By David Suzuki with Faisal Moola

Are you a lumper or a splitter? Well, that depends on how you define a species. And how we define species has direct implications on our ability to protect them.

This spring, scientists celebrated the 300th birthday of Swedish biologist Carl Linneaus, one of the true giants of biology and the father of taxonomy — the classification of living things. Before Dr. Linneaus's time, species were described according to "phrase names," actual descriptions of plants or animals, which could be entire sentences or even paragraphs long. You can imagine how complicated and confusing such a system would be. Dr. Linneaus changed all that by naming and classifying the diversity of life on Earth according to a hierarchical system of Kingdoms, Classes, Orders and so on down to Species and sometimes Varieties.

Although it has changed and expanded over the years, modern biologists still use a similar system of classification. Dr. Linneaus would likely have approved of the additions, as he himself was constantly updating and changing his own work based on new information. Two of the greatest changes to the study of taxonomy have been the discovery of evolution and the use of DNA analysis to further refine our classification of species. But with these new ways of understanding life come new challenges.

While Dr. Linneaus thought that all species were created by God exactly as they were and needed only to be discovered by Man, we now know that species evolve over time. In fact, given the right conditions and time, a single species can actually branch off to become several entirely new species. And with modern DNA analysis, we are able to determine the genetic distance between species. For example, we now know that chimpanzees are our closest living relatives.

But, as was pointed out recently in a special edition of the journal Nature, these classification issues pose real problems for conservation efforts. At what point does variation within a species become significant enough that we have to accept that we are dealing with more than one unique species? Right now there is no consistent standard in the scientific community. Butterfly taxonomists, for example, tend to "lump" their specialty together — categorizing relatively few butterflies as unique species and instead choosing to differentiate them by subspecies. Ant taxonomists, on the other hand, tend to "split" their specialty into many different unique species and relatively few subspecies.

This inconsistency makes it more difficult to decide where to place our conservation priorities. Most conservation efforts are based on species lists — Canada's Species at Risk Act (SARA), for example. And although SARA has provisions to protect species, subspecies and "distinct populations," there is little agreement among scientists where one of these ends and another begins. Depending on who studies a creature, it could potentially be classified into any one of these groups. Yet in the real world, being classified as a unique species means you will get more attention from the public and from conservation agencies. For example, one well-known conservation plan is to focus on biodiversity "hotspots" — those areas that have the greatest number of unique species. But how were these species differentiated in the first place?

One way to avoid such problems is to take the conservation focus away from species and instead look at things from an ecosystem level. By protecting entire ecosystems, you not only protect the species that are a part of it, but also the services the ecosystem provides — such as water filtration and climate protection. However we proceed, it is clear that looking at species alone is not sufficient to provide us with the information we need to decide conservation priorities. And unless we have greater clarity, it's all too easy for discussions about conservation to break down into semantics and posturing. And that does neither the species, nor those trying to protect them, any good at all.

August 24, 2007