Iturbide et al 2016 (submitted)

data(Oak_phylo2) data(biostack)

# Extract raster values at grid coordinates
ac <- xyFromCell(biostack$bio13, 1:ncell(biostack$bio13))
ex <- extract(biostack$bio13, ac)

# Convert to a Spatial object and define projection
sp_grid_world <- SpatialPoints(ac[-which(is.na(ex)), ])
projection(sp_grid_world) <- CRS("+proj=longlat +init=epsg:4326")

#TS method