In rare instances, DNA is known to have jumped from one species to another. If a parasite's DNA jumps to its host's genome, it could leave evidence of that parasitic interaction that could be found millions of years later—a DNA 'fossil' of sorts. An international research team led from Uppsala University has discovered a new type of so-called transposable element that occurred in the genomes of certain birds and nematodes. The results are published in Nature Communications. Dr. Alexander Suh at Uppsala University is an expert on the small stretches of DNA that tend to jump from one place to another, called transposable elements. Working with a team from eleven institutions in five countries, the researchers discovered a new type of transposable element that occurred in certain bird genomes but not others. By searching DNA databases, the team discovered that the only other animals that shared the new transposable element were nematode worms that are parasites of humans and other mammals.
'This finding was so unexpected that we were literally speechless at first,' says Alexander Suh. By comparing the DNA sequences of each instance of the transposable element, Suh and his team were able to figure out that the transfer of DNA between nematodes and birds occurred in two waves across the entire tropics, including remote places like Madagascar. They involved charismatic groups of birds such as parrots, hummingbirds, manakins. Certain human diseases, such as avian flu and HIV/AIDS, are known to have jumped onto our species from animal hosts. Epidemiologists have only recently realized the importance of these so-called 'zoonoses'.