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Australasian Plant Conservation

Originally published in Australasian Plant Conservation 16(1), June - August 2007

Why taxonomy? Out of chaos, order!

Sally Stephens
ANPC, Canberra. Email: sally.stephens@anpc.asn.au

Sorting socks in Latin

Even in the most pedestrian aspects of our lives, we tend to classify things. Our socks go in the socks drawer, the shirts hang together in the wardrobe separate from dresses or trousers. Spoons probably all nestle in a compartment beside the forks which lie separately from the knives. Those big clunky kitchen utensils are probably less sorted in a big drawer where we can grab them when needed – but they still have been classified by their use in the kitchen. You certainly wouldn’t put them in the dining room sideboard with the fine table linen.

This year has seen the 300th birthday of the king of all classifiers – Carl Linnaeus (the name Carl von Linné came much later, after he had been ‘ennobled’ by the Swedish king). He was born in Sweden on 13 May or 23 May 1707, depending on which calendar you were using at the time (Wikipedia 2007). One could imagine such imprecision might intrigue someone who is remembered for adding logic and clarity to the whole chaos of the living universe!

Most people working with plants and animals use the Linnaean system of naming organisms whether they know it or not. Without it, we wouldn’t be trotting out names such as Homo sapiens or Eucalyptus rossii or Pisolithus albus. Even if someone’s scientific education hasn’t extended beyond high school, they will probably have learnt about Linnaeus and his contribution to the ordering of the natural world. They may have forgotten it, but they’ll still be using it if they ever use a scientific name, wrapping their tongues around those Latin (and Greek) names.

This giving of two names (binomial nomenclature) that together uniquely identify each type of organism is the basis of the Linnaean system. Based on physical similarities and apparent relationships, organisms could be organised into several hierarchical groups, from species, to genus and then to family and so on. But it’s the scientific name, that binomial we are all familiar with, that has enabled scientists the world over to communicate.
The methods of determining whether an organism is a unique species have changed, with genetic relationships often over-riding physical similarities, but the Linnaean binomial naming of them remains very much the same. Linnaeus’s system was so simple and workable that any modifications since have really just been expansions within the layers of hierarchy.

In addition to introducing binomial nomenclature and synthesising a classification of living things, Linnaeus was also a great teacher. These accomplishments are being celebrated around the world as part of the tercentenary of his birth. In the Resources section (p. 28) are details of special issues of several publications by Botanic Gardens Conservation International that feature the work and legacy of Linnaeus.

Taxonomy and conservation

Research in taxonomy has rarely been high on any Government funding priority list, probably because it’s seen as non-applied investigation with outcomes of dubious value. Surely this is knowledge for the sake of knowledge, the dusty realm of an esoteric group of scientists with classification on their minds!

In fact, taxonomy is the tool by which we describe, sort and name organisms so that we can create some order out of an otherwise chaotic assemblage of organisms. It also enables us to recognise if an organism is known (‘described’) or unknown. As unknown species are described, we accumulate knowledge of species and their relationships. There are many more organisms than have been formally described, particularly in the less-studied groups. For example, there are an estimated 1.5 million fungi in the world, of which only 72,000 have been described (4.8%). Bryophytes fare better, particularly in Australia, with 84% of the estimated 2,200 species now described (Chapman 2005). Even for the better known groups, such as the flowering plants, new native species continue to be discovered around Australia every year.

Good taxonomy is essential to any work that requires an understanding of species and their relationships with other organisms and the environment they live in. Taxonomy provides the language with which we can describe and discuss living organisms.

For some years Iworked in the Endangered Species Program of the then Australian Nature Conservation Agency (long-since absorbed into the Commonwealth’s environment department, currently the Department of Environment and Water Resources). Decisions to list species as threatened or to fund conservation work were often determined by the taxonomic status of the plants or animals in question.

