History of Biological Taxonomy BIOL447/ January 2016

William Sharp MacLeay ( )  1821: circles-within- circles 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  Vertebrata—(vertebrates)—"typical"—"most perfect"  Annulosa—(arthropods)—"subtypical"—well- armed 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  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

Charles Robert Darwin ( )  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  Darwin's only work on taxonomy, in 4 volumes ( ) 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 ( )  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)  Differing views on … (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

Darwinism  Natural selection = primary agent of change  Adaptations rarely evolve more than once independently  Phylogeny reconstruction should be possible Proponents: Darwin Thomas H. Huxley ( ) E. Ray Lankester ( )

Neo-Lamarckism  Adaptations acquired by an organism are passed to offspring 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 Frederick Wood Jones ( ) Edward Drinker Cope ( )

Orthogenesis  Theistic view 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 ( ) Henry Fairfield Osborn ( )

International Code of Zoological Nomenclature  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 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

Evolutionary Taxonomy  Major proponent: Harvard's Ernst Mayr ( ) 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

Phenetics  Classification based on overall similarity, reasoning that similarities result from common ancestry  Strong early reliance on computer analyses Numerical Taxonomy (1963) by R.R. Sokal and P.H.A. Sneath

Cladistics  Classification solely on shared derived characters (=synapomorphies) 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 ( ): the “father” of cladistics 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

Readings for Next Time  Schuh & Brower: ;  Winston: ;  Additional:None