Unusually Flexible Super-Genes Discovered
Scientists have dubbed the DNA complement of fountain grass a "super-genotype" because the genes function like no others yet encountered.
The invasive grass is equipped with a single, multi-purpose genotype that can adapt to a wide array of environmental conditions.
Fountain grass, scientifically known as Pennisetum setaceum, is a garden ornamental that has naturalized in Australia, Fiji, United States, and many parts of southern Africa. Unique selective pressures presented by the different environmental conditions have not modified the genetic makeup of the exotic populations, as would be expected. Although the grass produces new plants from seed, the seeds develop without pollination, so no recombination of chromosomes ever occurs. Researchers conclude that all the fountain grass in the world, whether from South Africa, California, Hawaii or its native Egypt, are genetically identical.
The universal genetics of this species makes it remarkable that the plant thrives in such a broad range of habitats. Fountain grass grows well in the desert sand dunes of its native range, on the mountain grasslands of California and in the semi-arid volcanic ash of Hawaii. Its single genotype is so malleable, that the grass grows well under diverse levels of water, ph, nitrogen and other nutrients.
Nevertheless, the threat fountain grass poses to local biodiversity does vary among locations. In Hawaii, the grass forms aggressive monocultures covering large expanses of mountainside. In California and South Africa, it is considered moderately invasive, establishing mainly on previously disturbed soils. In Namibia, fountain grass is confined to roadsides and doesn't present a hazard to natural ecosystems.
The authors of this study speculate how the super-genotype evolved through natural selection under rapidly changing environmental conditions in northeastern Africa. Now fountain grass's exceptional plasticity puts its far beyond the norms contemplated by Darwinian evolution.
Johannes J. Le Roux, Ania M. Wieczorek, Mark G. Wright and Carol T. Tran. 2007. Super-Genotype: Global Monoclonality Defies the Odds of Nature. PLoS ONE Ecology. 2(7): e590.