Ant invaders strand seeds without rides. (Biology).Argentine ants The Argentine ant (Linepithema humile, formerly Iridomyrmex humilis) is a tiny dark ant native to northern Argentina, Uruguay, Paraguay, and southern Brazil. crowding out native ones in South Africa South Africa, Afrikaans Suid-Afrika, officially Republic of South Africa, republic (2005 est. pop. 44,344,000), 471,442 sq mi (1,221,037 sq km), S Africa. are disrupting plants there, too, by failing to disperse disperse /dis·perse/ (dis-pers´) to scatter the component parts, as of a tumor or the fine particles in a colloid system; also, the particles so dispersed. dis·perse v. 1. seeds. The effects of Argentine ants make a great test case for the importance of mixed-species partnerships, or mutualisms, says Caroline E. Christian of the University of California, Davis The University of California, Davis, commonly known as UC Davis, is one of the ten campuses of the University of California, and was established as the University Farm in 1905. . Ecologists have worried for years that disrupting mutualisms could start a cascade-of misfortunes. However, Christian points out, experimental data have been scarce. To fill this gap, she turned to South Africa's chaparral-like fynbos, where fires maintain a boom-and-burn cycle in vegetation. About a third of plant species rely on ants to protect their seeds. The ants eat nubbins off the seeds' outsides and leave remainders in underground nests, safe from fire and rodents. The small, aggressive Argentine ants are now sweeping into the region. Some of the native ants are holding their own, but other species have already vanished. In experiments, Christian found no signs that the Argentine ants dispersed any seeds. She also discovered that two native ants that resist the invaders are relatively poor dispersers of large seeds. Two native species that perish TO PERISH. To come to an end; to cease to be; to die. 2. What has never existed cannot be said to have perished. 3. When two or more persons die by the same accident, as a shipwreck, no presumption arises that one perished before the in invasions collect more than four times as many large seeds as the tougher pair does. After an experimental fire, Christian found only a tenth as many large-seeded plants in invaded areas as in uninvaded plots. In the Oct. 11 NATURE, she contends that her findings illustrate the critical ecological importance of mutualisms. Christian warns that the analysis highlights the dangers for ant invasions, "one of the most overlooked aspects of the global biodiversity biodiversity: see biological diversity. biodiversity Quantity of plant and animal species found in a given environment. Sometimes habitat diversity (the variety of places where organisms live) and genetic diversity (the variety of traits expressed crisis." --S.M. |
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