Code from: Scrutinizing the Wallacean shortfall: Global gaps in snake occurrence data across space and environment

Occurrence records are fundamental for ecological and evolutionary
research, providing key information on species’ geographic ranges.
However, these records are often taxonomically, spatially, and temporally
biased, requiring caution in their use. Here, we analysed the spatial
coverage of occurrence records for over 3,500 snake species worldwide to
identify geographical gaps, biases, and priority areas for
surveys. To do this, we first compiled occurrence records for all
continental snake species worldwide and assigned them to an equal-area
grid. Recognizing that biogeographic realms differ in evolutionary
histories, environmental conditions, and sampling efforts, we conducted
all analyses separately for each realm. Using this global dataset, we then
calculated inventory completeness metrics to identify well-sampled grid
cells. We then used high-resolution climate data to describe the
environmental space of each realm and evaluate the extent to which its
climatic gradients are represented by well-sampled cells. Finally, we
calculated geographic and environmental distances from each cell to the
nearest well-sampled cell within each realm, thereby identifying priority
areas for future surveys.