Historical Systematics
Announcements:
Lecture Assignment 5 will be distributed today. It is due in lecture on Monday, May 4th (or anytime before).
Lecture Assignment 6 will be distributed soon. I will use your five best lecture assignment grades to calculate your final lecture assignment score.
Our final lecture exam is scheduled for Thursday, May 14th, from 8 to 11 AM in this room. This exam will be comprehensive and will be worth 20% of your final grade. There is a sample final lecture exam in the back of your Class Notes (pp. 269-284). The exam will be similar in style to what you saw in Lecture Exam 2.
Final lab exam on Tuesday, May 5th (stations in lab) and Wednesday, May 6th (slides in lecture). Your final lab exam will also be comprehensive.
Congratulations to Charles and Peter for being the first to answer the riddle and for providing an image.
Text and Other Resources:
It is also worthwhile to revisit Chapter 2, Methods and Principles of Biological Systematics, esp. pp. 13, 20-21 (Hennigian Argumentation and the parsimony method, and 35-37 (Comparing Phylogenetic Classifications ...)
Course Objectives:
After studying this material you should be able to:
Hunters and Gatherers, and the Preliterate Period
"Ancient men (or more likely women) who made their living by gathering food from the landscape were of necessity practical plant taxonomists. Through experience, they learned which plants were edible and which were not. Those people who failed to learn this distinction also failed to become our ancestors." (Theodore Barkley)
Humans have always been classifying plants in some way or another:
Thus, the first classifications of plants were UTILITARIAN. People needed to know if plants were useful for food, fiber, fuel, medicines, etc., or were poisonous or otherwise dangerous.
Preliterate humans engaged in plant identification, plant descriptions, and plant classifications, with this record passed on verbally from one generation to the next. By necessity, they had to be practicing plant taxonomists. Arguably, taxonomy is probably the oldest of sciences.
The Flowering of Plant Classification
"Taxonomy is at the same time the most basic and the most derived or synthetic field of biology. It is basic because a system of naming and classifying organisms is needed in order to communicate knowledge about them to others, and hence every field of biology uses the results of taxonomy. It is also the most derived field because it has no data of its own, but uses those from every other discipline, thus progressing with advances in accumulated knowledge and technology."
The system of classification used for plants in a particular place at a particular time reflects the:
Thus, ideas on how to classify living things have changed considerbly over time. "Understanding classifications thus means that we need to understand their history. In the past, makers of classifications had quite different ideas about nature and about the role of classification than they do today." (p. 39, text)
Classifications were used historically as an aid to memory (before computers and widespread use of books).
Remember, the terms taxonomy and systematics are often used interchangably, but taxonomy applies to the science of classification (and naming), while systematics implies the study of evolutionary relationships. Today's lecture is about the evolution of "taxonomy" into "systematics."
Ancient Literate Western Civilizations
Theophrastus (Greek, lived ca. 370 - 285 BCE). "Father of Botany" or "Father of Taxonomy." A student of Plato and Aristotle. Wrote Enquiry into Plants (10 books, 9 survive) and The Causes of Plants (8 books, 6 survive; both translated into English), among some 200 other works; named ca. 500 species of plants. He classified plants into trees, shrubs, undershrubs, herbs. Also considered flowering and non-flowering plants; external and internal structures; annual, biennial, perennial; and some basic floral structures (ovaries superior or inferior, distinct and sympetalous corollas).
Dioscorides (40-90 CE). Greek physician. Wrote De Materia Medica which described the medicinal attributes of 600 species of plants; mints (Lamiaceae) and umbels (Apiaceae) recognized as groups. Through various translations and editions, this work was used for the next 1,000 years, and if you owned a copy of this work, you would be guaranteed success and fortune. Juliana Codex, an important, illustrated copy of this work, was created ca. 515 CE for a princess; Vienna Dioscorides is a copy of this work. It may have even been used as a hospital textbook, aiding the pharmacologist in the recognition of each plant. See Wikipedia, for illustrations.
Pliny the Elder (Roman; lived 23-79 CE, died during the famed eruption of Mt. Vesuvius). Natural Philosopher (naturalist) and military commander. Most important work was Naturalis Historia, an encyclopedia into which Pliny collected much of the knowledge of the time (160 volumes, in which 37 survive). It was used as a reference for centuries by countless scholars, especially in medicine, agriculture, and plant products, and was among the first works to be printed by moveable type.
Middle Ages
Between the fall of the Roman Empire and the Renaissance, there was little original science or observations in Western Europe (the "Dark Ages"). The Ancients were thought to have possessed all knowledge, and their works were copied (and copied and copied and copied and copeid and copid and cpded nad kpide) repeatedly. This led to considerable loss of information and the transmission of much misinformation. However, many Greek and Roman texts were translated into Arabic. Cultures in Arabia, China, Japan, India and the Americas were flourishing at this time.
