Study: Elephants Maintain Genetic Diversity in Savanna, Could Insure Against Climate Change
The African savanna elephant holds the prize for largest living terrestrial animal, and now it apparently just set another land record: the longest distance mover of seeds. The pachyderms can transport seeds up to 65 kilometers, according to a study of elephant dung in South Africa. That’s 30 times farther than savanna birds take seeds, and it indicates that elephants play a significant role in maintaining the genetic diversity of trees on the savanna.
“The scale of movement is really mind opening,” says Greg Adler, an ecologist at the University of Wisconsin in Oshkosh who was not involved in the study. “The implication is that elephants are absolutely critical to the integrity of these African savanna ecosystems.”
On the savanna, elephants certainly trump the other known seed dispersers. Ants tend to move seeds about a meter, vervet monkeys less than 850 meters, and trumpeter hornbills as far as 2000 meters. In addition to their more expansive range, elephants can eat larger fruit than many other species, such as the meter-long seed pods of the sausage tree. And then there’s the sheer volume: Each elephant may deposit nearly 3200 seeds a day, estimates Joseph Dudley, an ecologist with Leidos, a science and engineering company in Germantown, Maryland, who studied savanna elephants in Zimbabwe in the 1990s.
The genetic diversity of many tree species is maintained, and local inbreeding prevented, when their seeds are scattered widely by elephants. “They’re seeding genes—literally—across the landscape.” And it could provide insurance against climate change, he adds, by taking seeds into areas where the conditions may become suitable for the trees in the future.