Availability of phylogenetic data by year of publication.

The number of studies with available phylogenetic data---as tree files, alignments files or both procured either from online archives or by direct request---organized by year of publication (barplot). Phylogenetic data of some kind (tree and/or alignment files) were available from an online archive for approximately 25% of the studies, and additional data were successfully solicited by direct request for 42% of the studies. Complete datasets were unavailable for 60% of published studies, and data of any kind were unavailable for 33% of studies. The 'policy' arrow indicates the onset of several community initiatives to improve the sharing and preservation of evolutionary (including phylogenetic) data, which coincides with a marked increase in the deposition of phylogenetic data to online archives. For each pair of barplots, the left/right bars correspond to archived/solicited data, respectively.