NCPA - National Center for Policy Analysis


June 11, 2008

To this day, scientists struggle with determining what a species is.  A better definition can influence which animals make the endangered list, says science essayist Carl Zimmer. 

For example:

  • Formal taxonomic systems first identified species based on visual traits, such as fins or fur.
  • Later, the species concept changed, specifying that two organisms should be capable of breeding.
  • Today biological diversity can be ascertained by sampling DNA and tracking how a species descended from a common ancestor.

The debate over species definition is far from over and is more than a mere academic spat; proper classification is essential for designating the endangered list, says Zimmer.  Defining species can have a huge effect on whether an endangered group gets protected, and whether a habitat is saved or lost. 

For instance:

  • The U.S. red wolf known as Canis rufus has been the subject of an enormous project to save it from extinction.
  • Meanwhile, Canadian scientists argue that Canis rufus is just an isolated southern population of Canis lycaon, a Canadian wolf that is not endangered.

Source: Carl Zimmer, "What Is A Species?" Scientific American, June 2008.

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