Classification Classification • classification is the 3rd goal of systematics • ancient search for “natural” system of classification • important non-Western systems • Parashara (India) 2000 BC • Chinese • Aztecs • Egyptians • Mayan (Tzeltal) - ethnotaxonomy
Systems of Classifications Artificial Classifications
Examine three main systems of Theophrastus (372-287 BC) took the classifications and how they “evolved” in philosophical ideas of Plato and Aristotle and the context of western civilization applied them to taxonomy
‘essentialism’
Habit as an “essence” or essential character
herb subshrub shrub tree
1 Artificial Classifications Artificial Classifications
Theophrastus (372-287 BC) took the Scalae Naturae This linear gradation concept is the philosophical ideas of Plato and Aristotle and Aristotlean Scalae Naturae or Great applied them to taxonomy De Historia Plantarum Chain of Being or Ladder of Life
‘ ’ essentialism Unidirectional progression and rank on ladder leads to (false) ideas of Habit as an “essence” or essential relationships – “fish more closely character related to molluscs than fish are to humans” herb subshrub shrub tree Concept of ladder of life still around today and causes much of the Theophrastus saw a linear gradation when controversy and mis-understanding essences are used to arrange organisms surrounding evolution
Artificial Classifications Artificial Classifications
Evolution does not advocate this . . . back to Theophrastus and his “ladder” of life, but rather advocates a classification of plants “branching tree”
Evolution asserts (testable!) that fish • clearly artificial as conifers are white pine are more closely related to humans placed with some (woody) A because they have a more recent tree fern angiosperms and some (woody) ferns common ancestor A than the common red oak ancestor B with molluscs herb subshrub shrub tree
B • logical, efficient, easy, but rigid system of classification — a priori choice of characters
2 Artificial Classifications Artificial Classifications Herbalists - physicians: a second group using Herbalists - physicians: a second group using artificial systems of classification - 15-16th artificial systems of classification - 15-16th centuries centuries
• little emphasis placed on system of • herbals often lavishly illustrated classification of the plants — alphabetical • herbalists referred to as the or medicinal property ‘German Fathers of Botany’ De Historium Stirpium - 1542
• less than 1000 species of plants were known; no need for intricate classification system in the herbals
Leonhart Fuchs Fuchsia
1580 - 1800: Pivotal Period 1580 - 1800: Pivotal Period
Artificial or Natural Systems? Artificial or Natural Systems? • world-wide trade and exploration — many new plant species were seen by European taxonomists Linnaeus & students’ travels
3 1580 - 1800: Pivotal Period 1580 - 1800: Pivotal Period
Artificial or Natural Systems? Artificial or Natural Systems?
Andrea Caesalpino (1519-1603) - Italian doctor Andrea Caesalpino (1519-1603) - Italian doctor • struggled with question how to form a Caesalpinia more ‘natural’ classification [De plantis Pisa, Italy libri XVI (1583)]
• private collection of 768 plants arranged in 266 sheets in 3 volumes • arranged by reproductive features of the plants - flowers and fruits
• first natural system, first • first natural system, first herbarium herbarium, first botanical garden arranged by classification
1580 - 1800: Pivotal Period 1580 - 1800: Pivotal Period
Artificial or Natural Systems? Artificial or Natural Systems?
John Ray (1628-1705) - English blacksmith John Ray (1628-1705) - English blacksmith
• argued that all parts of the plant • first recognized distinction between dicots should be used in classification and monocots • classified 18,000 species in 25 ‘classes’ of dicots Methodus Plantarum (1703) 4 ‘classes’ of first by fruit types and monocots subdivided by flower and leaf features many = orders today
4 1580 - 1800: Pivotal Period 1580 - 1800: Pivotal Period
Artificial or Natural Systems? Artificial or Natural Systems?
Pierre Magnol (1638-1715) - French botanist Carolus Linnaeus (1707-1778) - Swedish taxonomist ’ ‘ ’ • considered Ray s system of 29 classes • work of Caesalpino, Ray, and too cumbersome Magnol in producing a workable classification system culminated in • classified 76 ‘families’ — first to recognize ’ family level (Magnoliaceae honored after him) Linnaeus Sexual System • however, this classification system was a backward step to artificial!
