Unit Eight: Jane Lubchenco

Interview: Jane Lubchenco

As a community ecologist, Jane Lubchenco has worked on problems that point up the theme of this unit: The distribution and abundance of organisms are the products of history and of ongoing interactions with the environment. Using a combination of field and laboratory observations and experiments, she has focused on the causes of ecological patterns in the distribution, abundance, size, morphology, diversity, and life history of a variety of organisms, particularly in rocky intertidal communities. Her research has taken her from the coasts of Washington and California to Jamaica, Panama, and Chile. She is currently associate professor of zoology at Oregon State University, Corvallis, where she teaches both general and marine ecology. In the following interview, Lubchenco comments on the changing nature of ecology in recent years and some of the current controversies in the field. She also talks about the relation between ecology as a basic science and the environmental problems confronting the world, and she outlines her strongly held view that ecologists are crucial in the solution to these problems.

Dr. Lubchenco, at what point in your education did you become interested in studying ecology?

It was a gradual process. I've always been interested in being outdoors. I grew up in Colorado and did a lot of camping. But I became really turned on to marine organisms in the summer course I took at the Marine Biological Laboratories in Woods Hole, Massachusetts, between my junior and senior years at Colorado College. I became much more aware of the excitement of doing research, discovering new things. I became more aware of what wasn't known. When you read textbooks in college, you think everything's already known and there's nothing more to learn. But when you start doing research, it becomes obvious that there's a tremendous amount that isn't known and that discovery, exploring new territory, or challenging someone else's opinions is really exciting.

I think that's what led to my decision to go to graduate school. I started at the University of Washington in animal physiology, but I soon began participating in exciting discussions with the ecology students, reading papers, and going out in the field with them. The kind of ecology that was being done at Washington was totally different from what I'd known as an undergraduate. It was experimental, and I found out about a lot of organisms that were fairly new to me. That combination got me really interested in doing ecology, so I switched fields in graduate school.

Was the experimental approach you found at Washington part of a more general change that's occurred in ecology over the past couple of decades?

Very much so. Early ecology was descriptive and observational. The change to a more experimental approach was strongly influenced by two marine ecologists in particular: Joe Connell at the University of California at Santa Barbara and Bob Paine at the University of Washington. Much of their early work on rocky intertidal systems made people aware that experimentation was a tool that hadn't been used to its fullest in ecology. Now, in almost all fields of ecology, people are doing more experiments than they used to. There have been many changes in the way we view the world that I think are a direct outgrowth of experiments.

Are you implying that it would be good to break with many of the old ideas?

Actually, I think the pendulum may have swung too far with respect to the descriptive versus the experimental approaches. Doing one completely without the other is ludicrous. A lot of people might think, "This experimental approach is really hot stuff," and then run out and do experiments without describing the system or having a thorough understanding of its natural history. Without this background information, they'd just do some kind of experimental treatment they couldn't understand or didn't carefully control. So I think using both approaches is most reasonable. We can move on without totally breaking from the historical descriptive ecology.

When you talk about experimental science, people may think of test tubes and lab coats. Could you say a little about how experimentation is done in the field?

In the lab you have greater control than in the field. One reason field experimentation was so long in coming is that people thought there was too much that couldn't be controlled. And yet the virtue of doing experiments in the field is that you don't have control over everything else that's going on, so by manipulating just one thing, you can test the effect that one thing has in the context of the entire community.

For example, I studied the effects of herbivorous snails on seaweeds in tidepools in New England. It's fairly straightforward because you can manipulate one variable: You remove the snails from a tidepool and monitor the effect on the distribution and abundance of seaweeds in the pool. You have a second pool with snails left as a control, so you can see what effect the snails continue to have through time. You replicate the situation a number of times and you end up learning the effect of the snails on the seaweeds in the pools.

It's more difficult to get at questions that involve manipulating a number of different things. A more complicated experimental design would be, for example, if you wanted to know the effect of competition versus predation. One thing field ecologists are discovering in the process of doing experiments is the importance of what we're calling indirect effects, where one organism affects another organism through a third organism. We're coming to think indirect effects may be very important in the natural working of communities, but it's often difficult to get a handle on them experimentally.

There are mathematical models for population growth, and even models that have implications for population regulation that are based primarily on logic or laboratory experiments. Is there any way to tell how well these models work in natural populations?

In general, there hasn't been much success in applying laboratory models such as logistic curves to the real world, and a lot of people question the relevance of those models. I think the relevance is that you can learn about the population in the laboratory, and you can tinker with different kinds of interactions. But that doesn't necessarily tell you what is really going on in the natural situation for that population. The kinds of indirect effects that I was talking about, as well as catastrophes that can affect populations and the spatial dynamics, may be very different from what's going on in a laboratory culture.

