HOUSTON -- (March 11, 2009) -- A Rice University study of microbes from a Houston-area cow pasture has confirmed once again that everything is bigger in Texas, even the single-celled stuff. The tests revealed the first-ever report of a large, natural colony of amoebae clones -- a Texas-sized expanse measuring at least 12 meters across.
The research is available online and featured on cover of the March issue of Molecular Ecology.
Some large organisms like aspen trees and sea anemones are well-known for growing in large clonal colonies. For example, one colony of aspen clones in Utah contains more than 40,000 trees that share a massive root system.
In contrast, the short-lived patch of amoeba clones contained millions of genetically identical individuals of the species Dictyostelium discoideum. Though they typically live as loners, hunting and eating bacteria, D. discoideum are known to cooperate when food gets scarce and even to sacrifice their lives altruistically. Biologists say the discovery of the clonal colony could yield important clues about the evolution of such cooperative behavior.
"This discovery is important for our understanding of microbial social evolution because the processes of selection, cooperation and competition play out differently when populations are geographically mixed as opposed to being isolated in patches," said study co-author Joan Strassmann, the Harry C. and Olga K. Wiess Professor in Natural Sciences and chair of Rice's Department of Ecology and Evolutionary Biology.
Studies of clonal colonies in other species show that the colonies often appear at the edge of a species' natural range.
"People had seen this in studies of sea anemone and other species," said study co-author Owen Gilbert, a Rice graduate student in ecology and evolutionary biology. "There are thought to be two ways that these colonies can form at the edge of a species' natural range: e
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