Helping to Understand Biodiversity

25 March 1999

Ms Veronica Blazely
Acting Assistant Secretary
Biodiversity Conservation Branch
Environment Australia
GPO Box 636
CANBERRA ACT 2601

Dear Ms Blazely

A few months ago you were very helpful to me in my efforts to gain a better understanding of some aspects of the concepts of biodiversity, and of the Work Program on forest biological diversity adopted under the Biodiversity Convention. In particular, you told me in your letter of 14 September that as far as you were aware, no Australian ecosystem had yet been "fully researched and described" in the scientific literature. Your letter did not mention any ecosystems that had been partly described either, but if you are aware of any, perhaps you could let me know in due course.

You suggested to me that I might find it helpful to read the section on ecological interactions that apparently characterise ecosystems, contained in a 1994 publication titled "Australia's Biodiversity: an overview of selected significant components", which you were kind enough to send me. You were right. I did find it helpful, but only up to a point.

The examples of "ecological interactions" given in "Australia's Biodiversity" include the mistletoe bird, which eats and excretes the seeds of mistletoes, thereby helping to propagate the plant, ants which disperse the seeds of vascular plants, and possums and honey eaters which pollinate many flowering plants. As I read these examples of "ecological interactions", they began to ring bells from long ago high school biology classes, when we were taught about symbiosis. The word "symbiosis" does not appear in the index of "Australia's Biodiversity" (nor in the index of "State of the Environment 1996"). This struck me as a curious omission, since the concept of symbiosis is an important one in biology, and I had the impression it had been around for a long time. Why call a particular phenomenon of nature an "ecological interaction" when it has previously been known as "symbiosis"?

Was there some flaw in the concept of symbiosis that required its replacement?

Some quick research brought to light that the ancient Greeks had used the word "symbiosis" (which simply means "living together") but they used it mainly in a social sense. For example, it occurs in a book by Antipeter of Tarsus, from the 2nd century BC, titled "Living with a Wife". The word apparently does not occur in the scientific writings of Aristotle, but his successor as head of the Peripatetic School of Athens, Theophrastus, seems to have come very close to identifying the phenomenon. Theophrastus (372-287 BC) wrote two books, "Inquiry into Plants" and "How Plants Grow". In one of them he recorded the observation that "olive lives with the ivy", which almost captures the essence of symbiosis, except that it does not identify any interdependence between the olive and the ivy.

The Encyclopedia Britannica attributes the scientific origins of "symbiosis" to a 19th century German botanist, Heinrich Anton de Bary (1831 - 1888). De Bary was apparently the first to show that lichens consist of a fungus and an alga in intimate association. He is said to have coined the term "symbiosis" in 1879 to mean an internal, mutually beneficial partnership between two organisms.

It seems from this that the scientific meaning of "symbiosis" is over a hundred years old, and that it has roots in antiquity, over 2000 years ago. With that kind of genealogy it's puzzling that a modern text about biodiversity and ecosystems didn't seem to want to acknowledge the concept, or build it into an important conceptual model.

I looked for the word in other modern texts dealing with ecology, in case they might contain an explanation of why the term had apparently fallen into disuse, or been found wanting in some way. Instead, I found that it still seemed to be in good standing. Here are some samples of what I found, with the help of the Woden Town Centre Library.

From Edlin H.L., Man and Plants, Aldus Books, London, 1967:

"Lichens are an example of symbiotic fungi-species that live in mutually beneficial association, or symbiosis, with other plants. A lichen comprises two organisms, a fungus and an alga. Commonly found on bare rocks, old stone walls, and other places where the soil is too thin to support higher plants, lichens often consist of a crust-like fungus enclosing a large number of single-celled algae. For the fungus, the association has the advantage that the algae are capable of photosynthesis, so that the lichen plant as a whole does not have to rely on the meagre supply of nutrients available form the soil."

