morphological, genetic, etc.)

2. Computational (computers & similarity metric)3. Objective4. Repeatable

VII. Phenetics (Phenetic Approaches to Classification)Recognize taxa based on similarity (overall similarity)

A. Adanson

B. Sneath & Sokal

Sneath & Sokal. 1973. Numerical taxonomy: The Principles and Practice of Numerical Classification.

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Example: Let’s classify the following three primate genera into two separate families.

Leontopithecus (tamarin)

Hylobates (gibbon)Homo (human, man)

Leontopithecus (golden lion tamarin)

PongoHomo

Hylobates (lar gibbon)

Homo

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Homo (human, man)

Homo erectus


1. Makes observations, collect data. Hairiness Habit Tail Pedalism

Leontopithecus (tamarin) high (0) arboreal (0) yes (0) 4‐ped (0)Hylobates (gibbon) high (0) arboreal (0) no (1) 4‐ped (0)Homo (human, man) low (1) terrestrial (1) no (1) 2‐ped (1)


2. Calculate similarities (states shared/Max possible) Hairiness Habit Tail Pedalism

Leontopithecus (tamarin) 0 0 0 0Hylobates (gibbon) 0 0 1 0Homo (human, man) 1 1 1 1

Record using a pairwise similarity matrix

tamarin gibbon humantamarin 1.00 0.75 0.00gibbon ‐‐‐‐‐ 1.00 0.25human ‐‐‐‐‐ ‐‐‐‐‐ 1.00

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3. Construct phenogram (type of dendrogram)


1. Group most similar taxa first




2. Add next most similar taxon(average similarity may have to calculated)

Human – tamarin: 0.00Human – gibbon: 0.25

0.13Average similarity of human to

gibbon/tamarin group






2. Add next most similar taxon(average similarity may have to calculated)

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4. Classify

Hylobatidae: Hylobates (gibbon) + Leontopithecus (tamarin)

Hominidae: Homo (human)

VII. Phenetic Approaches to Classification

D. Considerations

1.) Why did phenetics florish after 1950’s?


D. Considerations

2.) Pros?

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D. Considerations

3.) Cons?

VIII. Cladistic Approaches to Classification

A. Willi Hennig (German; 1913‐1976)

Grundzüge einer Theorie der Phylogenetischen Systematik (Hennig, 1950).

Phylogenetic Systematics (Hennig, 1966)


B. Hennigian Principles

1. Classification consistent w/ phylogenyi.e., named taxa above sp‐level are clades or are monophyletic

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a. Clade/monophyletic group = grp. incl. a common ancestor and all of its descendants.




Cladogram depicting phylogeny of 3 taxa

Good: Genus 1: Sp B and C. Genus 2: Sp A.

a. Clade (monophyletic group) = grp. incl. a common ancestor and all of its descendants.




Good: Genus 1: Sp B and C. Genus 2: Sp A.


• B and C comprise a clade. • B & C share a more recent

common ancestor than either does w/ A.




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Good: Genus 1: Sp B and C. Genus 2: Sp A.Family: Genus 1 & 2





Bad:Genus 1: Sp B and A. Genus 2: Sp C.






b. Not all clades have to be named. Ranks applied are arbitrary.




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How many clades are represented here?

I

H

G

F

E

D

C

B

A

I

H

G

F

E

D

C

B

A

1 family 4 genera

I

H

G

F

E

D

C

B

A

1 order

2 families

4 genera

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b. Not all clades have to be named. Ranks applied are arbitrary.c. Phylogenetic inference usu not appropriate below species.




B & C related by phylogeny

Pops & orgs within B and C are related

by tokogeny



2. Clades marked by synapomorphy(s). Shared, derived, homologous character state(s)

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a. Homology vs. Non‐homology & Analogy

Homologous character states: Forelimbs & bones within

Non-homologous states:Wings

Homologous character states: Presence of stems, leaves, flowers, etc.

Non-homologous States:Arborescent growth.

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Vasculature Seeds Flowers

Mosses 0 0 0Ferns 1 0 0Conifers 1 1 0Angios 1 1 1




a. Homology vs. Analogy or Convergence

b. Types of Homology: Apomorphy

SynapomorphyAutapomorphy

PlesiomorphySymplesiomorphy

ApomorphyPlesiomorphy

Hairiness Habit Tail Pedalism

tamarin high (0) arboreal (0) yes (0) 4‐ped (0)gibbon high (0) arboreal (0) no (1) 4‐ped (0)human low (1) terrestrial (1) no (1) 2‐ped (1)

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Phenogram was based on overall similarity(plesiomorphies weighted equally to apomorphies)



Plesiomorphies are uninformative.

No evidence for this clade




High hairiness plesiomorphic in mammals


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High hairiness plesiomorphic in mammalsArboreal is plesiom. in primates





High hairiness plesiomorphic in mammalsArboreal is plesiom. in primates4-ped is plesiom. in vertebrates. No evidence

for this clade



Wrong.

Autapomorphies are uninformative. 00 10

1

1


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0 1

Synapomorphies are informative



0 1

Autapomorphies do not change this. 00 10

1

1

Same data, different groupings (Cladistics vs. Phenetics):

1. Both based on lots of data, repeatable, objective, computational.

2. Both use dendrograms to represent how they presume taxa are related.

3. Phenetics based on overall similarity, cladistics based on special similarity (synapomorphies).

Phenogram

Cladogram

Phenetic classificationFamily 1: gibbons & tamarinsFamily 2: humans alone

Cladistic classificationFamily1: gibbons & humansFamily 2: tamarins alone

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Hamamelidae

Cronquist vs. Hennig:

1. Both evolutionary.

2. Both based on lots of data, but Cronquist’s methodology was subjective (authoritarian) and not as objective or repeatable as Hennig’s.

3. Both used tree-like diagrams to represent how they presume taxa are related. (Though Cronquist’s Besseygrams are less precise than a cladogram)

4. Cronquist willing to recognize nonmonophyletic groups. Hennig not willing.

Angiosperms are monophyletic: therefore, we could recognize as a Sp (e.g., Magnoliophyta or Magnoliopsida)

asteridscaryophyllids

rosids

monocotsmagnoliids

nymphaeids(water-lilies & friends)

Ranunculids& other primitive eudicots


rosids

monocotsmagnoliids



But what about classic subdivision into “monocots” &“dicots?” e.g., Cronquist (1981) Which of Cronquist’s classes is not monophyletic?

Magnoliophyta (angiosperms)Magnoliopsida (dicots)Liliopsida (monocots)

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But what about classic subdivision into “monocots” &“dicots?” e.g., Cronquist (1981) Which of Cronquist’s classes is not monophyletic?

Magnoliophyta (angiosperms)Magnoliopsida (dicots)Liliopsida (monocots)


rosids

monocotsmagnoliids



More: Cronquist’s Magnoliidae included water-lilies, Magnoliids, and some primitive eudicots. Emphasis on floral Symplesiomorphies.


rosids

monocotsmagnoliids



Dr. Hardy’s classifications of angiosperms:

Magnoliopsida (angiosperms)Various monophyletic subclasses.

Asteridae

Rosidae

Caryophyllidae

Proteidae

Ranunculidae

Liliidae

Magnoliidae

Nymphaeidae

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Topic 04 History of Plant Systematics &...

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