Linnaeus - Sexual System Linnaeus - Sexual System
What did he do? Take a closer look inside Species Plantarum • greatest achievement - Species st Plantarum in 1753 arranged as • 1 level based on number of Systema Sexuale stamens • 2nd level based on number of • classification based on pistils reproductive features like Caesalpino, but selective and features chosen a priori simply on workability
5 Linnaeus - Sexual System Linnaeus - Sexual System
Take a closer look inside Species Take a closer look inside Species Plantarum Plantarum
• Linnaeus got some intense • Linnaeus got some intense criticism – especially from Johan criticism – especially from Johan Siegesbeck Siegesbeck
• “loathsome harlotry . . . who • “would God allow 20 men or would have thought that more [the stamens] to have one bluebells, lilies, and onions could wife in common [the pistil]?” be up to such immorality?”
Linnaeus - Sexual System Linnaeus - Sexual System
Take a closer look inside Species How does it work? Oenothera Plantarum biennis or evening primrose
• Linnaeus got some intense criticism – especially from Johan Siegesbeck
• “would God allow 20 men or more [the stamens] to have one wife in common [the pistil]?” • Oenothera has 8 stamens - placed in Octandria (1st level) • Linnaeus had the last laugh • Oenothera has 1 pistil (but 4 fused Sigesbeckia orientalis L. – St. Paul’s wort carpels) - placed in Monogynia (2nd level)
6 Linnaeus - Sexual System Linnaeus - Sexual System
Note that Oenothera is placed with other Linnaeus and followers DID realize that genera of the family Onagraceae the system would have issues
Gaura = Epilobum • cacti and cherries have little overall Oenothera similarity to each other
• but both have many stamens and a single pistil — placed in Polyandria / Monogynia Opuntia Prunus • Linnaeus more concerned with mechanics: usable, predictable, expandable, immutable
• Sexual System artificial, and thus backward step away from‘natural” classifications
Natural Classifications Natural Classifications
Period of Natural Systems: 1760 - 1880 Period of Natural Systems: 1760 - 1880 • late 18th century saw • de Jussieu family of Paris accumulation of botanical produced the most complete collections ‘natural’ classification
• Linnaeus had provided popular and efficient cataloguing scheme • their natural system came from but unrelated plants were often the practice of ‘taxonomic grouped • taxonomists reconsidered gardens’ purposes of classification; revisited older ‘natural’ ideas
Antoine-Laurent de Jussieu
7 Natural Classifications Natural Classifications
Period of Natural Systems: 1760 - 1880 Period of Natural Systems: 1760 - 1880
• private and public gardens were then • Bernard de Jussieu experimented by arranged according to the Linnaean replanting in the Trianon Garden on Sexual System of classification Versailles Palace grounds so that those most “similar” looking on the basis of many features would be in proximity
Linnaean Gardens in Uppsala, Sweden Antoine - Bernard - nephew uncle
Natural Classifications Phylogenetic Classifications
Period of Natural Systems: 1760 - 1880 Phylogenetic systems date to 1859 and publication of Origin of Species by Charles Darwin • Antoine Laurent de Jussieu published Genera Plantarum in 1789 based on the de Jussieu family’s new, more natural classification system - and today reflected in the plantings at the Trianon Gardens
8 Phylogenetic Classifications Phylogenetic Classifications
Phylogenetic systems date to 1859 and publication of Phylogenetic systems date to 1859 and publication of Origin of Species by Charles Darwin Origin of Species by Charles Darwin
• ‘Natural’ had meant different things to • ‘Natural’ had meant different things to different people different people
• to Linnaeus and others ‘natural’ referred • to Darwin, ‘natural’implied that two to the ordered structure of the universe and species looked similar because they shared biota as ordained by God - specific or features from a common ancestor in their special creation genealogy
• to others “natural” groupings of taxa into larger groups implied relationships based on genealogy - with or without a God
Phylogenetic Classifications Phylogenetic Classifications
Phylogenetic systems to Darwin must include Phylogenetic systems represented by genealogy + amount of change (or similarity) the “tree” metaphor
• “classification must be genealogical” • Darwin argued that “common ancestry” is a fact — and outcome • “genealogy alone does not give is a phylogenetic ‘tree’ classification” • less than a decade later Ernst • “descent with modification” : or Haeckel published the first tree of genealogy plus change = evolution life
• all classification systems since have been phylogenetic
9 Phylogenetic Classifications Phylogenetic Classifications
