Taxonomy – the science of species discovery

Our planet has life on it, and for that reason, it may be unique in the universe. Ironically enough, we know much more about some of the planets floating thousands of kilometres away than we do about most of the species living right here on Earth.

The science of discovery

So far, we’ve catalogued 1.9 million kinds of plants, animals and microbes. But this is only the tip of the iceberg. There are probably more than 10 million species sharing our planet, which means we only know about 20% of them.

The scientific discipline dedicated to describing, classifying and making sense of the biodiversity all around us is called taxonomy.

Taxonomists describe and classify new species by comparing characteristics shared by groups of organisms, which may be anatomical, behavioural or even molecular. For example, the exquisitely detailed claw of a crab, the reproductive behaviour of a bird or the DNA inside each cell of a plant are all characteristics that can be used to compare and classify different species.

When building their classifications, taxonomists try to piece together the evolutionary relationships between different taxa. Since all life is descended from a common ancestor, it’s possible to show how species have branched out into the diversity we now see all around us. This can be visualised with a cladogram, which is a diagram showing how different species or groups are thought to be related to each other.

Taxonomy is also concerned with the bigger questions, such as how species are even defined in the first place. The most common and probably the most intuitive definition of species is a group of organisms that are able to interbreed. However, defining species is not always as simple as this, and there are many other competing definitions.

Taxonomy in Aotearoa

New Zealand has at least 29 taxonomic collections spread between museums, universities, Crown research institutes and other research centres. These collections hold about 12 million specimens, and about 80% of these are invertebrates, owing to their incredible diversity. Other specimens include non-invertebrate animals, plants, microbes and fossils, and each collection has its own speciality. We have approximately 360 taxonomists working in New Zealand, although only a subset of these are employed in full-time roles. Some of the larger organisations employing taxonomists as scientists and curators include:

• Crown research institutes such as Landcare Research, GNS Science, Scion, NIWA and the Cawthron Institute
• museums such as Te Papa, Auckland Museum, Canterbury Museum and Otago Museum.
• tertiary education providers including University of Auckland, University of Canterbury, Lincoln University, Massey University, University of Otago and Unitec.

Landcare Research houses the largest collection – the New Zealand Arthropod Collection – and employs many taxonomists to describe species, revise outdated classifications, curate the collection and publish important identification resources.

Fauna of New Zealand is a series of monographs (in-depth taxonomic study on a particular group) that details land-based invertebrates. Each volume typically includes a checklist of taxa in that group and an introduction to the group as well as descriptions of new and existing species alongside diagrams and illustrations. Electronic copies of every volume are also available online.

Why is taxonomy important?

Taxonomic expertise is built up over many years and represents a very specialised form of knowledge, particularly for people who are experts in certain taxa. Describing and classifying biodiversity is the foundation upon which all the life sciences rest. The ability to communicate clearly about different species or higher groups is only possible when they have an unambiguous name and confident classification.

There are many other reasons why taxonomy is important.

New Zealand has signed international agreements that require countries to identify, classify and protect their species for the benefit of humankind (for example, the UN Convention on Biological Diversity). In order to conserve and monitor our native biodiversity, we need to know what species we have, where they are found and how their numbers or diversity are changing over time. Authoritative taxonomic expertise is essential for accurate identifications as well as delimiting closely related species and building the kinds of resources that other people can use to identify and monitor biodiversity.

Our economy is built on living things and the products they produce. Taxonomy provides the skills needed to identify species that may have economic potential. Our undiscovered native species may possess structures, substances or behaviours that lead to novel foods, fibres, medicines or fuels. If New Zealand wants to be taken seriously as an innovator during the current biotech revolution, it needs to invest in taxonomy.

Biosecurity is fundamental to the New Zealand economy. All of our top exports – dairy, meat, seafood, fruits and vegetables, wine, timber – are expected to be pest-free and disease-free. When they aren’t, ongoing access to export markets is jeopardised, which puts jobs at risk. Identifying pests and diseases at the border is one of the most important reasons for training taxonomists and investing in taxonomic collections.