The team observed viruses as they evolved over hundreds of generations to infect bacteria. They found that when the bacteria could evolve defences, the viruses evolved at a quicker rate and generated greater diversity, compared to situations where the bacteria were unable to adapt to the viral infection.
The study shows, for the first time, that the American evolutionary biologist Leigh Van Valen was correct in his 'Red Queen Hypothesis'. The theory, first put forward in the 1970s, was named after a passage in Lewis Carroll's Through the Looking Glass in which the Red Queen tells Alice, 'It takes all the running you can do to keep in the same place'. This suggested that species were in a constant race for survival and have to continue to evolve new ways of defending themselves throughout time.
Dr Steve Paterson, from the University's School of Biosciences, explains: "Historically, it was assumed that most evolution was driven by a need to adapt to the environment or habitat. The Red Queen Hypothesis challenged this by pointing out that actually most natural selection will arise from co-evolutionary interactions with other species, not from interactions with the environment.
"This suggested that evolutionary change was created by 'tit-for-tat' adaptations by species in constant combat. This theory is widely accepted in the science community, but this is the first time we have been able to show evidence of it in an experiment with living things."
Dr Michael Brockhurst said: "We used fast-evolving viruses so that we could observe hundreds of generations of evolution. We found that for every viral strategy of attack, the bacteria would adapt to defend itself, which triggered an endless cycle of co-evolutionary change. We compared this with evolution against a fixed target, by disabling the bacteria's ability to adapt to the virus.
"These experiments showed us that co-evolutionary interactions between species result in more genetically diverse populations, compared to instances where the host was not able to adapt to the parasite. The virus was also able to evolve twice as quickly when the bacteria were allowed to evolve alongside it."
thinkahol * on 04 Nov 10A new study in The Lancet rates the harmfulness of 20 psychoactive drugs according to 16 criteria and finds that alcohol comes out on top. Although that conclusion is generating headlines, it is not at all surprising, since alcohol is, by several important measures (including acute toxicity, impairment of driving ability, and the long-term health effects of heavy use), the most dangerous widely used intoxicant, and its abuse is also associated with violence, family breakdown, and social estrangement. A group of British drug experts gathered by the Independent Scientific Committee on Drugs (ISCD) rated alcohol higher than most or all of the other drugs for health damage, mortality, impairment of mental functioning, accidental injury, economic cost, loss of relationships, and negative impact on community. Over all, alcohol rated 72 points on a 100-point scale, compared to 55 for heroin, 54 for crack cocaine, and 33 for methamphetamine. Cannabis got a middling score of 20, while MDMA (Ecstasy), LSD, and psilocybin mushrooms were at the low end, with ratings of 9, 7, and 6, respectively.
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