Transcript History of Biological Taxonomy

History of
Biological Taxonomy
BIOL447/647
21 January 2016
William Sharp MacLeay (1792-1865)
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1821: circles-withincircles taxonomy
Always five circles
“Osculant” types joined
each circle to two
adjacent circles
Types of circle
correspond, from one set
to next
Animalia’s five circles
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Vertebrata—(vertebrates)—"typical"—"most
perfect"
Annulosa—(arthropods)—"subtypical"—wellarmed for conflict, noxious, destructive, "evil"
Radiata—(jellyfishes)—"natatorial"—highly
aquatic
Acrita—(corals, hydras)—"suctorial"—"low,
imperfect"; feed by "suction"
Mollusca—(mollusks)—"rasorial"—domesticated
and useful (i.e., as shellfish)
Vertebrata's five circles
Typical—Mammalia
Subtypical—Reptilia
Natatorial—Pisces
Suctorial—Amphibia
Rasorial—Aves
HANDOUT—O’Hara 1986
More MacLeayian taxonomy
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Other subtypical groups: Ferae among
Mammalia; shrike family among Raptores;
Ophidia among Reptilia
Other natatorial groups: Cetacea among
Mammalia; Cephalopoda among Mollusca
Other suctorial groups: Testudines among
Reptilia; Coleoptera among Insecta; armadillos
and pangolins among Mammalia
Other rasorial groups: ungulates among
Mammalia; Canidae among Ferae; Hymenoptera
among Insecta
MacLeay’s Influence
Enthusiastically supported in Chambers'
Vestiges of the Natural History of Creation
(1845)
 Intrigued Darwin for a time, during 20
years he had Origin on a back burner
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Charles Robert Darwin (1809-1882)
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Origin of Species (1859)
included predictions about
phylogeny reconstruction:
"Our classifications will
come to be, as far as they
can be so made,
genealogies; and will then
truly give what may be
called the plan of creation.
The rules for classifying
will no doubt become
simpler when we have a
definite object in view."
The Only Illustration
in Origin of Species (1859)
Sketch in private
notebook, 1837
Darwin’s Barnacle Work
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Darwin's only work on
taxonomy, in 4 volumes
(1846-1854)
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Jos. Hooker had told him
Origin would be better
received if he had done
taxonomic work
No reference to evolution,
but clearly phylogenetic
Ernst Haeckel (1834-1919)
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Professor at Jena
Coined phylogeny,
phylum, and ecology
Developed visual
phylogenetic tree
Biogenetic law:
“Ontogeny
recapitulates
phylogeny."
Three Schools of Thought
(Late 1800s Into Early 1900s)
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Differing views on …
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(a) how evolution proceeds
(b) whether characteristics evolve only once
(homology), or numerous times, independently
(homoplasy)
thus (c) whether phylogenetic reconstruction
can be accurate
Darwinism
 Neo-Lamarckism
 Orthogenesis
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Darwinism
Natural selection = primary agent of
change
 Adaptations rarely evolve more than once
independently
 Phylogeny reconstruction should be
possible
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Proponents:
Darwin
Thomas H. Huxley (1825-1895)
E. Ray Lankester (1847-1929)
Neo-Lamarckism
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Adaptations acquired by an organism are
passed to offspring
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J.B. Lamarck's Philosophie Zoologique (1809)
Multiple origins from similar environmental
pressures ("convergence")
 Phylogeny difficult to reconstruct
 Finally discredited by rise of genetics in
early 1900s
 Proponents: Haeckel
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Frederick Wood Jones (1879-1954)
Edward Drinker Cope (1840-1897)
Orthogenesis
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Theistic view
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Internally-directed evolution a sort of “plan of God”
Various groups have same internal plan (“parallelism”)
Major taxa had a pre-directed ontogeny, unlinking
organism and environment, ending in extinction
Much room for multiple origins of characteristics
Would greatly obfuscate phylogeny
reconstruction
Proponents:
St. George Jackson Mivart (1827-1900)
Henry Fairfield Osborn (1857-1935)
International Code of
Zoological Nomenclature
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Late 1800s: countries adopted differing codes of
nomenclature
1901: 5th International Zoological Congress,
resulted in the first International Code of
Zoological Nomenclature (issued 1905)
Revised periodically since then
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Most recently in January 2000, with revisions covering
such items as web-based publications
International Commission on Zoological
Nomenclature (ICZN) issues opinions
Three Competing Schools of Thought
(Latter Half of the 20th Century)
Evolutionary Taxonomy
 Phenetics
 Cladistics
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Evolutionary Taxonomy
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Major proponent: Harvard's Ernst Mayr
(1904-2005)
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Systematics and the Origin of Species (1942)
Principles of Systematic Zoology (1969)
“Old school”
 Classifies based both on phylogenetic
relationships, and degree of differentiation
within parts of an evolutionary tree
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Phenetics
Classification based on overall similarity,
reasoning that similarities result from
common ancestry
 Strong early reliance on computer
analyses
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Numerical Taxonomy (1963) by R.R. Sokal
and P.H.A. Sneath
Cladistics
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Classification solely on shared derived characters
(=synapomorphies)
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Ignore ancestral features (=plesiomorphies)
All members of taxon are more closely related to
other members of that taxon than to members of
any other taxon of equal rank
German entomologist Willi Hennig (19131976): the “father” of cladistics
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Grundzűge einer Theorie der phylogenetischen
Systematik (1950)
English synopsis in a review article (1965) and English
translation, Phylogenetic Systematics (1966)
And the Winner is…
Willi Hennig
Schuh and Brower Table 1.1 p. 12
The Rise of Molecular Methods
Protein electrophoresis comparisons
began in mid 1960s, popular by 1970s
 Restriction enzymes then just beginning
to be used on DNA, with electrophoretic
separation
 DNA sequencing invented in 1977
 PCR invented in 1987
 Minisatellite DNA studies started 1987
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Readings for Next Time
Schuh & Brower: 173-188; 201-208
 Winston:
129-188; 407-432
 Additional:
None
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