PastView: a user-friendly interface to explore evolutionary scenarios

Background Ancestral character states computed from the combination of phylogenetic trees with extrinsic traits are used to decipher evolutionary scenarios in various research fields such as phylogeography, epidemiology, and ecology. Despite the existence of powerful methods and software in ancestral character state inference, difficulties may arise when interpreting the outputs of such inferences. The growing complexity of data (trees, annotations), the diversity of optimization criteria for computing trees and ancestral character states, the combinatorial explosion of potential evolutionary scenarios if some ancestral characters states do not stand out clearly from others, requires the design of new methods that operate on tree topologies and extrinsic traits associations to ease the identification of evolutionary scenarios. Result We developed a tool, PastView, a user-friendly interface that includes numerical and graphical features to help users to import and/or compute ancestral character states and extract evolutionary scenario as a set of successive transitions of ancestral character states from the tree root to its leaves. PastView offers synthetic views such as transition maps and integrates comparative analysis methods to highlight agreements or discrepancies between methods of ancestral annotations inference. Conclusion The main contribution of PastView is to assemble known numerical and graphical methods into a multi-maps graphical user interface dedicated to the computing, searching and viewing of evolutionary scenarios based on phylogenetic trees and ancestral character states. PastView is available publicly as a standalone software on [www.pastview.org][1]. [1]: https://www.pastview.org