Ecological niche structure determines rangewide abundance patterns of species

Abstract

Spatial abundance patterns across species’ ranges have seen intense attention in macroecology and biogeography. One key hypothesis has been that abundance declines with geographic distance from the range center (‘abundant-center hypothesis’), but tests of this idea have shown that the effect does not hold generally, and indeed may be true only in a minority of cases. We explore an alternative hypothesis: that species’ abundances decline with distance from the centroid of the species’ habitable conditions in environmental space (the ecological niche). We demonstrate consistent negative abundance-ecological distance relationships across 10 of 11 species (turtles to wolves), and that relationships in environmental space are consistently stronger than relationships in geographic space.