The study used a lab-based artificial ecosystem of communities of bacteria to examine what happens when the bacteria move around and evolve to live in different parts of the ecosystem over the course of hundreds of generations. The scientists measured the effect this dispersal of species has on the productivity and biodiversity of the ecosystem over all.

‘Productive‘ ecosystems are defined as those that support a large total amount of living matter, from tiny microbes up to plants and animals. Scientists refer to this measurement of the amount of life present as an ecosystem’s ‘biomass‘. A number of studies in the last decade have shown that ecosystems that have a high biodiversity - meaning they are rich in variety of species - are also highly productive over short time scales, but until now the underlying processes creating this link between high levels of biodiversity and productivity over evolutionary time scales have not been understood.

The scientific team behind this new research found that both the biodiversity and productivity of an ecosystem are at a peak when there is an intermediate rate of dispersal of species - not too little and not too much - between different parts of the ecosystem.

When there is little or no dispersal, populations of species that remain in harsh areas of an ecosystem are unable to adapt to their environment due to a low population size and lack of genetic variation. Conversely, when there is too much dispersal in an ecosystem, species evolve to be ‘generalists‘ that can survive in many habitats, but fail to thrive in any given one.

Dr Craig Maclean, one of the authors of the March 13 study at the NERC Centre for Population Biology at Imperial College London, explains that an intermediate rate of dispersal creates a ‘happy medium’ wherein species move around enough to ensure that harsh environments are adapted to, but not so much that they become generalists.

Read Full Story Here