Distilling complex evolutionary histories with shiftPlot

Abstract

Phylogenies form the backbone of many modern comparative methods and are integral components of contemporary science communication. Recent years have seen drastic increases in both the size and complexity of phylogenetic data as computational resources and genetic/trait databases expand. Graphical representations of these massive phylogenetic datasets push against the limits of legibility, often veering closer to artwork than scientific figures optimized to communicate results. While attractive scientific illustrations are certainly a laudable goal, researchers may want to opt for simpler representations to communicate results more concisely. Here, we introduce a new R package, shiftPlot, which implements methods for simplifying and plotting phylogenetic comparative data on discrete traits. Specifically, shiftPlot automatically finds and collapses clades exhibiting the same character state, effectively creating smaller phylogenies that may be more legibly rendered on standard page sizes. Further, these visualizations more clearly communicate evolutionary dynamics by emphasizing state shifts over tip states. While there are undoubtedly situations where this graphical approach will not be suitable (e.g., continuous traits), we believe shiftPlot will prove useful for modern researchers faced with the task of communicating the results of complex phylogenetic analyses.