SALT LAKE CITY, June 14, 2012 In Israel's Negev Desert, a plant called sweet mignonette or taily weed uses a toxic "mustard oil bomb" to make the spiny mouse spit out the plant's seeds when eating the fruit. Thus, the plant has turned a seed-eating rodent into a seed spreader that helps the plant reproduce, says a new study by Utah and Israeli scientists.
"It's fascinating that these little mice are doing analytical chemistry, assaying the fruit for toxic compounds" and learning not to bite into the seed, says Denise Dearing, a coauthor of the study and professor of biology at the University of Utah.
"It adds a new dimension to our understanding of the ongoing battle between plants and animals," she adds. "In this case, the plants have twisted the animals to do their bidding, to spread their progeny."
The study was set for online publication June 14 in the journal Current Biology.
The study illustrates the first known case within a single species of what is known as the "directed deterrence" hypothesis, namely, "the fruit is trying have itself eaten by the right consumer one that will spread its seeds," Dearing says. "The plant produces a fruit to deter a class of consumers that would destroy its seeds."
The best known example before the new study involved chili peppers and two different classes of animals. Chili peppers deter mammals from eating their seeds because mammals can register pain from the ingredient capsaicin. Birds "don't feel the heat at all," says Dearing. "They tend not to crush the seeds while they are feeding, so they are good dispersers of chili pepper seeds."
The researchers observed two other species another spiny mouse species and a rodent named the bushy tailed jird also spitting out sweet mignonette seeds while eating the fruit. They say the new study is the first to find seed-spitting in rodents, although it has been documented previously in several primate species.
|Contact: Lee Siegel|
University of Utah