BIO 2 Ordering Diversity - 1 BIO153: Lecture 2 Ordering...

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Unformatted text preview: 1 BIO153: Lecture 2 Ordering Diversity January 9, 2009 Topics: species concepts taxonomy & the Linnean system introduction to phylogenetic analysis: types of characters; types of groups The species concept The species is the fundamental unit in classifying the diversity of life However, its tricky to define! Criteria for recognition of species: 1. common descent (must trace ancestry to a common ancestral population) 2. smallest distinct grouping 3. reproductive isolation from other organisms* *what about asexual organisms? Reproductive isolation is defined as occupation of a particular ecological niche so that the population responds as a unit to evolutionary processes such as selection and drift. There have been many attempts to provide a species definition that works for all types of organisms; this is still an unresolved issue in modern biology. Modern biologists tend to use the phylogenetic species concept the irreducible (basal) grouping of organisms diagnosably distinct from other such groupings and within which there is a parental pattern of ancestry and descent. This approach focuses on reconstructing the historical pattern of evolution by tracing descent relationships 2 Taxonomy = arrangement law taxonomy: formal system for naming and classifying species Linnean system for naming species: binomial nomenclature Form: Genus + species (authority) e.g. Virginia opossum: Didelphis virginiana (Linnaeus 1758) Didelphis = two-wombed virginiana = of Virginia (*** A note on the use of bionomial nomenclature in BIO153: We are fussy about the proper use of the Linnean system, so please use it correctly! 1. The name of the genus is ALWAYS capitalized (e.g. Didelphis ). 2. The species epithet (species name) is NEVER capitalized (e.g. virginiana ). 3. If typed out, a scientific binomial should be italicized . If handwritten, the binomial should be underlined . (THIS APPLIES TO BIO153 TESTS!) 4. Once you have given the full binomial, you can abbreviate the genus name: Didelphis virginiana is the only marsupial native to North America. D. virginiana is nocturnal. 5. You are not responsible for knowing or indicating the scientific authority for any species name.***) 3 The Linnean ranks: (Domain) (not a mandatory rank) Kingdom Phylum (animals)/ Division (plants) Class Order Family Genus Species ranks are nested & hierarchical major ranks are called taxa (singular = taxon ) 7 mandatory ranks There may be intermediate rankings: e.g., between Order and Family, there may be 2 additional ranks Suborder and Superfamily)....
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This note was uploaded on 04/25/2010 for the course BIOLOGY BIO153 taught by Professor Cordon during the Fall '10 term at University of Toronto- Toronto.

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BIO 2 Ordering Diversity - 1 BIO153: Lecture 2 Ordering...

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