In the coastal forests of Northern California, the most abundant vertebrates are amphibians such as salamanders and frogs. "Abundance" refers to the total number of animals in a given area, but Northern California is also home to a rich diversity of amphibian species. With around 30 species of amphibians inhabiting the area, one might think that we have discovered all the species. But what researchers are discovering, in some cases, is that we may be lumping many species together and calling them one.
When organisms are lumped together due to similarities in their physical traits, such as coloration or body shape, the result is called a cryptic species complex. Cryptic species complexes are not restricted to amphibians, and can be found in other animals and plants. A species of salamander called the Black Salamander (Aneides flavipunctatus) has recently been described as a cryptic species complex. This organism is currently being split into three species, while further investigation could reveal the complex containing five or more species.
So how have so many species slipped through the cracks of our taxonomic system? One reason for this recent change is the emergence of new molecular methods that allow the genetic structure of a species to be more accurately described. Old genetic methods looked at the DNA sequence of only a single gene to help define species, but what geneticists are just realizing is the information in one gene alone isn't always enough to accurately define a species.
A new approach to defining species uses multiple genes, along with other types of data such as differences in the physical structure of the organism (morphology) and how that organism interacts with its environment (ecology). This comprehensive approach is much more effective in determining what makes one group of organisms sufficiently distinct to be called separate species.
Why is it so important that we can distinguish between species that look alike? One hazard of lumping many species together is the potential for one of the species to become endangered or go extinct without anyone knowing. Without defined ranges and population estimates for each true species it is nearly impossible to provide adequate habitat protection and to implement conservation measures. Because of the overall decline in amphibian populations both locally and worldwide, it is especially important to know what species exist so that we can effectively protect them. This protection will allow future generations of humans to enjoy the benefits of these animals, while preserving their right to exist in their natural habitat.
A submission of the Science Media and Communications Seminar at Humboldt State University.Contact: Jeffrey White, Department of Biological Sciences; firstname.lastname@example.org.