Lecture VIII - Species and Speciation

Lecture VIII - Species and Speciation - Lecture VIII...

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Lecture VIII – Biological Species
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What is a Species? Unlike all other taxonomic classifications, species exist independent of scientific convention In fact, most human societies are able to correctly identify most species as independent units without any “scientific” tools (such as genetics, morphometrics, etc.) by observation alone So, again, what is a species?
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Species – Early Taxonomy Carolus Linnaeus, or Carl von Linné (1707 – 1778), a Swedish botanist and physician who established the basis for the taxonomic system used today Defined species as the lowest division of organisms in the taxonomic hierarchy
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Species – Early Taxonomy According to this type of typological division, species are a group of organisms that conform to certain fixed properties This definition is based on Platonic philosophy of ideal forms and on the concepts of special creation and immutability of species
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Linnean Taxonomic Hierarchy Has changed somewhat, but essentially the same Domain – Kingdom – Phylum/Division – Class – Order – Family – Genus – Species Some intermediate classifications using prefixes super-, or suffixes sub- are used, some use tribe as an intermediate between Family and Genus Species are named using Binomial system: Genus species , for example, Canis lupis . Always italicized, always including genus http://www.southwestwildlife.org/Animal%20Photos/images/Mexican%20Gray%20Wolf%201.jpg
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Later Definitions Morphological Species Biological species Phylogenetic / Evolutionary / Darwinian species http://www.soundtrackcollector.com/images/cd/large/Species_SILCD29407.jpg
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Morphological Species A group that differs morphologically from others, or Morphological variation is lower within the group than between this group and others
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Biological Species Definition by Ernst Mayr (1904-2005) A species is not a group of morphologically similar individuals, but a group that can breed only among themselves, excluding all others (Mayr 1942) Cannot define species that reproduce asexually http://evolution.berkeley.edu/evosite/evo101/images/frogcartoon.gif
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Phylogenetic Species Phylogenetic / Evolutionary / Darwinian species : a group of organisms with a shared ancestor, and a lineage that maintains its integrity with respect to other lineages through both time and space Most species described using morphological data, and are, in essence, Morphological species http://www.tolweb.org/tree/learn/concepts/ConceptsImg/BembidionSpecies.jpg
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This note was uploaded on 01/23/2010 for the course BIOS 230 taught by Professor Gibbons during the Fall '08 term at Ill. Chicago.

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Lecture VIII - Species and Speciation - Lecture VIII...

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