Molecular biologists are now capable of altering the genomes of organisms in the laboratory. Is it possible to predict how populations of altered organisms will behave in the field?

I think the molecular biologists doing the work with genetically engineered species need to have input from ecologists. There are ecological studies concerning the success of invaders, for example, that can teach us some lessons about what kinds or proportions of organisms tend to be successful, what characteristics they have. This kind of information can help us make more responsible judgments. But there have been tremendous communications problems between the molecular biologists and the ecologists. This is an example of why it's important for biology students to have an appreciation of the whole spectrum of the field, not just cell biology or ecology, for example.

Since we're considering questions of population ecology, another important concept is carrying capacity. As best as we can tell empirically, our own population hasn't reached it yet. Do you have any speculations as to what factors will be most important in determining carrying capacity for the human population?

When I was teaching general ecology once, I asked for a definition of "K" on an exam, and one of my students answered that this was caring capacity: the environment can only care for so many organisms at any one time. I think the reason we haven't reached the carrying capacity is that we have the ability to modify our environment to increase the carrying capacity. There are obvious limits to that, though. The famines in Africa, for instance, show us the limits of carrying capacity on a local level. I think it's a very pressing problem and something needs to be done about it, but it's not very clear what the carrying capacity of the Earth is in a global sense.

Considering that so many environmental problems require local solutions, is it productive to think on the global level?

I think we have to. A good example is the effect that cutting down the tropical rain forests seems to be having on global weather patterns and the way that impinges on the success or failure of crops throughout the world. There's a direct global impact on human populations. Some questions need to be considered on a local level and others on a global level, depending on what the connections are.

The impact of the tropical rain forest on the global atmosphere relates to the hypothesis of the world as a superorganism. Is this just a metaphor, or does the Earth have a metabolism in a sense? Can we think of the Earth as a superorganism?

I wouldn't go so far as to say that it's a superorganism, in the sense that there is regulation going on. But I think it is clear that what occurs in one part of the world can have tremendous consequences in another part of the world. Tropical deforestation and acid rain are prime examples of that. Which is to say that I don't completely buy the superorganism concept, but that doesn't give us free rein to be irresponsible.

I'd like to shift the subject now to the area of ecology you're most directly involved with: communities. To begin, how would you define a community?

There is tremendous disagreement about this term. A lot of people use the word community to describe groups of species that are interacting in what I call taxon communities: bird communities, plant communities, and so on. That's a more restrictive definition than the one I prefer to use, which is all the groups of interacting organisms in a particular habitat. That definition is too complex for people in many fields of study to deal with. In my research field of rocky intertidal habitats, we're lucky in that we can define and study the macroscopic organisms that are all in one place, and for simple communities, we can get a fairly good handle on most of the things that are there. But tropical rain forests or coral reefs, for example, are much more difficult units to study. So people have broken them down into simpler units: either the taxonomic communities or some subset of the entire community.

Do you think it's useful, in terms of the kinds of questions that are asked, to make a distinction between ecosystems and communities?

They integrate. I think ecosystem ecologists do study all the things that are present but on a different, larger scale. The way in which the physical environment and the entire community interact is their greatest concern.

One thing I think all ecologists are becoming more aware of is the importance of history in ecology. You may start out with the same kinds of physical interactions but end up with very different biological interactions as a function of historical differences between the sites: who happens to be there, who happens to get there. There are a number of cases where the presence or absence of one group of organisms could have totally changed the system. Two examples come to mind: the invasion of the placental mammals in South America following the land bridge opening up and the devastation of the marsupial mammals; and the theory that early humans had a devastating effect on large mammals in North America. Those are both examples about which people argue.

But some of the historical factors might just be flukes of chance?

Oh, yes. This is why it's very interesting to look at comparable areas in different parts of the world: rocky intertidal, grasslands, chaparral, whatever.

This brings up a more general question about changes in the philosophy of ecology. The old idea of nature in balance, with everything having its place, seems to be breaking down somewhat, and people seem to be recognizing that there are many unpredictable factors. Do you agree?

There certainly is a change in that respect. For example, the notion that most communities, most populations, were pretty much at equilibrium has been very seriously challenged in the last few years. And as a result, I think ecologists are now in the process of redefining the kinds of generalizations we can make. For instance, one of the real controversies in the last few years has been whether predation or competition is more important in structuring communities. I think it's a fruitless question. They're both important to different degrees, so it's more productive to ask under what conditions we are likely to find organisms being strongly affected by predators, by competition, or by some interaction of the two.

