Spatial isolation is known to promote speciation — but researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have now shown that, at least in yeast, the opposite is also true. New ecological variants can also evolve within thoroughly mixed populations.
The idea that speciation is based on the selection of variants that are better adapted to the local environmental conditions is at the heart of Charles Darwin’s theory of the origin of species — and it is now known to be a central component of biological evolution, and thus of biodiversity. Geographic isolation of populations is often regarded as a necessary condition for ecotypes to diverge and eventually form new species. When populations of a given species are separated by geographic barriers, favorable mutations that emerge in either can become fixed locally, as mating between the two populations is precluded. Whether or not speciation can occur under conditions in which gene flow between two populations is possible — such that genetic mixing can still occur — remains controversial. In order to resolve the issue, LMU evolutionary biologist Jochen Wolf and his group in cooperation with Simone Immler (University of East Anglia, UK) have used baker’s yeast as a model system to experimentally explore what happens when the degree of gene flow between genetically differentiated populations is gradually increased.Ludwig-Maximilians-Universität München, “Evolution: Speciation in the presence of gene flow” at ScienceDaily
Their results don’t seem to have supported classical Darwinism but they have a really hard time explaining that.
The paper is paywalled.
See also: A physicist looks at biology’s problem of “speciation” in humans