From Owen, D.F., What is Ecology, OUP, 1980:

"In symbiotic (mutualistic) associations both participants benefit. The most familiar example is the relationship between flowering plants and their insect pollinators: both groups are completely dependent on each other. Lichens - ranging from the grey or yellow encrustations on walls to the feathery growth of 'Spanish moss' on trees in tropical forests - are an association of fungus and alga so close that they cannot be separated. The fungus obtains oxygen and carbohydrates from the alga, while the alga gains water and mineral salts from the fungus, as well as protection from desiccation and a means of attachment to the substrate. Ants of the genus Pseudomyrmex are symbiotic with various species of swollen-thorn acacia in Central America. The ants live and raise their broods of larvae inside the enlarged stipular thorns of the acacias and feed from specialized nectaries on the leaves. The tips of the leaflets are modified into unique structures, called Beltian bodies, which are rich in proteins and fats. These are harvested by ants and are cut up and fed to their larvae. Swollen-thorn acacias produce new leaves throughout the year, even in areas with a pronounced dry season, so the ants are not only housed but are fed by the tree. The relationship is mutually beneficial because the aggressive worker ants keep the tree free of herbivorous insects, bite and cut vegetation touching the acacia, and clear plants from the area round the tree. Untenanted acacias are quickly defoliated or choked by vegetation and rarely, if ever, produce a seed crop."

"Many of the fungi could not exist without their tree partner. Some kinds of toadstools, for instance, are only found in oakwoods, because they can only grow if their mat of fungal threads is attached to the roots of an oak tree.

This system of partnership in nature is called symbiosis. There are many other examples, such as the microbes living in the special "stomach" of cattle and sheep, and the bacteria in the root nodules of clover.

Some partnerships take a different form. Sharks, for example, benefit from "cleaner fish", which follow them around and eat small organisms on their skin. This removes irritation from the shark and provides the cleaner fish with food, to the benefit of both. This, then, is another example of symbiosis.

An even more remarkable example of symbiosis is the way ants "farm" aphids. The ants stroke the body of the aphids, causing them to release honeydew, which they then carry back to feed their young. In return, the ants guard the aphids from predators. Some ants even round up their aphids and take them to the safety of the ants' nest at night."

You will see by now, I'm sure, how odd I found the reluctance of "Australia's Biodiversity" to talk about "symbiosis" and why I found the paper slightly perplexing. It had raised as many questions as it answered. The exact same phenomena that it chose to summarise as ecological interactions, others were quite happy to call symbiosis. Why? "Australia's Biodiversity" had two main departmental authors, and was refereed by 26 people, three of whom were professors, and 19 of whom were Ph D's. None of them seem to have wanted to acknowledge the link to biology, by using the perfectly serviceable term it had given them to label the phenomenon they were describing.

"Biotic interactions may occur between members of the same species (intraspecific interactions) or between two or more species (interspecific interactions). They may involve nutritional benefits, space in which to live, shelter or protection, transport, or reproductive capability. Many interactions are highly specialised and complicated, involving adaptive changes in structure, function, behaviour, and ecology. Some create negative effects upon the interactants, reducing survival or reproductive success; other interactions produce positive effects, increasing survival or reproductive success. In some cases, members of an interaction are apparently unaffected."

The range of interspecies associations can apparently be classified according to whether one or both species in such an association benefit, or suffer. Symbiosis seems to be an example of the category of association known as mutualism, either obligative or facultative. Competition, predation, and parasitism are examples of different kinds of interspecies association. Something called "antibiosis" occurs when one species interferes with or injures another through the secretion of a chemical substance. "Commensalism" occurs when one species benefits from interaction with a second species, but the second species is unaffected. Most dramatically, the category of "mutual antagonism" applies to those interactions where both species involved are harmed, or even killed.

There is apparently even a category of interspecies association known as neutralism, where two species sharing a localised resource or habitat are completely unaffected by each other. (I am sorry to tax you with what are obviously a lay person's gropings towards understanding, but there is point to it, I think.)

Britannica represents these different categories of biotic interactions in a matrix, showing two species, and all the possible combinations of positive, neutral and negative interactions between them. It looks like this:

		Species B (small, weak)
		+	0	-
		+,+ interdependence (obligative mutualism) protocooperation (facultative mutualism)	+, 0 commensalism	+, - herbivory predation
		0, + commensalism	0, 0 neutralism	0, - amensalism (competition)
		-, + parasitism parasitoidism	-, 0 amensalism (antibiosis)	-, - mutual antagonism

Even in the abstract, this is a rich tapestry of biotic interactions, I'm sure you will agree. Symbiosis appears to be but one thread of that tapestry, (in the top left corner of the matrix). I have no idea how important the various categories of biotic interaction are in terms of the frequency of their occurrence, but I suppose it is possible that competition is just as important as obligative or facultative mutualism (symbiosis), because it may frequently be the key to controlling populations of particular species. Neutralism may be important too, even if unexciting, because it serves to remind us that many species don't seem to mind what company they keep, and can be found across a fairly wide range of habitats.

