Bio 105 27 January 2004

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Bio 105 27 January 2004

• Elements of biological diversity
• Biological hierarchy of organization
• Biological species concept
• Species definitions absolutes or cultural
  constructs?
• Cataloguing biodiversity
• Number described species
• Estimates of number of undescribed species

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Elements of Diversity
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What is a species?

• Morphological Species Concept
• Visible characters

• Biological Species Concept
• Reproductive isolation

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Biological species concept

• a population whose members are able to interbreed
  freely under natural conditions
• AND
• is reproductively isolated from other groups
  (Mayr 1963).

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Tigons and Ligers

• Tigers

• Lions

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Each species is

• a closed gene pool.
• evolves certain hereditary traits
• comes to occupy a unique geographic range.

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Difficulties with BSC natural and fertile hybrids

• Oaks hybridize freely in nature
• Hybrids are fertile
• San Diego oaks

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Difficulties with BSC ring species, e.g.
Ensatina salamanders in California
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Commonly accepted view of a species

• a group of organisms at one place at one time,
  having a diagnostic set of features.

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The species a cultural construct?

• 1928 Ernst Mayr
• western New Guinea highlands
• 136 species of birds
• 11 correspondence with classification by local
  Arfak hunters

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But.

• E.O. Wilson
• n.e. New Guinea
• 210 ant species
• Saruwagets did not recognize different ant
  species.