Phylogeny and Systematics. Chapter 10. Taxonomy. Taxonomy produces a formal system for naming and classifying species to illustrate their evolutionary relationship. Taxonomy & Systematics. Taxonomy Formal system for naming and classifying species. Systematics
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Introduction of evolutionary theory into animal taxonomy changed taxonomist’s role from one of classification to systematization.
Classification denotes the construction of classes.
Grouping of organisms that possess a common feature called an essence used to define the class.Taxonomy
Systematization changed taxonomist’s role from one of classification to systematization. places groups of species into units of common evolutionary descent.
Character variation is used to diagnose systems of common descent.
No requirement that an essential character be maintained throughout the system for its recognition as a taxon.Taxonomy
Aristotle’s two kingdom system included plants and animals.
One-celled organisms became a problem
Haeckel (1866) proposed Protista for single-celled organisms.
R.H. Whittaker (1969) proposed a five-kingdom system to distinguish prokaryotes and fungi.
Traditional groupings based on embryological and anatomical characters:
Branch A (Mesozoa): phylum Mesozoa, the mesozoa
Branch B (Parazoa): phylum Porifera, the sponges and phylum Placozoa
Branch C (Eumetazoa): all other phyla
Branch C ( changed taxonomist’s role from one of classification to systematization.Eumetazoa): all other phyla
Grade I (Radiata): phyla Cnidaria, Ctenophora
Grade II (Bilateria): all other phyla
Division A (Protostomia): Protostome characteristics
Acoelomates: phyla Platyhelminthes, Gnathostomulida, Nemertea
Pseudocoelomates: phyla Rotifera, Gastrotricha, Kinorhyncha, Nematoda, Nematomorpha, Acanthocephala, Entoprocta, Priapulida, Loricifera
Eucoelomates: phyla Mollusca, Annelida, Arthropoda, Echiurida, Sipunculida, Tardigrada, Onychophora.Major Subdivisions of the Animal Kingdom
Recent molecular phylogenetic studies have challenged traditional classification of Bilateria.
Grade II: Bilateria
Division A: (Protostomia):
Lophotrochozoa: phyla platyhelminthes, Nemertea, Rotifera, Gastrotricha, Acanthocephala, Mollusca, Annelida, Echiurida, Sipunculida, Phoronida, Ectoprocta, Entoprocta, Gnathostomulida, Chaetognatha, Brachiopoda
Ecdysozoa: phyla Kinorhyncha, Nematoda, Nematomorpha, Priapulida, Arthropoda, Tardigrada, Onychophora, Loricifera
Division B (Deuterostomia):
phyla Chordata, Hemichordata, Echinodermata