Saint Albertus Magnus (d. 1280), "Aristotle of the Middle Ages." Most modern knowledge of Aristotle was preserved by Magnus. He wrote De vegetabilis and distinguished monocots from dicots, and vascular from nonvascular plants.
Renaissance
The Renaissance was a cultural movement that spanned roughly from the 14th to the 19th century. This period of intellectual transformation approximately spans the period between the Middle Ages and the Modern era. It was a time of original thought and development of the arts, literature, and the beginnings of modern science.
Two important technological innovations: the printing press, and the science of navigation. The former made botanical (medicinal) information available to all, and the latter started the age of exploration, immediately increasing the number of plant species being discovered
Herbalists, People sought originality. They looked at plants, and not just accepted and copied what the Ancients wrote and drew. These ancient herbals were based on firsthand observations by their authors. Moveable type made books more widely available. Exploration brought new, unknown plants to Europe to be described. There was a need for medical information.
Once more, classification was primarily UTILITARIAN.
Pre-Linnaean
Herbarium specimens first made by Luca Ghini in Italy (about 1532). Ghini was Director of the botanic garden in Pisa.
First botanical garden established in Pisa, Italy (1543), and later in Florence and Padua (1545)
Andrea Caesalpino or Andreas Caesalpinus (1519-1603), Italian physician, philosopher, and botanist, De plantis libri XVI (1583). Caesalpino succeeded Ghini as director of the botanic garden in Pisa.
Joseph Pitton de Tournefort (1656-1708), French, Eléments de botanique (1694), then translated into Latin as Institutiones rei herbariae (1700 and 1719); 700 genera and 7,000 species; "Father of the Genus Concept," first to make a clear definition of the concept of genus for plants--this made classifications easier, preparing the way for Linnaeus. He travelled extensively and collected plants in western Europe and Asia Minor; recognized trees and herbs (as traditionally done), but also floral characters, such as petals free vs. petals connate and flowers actinomorphic vs. zygomorphic. He coined the word "herbarium."
John Ray (1627-1705), British, "Father of English Natural History," Synopsis methodica stirpium Britannicarum (the first British flora, an account of all the plants that grow wild in a particular geographic region), Historia Plantarum (3 volumes, 17,000 species), travelled extensively in Europe and produced a classification system that relied on original observations of multiple characters of leaf, flowers and fruits. Plants that looked alike were grouped together, but his system was complicated (he believed in "essential" characters; these split natural groups and lumped together unnatural ones). Monocots and dicots recognized, as well as many plant families we now recognize today. He coined the word "species."
Linnaeus
By the middle of the 18th century, many developments made the science of botany ready for a person to synthesize information. People needed an easy, rapid way to identify and name plants. Travel was widespread during this time because of advances in navigation. There were the first microscopes, widespread use of herbarium specimens, and printed books were widely available.
Carl von Linné or Carolus Linnaeus (1707-1778) "Prince of Botany"
Systema Naturae (1735, and multiple editions thereafter to 1767)
Species Plantarum (1753) 7,700 species recognized
Genera Plantarum (1754) 1,105 genera recognized
Linnaeus on YouTube, a film about Carl Linnaeus
Linnaeus' sexual system of classification (Marriages of Plants). The system was risqué and explicit, but so simple that its appeal was instantaneous. Basically, the system involved counting the number of stamens (which gave the Class) and the number of pistils (which gave the Order=Family). In many cases his system of classification was incorrect because unrelated plants were placed together.
Species Plantarum was published May 1, 1753 and is the starting point for botanical nomenclature. He popularized the system we now call the Binomial System of Nomenclature; however, the idea of binomials can be traced back to the Herbalists
Post-Linnaean French and Swiss
The French and Swiss never adopted the system of Linnaeus--they were working on their own NATURAL systems of classification. They wanted to try to provide more information content in their classifications.
Michel Adanson (French; 1727-1806), Familles naturelles des plantes (1763) and Familles des Plantes (1963-1964, republished posthumously), considered all characters (organs) when making a classification (not just "essential" characters), with those species possessing the greatest number of similarities grouped together. He showed that every plant characteristic varied within natural groups and concluded that no one character was essential for defining a group, and that groups could be defined only by combinations of characters (Judd et al., 2008, p. 46). He did not believe that any one character is more important than another. Adanson's system introduced many terms which were ridiculed by defenders of Linnaeus' Sexual System.
Jean-Baptiste de Lamarck (1744-1829), French, Flore Françoise; hypothesized evolutionary change through inheritance of acquired characters (Lamarckism)--not scientifically correct, but did present the idea that species could change over time. Used identification keys very similar to present-day dichotomous keys.
