Data from: The role of spore size in the global pattern of co-occurrence among Selaginella species
Margaroni, Sofia; Petersen, Kurt B.; Gleadow, Roslyn; Burd, Martin (2019), Data from: The role of spore size in the global pattern of co-occurrence among Selaginella species, Dryad, Dataset, https://doi.org/10.5061/dryad.3k8c480
Aim: Separation of regeneration niches may promote coexistence among closely related plant species, but there is little evidence that regeneration traits affect species ranges at large geographic scales. Here we address patterns of co-occurrence within the genus Selaginella, an ancient lineage of free-sporing, heterosporous, vascular plants. Specifically, we ask whether differences between species in spore size are associated with the extent of overlap in their geographic ranges, a measure of opportunity for ecological interaction. Taxon: Selaginella (Selaginellaceae: Lycopodiales) Methods: We used quantile regression to examine the relationship of spore size ratios (pairwise ratios for megaspores and microspores of co-occurring species) to the area of range overlap and to latitude for a worldwide sample of 112 Selaginella species. Phylogenetically informed tests of statistical significance were used for each percentile relationship examined in the quantile regressions. Results: Large pairwise disparities in megaspore sizes were significantly associated with large range overlap. Disparities also tended to be larger at low latitudes. Microspore size differences, in contrast, were unrelated to shared range area or latitude. Main conclusion: Megaspore size appears to affect coexistence at a broad regional scale among Selaginella species, in at least some cases. The pattern is consistent with some degree of competitive structuring of size-related aspects of dispersal and establishment of propagules among some co-occurring species. Habitat complexity, such as open microsites within otherwise closed and shaded vegetation, seems likely to promote reproductive niche separation and may account for the latitudinal structure in Selaginella spore sizes.
National Science Foundation, Award: EF-0553768