Seagrass‐associated fungal communities follow Wallace's line, but host genotype does not structure fungal community

Abstract

Aim To test whether or not fungal communities associated with the widespread seagrass, Syringodium isoetifolium can be differentiated on either side of Wallace's line, a boundary line separating Asian and Australasian fauna. Additionally, we examine whether host multilocus genotype predicts fungal community composition. Location A total of 77 samples were collected from 14 sampling sites spanning the Indonesian archipelago. Methods We sequenced the fungal ITS1 gene using Illumia MiSeq technology and used a clustering‐free Divisive Amplicon Denoising Algorithm to infer ribosomal sequence variants. Data were analysed via non‐metric multidimensional scaling, Mantel tests and permutational multivariate analysis of variance. Binary and quantitative null models were used to determine whether results significantly deviated from random. Host genotype was determined by genotyping at 18 microsatellite loci and standard genetic analysis was performed in the R package APE. Results Significant differences in fungal community composition were detected on either side of Wallace's line (p = <.001 R2 = .040). A significant distance decay of similarity pattern was observed between ribosomal sequence variants and geographical distance (p = .001 R2 = .227) and several fungal ribosomal sequence variants were significantly associated with sampling sites found either east or west of Wallace's line. Main conclusions Fungi are generally considered to have excellent dispersal potentials and marine fungi have the potential to disperse far and wide in an environment that has no obvious barriers to dispersal. Despite this assumed excellent dispersal potential, we show that fungal communities on either side of Wallace's line are significantly different from one another. We speculate that limited dispersal and differences in habitat type are responsible for the observed pattern. Work examining biogeographical patterns in marine fungi is still in its infancy and further research is required to fully understand marine fungal biogeography.

Population genetics of the collector urchin, Tripneustes gratilla, in the Indonesian archipelago

“…Similar patterns of genetic differentiation to what is reported here have been documented in numerous taxa in Indonesia (e.g., seagrasses, seagrass‐associated fungi, mangroves, and fish) (Dohna, Timm, Hamid, & Kochzius, ; Hernawan et al, ; Wainwright, Zahn, Arlyza, & Amend, ; Yahya et al, ).…”

Distinct fungal communities associated with different organs of the mangrove Sonneratia alba in the Malay Peninsula

“…We also show a significant pattern of positive distance decay, meaning that fungal communities from geographically closer sites are more similar to one another than those that are more distant. This is consistent with work on a variety of other assumed highly dispersive taxa, from mammals to microorganisms, showing community or genetic structuring in the marine environment which has no obvious barriers to dispersal (Hoffman et al 2012 ; Xu et al 2017 ; Wainwright et al 2018 , 2019a , 2020 ). This contrasts with the traditionally held view that marine environments are open with few, if any limitations imposed on dispersal.…”

“…Studies on marine fungi remain sparse despite the recent interest, particularly those examining biogeographic patterns (Amend et al 2012 , 2019 ; Wainwright et al 2017 , 2018 ; Ettinger and Eisen 2019 ), which is unfortunate as marine systems offer a potential treasure trove of undescribed marine fungal biodiversity. In 2011, only 537 obligate marine fungi had been identified (Jones 2011 ).…”

Seagrass‐associated fungal communities show distance decay of similarity that has implications for seagrass management and restoration

“…However, just as work on assumed highly dispersive marine macroorganisms has revealed biogeographic patterns contrary to the expectation of homogeneity (Rocha & Bowen, ), there is increasing evidence that this is also the case for microorganisms (Wainwright, Afiq‐Rosli, Zahn, & Huang, ; Wainwright, Bauman, Zahn, Todd, & Huang, ). For example, fungal communities associated with the widespread seagrass Syringodium isoetifolium from across the Indonesian archipelago are highly differentiated on either side of Wallace's line (Wainwright, Zahn, Arlyza, & Amend, ). Likewise, Vincenot et al () report strong geographic structuring in a basidiomycete that disperses via aerial spores.…”