Evolution research is New Scientist front cover
Evolutionary research led by the Univeristy's Professor Mark Pagel, and published in the journal Nature, is featured as the front cover story in the popular science magazine New Scientist this week.
The research found that the mechanism by which new species arise is probably not due to natural selection, but is caused by random events. These findings, published in the Journal Nature, provide a new interpretation of the Red Queen hypothesis, which is based on natural selection, and has previously been used to describe rates of occurrence of new species.
The research shows that collections of closely-related species produce new species (speciation) at a constant rate over millions of years; with new species appearing at random intervals over long periods of time. The difference between this and other views of speciation is that these new findings separate actual speciation events from the gradual changes caused by natural selection.
This model of why new species appear suggests that rare random events happen to species, and that these cause reproductive isolation. These random events could be a number of things, ranging from changes to the environment, to changes in mating preferences, to genetic changes. The reproductive isolation these random events cause prevents the successful mixing of genetic material with individuals outside the isolated group, and hence create a new species.
Professor Mark Pagel from the School of Biological Sciences said “We think this research can transform our understanding of how speciation occurs. Our research indicates that the idea that new species occur by gradually becoming more and more adapted to their particular niches, is not true. In fact, we have found that new species appear due to rare random events that seem to simply just happen.”
The research could explain such things as why there are more than sixteen mouse lemur species in Madagascar that appear to be identical, or why there are so-called living fossils, and why some groups include so many more species than others. Currently, the main theory used to describe the rates of speciation is known as the Red Queen hypothesis, originally proposed by Leigh Van Valen in 1973. The term 'Red Queen Hypothesis' was originally taken from the Red Queen's race in Lewis Carroll's book 'Through the Looking-Glass'. This is a view of nature in which species continually evolve but do not become better adapted because the environment is continually changing. The Red Queen hypothesis describes speciation as a constant race against a constantly changing environment in which "It takes all the running you can do, to keep in the same place". In this hypothesis, over long periods of time a species accumulates enough changes that it becomes a new species.
During this research the claims that the Red Queen hypothesis makes about speciation occurring at a constant rate were tested. Evolutionary biologist Professor Mark Pagel and colleagues used phylogenetic and statistical techniques to rigorously test the Red Queen hypothesis against other models of speciation.
This research "Phylogenies reveal new interpretation of speciation and the Red Queen" has been published in the journal Nature (Nature 463, 349-352) .
This research was supported by grants from the Natural Environment Research Council (NERC), and the Leverhulme Trust.