Colorist
Understanding why species and individuals are found in some places and times, but not in others, is a fundamental goal of ecology. Maps play an important role in pursuit of that goal because they give form to complex sets of assumptions, hypotheses, and predictions about the distributions of biological entities. Traditionally, range maps and home range maps have been used to offer generalized perspectives on where species and individuals are located in space and time. As our understanding of distributions becomes increasingly nuanced and precise, however, researchers need new approaches for visualizing patterns of distributional stasis and change.
Matt Strimas-Mackey, Tom Auer, and I developed the colorist package for the R statistical computing environment in an effort to address this need. In addition to enabling simultaneous display of a series of distributions through the use of small multiples, colorist provides functions for extracting several features of interest from a set of distributions and for visualizing those features using HCL-based (hue-chroma-luminance) color palettes. The resulting maps allow for “fair” visual comparison of intensity values (e.g., occurrence, abundance, or density values) across space and time and can be used to address questions about where, when, and how consistently a species, individual, or group of organisms is likely to be found.
Overview of visualization approach and colorist functions. Users stack raster layers describing species distributions or utilization distributions in preparation for use in colorist. Cell values must be comparable across layers. Then, distribution metrics are calculated using metrics functions, an appropriate palette is selected using a palette function, metrics and palettes are combined in a map function, and a legend can be constructed using a legend function.
supplementary information
Schuetz JG, Strimas-Mackey M, Auer T (2020) colorist: Coloring Wildlife Distributions in Space-Time. R package version 0.1.2.
Schuetz JG, Strimas-Mackey M, Auer T (2020) Colorist: an R package for coloring wildlife distributions in space-time. Methods in Ecology and Evolution. pdf