Press release: Teamwork in the tropics: pollinators and frugivores are less choosy
Nr. 167/2012 - 13.09.2012
Scientists analyse pollination and seed dispersal in worldwide study
(pug) Seed-dispersing birds and pollinating insects in the tropics are – contrary to prior doctrine – less specialised on individual plant species than in the temperate zones. This is the outcome of a study conducted by an international research group that includes the University of Göttingen and the LOEWE Biodiversity and Climate Research Centre (Bik-F) in Germany. The results suggest that ecosystem functions such as pollination and seed dispersal have a higher tolerance against extirpations of individual species in the tropics than in temperate communities. The study was published in the journal Current Biology.
The South American Andean Cock-of-the-rocks eats the fruits of over 100 plant species and disperses their seeds. Bees and plants profit from a similar win-win situation: bees forage on plant nectar, and in return they pollinate the next flower they visit. The scientists analysed this „Who with whom?“ in a worldwide study and discovered that the specialisation of pollinators and seed dispersers on individual plant species decreases towards the equator. This is somewhat unexpected, because since Darwin the co-evolution of reciprocal specialisation has been regarded as an important explanation for the higher plant diversity in the tropics.
„The results of our global analysis contradict the assumption that ecological communities in the tropics are generally more specialised than those in the temperate zones,“ say Dr. Matthias Schleuning from BiK-F and Dr. Jochen Fründ from Göttingen University. Furthermore, the specialisation between animal and plant species rather tends to be a consequence of the available resources than the result of long-term adaptation processes. „A simple explanation for this could be that the high tropical plant diversity provides many different resources to animals in a low density. Whoever is not especially choosy is at an advantage, because then the next food source is not very far away, making foraging more efficient,“ says Dr. Fründ.
The lower specialisation in the tropics also provides advantages for the plants – plants interacting with a number of animal species have a lower risk of extinction if individual species of pollinators or seed dispersers disappear or decline in number. The scientists therefore suppose that certain ecosystem functions such as pollination and seed dispersal are less susceptible to disruption in the tropics than in the temperate zones. Due to the generalised relationships and greater diversity, more species can replace the functions of individual declining species. Such failures in the relationship between animals and plants can even have a considerable economic impact. This is demonstrated by the current massive collapse of bee colonies in the US, which leads to particularly high costs in those areas where there is a lack of alternative pollinators.
Original publication: Matthias Schleuning et al. Specialization of Mutualistic Interaction Networks Decreases toward Tropical Latitudes. Current Biology 2012. http://dx.doi.org/10.1016/j.cub.2012.08.015.
Contact:
Dr. Jochen Fründ
Georg-August-Universität Göttingen
Faculty of Agricultural Sciences
Division of Agroecology
Grisebachstr. 6, 37077 Göttingen
Phone +49 551 39-22359
Email: jfruend@uni-goettingen.de
Web: www.agroecology.uni-goettingen.de