Areas of endemism of selected seed plants in southcentral/southwestern USA

Areas of endemism (AEs) are fundamental entities of analysis in
biogeography and a key step for biogeographical regionalization. Even
though many studies have contributed to the biogeographical knowledge of
southern USA flora, no endemicity analysis (EA) has been conducted that
would include a large number of native seed plant species from different
families. A new analysis of plant spatial patterns is important as a first
step for a future updated floristic regionalization of North America North
of Mexico. It has become easier to accomplish owing to the increased
availability of large-scale digitized distributional data and statistical
methods of biogeographic analysis. Here we identify the AEs in SC/SW USA
using digitized plant specimen data available from IDigBio. We built a
database with 81,851-specimen point records of 400 selected mostly
angiosperm species and applied the NDM/VNDM method of endemicity analysis.
We then compare the established 26 AEs in the area of study with the
floristic provinces in two comparatively recent regionalization systems of
USA. To understand the spatial patterns, we pay some attention to the
information on relationships of the endemic species found in phylogenetic
literature.