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Using a unique and comprehensive checklist of bee distributions and more than 5,800,000 public records of bee presence, a team of researchers from China, the United States and Singapore described global patterns of bee biodiversity. Their results show that there are more bee species in the Northern Hemisphere than in the Southern Hemisphere and more in arid, temperate environments than in the tropics.
High resolution projections of bee species richness. Image credit: Orr et al., doi: 10.1016 / j.cub.2020.10.053.
Many plants and animals follow a pattern, known as a latitudinal gradient, in which diversity increases towards the tropics and decreases towards the poles.
Bees are an exception to this rule, having more species concentrated away from the poles and less close to the equator, a pattern known as a bimodal latitudinal gradient.
There are far fewer bee species in forests and jungles than in arid desert environments because trees tend to provide fewer food sources for bees than low-lying plants and flowers.
“People think of bees only as honey bees, bumblebees and perhaps a few others, but there are more species of bees than birds and mammals combined,” said co-lead author Dr. John Ascher, a researcher at the National University. of Singapore.
“The United States has by far the largest number of bee species, but there are also large areas of the African continent and the Middle East that have high levels of unknown diversity, more so than in tropical areas.”
To create their map, the scientists compared data on the presence of individual bee species with a huge checklist of more than 20,000 species compiled by Dr. Ascher and accessible online on the DiscoverLife.org biodiversity portal.
Cross-referencing multiple datasets with complementary coverage produced a much clearer picture of how the numerous bee species are distributed across different geographic areas.
This is an important first step in assessing the distribution and potential decline of bee populations.
“We are extremely interested in the abundance of bees, but it is something that has to be done in relation to a baseline,” said Dr. Ascher.
“We are trying to establish that baseline. We can’t really interpret abundance until we understand species richness and geographic patterns. “
While there is still a lot to learn about what drives bee diversity, the authors hope their work will help in the conservation of bees as global pollinators.
“Many crops, especially in developing countries, depend on native bee species, not honey bees,” said lead co-author Dr Alice Hughes, a researcher in the Xishuangbanna Tropical Botanical Garden at the Chinese Academy. of sciences.
“There is hardly enough data out there on them, and providing a reasonable basis and analyzing it sensibly is essential if we are to maintain both the biodiversity and the services these species provide in the future.”
The team document was published in the journal Current biology.
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Michael C. Orr et al. Global patterns and drivers of bee distribution. Current biology, published online November 19, 2020; doi: 10.1016 / j.cub.2020.10.053
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