A novel, data-driven approach to derive spatially coherent extent of
occurrence maps for biogeographic studies
Abstract
As a source of information on species’ geographic distributions,
macroecologists and biogeographers have had to rely on expert-derived
range maps to study biodiversity patterns at large scales. In addition
to being biased towards well-studied taxa and subjective by nature, such
maps suffer from a lack of consistency in how species’ absences are
treated within the wider distribution. Using the finer resolution of the
Interim Biogeographic Regionalization for Australia (subregions) and
example sets of Australian species as study system, we developed a
reproducible, data-driven approach to map the extent of occurrence (EOO)
of hundreds—or even thousands—of species by combining presence-only
data and subregions (i.e., non-equal-sized operational units that
represent homogenous areas of unique environmental features) within a
unifying quantitative framework. From data-driven and expert-derived
range maps for 533 birds, species richness’ estimates differ at three
biogeographical scales—whit bias (mean error) at coarser resolution
(ecoregion) being half that at subregional scale—and the spatial
association between pairs of these birds’ presence-absence maps vary
from nearly zero to almost one (representing such pattern almost either
differently or identically, respectively). Holes within the wider
distribution of the EOO maps for pairs of amphibians, mammals, reptiles,
and plants seem to respond to the demarcation of different
subpopulations over Australia rather than causing an underestimation of
a species’ empirical distribution. These results demonstrate that this
approach can reliably map EOO of species whose distributions aligns with
three broad types of geographic patterns (wide-range,
habitat-specialists, and range-restricted species). This alternative to
expert-derived range maps can serve as a basis for more robust,
data-driven studies of biogeographic biodiversity patterns, thus
improving our understanding and conservation efforts of global
biodiversity.