Research Progress in Area 3 方向 ( 三 ) 課題進展 161 Abstract Decapod crustaceans are well-represented in various bathymetric ecosystems, but how they adapt to such extreme environments has remained poorly understood. To comprehensively elucidate how decapods and their symbiotic microbes evolve to thrive in this hostile habitat, the proposed study will extensively catalogue gut microbiome diversity of decapods in different bathymetric ecosystems, assiduously analyze the metagenomes of the symbiotic microbes and the genomes of decapod hosts, and construct the evolutionary history of key endosymbiotic microbe taxa and their hosts. Based on these analyses, we will be able to identify the core microbe communities and their functional diversity associated with disparate habitats, and explore how the decapod-microbes symbiotic relationships evolved by testing if they coevolve in diverse deep sea environments. Research Activities and Progress • Gut microbial communities in >250 individual from 80+ decapod species inhabiting distinct environments and exhibit different phylogenetic history were examined using metabarcoding analyses of the 16S rRNA gene; • Metagenomic sequencing was conducted on ~15 decapod species of species; • Molecularphylogenyof thedecapodhost species was reconstructed using transcriptomic and sanger sequencing data as a backbone tree; • Samples for deepsea decapod species were collected for metagenomic and genome sequencing. Key Findings • Phylogenetic studies suggest multiple colonizations into deepsea and hydrothermal vent habitat in major decapod groups (e.g. crabs, shrimp and squat lobster); • Comparison of host phylogeny and microbial composition revealed variable level of phylosymbiosis in across different decapod groups. Relationships were strongest amongst closely related species while the signal become weak at intergeneric level, suggesting the evolutionary constraint in microbial composition. Bacterial functional grouping is more conserved than taxonomy in the evolution of decapods. Research Output Publication 1 Trained personnel 2 Evolution of Decapod-microbe Symbiosis in the Deep-sea Biomes Prof Ling Ming Tsang The Chinese University of Hong Kong
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