New research from the University of Sydney's Charles Perkins Centre will create a seismic shift in the study of ecology, transforming one of the fundamental concepts of the field with cutting-edge nutrition research.
Published in Trends in Ecology & Evolution, the study merges modern nutrition research with niche theory, a core concept used by scientists to understand the range of circumstances in which an animal can survive and thrive. The breakthrough will have a major impact on conserving threatened species, predicting and managing the spread of invasive species, and understanding evolution.
Niche theory - in which animals are classified either as generalists, which can thrive in a wide variety of circumstances, or specialists, which can only survive in specific circumstances - is central to environmental management, particularly in the face of global climate change.
"This research is vitally important, and we believe it will become foundational for the field of ecology," said Dr Gabriel Machovsky-Capuska, from the University's Charles Perkins Centre and Faculty of Veterinary Science.
"At the centre of ecology and evolution is the niche concept, and at the centre of the niche concept is diet.
Prior to this study, there had been no attention given to what it meant nutritionally to be a dietary generalist.
"Ecologists had looked almost exclusively at the foods animals eat or their energy content, rather than the mixtures of nutrients and other compounds they contain."
Humans are a prime example of the flaws in dietary niche theory. Having thrived all over the planet in often extreme environments, they are considered the ultimate generalist species. However, what has allowed humans to spread is not physiological flexibility, as niche theory would have it, but the advancements in culture which have allowed them to exploit a wide range of food sources. Other animals may appear to survive on a wide variety of diets, but this may be because they need a variety of foods to fulfil very specific nutritional needs.
"The argument of niche theory historically went as far as saying that all animals are trying to do is get a certain amount of energy," said co-author Dr Alistair Senior from the Charles Perkins Centre and Faculty of Science.
"We have known for a long time that nutrition is much more complex than that - just think of how much we know about human health or animal production - but this had not been considered as part of niche theory.
"Under the previous framework, researchers would look at a species that eats four or five different food types and say they are a generalist. They are clearly capable of catching fish or predating other animals or chewing through pinecones, but do they do that to very carefully regulate their overall diet balance or are they actually able to tolerate a wide variety of diet compositions?"
The study builds on pioneering research into nutritional ecology led by Charles Perkins Centre academics Professor Stephen Simpson and Professor David Raubenheimer, which has changed our understanding of animal and human nutrition by conceptualising diet as a multidimensional balance of macronutrients, rather than the a one-dimensional intake of food or energy.
Charles Perkins Centre researchers are now reapplying the fundamental ecological concepts used to research wild animals, about which very little is known, to humans, for whom there is an overabundance of information.
"This research will help us manage our relationships with the other species with which we share this earth," said Dr Machovsky-Capuska.
"Whether we like it or not, we are all reliant on the natural environment, and the more we can understand about it, the more we can predict and manage the impacts we have on that environment."