For example, the Common Brushtail Possum Trichosurus vulpecula vulpecula, well-known to suburbanites in the south-eastern states (and now all too well-known to New Zealanders), exists as a few relict populations in rocky outcrops and moist gullies west of Alice Springs. As this possum population is still regarded taxonomically as the same species as its common southern cousin, it has never received Commonwealth funding for research or conservation management nor is it listed on the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Repeated applications for Endangered Species Program funding for this disappearing population failed solely because the species was secure elsewhere.

The Common Brushtail Possum (Central Australian ‘subspecies’) is now listed as Endangered on the Territory Parks and Wildlife Conservation Act 2000 (TPWC Act), but a recent WWF discussion paper notes that: ‘the Central Australian “subspecies” of the brushtail possum … isn’t taxonomically a subspecies.’ (WWF 2006). Genetic studies aim to create a family tree of Brushtail populations from around Australia; this work should clarify how closely related the long-isolated Central Australian population is to the abundant southern population (Collins 2006).

The Venus-hair fern (Adiantum capillus-veneris) also hails from the Northern Territory and is listed as Vulnerable on the TPWC Act but is not listed on the EPBC Act. It occurs as a tiny population in damp crevices in a rocky gorge about 40 km from Alice Springs. The next known population occurs about 1000 km to the north (Peter Latz, pers. comm.). It is unknown whether this is a relict population from moister climate regimes or is possibly derived from wind-blown spores that ‘recently’ dispersed (NTGovernment fact sheet 2006). The inverted commas around ‘recently’ indicate that this could have occurred thousands of years ago – has long-term isolation resulted in any genetic divergence?

The taxonomic status of a species can affect its conservation management and legislative status. This affects government priorities, funding, recovery efforts and scientific endeavour. Inaction based on the view that a declining isolated population is genetically the same as an abundant population elsewhere (and therefore not worthy of conservation effort) could result in local extinctions and loss of biodiversity.

Even if the Central Australian possums prove to fit within the range of genetic diversity of the more abundant southern populations, are they not of value as an integral component of their landscape? Their loss from that landscape through local extinction is a loss of diversity within that landscape and must inevitably result in unknown and probably unpredictable changes to the ecology of an area. Similarly, the loss of a rarely seen fern will deplete the biotic richness of its landscape.

Taxonomy identifies the biotic components of our ecosystems and gives us the language to discuss them. It informs us of their evolutionary history and relationships. Incomplete knowledge of the taxonomy of a species or population can impede conservation managers. However, the use of taxonomy alone to determine conservation action can be deleterious. Taxonomic status can be used to neglect declining populations, if such populations are found to be similar to more abundant populations elsewhere. Taxonomic status should not be the sole basis of decision-making but just one of many tools employed.

More taxonomists needed NOW!

As Ralph Woodford, one of our long-standing members recently pleaded: There needs to be more funding for the training of taxonomists in all fields … and we need to make taxonomy something that students want to make a career out of. I have been to several conferences over the past two years and a common ground in all of them has been the lack of classification of our flora and fauna, be it monocots, dicots, fungi, mosses, lichens, insects etc; we only know some of them and to be able to understand their relationships we need to know what we are looking at! Taxonomy is the base building block for the understanding of the environment around us!

References

Chapman, A. (2005). Numbers of living species in Australia and the world. Report for the Department of Environment and Heritage, Canberra.

Collins, B. (2006). Phylogeographic analysis of mitochondrial DNA sequence from Brushtail Possums. James Cook University. http://plone.jcu.edu.au/hpc/users/research/phylogeographic-analysis-of-mitochondrial-dna-sequence-from-brushtail-possums

NTGovernment fact sheet (2006). Threatened species of the Northern Territory: Venus-hair fern (Adiantum capillus-veneris) http://www.nt.gov.au/nreta/wildlife/animals/threatened/pdf/plants/Adiantum_capillus-veneris_VU.pdf

Wikipedia (July 2007). http://en.wikipedia.org/wiki/Carolus_Linnaeus#Biography

WWF (2006). Reviewing the Threatened Species Provisions within Northern Territory Legislation. A discussion paper prepared by WWF-Australia.

http://wwf.org.au/publications/nt-threatened-species-discussion-paper-2006.pdf

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