Diversity, Dynamics and Function of Host-Associated Microbiomes in Marine Organisms

Marine organisms provide special microhabitats harboring highly diverse microbes such as bacteria, archaea, fungi, algae, and protozoans. Recently, the remarkable hidden genetic diversity of marine symbiotic microbes has been revealed with molecular approaches. Host-symbiont relationships have been widely observed in the ocean from the deep-ocean environment to coral reef ecosystems, and falls into three categories: commensalism, parasitism, and mutualism. This relationship is a dynamic that could be transient or persistent and shaped by both microhabitats within the host organism and the physiochemical environment. The consortia of host-associated microbiomes, rather than individual symbionts independently, play vital roles in the fitness, adaptation, and evolution of host organisms. Such effects also extend to community and ecosystem levels in terms of biodiversity, food web structure, and biogeochemical cycling that underpin the health of marine ecosystems. Thus, elucidating the diversity, dynamics, and function of the host-associated microbiome can provide insights into the drivers of biodiversity, the drivers of structure and function in marine ecosystems, and have important implications for conservation strategies.

Despite an increasing research interest in host-associated microbes, most of the studies have focused on certain groups such as pathogens, epibionts, or gut microbes. Little is known about the succession of complex multi-assemblage microbiomes associated with hosts, and how the microhabitats within a host and physiochemical environment jointly shape the symbiotic community remains elusive. Such a situation calls for uniting ecological and molecular approaches to characterize the diversity and function of host-associated microbiomes with different forms of symbiosis, particularly over a variety of temporal and spatial scales from an eco-evolutionary perspective.

This Research Topic will provide a venue for exchanging ideas and findings on microbiomes associated with diverse marine taxonomic groups from protists, seaweed, invertebrate, fish, and mammals. We welcome Original Research Articles, Reviews, Methods, Data Reports, and Perspectives that explore the following themes or other closely related topics :

• Diversity and assembly mechanism of marine host-associated microbiome

• Spatial and temporal distribution pattern of the host-associated microbiome and its regulating factors.

• Ecological functions of marine host-associated microbiomes with respect to host (fitness, adaptation, and evolution), community, and ecosystem (biodiversity, elementary cycling)

• Omics and bioinformatics methods tackling challenges in sequencing, assembly, and annotation of metagenomes of host-associated microbiome.