It is well known that the tropical regions near the equator have many more species than those near the poles. The publication of a prestigious journal Science addresses the question whether the interrelationships between animal species are stronger towards the equator.
A new study, which was attended by employees of the Entomological Institute of the Biological Center of the ASCR, confirms that interrelationships between animal species are stronger towards the equator, and reveals the global and elevational trend in predation on herbivores. Conclusions of this study were achieved with remarkably simple materials. In order to measure the rate of predation, scientists glued thousands of caterpillars made of plasticine to the vegetation. They were attached to plants in locations scattered all over the world along a 11,635 km long gradient from the Arctic Circle across South Australia. Afterwards, these “dummy caterpillars” have been exposed to predator attacks, and they have been visited several times to check for and detect possible attacks. From the available data, they found that a caterpillar living near the pole had an eighth chance of attacking the predator compared to the equator caterpillar. Interestingly, the pattern was not only mirrored on both sides of the equator, but also appeared along the elevational gradient. The precision of the implementation, consistency and standardization of methods was a key aspect to make the data comparable.
With regard to the global scope of the project, the project involved 40 scientists working on 31 study fields. Katerina Sam initiated the participation of the “Czech” team thanks to her previous experience with fake caterpillars and participation in the methodological planning of the project. She then run the experiments at Chodsko region, in Brisbane, and in Papua New Guinea with the help of her Papuan assistant Bonny Koane. Other employees of the institute who joined the project were Vojtěch Novotný and Yves Basset.
Roslin, T., Hardwick, B., Novotny, V., Petry, W. K., Andrew, N. R., Asmus, A., … & Cameron, E. K. (2017). Higher predation risk for insect prey at low latitudes and elevations. Science, 356(6339), 742-744. http://science.sciencemag.org/content/356/6339/742