Washington, Feb 17 (IANS): A new study that reconstructs the evolutionary tree of flu viruses may have implications ranging from the assessment of health risks for populations to developing vaccines.

The study challenges conventional wisdom and solves some of the mysteries surrounding flu outbreaks of historical significance.

The study, published in the journal Nature, provides the most comprehensive analysis to date of the evolutionary relationships of influenza virus across different host species over time.

In addition to dissecting how the virus evolves at different rates in different host species, the study challenges several tenets of conventional wisdom, for example the notion that the virus moves largely unidirectionally from wild to domestic birds rather than with spillover in the other direction.

It also helps resolve the origin of the virus that caused the unprecedentedly severe influenza pandemic of 1918.

The new research is likely to change how scientists and health experts look at the history of influenza virus, how it has changed genetically over time and how it has jumped between different host species, reported the Science Daily.

"We now have a really clear family tree of theses viruses in all those hosts -- including birds, humans, horses, pigs -- and once you have that, it changes the picture of how this virus evolved," said Michael Worobey.

Worobey is professor of ecology and evolutionary biology at the University of Arizona, and co-led the study with Andrew Rambaut, a professor at the Institute of Evolutionary Biology in the University of Edinburgh.

"The approach we developed works much better at resolving the true evolution and history than anything that has previously been used."

The team analysed a dataset with more than 80,000 gene sequences representing the global diversity of the influenza A virus and analyzed them with their newly developed approach.