A latitudinal signal in the relationship between species geographic
range size and climatic niche area
Abstract
Species with broader niches may have the opportunity to occupy larger
geographic areas, assuming no limitations on dispersal and a relatively
homogeneous environmental space. While there is general support for
positive \textit{geographic range size – climatic niche
area} relationships, a great deal of variation exists across taxonomic
and spatial gradients. Here, we use data on a large set of mammal ($n$
= 1225), bird ($n$ = 1829), and tree ($n$ = 341) species distributed
across the Americas to examine the \textbf{1})
relationship between geographic range size and climatic niche area,
\textbf{2}) influence of species traits on species
departures from the best fit geographic range size – climatic niche
area relationship, and \textbf{3}) how detection of
these relationships is sensitive to how species range size and climatic
niche area are estimated. We find positive
\textit{geographic range size – climatic niche area}
relationships for all taxa. Residual variation in this relationship
contained a strong latitudinal signal. Subsampling the occurrence data
to create a null expectation, we found that residual variation did not
strongly deviate from the null expectation. Together, we provide support
for the generality of \textit{geographic range size –
climatic niche area} relationships, which may be constrained by
latitude but are agnostic to species identity, suggesting that species
traits are far less responsible than geographic barriers and the
distribution of land area and available environmental space.