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Abstract BackgroundMarine symbioses are predominantly established through horizontal acquisition of microbial symbionts from the environment. However, genetic and functional comparisons of free-living populations of symbionts to their host-associated counterparts are sparse. Here, we assembled the first genomes of the chemoautotrophic gammaproteobacterial symbionts affiliated with the deep-sea snailAlviniconcha hesslerifrom two separate hydrothermal vent fields of the Mariana Back-Arc Basin. We used phylogenomic and population genomic methods to assess sequence and gene content variation between free-living and host-associated symbionts. ResultsOur phylogenomic analyses show that the free-living and host-associated symbionts ofA. hesslerifrom both vent fields are populations of monophyletic strains from a single species. Furthermore, genetic structure and gene content analyses indicate that these symbiont populations are differentiated by vent field rather than by lifestyle. ConclusionTogether, this work suggests that, despite the potential influence of host-mediated acquisition and release processes on horizontally transmitted symbionts, geographic isolation and/or adaptation to local habitat conditions are important determinants of symbiont population structure and intra-host composition.
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Differential patterns of connectivity in Western Pacific hydrothermal vent metapopulations: A comparison of biophysical and genetic models
Abstract Hydrothermal ecosystems face threats from planned deep‐seabed mining activities, despite the fact that patterns of realized connectivity among vent‐associated populations and communities are still poorly understood. Since populations of vent endemic species depend on larval dispersal to maintain connectivity and resilience to habitat changes, effective conservation strategies for hydrothermal ecosystems should include assessments of metapopulation dynamics. In this study, we combined population genetic methods with biophysical models to assess strength and direction of gene flow within four species of the genusAlviniconcha(A. boucheti,A. kojimai,A. strummeriandA. hessleri) that are ecologically dominant taxa at Western Pacific hydrothermal vents. In contrast to predictions from dispersal models, among‐basin migration inA. bouchetioccurred predominantly in an eastward direction, while populations within the North Fiji Basin were clearly structured despite the absence of oceanographic barriers. Dispersal models and genetic data were largely in agreement for the otherAlviniconchaspecies, suggesting limited between‐basin migration forA. kojimai, lack of genetic structure inA. strummeriwithin the Lau Basin and restricted gene flow between northern and southernA. hessleripopulations in the Mariana back‐arc as a result of oceanic current conditions. Our findings show that gene flow patterns in ecologically similar congeneric species can be remarkably different and surprisingly limited depending on environmental and evolutionary contexts. These results are relevant to regional conservation planning and to considerations of similar integrated analyses for any vent metapopulations under threat from seabed mining.
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- PAR ID:
- 10391949
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Evolutionary Applications
- Volume:
- 16
- Issue:
- 1
- ISSN:
- 1752-4571
- Format(s):
- Medium: X Size: p. 22-35
- Size(s):
- p. 22-35
- Sponsoring Org:
- National Science Foundation
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