Let's go back to your letter and "Australia's Biodiversity" for a moment. If you want me to regard the "ecological interactions" described in "Australia's Biodiversity" as precursors to ecosystems, in the sense that a large number of these "ecological interactions" constitute an ecosystem, then the fact that the examples of "ecological interactions" given in "Australia's Biodiversity" are all examples of symbiosis becomes more than just a trivial re-labelling of natural phenomena. What it could mean is that this brand of ecology has taken one kind of biotic interaction, namely mutualism, and elevated it into a general theory of biological organisation, namely the ecosystem. This would explain why the concept of competition often does not seem to sit easily with ecology. Nature, which used to be "red in tooth and claw", has become mutually supportive in your Department's brand of ecology. In ecosystems, species help other species, and themselves benefit by doing so. Co-operation rules.

The definition of an ecosystem is "a dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit", ("State of the Environment, 1996"). What room is there in such a unit, would you say, for disfunctional interactions such as mutual antagonism, or even competition, which results in one species driving another species out?

Does this apparently selective focus mean that ecology is a branch of biology favoured by those who like to see stability, harmony and co-operation in nature, rather than competition, disturbance and strife? Does ecology prefer stasis to change? How does ecology explain change? If everything in an ecosystem is interacting nicely in a functional unit, what could give rise to change? If everything in the ecological unit is functional, where does disfunction come from? Perhaps it comes from mankind. I seem to remember you telling me earlier that, until very recently, Homo sapiens has had great difficulty in winning a place on the ecosystem team.

Thinking about these questions, I couldn't help wondering whether the authors of Australia's Biodiversity might have decided to keep quiet about symbiosis because doing so helped them to draw a veil over the missing link between the concepts of ecology and the concepts of biology, for the reason that the link may be a troubling one for ecology. It may point to a certain narrowness in the conceptual basis of the discipline. That narrowness may arise from ecologists having elevated one kind of biotic interaction into a general theory of biological organisation, with ecosystems as its core.

As the basis of a general theory, ecosystems may not quite make it. They may be more than a few bricks short of a load, because symbiosis by itself seems to leave out too much of the wealth of data we possess about how organisms behave.

Britannica's entry on Heinrich Anton de Bary appears on the same page as the entry on Mikhail Baryshnikov, a Russian ballet dancer famed for his prodigious leaps. With ecosystems, ecology seems to have performed a leap that easily eclipses Baryshnikov's best efforts - all the way from the mistletoe bird and de Bary's lichens to a general theory based on ecosystems. Of course, ecology's leap seems only to have been a leap of imagination, since we may not have any actual ecosystems, only hypothetical ones. Baryshnikov's leaps, on the other hand, were observable, measurable, and for many years, replicable. This means that despite their more modest scale, Baryshnikov's leaps were firmly rooted not only in art, but also in science.

So much for the theoretical implications of the paper you kindly sent me. If there are other official publications that it would be helpful for me to study, perhaps you could let me know.

Your letter also seems to have some practical implications that may be less important but more pressing than the theoretical ones.

You said in your letter:

"In relation to your question about examples of 'real working ecosystems', there is clearly a research gap…While I am not aware of an example where all the interactions within a particular ecosystem have been fully researched and identified, there are many instances where interactions between species have been demonstrated."
(The "interactions" you were referring to were, of course, those described in "Australia's Biodiversity", which turned out to be so thought-provoking.)

Unless I'm mistaken, your words are a tacit admission that the ecosystem cupboard is completely bare, so to speak. A few crumbs, perhaps, but nary a loaf. At least in Australia, we seem to have no fully paid up ecosystems. The rest of the world might be bulging with ecosystems, but that wouldn't solve the problem that seems to be emerging.

The problem is that, for many years, employees of and consultants to the Australian government have been talking about ecosystems in this country as though they were real living entities, apparently without the benefit of knowing whether or not they exist. They may exist of course, it's just that we can't quite seem to put our finger on a single one. I'm sure you will agree that this is, at least, a singular inconvenience.

I spent a little time late last year looking through some of the milestone documents dealing with ecosystems and biodiversity, to see how they coped with this inconvenience. Those documents were:

• The Convention on Biological Diversity (1992)
• The National Strategy for the Conservation of Australia's Biological Diversity (1996)
• The "Biodiversity" chapter of The State of the Environment Report, 1996
• The Decision on a Work Program on Forest Biological Diversity adopted by the Fourth meeting of the Conference of the Parties to the Convention on Biological Diversity. (1998)

My colleagues helped me by extracting from these documents all the references to and statements about ecosystems they could find. The results of this exercise are contained in Attachments A, B, C & D to this letter.

