I need to measure distances between sequential points of GPS collar data which are in decimal degrees (lat/lon). I have successfully created a distance measurement through the package adehabitatLT in R, however, these measurements make no biological sense as they are the changes in decimal latitudes. I would like to change that into meters, but I don't know why. Previous papers on adehabitat show people using metric distances, but no explanation in the methods that I have found so far.
Any help to measure distances would be appreciated, either in R or in ArcGIS.