by Whit Gibbons

August 24, 2014

Q: I thought we were losing species worldwide, but I have read about DNA being used to discover a new salamander, lizard, flower, etc. How do scientists know when they have found a new species not already known to science?

A: We are indeed losing species on a global scale at a much faster rate than we discover new ones. Reports of discoveries of new species can be misleading, because all of them were already here. They just had not yet been identified by humans, which leads to the answer to the question.

The first step in discovering a new species is knowing which ones have already been documented. It typically takes an expert in a particular taxonomic group to recognize a species as new to science. Ecologists who explore regions where they are not familiar with the plants and animals read field guides about the flora and fauna. Such books have photographs or drawings and written descriptions of size, color, and general appearance of species. They include information about geographic ranges and the ecology of species. Examining museum specimens to learn about variations among species in a taxonomic group can also be important, as can a thorough review of scientific journals that might refer to the group of organisms in question.

The most likely places for new species to be discovered are unpopulated regions, especially in the tropics. For example, new species of bats are continuing to be described in Madagascar; a new monkey has been found in Tanzania; and a new species in the violet family was reported this year in the Philippines. To know the species were new, the scientists describing them had to be familiar with the particular taxonomic group and know traits of every known species in the world that could be related to it.

New species, particularly insects, are still being discovered even in North America, but those numbers pale in comparison to tropical regions. Unknown vertebrate species are less likely to be discovered in the United States, which has been surveyed extensively. However, the use of DNA and other genetic analyses has brought greater definition to the relationships among species. What once was thought to be a single species may be redefined as two or more.

For example, maps in U.S. field guides before the 1970s will show that a single species of the slimy salamander (Plethodon glutinosus) occupied most of the eastern United States. Today, herpetologists partition slimy salamanders into more than a dozen genetically distinctive species, each occupying a different part of the former range. Most of the “new” slimy salamander species cannot be distinguished from each other visually, behaviorally, or ecologically. These kinds of species descriptions clearly do not qualify as discovery of a never-before-seen species.

A different use of genetic analyses to “discover” a new species can be found in the recognition of two dwarf salamanders from the Carolinas. Since at least the 1980s, the tiny dwarf salamander was known to represent two distinct species. However, no one formally described them in a scientific journal until 2003. Genetic evidence along with morphological traits were used to formally classify two species that were already known to be distinct.

In 2007, museum specimens and DNA analyses were used to confirm the discovery of a new species of skink in the rainforests of Borneo. In this case, the scientists were not splitting an assumed single species into separate genetic units or giving official recognition to a species already known to have two distinct forms. This lizard had never before been seen by scientists. But it was only newly discovered; it wasn’t newly created.

Species new to science will continue to be found. But we must guard against the misconception that such species are new to the world. They have been here for millions of years. Our job is to ensure that both “old” and “new” species remain a part of our environment, now and in the years to come.

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