Classification of Organisms

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Classification of Organisms

• Chapter 15

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Taxonomy

• Taxonomy- science of naming and classifying
  organisms
• Carolous Linnaeus developed a simple system for
  naming organisms
• Used a two-word Latin name for each species
• Binomial nomenclature
• First word- genus
• Second word- descriptive word

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Scientific Names

• Genus- taxonomic category containing similar
  species
• Major characteristics
• First letter of first word always capitalized
• First letter of second word always lowercase
• No two organisms have the same scientific name

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Classification System

• Seven levels of classification
• Kingdom? phylum? class? order? family? genus ?
  species
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Great White Shark

• Kingdom Animalia
• Phylum Chordata
• Class Chondrichthyes
• OrderLamniformes
• Family Lamnidae
• Genus Carcharodon
• Species C. carcharias

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Classification

• Organisms within each level share certain
  characteristics
• As you move down in the levels of classification,
  the description and information becomes more
  specific

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Recognizing Species

• Biologists usually define species based on
  appearance and structure
• Biological species- group of actually or
  potentially interbreeding natural populations,
  reproductively isolated from other such groups
• Hybrids can be made between two species

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Evolutionary History

• Convergent evolution- organisms evolve similar
  features independently
• Example anteaters- long, sticky tongue few
  teeth large salivary glands

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Evolutionary History

• Analogous characters- similar features of
  organisms that evolve independently
• Phylogeny- evolutionary history of a species

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Cladistics

• Develop phylogenies through cladistics
• Cladistics- system of taxonomy that reconstructs
  phylogenies by inferring relationships based on
  similarities
• Scientists focus on unique characteristics to
  determine the sequence of organisms evolution
• Derived traits- unique characteristics of a
  particular group of organisms

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Cladogram

• Cladogram- diagram based on patterns of shared,
  derived traits that shows the evolutionary
  relationships among groups of organisms

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Cladogram

• Differences in morphological, physiological,
  molecular, and behavioral level between organisms
• New derived characters will show up on the
  cladogram as groups evolve

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Cladogram

• Do not pay attention to a lot of information
• Does not take into account the specifics of a
  character
• Such as size
• Evolutionary systematics- method of constructing
  phylogenies that involves weighing characters by
  their presumed evolutionary significance
• Not objective