Since eDNA was first used back in 1968, the field of molecular biology exploded with technologies like PCR, DNA sequencing, and microarrays. Modern microbiologists now regularly collect and sequence vast quantities of microbial eDNA from water, soil, and even the air – that field has come to be know as “metagenomics” [1]. Most microbial species can’t be detected any other way, because they are so small, similar, or difficult to grow in a lab.

Macrobiologists, the scientists who study larger organisms such as insects or whales, were slower to start using eDNA. Mainly this is because large organisms can be detected in many ways, starting with the simple fact that humans can actually see them! However, macrobiologists who study rare or elusive organisms soon learned that using eDNA could help.

Some of the first macrobiologists to use eDNA were actually forensic scientists trying to identify criminals (often an elusive organism) [2]. Humans constantly shed DNA-containing material and forensic scientists can extract eDNA from dust or fluids at crime scenes [3].

More recently, macrobiologists studying aquatic invasive species have used eDNA in water to locate bullfrogs or Asian carp during the early stages of an invasion [4,5]. This is when other detection methods are least effective, but it’s also when detection is most important (think ounce of prevention vs pound of cure). Aquatic eDNA surveillance, as it’s called, is particularly useful because in water, DNA-containing material spreads – so there’s an expanding cloud of eDNA to detect even when the invader is hiding.

1. Tringe, S. G. and Rubin, E. M. 2005. Metagenomics: DNA sequencing of environmental samples. Nat Rev Genet 6, 805-814.
2. Hochmeister, M. N., Budowle, B., Jung, J., et al. 1991. PCR-based typing of DNA extracted from cigarette butts. International Journal of Legal Medicine 104, 229-233.
3. Toothman, M. H., Kester, K. M., Champagne, J., et al. 2008. Characterization of human DNA in environmental samples. Forensic Science International 178, 7-15.
4. Ficetola, G. F., Miaud, C., Pompanon, F., et al. 2008. Species detection using environmental DNA from water samples. Biology Letters 4, 423-425.

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