Contact: Science Press Package Elephants, giraffes and the ants in their plants
Nobody wants to see the elephants, giraffes and other grazing animals disappear from the eastern African savanna, but it's not just people who would miss them. Researchers have discovered that many of the ants and trees that share the mammals' turf would suffer too.
Ecologists know a lot about "mutualistic" relationships, in which two species help the other to survive. These kinds of relationships are quite are common in ecosystems (think honeybees and flowering plants). But, researchers are just beginning to understand how other species in an ecosystem can affect these relationships, even though they might not seem to matter at first glance. A research team led by Todd Palmer, who works at the University of Florida, the University of California Davis and the Mpala Research Centre in Nanyuki, Kenya, studied the mutualistic relationships between the African savanna's whistling thorn tree, Acacia drepanolobium, and the four different ant species that use the tree for food and shelter. Each species depends on the tree in a slightly different way. For example, some live inside the plant's thorns, while another lives in holes in the plant's stems. The researchers fenced off some patches of these acacia trees so that elephants and other large grazers couldn't get at them. Without pruning from these mammals, the trees changed their growth patterns, producing less nectar for the ants to eat and fewer thorns for the ants to build homes in. As a result, a different ant species dominated over the others, and the overall ant colony size shrank. These effects in turn led to more attacks on the trees by stem-boring beetles and reduced the trees' ability to grow and survive. The study reveals one of the many ways that elephants, giraffes and other tree-grazing mammals contribute to their ecosystem. Many of these animals, such as the African elephant, are threatened by poachers, habitat loss and other changes. There are many reasons why we don't want to lose these animals, and Dr. Palmer and his colleagues have added another reason to the list. This study appears in the 11 January 2008 issue of the journal Science. ###
|
||||||||
