A precious clue in the environment
Living organisms constantly leave fragments of DNA in their environment: in water, air, or soil, through skin cells, hair, feathers, or feces. This environmental DNA (or eDNA) can be collected from water samples, as well as through other terrestrial or urban methods, providing a discreet and effective inventory of the species present.
🌊 Aquatic example: DNA collection from water
- Sample collection: using bottles or special pumps, water is collected at different depths.
- Filtration: The water is then passed through an ultra-fine filter that traps particles containing DNA.
- Safe storage: The filter is stored to prevent damage.
- Laboratory analysis: DNA is extracted, amplified using the PCR (polymerase chain reaction) method, and sequenced to identify the species present.
🌳 Terrestrial example: collecting DNA from urban soil.
In terrestrial environments, it is also possible to collect environmental DNA from the soil in urban parks or even from sidewalks!
- Collecting soil or urban dust: Using a small shovel or a brush, collect a small amount of soil or dust.
- DNA extraction: In the laboratory, samples are analyzed to detect DNA left behind by animals (footprints, hair, feces) or even plants (pollen, decomposed leaves).
- Species identification: This method makes it possible to compile an inventory of less visible urban biodiversity, such as small mammals, insects, and wild plants.
Why is this important for biodiversity? Environmental DNA makes it possible to:
- 📍 Identify and inventory rare or endangered species without disturbing them.
- 🌱 Better understand ecosystems, whether natural or urban.
- 🌍 Monitor the effects of climate change and human activities on nature.
Ideas for educational activities for your classes! (Lower Secondary – Life and Earth Sciences)
🔬 Hands-on workshop: Filtering and extracting environmental DNA
- Objective: To introduce students to the practical steps involved in collecting DNA from the environment.
- Materials: coffee filters, water samples (from a river or pond) or soil samples, soapy water to simulate extraction.
- Activity: Students filter water or sift soil, “extract” a fictional molecule, and share their observations.
🕵️ Scientific Study: Identifying Species Using DNA
- Objective: To use sequencing data to understand local biodiversity.
- Materials: cards with fictional “DNA codes” and the corresponding species.
- Activity: Students must match DNA fragments to species and solve an ecological mystery (for example: “Which animal left tracks on this urban trail?”).
Conclusion
Environmental DNA is a fascinating tool that bridges the gap between science and biodiversity conservation, whether in marine, terrestrial, or urban environments. By introducing young people to these methods, we encourage them to become active advocates for the environment.