Hierarchical
Representations of Species Distributions Using Maps, Images, and
Sighting Data
Allan D. Hollander, Frank W. Davis, and David M. Stoms
Geographic Information Systems technology permits
the generation of complex representations of species distributions,
while most of the data underlying these patterns are coarse. This
suggests the importance of structuring such data along axes of
differing data extent, tiling schemes, themes, and time, and displaying
different representations of distributions, the philosophy being
that comparison of multiple representations provides a sense of
the actual distribution through convergence of evidence. We present
an example using a lizard, the orange-throated whiptail (Cnemidophorus
hyperythrus), which is native to southern California. The analysis
was hierarchically structured by first mapping overall lizard
range limits, then suitable habitats within the range, and then
habitats over a local extent. Data sources include a generalized
range outline, museum records, and field observations, as well
as climate data, vegetation maps, and satellite imagery to serve
as associated environmental variables. Comparison of representations
resulting from these different data sources makes biases evident,
highlights areas of inadequate sampling, and can lead to new inferences
about habitat relationships. Finally, we discuss forthcoming improvements
in the technology that will facilitate creation and display of
families of models.