North Carolina is a global center of salamander biodiversity, with more than 60 species found in the state.
Why are there so many species? Exactly how many species are there? How are these species related to one another?
The Genomics and Microbiology Lab at the N.C. Museum of Natural Sciences has a team of researchers trying to answer these and other questions about amphibian biodiversity. I visited the lab, and with Bryan Stuart – the museum’s curator of herpetology – plus Nash Community College biology instructor David Beamer and his undergraduate students, we used next-generation DNA sequencing technology to explore questions of salamander diversity and evolution on the genetic level.
Every living organism on Earth has a genetic code made up of a four-letter alphabet – A, G, C and T – that represent four different nucleotides – sub-units of nucleic acids like DNA and RNA. We can compare the nucleotide sequences of multiple individuals or species to determine how they are related: The more similar the DNA sequence, the more closely related the individuals are. This information can then be used to generate a “phylogeny” or a family tree of organisms.
Traditional DNA sequencing technology typically limits the number of genes we can include in a genetic study due to sequencing costs and time required in the lab to generate DNA sequence data. However, last September, the museum’s Genomics Lab purchased an Illumina MiSeq next-generation DNA sequencer through a grant from the National Science Foundation. The MiSeq has allowed us to look at 33 unique genes simultaneously to explore questions about salamander biodiversity.
Our current project focuses on several species within the genus Eurycea, commonly known as two-lined salamanders. These are lungless salamanders that breathe through their skin. These species are found over large areas of the eastern United States, and many species are very similar in appearance; however, previous genetic studies suggest that populations in certain geographic areas, such as the Sandhills region of North Carolina, are very distinct. If these populations really are distinct, are they different enough to be considered new species or subspecies?
Our advanced sequencing technology is helping us investigate this question using more genetic data than ever before. Will we be adding additional salamander species to the list of those found in North Carolina? Stay tuned for updates on this study and others being conducted at the N.C. Museum of Natural Sciences.
Heather Farrington is research and outreach coordinator for the Genomics and Microbiology Lab at the N.C. Museum of Natural Sciences.