Taxonomic scaling, such as taxonomic coverage and taxonomic resolution, could affect the biodiversity patterns and their environmental determinants. A paper, lead by Chih-Fu Yeh, an undergraduate student when he started the project, was just online on this topic titled “Elevational patterns and hierarchical determinants of biodiversity across microbial taxonomic scales”.
By sampling along an extensive elevational gradient in subarctic ponds of Finland and Norway, we examined the diversity patterns of aquatic bacteria and fungi across taxonomic scales and quantified cross-phylum congruence in multiple biodiversity metrics and evaluated the relative importance of climate, catchment and local pond variables as the hierarchical drivers of biodiversity across taxonomic scales. We focused on three aims. First, we explored the elevational patterns across 22 microbial phyla and quantified cross-phyla congruence in species richness, evenness and LCBD of bacteria and fungi. Second, we investigated how taxonomic coverage (i.e., the shift from the whole community to individual phylum levels) affected the elevational patterns in biodiversity and the relative importance of hierarchical drivers of local, catchment and climatic factors. Third, we further explored how downscaling to higher taxonomic resolution levels (i.e., the shift from domain to genus) affected the elevational patterns in biodiversity and the relative importance of hierarchical drivers acting on various taxonomic resolution levels.
The main findings are the following.
(1) Elevational patterns in species richness and local contribution to beta diversity, but not in evenness, were congruent across bacterial phyla.
(2) Taxonomic downscaling significantly changed the elevational patterns of microbes, indicated by weaker and more complex diversity-elevation relationships.
(3) Bacterial diversity at lower taxonomic resolution levels were predicted well by climatic variables, while those at higher taxonomic resolution levels were more relevant to local environmental filtering.
(4) Niche conservatism of temperature preference was phylogenetically deeper than that of water chemistry variables.