Temperature and food resources affect the species diversity of wild bees. The combination of these two factors plays a particularly important role, as researchers from the University of Würzburg have shown.
The team climbed Africa’s highest mountain - Mount Kilimanjaro in Tanzania - and used it as an ecological model. "When you climb a mountain, the temperature will drop with elevation at a rate of around six degrees Celsius per kilometer – that is about a thousand times faster than if you were moving from the equator towards the poles," explains Professor Ingolf Steffan-Dewenter, Head of the Würzburg Department of Animal Ecology and Tropical Biology. Other environmental factors that change only slowly along latitudes also vary very quickly with increasing height. Therefore, high mountains allow the factors determining species diversity in global climate zones to be studied in a compact surrounding.
The result of the Würzburg study: the higher up on the mountain, the less wild bee species were found. However, at 4550 meters above sea level they encountered a surprise: a bee species of the genus of apex-burrow bees. At this altitude, the researchers had not expected to find any bees at all.
The biologists installed bee traps at 60 locations on Mt. Kilimanjaro in twelve different types of ecosystems, from savanna and forest to coffee plantations, and at different altitudes. Three times within two years, the traps were set-up and emptied after two days. The researchers then counted and identified the trapped insects. Additionally, the team collected data on temperature, precipitation, number of flowers and intensity of human land use at the study sites.
"We found that temperature has a significant impact on species diversity,” summarized postdoc Marcell Peters in the press release. Moreover, the team found that bees visit fewer flowers at lower temperatures than they do when it is warmer, even though flowers are abundant. “Hence, temperature seems to regulate the accessibility of resources and is therefore more relevant than the availability of resources,” concluded Peters.
These findings might allow a better understanding of how animals respond to environmental changes. Thus, wild bee research can also contribute to the exploration of ecological mechanisms of other animals.
Here you read the complete press release.
The website of the research team from Würzburg