Public Release:  Gene migration helps predict movement of disease

Institute of Physics

Until recently, migration patterns, such as those adopted by birds all across the Amazonian rainforest, have not been thought to play an important role in the spreading of beneficial genes through a population.

Researchers have now, for the first time, been able to predict the chance of a gene spreading when given any migration pattern, potentially providing an insight into the migration patterns of animals throughout history.

Even more impressively, the concepts from these predictions can be applied to tracking the route of cancer through the body, and viruses or bacteria through a population.

The study, published today, 14 July 2011, in the Institute of Physics and German Physical Society's New Journal of Physics, has provided a computation to make these predictions, performed within seconds on a normal computer.

"Give me your migration pattern, I'll give you the chances of success of your mutant," said lead author Professor Bharum Houchmandzadeh, of CNRS and Laboratoire Interdisciplinaire de Physique.

A mutant is a gene that has been altered naturally so that its normal function, or expression of a trait, is affected. The large majority of mutations have damaging effects; however, some can be beneficial ― the mutation may be able to help the organism withstand environmental stress or help it reproduce more quickly.

As a result, beneficial mutations tend to become more common throughout a population.

Since the discovery that evolution is a chance game more than seventy years ago, evolutionary theorists have been calculating the chances of beneficial mutations making their way through a population, with little or no attention being paid to the effect that migrations might have on these chances.

One of the reasons for this disregard is the fact that migration patterns are very hard to evaluate due to their sometimes complex nature. Take, for instance, a species of plant situated along a river: the upstream plants can send their seeds down the river, but the reverse is impossible.

Previous research has found that there are two dominant types of migration pattern and the researchers have taken things one step further by applying a neat set of mathematical tools to represent those patterns.

The first migration pattern assumes that when you die, someone else's progeny will replace you. For example, a tree has to die to free up the space for another to grow in its place. For this type of behaviour, the researchers showed that migrations decrease the chance of a mutation spreading and that there is an upper limit to the chance of success.

The second migration pattern assumes that your progeny will kill someone and replace them; much like viruses, bacteria and cancer. For this type of behaviour, some migration patterns can greatly enhance the chance of a mutant's success and can even make it certain.

These calculations allow one to detect all the migration patterns when given the chance of success of a certain mutant.

Professor Houchmandzadeh continues, "Suppose we are speaking of the spread of epidemics. A virus can jump from one individual to another during a single encounter. The migration pattern in this case is then the network of people meeting each other.

"An epidemiologist could use our formulas to compute the best way to limit encounters between individuals and therefore slow the spread of epidemics."

###

From 14 July 2011 this paper can be downloaded from http://iopscience.iop.org/1367-2630/13/7/073020

Notes to Editors

Contact

1. For further information, a full draft of the journal paper or contact with one of the researchers, contact IOP Publishing Press Assistant, Michael Bishop:
Tel: 0117 930 1032
E-mail: Michael.Bishop@iop.org

The fixation probability of a beneficial mutation in a geographically structured population

2. The fixation probability of a beneficial mutation in a geographically structured population Houchmandzadeh and Vallade 2011 New J. Phys. 13 073020 will be freely available online from 14 July 2011. It will be available at http://iopscience.iop.org/1367-2630/13/7/073020

New Journal of Physics

3. New Journal of Physics publishes across the whole of physics, encompassing pure, applied, theoretical and experimental research, as well as interdisciplinary topics where physics forms the central theme. All content is permanently free to read and the journal is funded by an article publication charge.

IOP Publishing

4. IOP Publishing provides publications through which leading-edge scientific research is distributed worldwide. IOP Publishing is central to the Institute of Physics (IOP), a not-for-profit society. Any financial surplus earned by IOP Publishing goes to support science through the activities of IOP. Beyond our traditional journals programme, we make high-value scientific information easily accessible through an ever-evolving portfolio of community websites, magazines, conference proceedings and a multitude of electronic services. Focused on making the most of new technologies, we're continually improving our electronic interfaces to make it easier for researchers to find exactly what they need, when they need it, in the format that suits them best. Go to http://publishing.iop.org/

The Institute of Physics

5. The Institute of Physics is a leading scientific society promoting physics and bringing physicists together for the benefit of all.

It has a worldwide membership of around 40 000 comprising physicists from all sectors, as well as those with an interest in physics. It works to advance physics research, application and education; and engages with policy makers and the public to develop awareness and understanding of physics. Its publishing company, IOP Publishing, is a world leader in professional scientific communications. Go to www.iop.org

The German Physical Society

6. The German Physical Society (DPG) with a tradition extending back to 1845 is the largest physical society in the world with more than 59,000 members. The DPG sees itself as the forum and mouthpiece for physics and is a non-profit organisation that does not pursue financial interests. It supports the sharing of ideas and thoughts within the scientific community, fosters physics teaching and would also like to open a window to physics for all those with a healthy curiosity.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.