Abstract:
Both abiotic and biotic conditions may be important for biodiversity. However, their relative importance may vary among
different diversity dimensions as well as across spatial scales. Spiders (Araneae) offer an ecologically relevant system for
evaluating variation in the relative strength abiotic and biotic biodiversity regulation. We quantified the relative importance
of abiotic and biotic conditions for three diversity dimensions of spider communities quantified across two spatial scales.
Spiders were surveyed along elevation gradients in northern Sweden. We focused our analysis on geomorphological and
climatic conditions as well as vegetation characteristics, and quantified the relative importance of these conditions for the
taxonomic, phylogenetic, and functional diversity of spider communities sampled across one intermediate (500 m) and one
local (25 m) scale. There were stronger relationships among diversity dimensions at the local than the intermediate scale.
There were also variation in the relative influence of abiotic and biotic conditions among diversity dimensions, but this variation
was not consistent across spatial scales. Across both spatial scales, vegetation was related to all diversity dimensions
whereas climate was important for phylogenetic and functional diversity. Our study does not fully support stronger abiotic
regulation at coarser scales, and conversely stronger abiotic regulation at more local scales. Instead, our results indicate that
community assembly is shaped by interactions between abiotic constrains in species distributions and biotic conditions, and
that such interactions may be both scale and context dependent.