Bentham & Hooker at Kew Royal Botanic Gardens first Engler and Prantl produced the monumental Die systematists to wrestle with phylogenetic classifications Naturlichen Pflanzenfamilien between 1887-1915
• provided Darwin with much of his botanical evidence for evolution
• rudimentary phylogenetic system quickly over-shadowed by two younger Germans George Bentham Joseph Hooker Adolph Engler Karl Prantl 1800-1884 1817-1911 1844-1930 1849-1893
Phylogenetic Classifications Phylogenetic Classifications
Engler and Prantl produced the monumental Die Engler - Prantl classification system became the standard Naturlichen Pflanzenfamilien between 1887-1915 to arrange herbaria and floras by early 20th century
• original classification • stressed that “simple” was ‘natural’ and based flowers - that is with few or no on many characters parts - were “primitive”
• by 1915 their system had • e.g., “Amentiferae” - a group a phylogenetic flavor with with reduced flowers were simple plants listed first considered primitive and progressing to more complex plants • their system can be called Adolph Engler Karl Prantl “simple = primitive” or “Salix Salix - willow 1844-1930 1849-1893 = primitive”
10 Phylogenetic Classifications Phylogenetic Classifications
Engler - Prantl classification system became the standard Charles Bessey revolutionized the classification of to arrange herbaria and floras by early 20th century angiosperms by his ideas on primitive vs. advanced characters
• hypothesized the primitive vs. advanced state of many Charles Bessey (1848-1915) characters of plants - see at University of Nebraska handout
• Bessey’s ‘dicta’ or rules were the basis of his phylogenetic classification scheme Salix - willow University of Wisconsin Student Herbarium – five • formed the basis for all years ago - Salicaceae listed first in dicots subsequent modern systems
Phylogenetic Classifications Phylogenetic Classifications
What were Bessey’s main dicta or rules? Bessey’s dicta or rules
Character Primitive State Advanced State • similar to foliar theory of the flower all present, many in loss of parts, few in 1. Floral parts number number • “Magnolia = primitive” idea 2. Floral fusion parts separate parts fused • general trend in angiosperms 3. Floral symmetry actinomorphy zygomorphy has been reduction, loss, and fusion 4. Ovary position hypogynous epigynous
11 Phylogenetic Classifications Phylogenetic Classifications
‘ ’ ‘ ’ sympetaly Bessey’s classification ( cactus ) Bessey’s classification ( cactus ) epigyny actinomorphic • Bessey produced a classification system based on sympetaly hypogyny polypetaly his rules zygomorphic epigyny actinomorphic • orders (-ales) of flowering plants attached showing • zygomorphy, fused petals, relationships and degree of and inferior ovary are found primitive vs. advanced features further up the chart
• order Ranales (Magnolia) polypetaly • order Ranales (Magnolia) polypetaly considered most primitive hypogyny considered most primitive hypogyny actinomorphic actinomorphic
Phylogenetic Classifications Phylogenetic Classifications
Contemporary classifications Contemporary classifications • most based on Bessey’s • most based on Bessey’s principles principles • which characters stressed, • which characters stressed, though, varies (subjective) though, varies (subjective) Takhtajan Cronquist Takhtajan Cronquist (d. 2009) (d. 1992) (d. 2009) (d. 1992)
Armen Takhtajan’s and Arthur Cronquist’s best developed of the Cronquist’s are similar with contemporary classifications subclasses (-idae) as the major based on morphology groupings
12 Phylogenetic Classifications Phylogenetic Classifications
Contemporary classifications Molecular classifications • Rolf Dalhgren (d. 1987): • the 1993 paper examining DNA Danish taxonomist who of 500 genera of seed plants emphasized chemical features revolutionized phylogenetic classification • Robert Thorne (d. 2014; Rancho Santa Ana Botanical Garden): was still modifying his morphology based system using DNA evidence Dalhgren
Thorne
Phylogenetic Classifications Phylogenetic Classifications
Molecular classifications Molecular classifications • Angiosperm Phylogeny Group • APGIII (2009) – used in course • Angiosperm Phylogeny Group • APGIII (2009) – used in course classification — APGI (1998), and Plant Systematics, 2nd ed. classification — APGI (1998), and Plant Systematics, 2nd ed. APGII (2003) text [APGIV (2016) “tweaked”] APGII (2003) text
• APG uses DNA and a lot of morphology
• e.g., use of pollen features to delimit “eudicot” – the 3-pored pollen bearing flowering plants
13 Phylogenetic Classifications Phylogenetic Classifications
Molecular classifications UW Botany Department Student Herbarium • Angiosperm Phylogeny Group classification — UW Botany Gardens first garden based on the APG system!
