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Systematics. ordering living organisms by groups called taxa taxa are ordered from largest to smallest; the smallest taxon is called the specific epithet. Classification Hierarchy : e.g. Mockingbird. Kingdom- Animalia Phylum- Chordata Class - Aves Order- Passeriformes Family- Mimidae
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Systematics • ordering living organisms by groups called taxa • taxa are ordered from largest to smallest; the smallest taxon is called the specific epithet
Classification Hierarchy: e.g. Mockingbird • Kingdom-Animalia • Phylum- Chordata • Class- Aves • Order- Passeriformes • Family- Mimidae • Genus - Mimus • Specific Epithet- polyglottos
Species is biologically meaningful, all other taxanomic levels are subject to the philosophies of systematics.
Traditional Classification of Vertebrates • Kingdom Animalia: Multi-celled animals are classified into 18 major phyla. Each phylum represents a group that shares in common a set of characters that is unique among animals. • Phylum Chordata (74,500)- vertebrates, tunicates, lancelets; possess a dorsal hollow nerve cord, notocord, and gill slits
Subphylum Vertebrata • Class Agnatha- lampreys • Class Chondrichthyes- cartilaginous fish • Class Osteichthyes- bony fish • Class Amphibia- amphibians • Class Reptilia- reptiles • Class Aves- birds • Class Mammalia- mammals
Conventions for Printing Scientific Names • The genus and species name constitute the scientific name for the species. • The genus and species names must always be underlined or printed in italics indicating they are derived from a foreign language. • The genus name should always be capitalized and the species name should always be lower case. • All other taxa are capitalized.
Cladistics- Phylogenetic Systematics reflects phylogenetic or evolutionary history of the organism.
Basic Tenants of Phylogenetic Systematics • Only shared derived characters are useful in deducing relationships. • Speciation produces two sister species. • Speciation is recognizable only if the divergence of the populations are accompanied by the origin of a derived character.
Some Definitions • monophyletic- the clade contains the ancestor and all descendants • paraphyletic- some divergent taxa are excluded • polyphyletic- unrelated species that look alike (homologous species) are merged into taxa
autoapomorphic -vs- synapomorphic autoapomorphic- a derived character state occurring in a single descendent taxon synapomorphic- a shared derived character in two or more taxa