"This is probably the best example of deception as regards to seed dispersal," Midgley said. However, although the nuts smell like dung, neither the dung beetles nor their young can eat the hard seeds - a classic example of biological deception. The researchers analyzed the chemicals the seeds give off and found their concentration and composition are similar to those released by the dung of antelopes, such as elands and bonteboks. The round shape of these nuts makes it easier for the dung beetles to roll them, the scientists said. Dung beetles feast on dung, and lay their eggs in dung for their young to eat. Instead, the scientists found that dung beetles rolled the nuts away and buried them.
"We suspect that the smell of the nuts repels small mammals," Midgley said in a statement.
#CLEVER RUSE CRACKED#
However, when the scientists cracked the nuts open, the rodents found the innards tasty. The researchers set up motion-sensing cameras that revealed that rodents either ignored or were even repelled by the nuts. "I have nine-month-old seeds in a paper bag in my office that are still very pungent," Midgley said in a statement. Intriguingly, Ceratocaryum argenteum nuts possess a pungent scent, which is unusual among nuts because it raises the chances of them getting eaten. Furthermore, these nuts are larger than those of any of related species - they are four-tenths of an inch (1 centimeter) wide, about the size of antelope droppings. The nuts of this species are unusual - instead of having smooth, black seed coats like the nuts of the rest of this plant's family, they have rough brown seed coats, the researchers said.
The scientists focused on Ceratocaryum argenteum, which is found in the fire-prone shrub lands on deep sands in South Africa. The researchers discovered that this clever ruse gets dung beetles to spread the seeds.
"Imagine the smell of a sheep or goat dropping - that is what they smell like," Midgley told Live Science. Now, Midgley and his colleagues found nuts in South Africa that resemble antelope droppings. Some plants do produce hard red or black seeds that resemble berries, such as the lucky bean tree of South Africa, but these do not seem to fool birds, and are hardly ever eaten or dispersed, he said. However, until now, there were no convincing examples of seeds that used mimicry to disperse themselves, said study lead author Jeremy Midgley, an evolutionary ecologist at the University of Cape Town in South Africa.