Soil fungal diversity and community assembly: affected by island size or type?

Abstract

Fungi have a huge biodiversity and play important roles in soil biogeochemical cycling in island ecosystems. Although island biogeography has been widely studied for macroorganisms, fungal community assembly in true islands and its relationship with island area are less documented. We examined soil fungal communities in 18 oceanic islands of two types (eight non-coral islands and 10 coral islands) using the Illumina MiSeq sequencing technique. Our results showed that fungal α-diversity (species richness) was substantially different among the oceanic islands, with a higher value in non-coral islands than in coral islands. Fungal α-diversity was significantly affected by soil potassium and magnesium (Mg) and plant communities in non-coral islands, whereas only soil Mg significantly affected it in coral islands. Soil fungal community composition was significantly different in the non-coral and coral islands and was influenced by soil property, plant community, and spatial distance. The ecological stochasticity model showed that the fungal community assembly was mainly governed by deterministic processes regardless of island type. Fungal β-diversity, but not α-diversity, increased significantly with increasing island area. These findings have implications for the better prediction of soil fungal community dynamics in island systems and biodiversity conservation in fragmented habitats.

Compartment and Plant Identity Shape Tree Mycobiome in a Subtropical Forest

“…We found that fungal community assembly was mainly driven by a deterministic process, rather than a stochastic process, across the three compartments of leaf, root, and soil. Similarly, previous studies demonstrated that soil fungal community assemblies were strongly shaped by deterministic (niche-based) factors (e.g., [ 40 , 41 ]). For root-associated fungal communities, deterministic processes dominated at most of the sites ( 42 ), while neutral processes still had a minor influence on community assembly and might be important in spatially isolated communities as well as those with strong gradients of fungal diversity ( 42 , 43 ).…”

“…A neutral community model, proposed by Sloan et al ( 76 ), was used to determine the contribution of stochastic processes to the fungal community assembly by predicting the relationship between the occurrence frequencies of OTUs (the proportion of local communities in which each OTU is detected) and their abundance (the mean relative abundance across all local communities) ( 41 , 76 ). This model emphasizes the effect of stochastic dispersal and drift but ignores the ecological differences between species and their responses to the surrounding environment.…”

“…In this model, the estimated migration rate ( m ) was a parameter for evaluating the probability that a random loss of an individual in a local community would be replaced by a dispersal from the metacommunity. When the migration rate ( m ) is close to 0, community assembly tends to be more deterministic, and when m is close to 1, it tends to be determined by stochastic process ( 41 , 76 ). The parameter R 2 represented the overall fit to the neutral model.…”

Temporal variations in root-associated fungal communities of Potaninia mongolica, an endangered relict shrub species in the semi-arid desert of Northwest China

“…By contrast, stochastic processes emphasize the role of probabilistic dispersal and ecological drift ( Hubbell, 2001 ; Vellend et al., 2014 ). In recent decades, an increasing number of studies indicated that deterministic and stochastic processes simultaneously drive fungal community assembly, but the relative importance of these two processes is dependent on scales and habitats type ( Schröter et al., 2019 ; Hussain et al., 2021 ; Zhang et al., 2021 ; Zheng et al., 2021 ). For example, soil fungal communities in the island were mainly governed by deterministic processes regardless of island type ( Zheng et al., 2021 ).…”

Genomes of keystone Mortierella species lead to better in silico prediction of soil mycobiome functions from Taiwan’s offshore islands

“…Coral are highly porous; the low trace-nutrients and waterretention properties do not favour plant growth [73]. While plant being a significant determinant for fungal diversity [11], this translates to lowered soil fungal diversity as reported in other oceanic coral islands [74]. Microbiome study of Taiwan's offshore island have highlighted the difference and important in soil type and the distinct microbiome structure observed between the Matsu archipelagos, GI and OI [33].…”