I think we're redefining the level of the questions, and that, again, has been a direct outgrowth of attempts to design complicated experiments to measure the effects of predators, herbivores, competitors, all in a single system.

Where does community ecology stand today on the question of whether communities are highly ordered, with all parts connected, or a collection of organisms that just happen to be in the same place at the same time?

Somewhere in the middle. We certainly have evidence that the organisms in particular communities share many common requirements, but it's not always a cohesive unit. There are definitely functional groups within communities, and roles that different organisms, different species, play. And there are connections created by the predator-prey interactions and by interactions of competitors within a community. The end result is a group of organisms that have very strong effects on one another. Sometimes there are very obvious adaptations of certain species to others in the community. So I think that neither extreme expresses adequately what we view as reality today; there are elements of both.

What would you say are the important general questions that permeate community ecology today?

In addition to basic questions about distribution, abundance, and diversity, stability has become a very interesting topic in community ecology. How stable are communities? How long do organisms persist? How much force does it take to knock a system away from the state that it's in, and how fast does a system rebound once it has been disturbed? And to get at those questions, you have to be able to focus on populations as well as the community-level phenomena. There are many other important topics too that impinge on both population and ecosystem ecology, which is one reason that studying communities is so interesting.

In considering the various interactions in communities, the idea of coevolution is bound to come up. Could you talk about your recent research on modifications or evolution of certain life histories in algae that may be adaptive as a defense against herbivores?

First let me say that, to me, "coevolution" implies a change in some feature of each of the species in response to the other. That's a very difficult thing to document. There are many organisms that are well adapted to a predator, but the predator wasn't necessarily the selective agent causing the change or the evolution of a particular morphology or chemical defense. A lot of coevolution probably does occur in simple systems, but in complex systems I think there's a lot less. It may be a sort of diffuse evolution that's not "co-": it's not tied closely to another species, where they have evolved in tandem, first one changing, then the other, modified through time. I think that a lot of systems are described as being coevolutionary when we don't really have good evidence that they are.

Some of the seaweeds I've worked with are very nicely adapted to avoiding herbivores. One group of algae has a very interesting life history, with an upright morphology for part of the year and a prostrate, crustose morphology for the other part of the year. There's reproduction between each phase to make the other stage. It's very nicely coordinated with the presence and absence of the periwinkle grazers in New England and also with grazing by some of the limpets in Oregon. The phase that is grazer-resistant co-occurs with the grazers, whereas the grazer-susceptible phase is most abundant during the season when the grazers are least active. Experimental removal of the grazers demonstrated that the grazer-susceptible phase can live during the "wrong" time of year if it is not continually eaten by herbivores. We think this type of life history — with two totally different morphologies — could have been selected for by a predictable variation in the presence of a strong selective agent, like herbivores, that operates on a seasonal basis.

To enlarge the picture and think about ecosystems, where ecologists are concerned primarily with energy and chemical transfer through the whole system, could you give an example of how human intervention, either purposeful or accidental, has altered nutrient cycling in an ecosystem?

The massive deforestation that's going on in tropical rain forests is a prime example of that. It totally alters the way nutrients are cycled through the system. There's a changeover from the lush tropical forest, with an incredible diversity of plants and animals, to an area that is initially used for grazing but then often becomes totally useless because of changes in rainfall patterns. The nutrient flow through those systems is completely altered.

There has been some criticism of the role that ecologists have played in relation to environmental problems, just telling us all the bad things that are happening to us. Is there any constructive role for ecologists, as scientists, in dealing with environmental concerns?

I think ecologists have been important in increasing the general public awareness of the fact that people are part of their communities and of the biosphere and that their actions have important consequences. But we're beginning to be more directly involved. In the last two years, the Ecological Society of America has established an office in Washington, D.C., whose primary function is to make available information that pertains to various decisions-legislation that is being debated, for instance. This office will point legislators toward the ecologists that have information on specific problems and act as a sort of translator and facilitator. This is something that's been sorely missing and is critically important. There are cases where we have a fair amount of ecological knowledge, but decisions are made totally devoid of any ecological input because so many ecologists are sitting in their ivory towers doing their basic research and don't have the proper avenues to communicate. This is just beginning to change, and it needs to change quickly, because there are some real serious problems we need to deal with soon.

There is also a need for a significantly larger amount of money to be pumped into ecological studies. It's very important for us to have enough funding to gain a clear understanding of the factors involved in the problems. With increased funding and improved communication with the decision makers, ecologists can be serious participants in the solutions to our environmental problems.

©2005 Pearson Education, Inc., publishing as Benjamin Cummings