slatkin7Answers - Bio 1B, Spring, 2007, Evolution section 1...

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Bio 1B, Spring, 2007, Evolution section 1 of 3 Updated 3/8/07 8:50 AM Lecture 7 7 Species Problem Reading: 7 th edition 472-476; 6 th edition 464-468;. What is a species 1 ? Morphological species concept (MSC) The MSC classifies organisms into species based on their morphology. Individuals in the same species are similar to one another in morphology. Individuals in different species are different in morphology. The Linnaean system of classification and most traditional methods of classification use the MSC. The MSC emphasizes morphology rather than behavior in part because classification was and still is often done with preserved specimens or fossils. One problem with the MSC is that it is difficult to say what differences in morphology are important for distinguishing species and how different two groups organisms have to be in order for them be classified as different species. Some species are polymorphic, but the traits that are polymorphic are not used to distinguish species. Males and females of sexually dimorphic species may be very different from each other, as in the birds of paradise, yet they are classified as members of the same species. In practice, the application of the MSC to a group of organisms takes experience and practice. In some species, it is difficult even for specialists to know whether a group is a single polymorphic species or several separate species. Adults of the tropical butterfly, Astraptes fulgerator , are monomorphic but the larvae are polymorphic. The biological species concept (BSC) The BSC groups organisms into species that are reproductively isolated from one another, meaning that members of different species do not interbreed under natural conditions or, if they do, they do not produce viable or completely fertile offspring. The BSC is regarded as the correct definition of a species
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This note was uploaded on 09/07/2008 for the course BIO 1B taught by Professor Carlson,mischel,power during the Spring '07 term at University of California, Berkeley.

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slatkin7Answers - Bio 1B, Spring, 2007, Evolution section 1...

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