Thursday, March 29, 2007

Evolutionary Ecology: Understanding evolutionary bursts

Ottawa (Canada), 29 March: The diversity of life is thought to have arisen through a series of bursts of evolution, referred to as adaptive radiations. Two studies published online in Nature this week identify predation and immigration history as key factors that influence this process.

Both groups manipulated microbial systems, which can evolve quickly over time, to study the processes influencing adaptive radiation. Justin R. Meyer and Rees Kassen looked at the effects of a predator, the single-celled eukaryote Tetrahymena thermophila, on the subsequent diversification of its prey, the bacterium Pseudomonas fluorescens. The presence of predators stifled the bacterium’s ability to diversify. The duo think that this may explain why adaptive radiation seems to occur after mass extinctions and on deserted islands, when predators are rare.

Tadashi Fukami and colleagues found that the sequence in which different species arrive in a given isolated habitat also affects subsequent bacterial diversification. And even small changes in immigration history can have a big knock on effect. Together, the findings show that the origins, extent, function and stability of biodiversity can only be understood by integrating ecology with evolution.
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