Increase in species displayed in Ensembl. The number of species included in the Ensembl release has risen rapidly, from only one (human) in the original release to fifty in 2009. Each new species not only adds arithmetically to the amount of data in the main species database, but also geometrically to any cross-species analyses such as the Ensembl Compara databases. Lower-coverage genomes generally produce smaller databases but are more numerous than the high-coverage genomes. In addition, existing species may gain new data types, for example variation data, further increasing the demand on storage space.