Let’s say you want to know what animal species are present in a forest. You could walk along line transects and record the species visually observed. You could set up trail cameras to take pictures of passing animals for as long as there is enough space in the memory card and battery life in the cameras. You can use the acoustic survey method to study bats, birds, frogs, and even some monkey species, as they can be distinguished based on their sounds and calls.

Depending on the size of your study area, making a list of the animal species present might take a several hours to several months because you will need to carry out various methods to identify them, which may also require species experts.

These are well-established conventional methods for biodiversity monitoring, but is there no single method to find all the species in a given area at once? A one-size-fits-all t-shirt?

There is a rapidly developing method that can identify a good portion of species in a given study area, including those living on the ground, in the ground, in the water, and even those flying in the air.

Every organism contains genetic material called deoxyribonucleic acid (DNA), passed down from parents to children. All organisms from the same species have very similar DNA.

This technology takes advantage of the traces that organisms leave of their DNA in their environment, whether feathers, skin, scales, urine, or faeces. These traces, known as environmental DNA (eDNA), can be found in soil, water, and air.

This shiny new method is called DNA metabarcoding. Simply put, it identifies organisms by matching their DNA with reference DNA from the gene database or library. It is like matching the barcode of products when you check out at the supermarket.

The process begins with collecting water or soil, or even air, samples from the study area. These samples typically contain genetic material from diverse organisms, including bacteria, plants, and animals.

Once samples are collected from the field, they are brought to the laboratory. DNA is separated from the samples, amplified, and sequenced to generate vast amounts of genetic data that can be compared with existing DNA databases and reference libraries such as GenBank for species identification.

DNA metabarcoding can detect a broad range of organisms at once, providing a snapshot of the species diversity within the study area. That way, you can avoid performing various sampling methods. How convenient is that!

Of course, no method is perfect, even DNA metabarcoding. Since it is still developing, there are limitations. The public gene library has the DNA references of many species but this is still a small fraction of all the species on earth, so far. There can be contamination in the samples, which could disrupt the results. Errors can occur not only during sample collection in the field but also in the laboratory.

Compared to DNA metabarcoding, conventional methods have stronger standardised techniques for sampling and for interpreting the datasets. Besides, in the context of biodiversity monitoring, conventional methods can provide detailed information, such as abundance, age, sex ratios, and individual animals’ special characteristics, such as colours and conditions, which DNA metabarcoding cannot tell us.

Conventional methods are like pictures with tiny pixels portraying good resolution, but their taxonomic scope is limited, whereas those of DNA metabarcoding cover a broad range of species, but the resolution is coarse.

Is there the best of both worlds?

Yes! Robert Holdaway and colleagues, including Ian Dickie working at Lincoln University, suggested that combining DNA metabarcoding with conventional monitoring methods will benefit scientists in many ways.

Using them together will enable scientists to test and improve the reliability and accuracy of our still-developing DNA metabarcoding method. Moreover, combining them will result in a higher chance of detecting species from the same lineage.

Robert and colleagues provided three case studies in New Zealand that can benefit from the dynamic duo.

First, the duo can be of advantage to the nationwide measurements of New Zealand’s biodiversity. They can provide greater taxonomic coverage and more thorough information on the relations among biodiversity, ecosystem functions, and services.

Second, integrating DNA metabarcoding with Māori biodiversity monitoring approaches will bring more understanding to the Māori worldview of interconnections among living and non-living beings. Metabarcoding can enhance biodiversity inventories, identifying species important and relevant to Māori which are rare or hard to find using conventional methods.

Third, combining DNA metabarcoding with traditional surveillance in detecting pest species at the early stage will secure native species and landscapes from harmful biosecurity threats, such as harmful pests and diseases.

In addition, DNA results shared from various surveys using the dynamic duo will be added to the reference libraries making them more resourceful and convenient for future research. Having more reference DNA sequences of species in the reference libraries, like GenBank, will make biodiversity monitoring much easier by identifying species with just a few clicks.

DNA metabarcoding is a rapidly developing and powerful tool for monitoring biodiversity. Integrating it into conventional methods will lead to a stronger method to get plausible results. Overall, as Robert and colleagues indicated, not only will they add value to New Zealand’s biodiversity and Māori culture, but they will also protect the native natural environment and species through early detection of pests.

This article was prepared by Master of Science postgraduate student Zin Mar Hein as part of the ECOL608 Research Methods in Ecology course.

Together, they will indeed make the best of both worlds for conservation.