Transposable elements and host genome evolution

Several recent reports have challenged the idea that transposable elements (TEs) are mainly 'selfish' or 'junk' DNA with little importance for host ev olution. It has been proposed that TEs have the potential to provide host g enomes with the ability to enhance their own evolution. They might also be a major source of genetic diversity, allowing response to environmental cha nges. Because the relationships between TEs and host genomes are highly var iable, and because the selfish, junk and beneficial DNA hypotheses are by n o means mutually exclusive, a single label for these relationships appears to be inappropriate and potentially misleading.