How many species are there? This simple question has eluded a concrete answer since Carolus Linnaeus created the species classification system almost 300 years ago. For centuries, intrepid individuals have braved some of the world’s most remote and hostile environments, bringing back detailed descriptions and specimens of never-before-seen organisms. This enterprise was not without risk, and many of these adventurous individuals never returned. Despite the risks and uncertain prospects of success, these seekers of species collectively described tens of thousands of organisms, greatly advancing our knowledge of the natural world.
Yet, even with these centuries of effort, it may be a surprise to hear that one of the biggest conservation challenges in the 21st century continues to be figuring out just how many species we share our planet with. The last several hundred years have yielded no slowdown of scientists making headlines through the exciting discovery of a new species. If anything, the pace of species discovery is continually increasing.
There are several reasons for this rapid pace. For example, technological advances and international collaborations are providing access to previously inaccessible regions. In addition, the use of DNA allows researchers to finally view species boundaries.
How does this work? The answer is in the genes. When we look at a group of individual plants or animals, they may look similar enough for us to consider them the same species. However, these organisms may be as unlikely to interbreed with each other as are we with, say, chimpanzees. This lack of gene sharing between populations gives us the molecular signature of where species boundaries are.
Recently, I led a team of researchers from Yale University, the National Oceanic and Atmospheric Administration, Texas A&M University at Galveston and the Museum of New Zealand Te Papa Tongarewa in an investigation of exactly where species boundaries are across the range of a group of Antarctic ice fishes called Cryodraco. For more than 100 years, species boundaries in this group have been unclear. Our study provides strong, DNA-based evidence that there is in fact more than one species of Cryodraco.
Why does this matter? In the case of Cryodraco, we’re contributing to the efforts of polar scientists racing to describe the biodiversity of Antarctica. Understanding how species diversity originates and is naturally maintained, is critical for forecasting how changes in climate or currents will impact this unique ecosystem in the future. More broadly, the efforts of scientists to identify species boundaries forms the foundation for studies across all biological disciplines, including studies of great economic and medical importance.
Our study (which appeared in a recent issue of Polar Biology) sheds light on how species are generated in Antarctica. But it is important to realize that new species are not just being found in faraway environments. In the past year, both a new species of an insect (a leafhopper) and frog were found practically in the shadow of the New Jersey Turnpike. Indeed, our quest to document all of Earth’s species is far from over.
Alex Dornburg is research curator of ichthyology at the N.C. Museum of Natural Sciences.