Data from: A Grinnellian niche perspective on species-area relationships

In this work, Grinnellian niche theory (a body of theory about geographic
distributions of species in terms of non-interacting niche variables) is
used to demonstrate that species-area relationships emerge with both size
of environmental space and size of geographic area. As environmental space
increases, more species' fundamental niches are included, thus
increasing the number of species capable of living in the corresponding
region. This idea is made operational by proposing a size measure for
multidimensional environmental space and approximating fundamental niches
with minimum-volume ellipsoids. This framework allows estimating a
presence-absence matrix based on the distribution of fundamental niches in
environmental space, from which many biodiversity measures can be
calculated, such as beta diversity. I establish that Whittaker’s equation
for beta diversity is equivalent to MacArthur’s formula relating species
numbers and niche breadth; this latter equation provides a mechanism for
the species niche-space relationship. I illustrate the theoretical results
via exploration of niches of the terrestrial mammals of North America
(north of Panama). Each world region has a unique structure of its
environmental space, and the position of fundamental niches in niche space
is different for different clades; therefore, species-area relationships
depend on the clades involved and the region of focus, mostly as a
function of MacArthur’s niche beta diversity. Analyzing species-area
relationships from the perspective of niche position in environmental
space is novel, shifting emphasis from demographic processes to
historical, geographic, and climatic factors; moreover, the Grinnellian
approach is based on available data and is computationally feasible.