Genetic Material Found in Environmental Samples
Get the scoop on environmental DNA, also known as eDNA! eDNA is the genetic material that creatures shed in their environment, like hair, skin, or poop. Think about a wriggly earthworm burrowing through the soil, leaving behind its slime and dead cells. The genetic material from the earthworm and other organisms, like plants and the slippery eels, will be in that soil sample. The same concept applies to aquatic ecosystems, like oceans, rivers, or lakes, where fish, plants, and other life forms deposit fragments of themselves.
Exploring Aquatic Ecosystems with eDNA
Ever wondered if you could name every creature in this picture, even the ones too small to spot without a microscope? eDNA helps scientists do just that! eDNA offers a speedy and accurate way to analyze ecosystems. Take a look at this image from Lake Wānaka. The massive, mean-looking fish is the common bully, but what about the smaller creatures lurking about?
Genetic Barcoding and eDNA
DNA holds the genetic blueprint of every living thing. This complex molecule is composed of two long strands containing a combo of four chemicals: Adenine, Thymine, Guanine, and Cytosine. These building blocks are rearranged in unique sequences, creating a code specific to each species - much like a barcode for your shopping finds at the supermarket.
Scientists use short sections of this unique sequence to create a barcode for an organism, then store these barcodes in databases for future identification. Because of advances in technology, scientists can now identify numerous species in a single sample, saving time and resources compared to traditional identification methods.
The eDNA Process
Here's a run-down of the eDNA process:
- Collect a Sample: Take a sample, like soil, water, or air, from a region of interest.
- Extract and Purify the DNA: Separate the DNA from the rest of the sample for further analysis.
- Amplify the DNA: Use a technique called PCR (polymerase chain reaction) to make more copies of the DNA.
- Identify the DNA Sequences: Match the extracted DNA sequences to known sequences (barcodes) in world databases to create a species list.
Why Use eDNA?
- Monitoring Ecosystems: eDNA allows scientists to track species within an ecosystem without capturing or disturbing them, making it less intrusive and damaging.
- Cost Effective: Physical monitoring of species can be time-consuming and expensive, especially when searching for rare species.
- Detecting Species: eDNA can help identify species that are difficult to track visually, like certain invertebrates or those with small populations.
Limitations of eDNA Testing
- Shedding Cycle: eDNA can be washed away quickly, or degrade due to sunlight or other natural processes.
- Incomplete Databases: Not all species have been sequenced, so there may be gaps in the barcode database.
- Identification Limitations: While eDNA can identify what species are present, it doesn't provide information on individual numbers, gender, or age.
Now that you have an idea about environmental DNA and its uses, you can better understand the science behind biodiversity monitoring and species detection.
Utilizing technology, scientists can employ data-and-cloud-computing advancements to store and access the barcodes of various organisms in databases, aiding in rapid identification when analyzing extracted eDNA sequences. By exploring environmental-science methods like eDNA, we can gather knowledge about climate-change effects on aquatic ecosystems, even detecting the presence of small, hard-to-spot species.