Dr. John Zaborsky – 2018 Bot400 TA
Arranging these named organisms in 1 dimensional linear space?
Issues in Grouping Issues in Grouping
1. Convergence a problem with any system 1. Convergence a problem with any system
Reduced flowers Inferior ovary Corolla tube Corolla tube
14 Issues in Grouping Issues in Grouping
2. “Tree Thinking” - what a phylogenetic tree is . . . 2. “Tree Thinking” - what a phylogenetic tree is not . . .
• various trees that you will see in this course Fish Newt Lizard Mouse Human
rooted rooted R
R unrooted rooted
R Is a Newt more closely related to a Fish than to a Human?
Issues in Grouping Issues in Grouping
2. “Tree Thinking” - what a phylogenetic tree is not . . . 2. “Tree Thinking” - what a phylogenetic tree is not . . .
Human Mouse Lizard Newt Fish Fish Newt Lizard Mouse Human
Same tree / topology! Same tree / topology!
Is a Newt more closely related to a Fish than to a Human? Is a Newt more closely related to a Fish than to a Human?
15 Issues in Grouping Issues in Grouping
2. “Tree Thinking” - what a phylogenetic tree is not . . . 2. “Tree Thinking” - what a phylogenetic tree is not . . .
Fish Human Mouse Lizard Newt Fish X Human X Mouse X Lizard X Newt
Same tree / topology!
Is a Newt more closely related to a Fish than to a Human? Tip reading is ladder reading, incorrect!
Issues in Grouping Issues in Grouping
2. “Tree Thinking” - what a phylogenetic tree is not . . . 3. Named groups are monophyletic (ancestors and all descendants) Fish Human Mouse Lizard Newt
ancestor of human and newt = ancestor
Newt is more related to Humans than Fish! They share a more recent common ancestor than either does with Fish.
16 Issues in Grouping Issues in Grouping
3. . . . vs. paraphyletic (not all descendants included - usually 3. e.g. Caesalpinoid legumes are paraphyletic because these are highly modified) - should these be allowed?
• faboid (beans, peas) and mimisoid (acacia, mimosa) legumes are highly modified
• but descended = ancestor from the common = excluded descendant ancestor of caesalpinoids = modifications
Issues in Grouping Issues in Grouping
3. . . . vs. polyphyletic (more than one ancestor - defined by 4. Not all monophyletic groups are named - limited categories convergent feature) - these are avoided available in ranked (Linnean) systems
= named group = ancestor = not named group = convergence
tree fern red oak
17 Issues in Grouping Issues in Grouping
5. Ranks are abitrary - but follow Linnean categories: 5. Ranks are abitrary - but follow Linnean categories: kingdom, phylum, class, order, family, genus, species kingdom, phylum, class, order, family, genus, species
Magnoliophyta Magnoliophyta or . . . Gymnosperms Gymnosperms Pinophyta Pinopsida = 4 phyla = 4 classes in 1 phylum Gnetophyta Gnetopsida Pinophyta Cycadophyta Cycadopsida
Ginkgophyta Ginkgopsida
Issues in Grouping Issues in Grouping
6. International Code of International Code of Phylogenetic Nomenclature or vs. Nomenclature or “ranked” / PhyloCode (established 2004) “Linnean” system • in practice and informally, http://www.ohiou.edu/phylocode/ recent phylogenetic classifications have been using a hybrid of ranked and • taxon based on phylogeny • ranked taxon defined based (a “clade”) - rankless on types rankless groupings • content of taxon specified • content of defined taxon not • APGIII uses ranks for by the phylogeny or tree specified except for type families and orders; informal rankless names for larger • any clade can be named • limited number of groups or groups APG III ranks can be named • what clade a species is in will not change! • what taxa a species is in can change!
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