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The characteristic properties of a species, indeed its entire phenotypic space are based on its fundamental set of genetic information –its genome. Genome sequencing projects have revealed this blueprint for hundreds of species, allowing comparisons to be made between the genomes of closely related species and those whose last common ancestor was extinct billions of years ago. These types of comparisons have revealed that many of the genes are well conserved between fungi, animals, plants, amoebas and even bacteria and archea. Nonetheless, despite this conservation, most of the DNA in these genomes differs. Even when the genomes of closely related species are compared dramatic variation is observed both on a large scale as well as on a smaller scale revealing that at least some regions of genomes are in constant flux. This observation has led to the speculation that it is not only the genes, but also these dynamic regions that contribute to what makes each species unique. Much of the non-conserved regions of genomes are made up of repetitive DNA derived from mobile elements. In fact, many of the changes that occur between closely related genomes are due to transposable elements (TEs). These changes occur either directly as a result of TE movement or indirectly through processes such as illegitimate recombination.