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Taxonomic Grouping . BIOL447/647 4 February 2010. Hierarchy in Taxonomy. Darwin’s phrase—"groups subordinate to groups" Linnaeus' scheme fits evolution fairly well MacLeay's quinarian system, not so well Circularity Osculant types Insistence on fives.
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Taxonomic Grouping BIOL447/647 4 February 2010
Hierarchy in Taxonomy • Darwin’s phrase—"groups subordinate to groups" • Linnaeus' scheme fits evolution fairly well • MacLeay's quinarian system, not so well • Circularity • Osculant types • Insistence on fives
Obligate and Non-obligate Levels of Taxonomy • Obligate: KPCOFG • Nonobligate levels used when “decided gaps” appear to occur at more than six levels of grouping • Helpful in large, diverse groups • More use in entomology than in, say, pogonophorology
Hexapoda (HANDOUT) Class Parainsecta 2 Orders Class Entognatha 1 Order Class Insecta 2 Subclasses 2 Infraclasses in latter 2 Divisions in latter 2 Superorders in one/3 in other 29 Orders total
Monotypic Taxa and Name Proliferation • Monotypic taxa arise when a branch of the tree of life experiences much extinction and/or little cladogenesis • Name redundancy • Ex: Monotypic Lissemydini sister to Cyclanorbini, with 4 spp. Lissemydini = Lissemys punctata
Monotypic Taxa (examples) • Phylum Placozoa, Trichoplax adhaerens • Division Ginkgophyta, Ginkgo biloba • Order Tubulidentata • Family Orycteropodidae • Orycteropus afer • Order Rhynchocephalia • Family Sphenodontidae • Sphenodon punctatus and S. guntheri
Monotypic Taxa (more examples) • 2 of 29 insect orders are monofamilial • Some nonobligate groups have only one subordinate group • 7 of 24 swallowtail genera are monotypic • 526 total species; 204 in type genus Papilio • 3 of 10 salamander families are monogeneric • 1 of 5 caecilian families is monogeneric • 8 of 27 frog and toad families are monogeneric; 3 are monotypic • 4 of 13 turtle families are monotypic and thus monogeneric
Monotypic Taxa (more examples) • Tuataras are monogeneric • 1 of 30 lizard families monogeneric (Helodermatidae) • 5 of 15 snake families monogeneric, 3 monotypic • 6 of 12 emydid genera are monotypic • 40 total species; 12 in Graptemys, one in type genus Emys • 9 of 14 trionychid genera are monotypic (22 total species)
Monotypic Taxa (one last example) Phylum Cycliphora Funch and Kristensen, 1995 (Symbiont on lobster mouthparts) Class Eucycliophora Funch and Kristensen, 1995 Order Symbiida Funch and Kristensen, 1995 Family Symbiidae Funch and Kristensen, 1995 Genus Symbion Funch and Kristensen, 1995 Species Symbion pandora Funch and Kristensen, 1995
The "Decided Gap" Principle • A genus is a group composed of one or more species that are separated from other genera by a decided gap, the size of which is in inverse ratio to the size of the group • A family is a group composed of one or more genera that are separated from other families by a decided gap, the size of which is in inverse ratio to the size of the group
Five rhino species, four genera Indian Sumatran White Javan Black Rhinoceros Dicerorhinus Ceratotherium Rhinoceros Diceros unicornis sumatrensis simum sondaicus bicornis
Readings for Next Time • Schuh & Brower: None • Winston: 323-336 • Additional: K through N • K. A classic criticism of the use of subspecies in taxonomy: Wilson, E.O., and W.L. Brown, Jr. 1953. The subspecies concept and its taxonomic application. Systematic Zoology 2:97111. • L. A beginner's guide to phylogeography: Avise, J.C., J. Arnold, R.M. Ball, E. Bermingham, T. Lamb, J.E. Neigel, C. Reeb, and N.C. Saunders. 1987. Intraspecific phylogeography: The mitochondrial DNA bridge between population genetics and systematics. Annual Review of Ecology and Systematics 18:489522. • M. A good example of phylogeography: Artiss, T. 2004. Phylogeography of a facultatively migratory dragonfly, Libellula quadrimaculata (Odonata: Anisoptera). Hydrobiologia 515:225234. • N. Another good example of phylogeography: Sabatino, S.J., and E.J. Routman. 2009. Phylogeography and conservation genetics of the hellbender salamander (Cryptobranchus alleganiensis). Conservation Genetics 10:12351246.