Comparative population genomics of Pacific deep-sea tubeworms and their bacterial endosymbionts: cryptic diversity and host-symbiont specificity
Final Report Abstract
In the deep sea, intriguing mutualistic symbioses exist between invertebrate animals and chemosynthetic bacteria that form the basis of many vent and seep ecosystems worldwide. The project intended to apply next-generation sequencing methods to investigate these associations in Pacific cold-seep tubeworms (Lamellibrachia barhami, Escarpia spicata), with particular focus on symbiont diversity and host-symbiont specificity. While the sub-projects on 16S amplicon sequencing and symbiont genome assembly could be carried out successfully, the study parts on host and symbiont population genomics could not be completed due to a combination of financial and technical problems. As I was not able to carry out these proposal parts as planned, I took on another project on symbiont transmission in deep-sea vesicomyid clams. The main results from the DFG-funded project are: 1) an unexpectedly low sequence variability in the 16S-V4 region of the tubeworm symbionts. The low polymorphism in this fragment made it difficult to distinguish mutations from sequencing errors, a problem that cannot be resolved by current OTU clustering pipelines. As far as I know this is the first study applying 16S amplicon sequencing in tubeworm symbionts, so that the insights from this work will be useful for other researchers trying to conduct similar analyses; 2) a nearly closed tubeworm symbiont genome, which was assembled using Illumina shotgun and Nanopore long-read sequencing in combination with Dovetail Hi-C and Chicago proximity ligation. This work will not only provide a valuable genomic resource that will help to address a variety of research questions, but also advance assembly pipelines for metagenomic data; 3) evidence that the maternally inherited symbionts of vesicomyid clams can be exchanged between host species through hybridization. These findings shed new light onto the (co-)evolution of animal hosts and symbionts in deep sea chemosynthetic ecosystems. As a result of this work I was offered a new postdoc position at the University of Rhode Island where I will investigate the comparative host-symbiont population genomics and physiology in vent snails of the genera Alviniconcha and Ifremeria.
Publications
- (2020): Intra-host symbiont diversity in eastern Pacific cold seep tubeworms identified by the 16S-V6 region, but undetected by the 16S-V4 region. In: PloS one 15 (1), e0227053
Breusing, Corinna; Franke, Maximilian; Young, Curtis Robert
(See online at https://doi.org/10.1371/journal.pone.0227053)
