Comparative genomics also tells us stories about the evolution of yeasts and filamentous fungi, and the genome rearrangements that marked their history. For example, several genes encoding proteins required for heterochromatin formation and RNA interference have been lost uniformly throughout the Hemiascomycetes, although some genes remain in a few species in a scattered pattern. Being the first eukaryote to have its genome fully sequenced, Saccharomyces cerevisiae was the forerunner for in silico methods of genome annotation in general, and gene finding in particular. Lessons learned from the comparatively simple genome of this budding yeast have paved the way for efficient genome analysis in other fungi as well as eukaryotes in general. Several fungal species are of important applied interest for mankind, and so it is essential to utilize comparative genomics to derive functional information about them.