I went to the University of Oxford and studied zoology at Lady Margaret Hall. After my freshman year I had to choose whether to do zoology or botany. Because of my interest in animal behavior I chose animals; I was interested in both plants and animals and my later career has merged to look at various animals and tropics. After Oxford I went to Imperial College, London where I worked at Silwood Park, their field station to the west of London.

Yes, Silwood Park is a world-class field station. Today it has more population ecologists at one site than anywhere else. I joined when it was significantly smaller. I was there for about 10 years in all and by the time I left, the Centre for Population Biology had been based there and it had expanded considerably. My doctoral thesis was with Mick Crawley and it was with him that I developed my later work on transgenic plants.

Well, at that stage, I was more or less alone but obviously guided by my supervisor. Mick was essentially a plant ecologist and my thesis was actually on the population dynamics of an insect that had recently invaded England. The common theme which started then, and has continued throughout my career, is an interest in the impact of invasion by alien species. I did have input from a number of other people at Silwood Park who were primarily interested in insect population dynamics, sex ratio theory, and similar topics.

Our project arose partly because Mick Crawley himself was sitting on the national

Advisory Committee on Releases to the Environment (ACRE) at the time. It soon became apparent that people were going to ask very basic questions about genetically modified plants, particularly their effect on the natural environment. Although we could theorize about what might happen there was no hard empirical data to guide us.

There was relatively little interest from the public when we started. When we were doing these experiments we were actually simulating invasions in natural habitat and monitoring what happened. Whenever we did this we had to seek government permission from ACRE. We had to demonstrate that we were taking adequate safety precautions and we also had to advertise in the areas where we were doing the experiments. By and large there was very little response to those announcements. I think we had one meeting with some interested local people in Cornwall but we were doing these experiments in Cornwall, Berkshire, and up in Sutherland and it was only really that one place where it sparked any interest. These days, of course, we have to contend with skeptics and activists who don’t draw the line at passive demonstrations. Some experimental crops have been ripped out by environmental activists.

  Your 1993 Nature paper was one of the first to address concerns that transgenic plants might be bad for the environment. Can you talk a little about that?

Essentially that paper asked what would happen if we introduced the genetically modified plants into a variety of different habitats. This research is quite context-specific, so we did it for different habitats in three different regions of the UK. We wanted to weed out those elements that were going to be generic from the other elements that were going to be context-specific.

Basically, our paper asks a very simple question: to what extent would the transgenic and conventional plant population increase in these particular natural habitats? We can measure that by a very simple parameter called the finite rate of increase—that is to say, the number of plants in one generation divided by the number of plants in the previous generation. Obviously if it is greater than one, that plant population is going to increase, and if it is less than one it is going to decline. The answer for the transgenic plants we were looking at was that they were never significantly fitter than their conventional counterparts. Now I need to qualify that with a couple of statements. The oilseed population will increase if you exclude competition from other plants: oilseed cannot compete effectively with natural vegetation. The other qualification was that we started these experiments in the late 1980s. At that stage the only transgenic plants available for experiments were plants that had either marker genes or herbicide-tolerant genes. Of course an ecologist would not expect these to have any kind of ecological advantage, but these were questions which needed to be answered with hard data.

The bottom line is essentially that these particular plants do not invade natural habitats and genetically modifying them does not make them any fitter to do so. In fact the seed survival was actually slightly reduced in the genetically modified plants—that might not be specifically because of the genetic modification but more in the way in which that particular line had been produced.

No, we were the only group with extensive experiments.

It continued my interest in both risk assessment in genetically modified organisms and invasion in general throughout the rest of my research career. I went on from there to consider genetically modified pathogens: how you alter the nature of the host pathogen interaction if you either insert or delete specific genes. I work with insect-specific viruses. A given virus will have a specific host range and attach to a number of species, and they can persist in the external environment in the form of little protein packages which protect the DNA. The insect then consumes these virus packages along with its food. Then it breaks down in the gut and infects the tissues and by the time the insect dies it is a bag of mush. The virus particles are spread all over the foliage to spread the cycle again. My interest in them is that they can be very easily formulated as a biopesticide and sprayed using conventional equipment, but one of their disadvantages is that they take time to kill the host—up to a week—which is not desirable, and that’s why they have been subject to genetic modification. There are ways in which you can enhance the speed in which they kill their host—I am interested in the ecological consequences of that.

  What are you doing now at CEH?

I’m considering the risk assessment of transgenic plants. I have a small group which aims to develop risk-assessment protocols to where we can maximize the more generic elements. Then we focus in on which elements of the risk-assessment program have to be case specific. We are considering those kinds of transgenic plants that we might expect could enhance the ecological fitness of those plants.

  Why did the Nature paper stimulate so much interest?

I think it is often cited to demonstrate why transgenic plants do not have enhanced ecological fitness. You have to be careful to qualify that because we are talking about those specific genes which have been inserted into that plant. So while it is an important part of the jigsaw you have to be careful about extrapolating too far. One reason the paper is so popular is that there are very few direct experiments, particularly in the UK, with transgenic plants in natural habitat. Under the current political climate I don't think it would be possible to repeat those experiments.

  The regulators would intervene?

It would be difficult. That is why we are taking a different approach. We are now trying to piece together all the information you need to know about the plant and its hybrids and wild relatives. Oil seed rape is a very popular study as it has wild relatives in the UK. This makes some predictive risk assessment and we can suggest whether or not particular transgenic plants could pose an ecological problem. I must stress that the best test of risk assessment will be very carefully monitored experiments in natural habitat.

Rosemary Hails, Ph.D.
Quantitative Ecology Group
Centre for Ecology and Hydrology
Oxford, United Kingdom