Data from: Interactions between soil habitat and geographic range location affect plant fitness

Populations are often found on different habitats at different geographic
locations. This habitat shift may be due to biased dispersal,
physiological tolerances or biotic interactions. To explore how fitness of
the native plant Chamaecrista fasciculata depends on habitat within, at
and beyond its range edge, we planted seeds from five populations in two
soil substrates at these geographic locations. We found that with reduced
competition, lifetime fitness was always greater or equivalent in one
habitat type, loam soils, though early-season survival was greater on sand
soils. At the range edge, natural populations are typically found on sand
soil habitats, which are also less competitive environments. Early-season
survival and fitness differed among source populations, and when
transplanted beyond the range edge, range edge populations had greater
fitness than interior populations. Our results indicate that even when the
optimal soil substrate for a species does not change with geographic range
location, the realized niche of a species may be restricted to sub-optimal
habitats at the range edge because of the combined effects of differences
in abiotic and biotic effects (e.g. competitors) between substrates.