Study shows that animals choose nutritious diet too

Posted by AFN Staff Writers on 18th January 2012

An international research team has found that predator animals that are given a choice of foods will select a diet that maximises their chances of reproducing.

The researchers, including Professor Stephen Simpson, an internationally renowned biologist from the University of Sydney, have shown for the first time that predatory animals choose their food on the basis of its nutritional value rather than just overall calorie content.

The findings, recently published in the Proceedings of the Royal Society B, are based on a study of the ground beetle, Anchomenus dorsalis, a garden insect that feasts on slugs, aphids, moths, beetle larvae and ants.

The international team of scientists from the University of Sydney, the universities of Exeter and Oxford in the UK, Aarhus University in Denmark and Massey University in New Zealand, collected female beetles from the wild and split them into two groups in the laboratory.

Half of the beetles were offered a choice of foods – some that were high in protein and some that were high in fat. The other half were not given a choice of foods: some of these beetles were only given high protein food, while the rest were just given high fat foods.

The beetles that were given a choice of foods ate the proportions of protein and fat that were optimal for producing healthy eggs. These beetles produced more eggs than the other beetles in the study that had no choice of foods.

University of Sydney’s Professor Simpson said, “Contrary to standard dogma, predators do balance their diet and show nutritional wisdom. Although we previously demonstrated this characteristic in spiders, predatory beetles, fish, mink and cats, this is the first study to show the adaptive reasons and benefits of diet selection.”

Lead researcher Dr Kim Jensen of the University of Exeter said, “At a time of year when many of us are focused on healthy eating, it is interesting to see that predators are also selective about what they eat. We show for the first time that they do actually select the foods that will give them the right balance of nutrients.”