The range expansion images in the "tif" folder are from the 8th day of growth and are in the "ome-tiff" format. The experiments were conducted using the procedure discussed in the "Experimental setup" section of our paper and the images were obtained following the procedure in the "Image acquisition and analysis" section. To open the ome-tiff images, we recommend using the "Bio-Formats" plugin in Fiji (https://fiji.sc/). The ome-tiff XML metadata can be read in other languages too (i.e. Python). We have also included the data that we extracted from the raw tif images using our Fiji-based image analysis toolkit (https://github.com/Range-Expansions/range_expansion_image_analysis_fiji). * The "masks" folder contains the binary masks of each fluorescent channel. * The "labeled_domains" folder contains color images indicating the locations of sector boundaries. Each sector is assigned a unique integer. * The "circle_radius" folder contains a binary mask of a circle that best fits the colony diameter. * The "homeland" folder contains a binary mask of a circle that best fits the circular mixed region where the expansions were originally inoculated. * The "composite" folder displays color-images of the expansions for easy visualization. * The "annihilation_and_coalescence" folder contains text files indicating the positions of annihilations and coalescences in our expansions (r = row, c=column of the image) and also includes images with the annihilations and coalescences selected (open the images using the Bio-Formats plugin in Fiji; the annihilations and coalescences that we selected are small crosses of different colors). We used our Python-based image analysis toolkit (https://github.com/Range-Expansions/range_expansion_image_analysis_python) to analyze this extracted data and create the figures in our paper.