Phylogenetic clustering of fungal communities in human‐disturbed streams

Abstract

Phylogenetic community structure is increasingly used to examine community assembly, but the influence of anthropogenic disturbance on phylogenetic community structure remains little explored. We examined how land‐use disturbance (forestry and agriculture) and naturally harsh environmental conditions (geologically driven acidity) affect the phylogenetic diversity of stream fungi. Using DNA from decomposing alder leaves, we calculated phylogenetic distances among fungal operational taxonomic units (OTUs). Closely related OTUs co‐occurred more often than expected by chance, but partitioning the relationship between phylogeny and niche differences showed evidence for niche conservatism only at short phylogenetic distances. Communities in human‐disturbed streams were phylogenetically clustered, whereas they were over‐dispersed in circumneutral near‐pristine streams. OTU richness did not decrease with disturbance; instead, some fungal taxa were replaced by closely related, more tolerant taxa. Fungal communities in naturally acidic reference streams also showed a tendency toward phylogenetic clustering, although much less so than in disturbed streams. Our results indicate different coexistence mechanisms in different environmental settings and a strong role for anthropogenic disturbance as a selective filter shaping the phylogenetic structure of instream fungal communities. The effects of human disturbances on the phylogenetic community structure of fungi occurred independently of taxonomic structure, suggesting utility of phylogenetic approaches to bioassessment.

Assembly processes of trophic guilds in the root mycobiome of temperate forests

“…NE is a more stressful environment because of its more acidic soil pH and warmer and drier climate. Therefore, our findings agree with earlier studies showing across a range of different kingdoms that stress results in niche-selection filtering, separating out more similar species from a regional pool that could tolerate harsh environments (Chase, 2007;Glassman, Wang, & Bruns, 2017;Mykrä et al, 2016;Štursová et al, 2014).…”

“…Although our models explain only part of the variation, our approach linking phylogenetic analyses with multivariate analyses is useful because it enables us to distinguish the nature of deterministic processes. Thereby, we can discern the life history traits that lead to convergence (here: forest management) under stress, which also leads to underdispersed fungal communities (this study, Mykrä et al, 2016;Štursová et al, 2014).…”

Environmental degradation results in contrasting changes in the assembly processes of stream bacterial and fungal communities

“…These earlier and our present results imply that many of the species occurring in disturbed sites could only sporadically occur or be even absent from near-pristine sites. Also, it is possible that anthropogenic disturbance selects species from the regional species pool instead of only leaving a subset from species occurring in near-pristine sites (Tolkkinen et al 2015, Mykrä et al 2016).…”

Understanding environmental change through the lens of trait-based, functional, and phylogenetic biodiversity in freshwater ecosystems

“…Carvajal- Castro and Vargas-Salinas (2016) assessed whether male body size and call frequency of Neotropical anuran assemblages were conserved, and found a strong phylogenetic signal. In another work, trait conservatism was evidenced only at short phylogenetic distances for stream fungi (Mykrä et al 2016). In the very few published papers of niche conservatism for freshwater realm beyond our review, a significant phylogenetic signal was discovered for many of the ecological optima of 217 diatom species (Keck et al 2016), and thermal tolerances and acclimation capacity of 82 fish species (Comte and Olden 2016).…”