Dispersal Limitation Expands the Diversity of Coral Microbiome Metacommunity in the South China Sea

Jiandong Zhang,Lijuan Long,Sijun Huang,Qingsong Yang,Yingting Sun,Anyi Hu,Junde Dong

doi:10.3389/fmars.2021.658708

Abstract

The coral microbiome is one of the most complex microbial biospheres. However, the ecological processes shaping coral microbiome community assembly are not well understood. Here, we investigated the abundance, diversity, and community assembly mechanisms of coral-associated microbes from a highly diverse coral metacommunity in the South China Sea. Compared to seawater, the coral microbial metacommunity were defined by highly variable bacterial abundances among individual coral samples, high species evenness but not high species richness, high β-diversity, and a small core microbiome. We used variation partitioning analysis, neutral community model, and null model to disentangle the influences of different ecological processes in coral microbiome assembly. Measured physico-chemical parameters of the surrounding seawater and the spatial factor together explained very little of the variation in coral microbiome composition. Neutral processes only explained a minor component of the variation of coral microbial communities, suggesting a non-stochastic community assembly. Homogeneous and heterogeneous selection, but not dispersal, contributed greatly to the assembly of the coral microbiome. Such selection could be attributed to the within-host environments rather than the local environments. Our results demonstrated that dispersal limitation and host filtering contribute significantly to the assembly of discrete coral microbial regimes and expand the metacommunity diversity.

Highlights

Coral reefs have some of the highest biodiversity and productivity among marine ecosystems, and offer valuable ecosystem services to other organisms, as well as to the human society (Knowlton, 2001; Costanza et al, 2014)
We respectively identified the core Operational Taxonomic Units (OTUs) in seawater and coral samples according to the criteria that only OTUs present in more than 80% of samples were considered as core OTUs (HernandezAgreda et al, 2016)
The water environment conditions likely did not correlate with the diversity level of the coral microbiome, neither the bacterial abundance of coral colony, the bacterial abundance appeared to correlate with the coral family

Summary

Introduction

Coral reefs have some of the highest biodiversity and productivity among marine ecosystems, and offer valuable ecosystem services to other organisms, as well as to the human society (Knowlton, 2001; Costanza et al, 2014). The variation across individual corals can be high, similar to the gut microbiomes of humans (Turnbaugh and Gordon, 2009). Hosts and their microbiomes are ecological systems and the multispecies assemblages are structured by multiple ecological processes such as ecological drift, dispersal, and the interaction among microbial members and between the microbes and their hosts (Miller et al, 2018). The mechanisms of community assembly governing the structure of coral microbiomes remain unclear, especially for the relative contributions of deterministic and stochastic processes such as dispersal, selection, and ecological drift

Methods

Discussion

Conclusion