The first one, the Convention itself, is relatively restrained. It calls on parties to the Convention to protect their ecosystems, and to rehabilitate and restore degraded ecosystems, but the words that the Convention uses could be understood in a contingent sense. That is, the call for the protection of ecosystems could be read as meaning that this is the obligation of contracting parties, if ever they find some ecosystems.

The National Biodiversity Strategy (Attachment B) is less restrained. When it says, for example, that:

"Australians have broad expertise in managing a diverse array of species, habitats and ecosystems…"

it doesn't seem to be talking about hypothetical ecosystems which may or may not turn out to be real. It seems to be talking about real working ecosystems, which we haven't quite been able to put our finger on. The National Biodiversity Strategy also says, inter alia:

"There are still many ecosystems, species and communities that are important for biological diversity conservation but that are not represented in protected areas or adequately conserved elsewhere"
and
"Both active and passive recreational benefits of our ecosystems are highly valued by an increasing number of people"
and
"Pollution of groundwater has adverse effects on ecosystems in both urban and rural environments"

Unless I'm mistaken, those statements were intended to be understood as statements of fact. Try as I might, I can't see how they can be understood that way, if you are not able to identify a single ecosystem for me.

The State of the Environment Report, 1996 (Attachment C) perhaps represents the fullest flowering of ecosystems:

• "A general recognition that some ecosystems are more prone to serious impacts than others has led to a process for proposing and listing endangered ecological communities under the Endangered Species Protection Act 1992"
• "…Use of four-wheel drive vehicles enables people to appreciate remote parts of Australia but can also lead to disturbance of sensitive ecosystems"
• "Many ecosystems and species will be sustainable only if the environment is managed in accordance with natural rather than economic or political boundaries"
• "Healthy functioning ecosystems are necessary to maintain the quality of the atmosphere and to maintain and regulate the climate, fresh water, soil formation, cycling of nutrients and disposal of wastes (often referred to as ecosystems services)" And so on.

I'm sure you can see the questions that these purportedly factual statements invite: which ecosystems are the authors talking about, and, how do they know that the statements they are making are true?

The "Biodiversity" chapter of the State of the Environment Report, 1996, was written by ten well-credentialled people and presumably reviewed by the State of the Environment Advisory Council, comprising another 16 eminent authorities on environmental matters. What on earth could they all have been thinking of in putting forward these statements as statements of fact, when we apparently haven't been able to identify a factual basis for them. If the statements had been offered as hypotheses, or beliefs, that would have been a different matter. They could have called the document, The State of Environmental Beliefs Report, 1966, or some such. Whatever they were thinking of, it is clearly beyond the ken of ordinary mortals like me, and perhaps you too.

Perhaps you should take the initiative to propose the revision of the National Biodiversity Strategy so that it achieves a stronger focus on working with what we know, rather than with what some of us apparently believe. Maybe someone should also have a quiet word with the State of the Environment team, to dissuade them, if possible, from using a government report as a vehicle for parading or promoting their personal beliefs. (It could also be suggested to them that the problem of classifying ecosystems, which they worry about on p. 4-26, would probably become much more tractable if they could first pin down some real ecosystems.)

Perhaps you should also warn the minister to be careful what he says about ecosystems, in case somebody asks him to point one out.

The problem with the last of the documents we examined, the CBD Work Program on Forest Biological Diversity (Attachment D) is not that it is full of purportedly-factual, but unverifiable statements. The problem is that Australia has outstanding commitments under the Work Program that may not be easy to fulfill. The decision on the Work Program, you will recall, exhorts us in various ways to implement something called the "ecosystem approach". It's hard to see how we can do this if we don't have any ecosystems. I could be wrong, but you might be facing the necessity of having to report back to the Conference of the Parties (COP) that we can't make sense of the commitment we have entered into. The COP might reply, of course, that we should press on and find some ecosystems, and that this is what they mean by "ecosystem approach". At least we would then know where we stand, even if it means having to divert significant resources away from documenting species and genera.

On the other hand, the COP might reply by saying:

"Don't be silly, of course you've got ecosystems. Everybody's got ecosystems. You've been telling us for years that you've got some beauties. Now get outa here and get on with the ecosystems approach, like we all agreed".

Sadly, such a response might leave us with no alternative but to sit very still, close our eyes very tight, and pretend there are some ecosystems at the bottom of the garden. I don't know about you, but I might have to leave that to others, because these days, frankly, I find that sort of thing a pretty big ask.

Regards

Warren Lang

Deputy Executive Director