Antoine-Laurent de Jussieu (1748-1836), French, Genera Plantarum (1789), "Father of Plant Families", developed a classification scheme for planting at the Jardin des Plantes in Paris: plants that looked alike based on a suite of similar characters (genera and families) were planted together. This was an attempt to reflect a NATURAL system of classification, a system that was becoming widely accepted. In fact, much of his system remains in use today.
(FACTOID: 76 of de Jussieu's families are conserved by the ICBN vs. just 11 for Linnaeus, although de Jussieu did retain Linnaeus' binomial nomenclature.)
Augustin Pyramus de Candolle (1778-1841), Swiss, Prodromus Systematis Naturalis Regni Vegetabilis (1824), a first (and last!) attempt of a flora of the world: 58,000 species and 161 families in seven volumes (encompassed taxonomy, ecology, evolution, and biogeography)
His son was Alphonse de Candolle (1806-1893), who eventually continued writing the Prodromus (adding 10 more volumes, for a total of 17) in collaboration with his own son, Anne Casimir Pyrame de Candolle. Alphonse de Candolle wrote the first Code of Botanical Nomenclature (1867) -- he was in law before he entered botany.
Theory of Evolution
Charles Darwin (1809-1882), England, On the Origin of Species (1859); provided the theoretical basis for NATURAL systems of classifications -- organisms that look alike do so because they are related and share a common ancestor. Showed that all species of life have evolved over time from common ancestors, through the process he called natural selection.
George Bentham (1800-1884) and Sir Joseph D. Hooker (1817-1911), England, Genera Plantarum (1862-1883), worked at Kew Botanical Gardens; recognized 7,569 genera in their NATURAL system of classification (they provided detailed, original descriptions). While published after Darwin's Origin of Species, there was no time to change their system of classification to reflect these new evolutionary concepts (Hooker was Darwin's closest friend and one of the first to accept Darwin's ideas). Many herbaria in the world still arranged according to this system. Bentham and Hooker's Handbook of the British Flora used by students for over a century.
Phylogenetic Systems
After the publication of Darwin's theory of evolution, biologists realized that the reason taxonomic groups shared certain suites of characteristics was because those groups were evolutionarily related to each other. Evolution provided the theoretial basis for these morphological similarities. Evolutionary thinking resulted in PHYLOGENETIC or PHYLETIC or EVOLUTIONARY systems of classification.
Asa Gray (1810-1888), American, A Manual of Botany of the Northern United States ("Gray's Manual;" 1848, and later versions). Appointed first professor of botany in the United States (in 1842, at Harvard University); Harvard becomes leading taxonomic botanical institution in US (Gray effectively created the Botany department). Gray important for unifying the taxonomic knowledge of the plants of North America. Gray's Manual of Botany published by M.L. Fernald in 1950 (8th ed.).
Adolph Engler (German; 1844-1930) and Karl A.E. von Prantl (German; 1849-1893), Die natürlichen Pflanzenfamilien (1887-1915; 23 volumes!)
Charles Edwin Bessey (1845-1915), American, The Phylogenetic Taxonomy of Flowering Plants (1915), a student of Asa Gray (went to work at Iowa State, then University of Nebraska)
John Hutchinson (1884-1972), Families of Flowering Plants, Genera of Flowering Plants
Robert F. Thorne (1920-present), A Phylogenetic Classification of the Angiospermae, Rancho Santa Anna Botanical Garden, Claremont, California
Armen Takhtajan (1910-present), Flowering Plants: Origin and Dispersal and Diversity and Classification of Flowering Plants, worked in Leningrad and the New York Botanical Garden
Rolf Dahlgren (1932-1985), A Revised System of Classification of the Angiosperms, University of Copenhagen
Arthur Cronquist (1919-1992), An Integrated System of Classification of Flowering Plants (1981) and The Evolution and Classification of Flowering Plants (1988), worked at the New York Botanical Garden. Until recently, his system of classification was used in IB 335. He was one of the most influential botanists of the 20th century.
Robert Sokal and Peter Sneath, Principles of Numerical Taxonomy (1963)
Willi Hennig, Grundzüge einer Theorie der Phylogenetischen Systematik (1950), later translated into English and published by the University of Illinois Press, Phylogenetic Systematics (1966)
Modern Phylogeneticists use both morphological and molecular data and modern methods of data analyses to study evolutionary relationships among organisms. Remember, a phylogenetic classification involves two components: (1) determining the phylogeny, and (2) using this phylogeny to produce a classification.
Here is a quote from Darwin in On the Origin of Species:
"I believe that the arrangement of the groups within each class, in due subordination and relation to the other groups, must be strictly genealogical in order to be natural; but the amount of difference in the several branches or groups, although allied in the same degree in blood to their common progenitor, may differ greatly, being due to the different degrees of modification which they have undergone; and this is expressed by the forms being ranked under different genera, families, sections or orders."
Would Darwin recognize paraphyletic groups?
Summary of Approaches to Classification and Major Contributors
Click here to get home!
