The ecological assembly line - first impressions count

24 May 2000

New research out today in Nature, shows that communities made up of more than two species of animal exhibit very different and surprising patterns in abundance depending on how they are created. This has important implications for our understanding of how communities of species in the natural world behave.

The research carried out at the University of Liverpool, funded by the Natural Environment Research Council, was conducted in an artificial laboratory habitat, which simplifies the natural world into a neat, easily-controlled package. It has provided the first opportunity to tease apart the complicated interactions that may exist between several different species, in this case a moth and two of its natural enemies, a viral pathogen and a wasp predator.

The studies discovered that in each of the three-species systems, the predatory wasp and its moth prey show surprising changes in numbers when compared with the simpler two-species interactions (moth-predator and moth-virus), which have regular cycles of numbers over a single generation. According to Dr Steven Sait, part of the research team based at the University of Liverpool, the experimental three-species systems showed very different and unexpected changes in numbers depending on which natural enemy (wasp or virus) was invading an established community of the other two organisms. For instance, when the wasp was the invader, the predator and prey again cycled steadily in abundance, but this time over several generations. But when the virus invaded, the predator and prey were capable of irregular changes in abundance, which never settled to a steady pattern.

A mathematical model of the three species interaction, developed by the NERC Centre for Population Biology, was able to reproduce faithfully the dynamic patterns created in the laboratory. In the future the model can be used to look at how a variety of circumstances, in addition to those tested so far, affect the abundance of these species at any one time.

"We wouldn't have predicted these patterns from our knowledge of the simpler systems alone", says Steven Sait, "The more complex the system, the greater the variety of patterns in abundance we see. Perhaps most important is the role of invasion - knowing how that works will help us predict the outcome of invasions in the natural world, such as in biological control and conservation."

Further information

Dr Steven Sait
Population and Evolutionary Biology Research Group,
School of Biological Sciences, University of Liverpool,
Nicholson Building, Brownlow Street,
Liverpool, L69 3GS.
Tel: 0151 794 5295
Fax: 0151 794 5094

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411561
Mob: 07917 557215

Notes

1. This research was the result of collaborative work between Dr. Steven Sait, who is currently supported by a NERC Advanced Fellowship, Prof. Michael Begon and Dr. David Thompson, who were originally awarded the NERC grant from which the latest results are derived (all at the School of Biological Sciences, University of Liverpool), and Prof. Charles Godfray and Wei-Chung Liu, (the director and his PhD student at the NERC Centre for Population Biology, Imperial College at Silwood Park), who were responsible for generating a model of the experimental data.

2. NERC is the leading body in the UK for research, survey, monitoring and training in the environmental sciences. NERC funds research in universities and in its own Centres and Surveys. NERC trains scientists for the future - more than 3,000 postgraduate students have been funded by NERC over the last five years.

Press release: 10/00

The ecological assembly line - first impressions count

Press links

Recent press news