How ants thwarted lions on the African savanna

This study was a beautiful snapshot of how complicated ecosystems can be—this idea that you pull on a single thread and the whole system reacts,” says Meredith Palmer, an ecologist at Fauna & Flora International who was not involved in the work, published today in Science . Across tens of thousands of square kilometers of eastern Africa, a type of acacia called the whistling thorn tree ( Vachellia drepanolobium ) sits at the heart of the ecosystem, accounting for 70% to 99% of woody plant mass wherever it grows. The trees provide nectar to native acacia ants ( Crematogaster spp .), which live in the hollow, spiky bulbs growing along their branches. In exchange, the ants defend the tree from herbivores, swarming up the nostrils of African bush elephants ( Loxodonta africana ) hungry enough to get past the spines. Increasingly, however, the tiny insect sentinels are disappearing. At some point in the early 2000s, big-headed ants ( Pheidole megacephala ), thought to be native to an island in the Indian Ocean, showed up in Kenya. Although humans likely played a role in their arrival, no one knows exactly how they got there. But their impact is clear: They attack native acacia ants and consume their young, leaving whistling thorn trees defenseless against munching elephants. For Jacob Goheen, a wildlife ecologist at the University of Wyoming (UW) and senior author of the new study, the observatio...
Source: Science of Aging Knowledge Environment - Category: Geriatrics Source Type: research