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- Berggren, Hanna
(författare)
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Consequences of Environmental Variation for Fish and Their Skin Associated Microbial Communities
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Environmental conditions that vary in space and time influence the distribution, abundance, diversity and evolution of individuals, populations, species and communities. This thesis explores how environmental variation affects diversity at different levels of biological organization, and across a wide range of spatiotemporal scales, by studying fish and their associated microbiomes. The specific aims were to investigate i) effects of coarse- and fine-scale environmental variation for the performance of fish populations and individuals, and ii) ecological drivers impacting the structure and dynamics of microbial communities associated with fish hosts.For the first aim, I studied effects of environmental variation both within and between local habitats, by comparing populations of spawning migrating pike and monitor sun-basking behaviour of carp individuals. Results revealed that natal spawning site fidelity can promote evolution of local adaptations and population differentiation on relatively fine spatial scales in relation to the species dispersal capacity. I also demonstrated that fish can actively thermo-regulate and attain body temperatures in excess of the surrounding water by sun-basking, and that this translates into faster growth. Homing and sun-basking behaviour thus are important drivers of phenotypic diversity among and within populations and can also - as it turned out - influence the microbial communities associated with fish skin.For the second aim, I used a mixture of observational and experimental approaches to characterize and identify sources of variation in microbial communities associated with fish skin of perch, roach and carp. An important finding was that fish skin microbiomes are highly dynamic biodiversity hotspots. Results further suggested that variation in the assembly, composition, spatial structure, and temporal shifts of these microbiomes are influenced by stochastic events in combination with ecological filtering imposed by environment and host phenotype, most notably behaviour. A key conclusion that emerges from this thesis is that diversity at one level of biological organisation seems to support and increase diversity at a higher hierarchical level of organisation. My thesis thus adds to the knowledge, and contribute new understanding and insight into, how environmental heterogeneity and the complex interplay between different species and hierarchical levels generate and maintain biodiversity.
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- Berggren, Hanna, et al.
(författare)
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Ecological filtering drives rapid spatiotemporal dynamics in fish skin microbiomes
- 2024
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Ingår i: Molecular Ecology. - : John Wiley & Sons. - 0962-1083 .- 1365-294X. ; 33:18
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Tidskriftsartikel (refereegranskat)abstract
- Skin microbiomes provide vital functions, yet knowledge about the drivers and processes structuring their species assemblages is limited-especially for non-model organisms. In this study, fish skin microbiome was assessed by high throughput sequencing of amplicon sequence variants from metabarcoding of V3-V4 regions in the 16S rRNA gene on fish hosts subjected to the following experimental manipulations: (i) translocation between fresh and brackish water habitats to investigate the role of environment; (ii) treatment with an antibacterial disinfectant to reboot the microbiome and investigate community assembly and priority effects; and (iii) maintained alone or in pairs to study the role of social environment and inter-host dispersal of microbes. The results revealed that fish skin microbiomes harbour a highly dynamic microbial composition that was distinct from bacterioplankton communities in the ambient water. Microbiome composition first diverged as an effect of translocation to either the brackish or freshwater habitat. When the freshwater individuals were translocated back to brackish water, their microbiome composition converged towards the fish microbiomes in the brackish habitat. In summary, external environmental conditions and individual-specific factors jointly determined the community composition dynamics, whereas inter-host dispersal had negligible effects. The dynamics of the microbiome composition was seemingly non-affected by reboot treatment, pointing towards high resilience to disturbance. The results emphasised the role of inter-individual variability for the unexplained variation found in many host-microbiome systems, although the mechanistic underpinnings remain to be identified.
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- Berggren, Hanna, et al.
(författare)
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Effects of environmental translocation and host characteristics on skin microbiomes of sun-basking fish
- 2023
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : Royal Society. - 0962-8452 .- 1471-2954. ; 290:2013
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Tidskriftsartikel (refereegranskat)abstract
- Variation in the composition of skin-associated microbiomes has been attributed to host species, geographical location and habitat, but the role of intraspecific phenotypic variation among host individuals remains elusive. We explored if and how host environment and different phenotypic traits were associated with microbiome composition. We conducted repeated sampling of dorsal and ventral skin microbiomes of carp individuals (Cyprinus carpio) before and after translocation from laboratory conditions to a semi-natural environment. Both alpha and beta diversity of skin-associated microbiomes increased substantially within and among individuals following translocation, particularly on dorsal body sites. The variation in microbiome composition among hosts was significantly associated with body site, sun-basking, habitat switch and growth, but not temperature gain while basking, sex, personality nor colour morph. We suggest that the overall increase in the alpha and beta diversity estimates among hosts were induced by individuals expressing greater variation in behaviours and thus exposure to potential colonizers in the pond environment compared with the laboratory. Our results exemplify how biological diversity at one level of organization (phenotypic variation among and within fish host individuals) together with the external environment impacts biological diversity at a higher hierarchical level of organization (richness and composition of fish-associated microbial communities).
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- Berggren, Hanna, et al.
(författare)
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Fish skin microbiomes are highly variable among individuals and populations but not within individuals
- 2022
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Ingår i: Frontiers in Microbiology. - : Frontiers Media S.A.. - 1664-302X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Fish skin-associated microbial communities are highly variable among populations and species and can impact host fitness. Still, the sources of variation in microbiome composition, and particularly how they vary among and within host individuals, have rarely been investigated. To tackle this issue, we explored patterns of variation in fish skin microbiomes across different spatial scales. We conducted replicate sampling of dorsal and ventral body sites of perch (Perca fluviatilis) from two populations and characterized the variation of fish skin-associated microbial communities with 16S rRNA gene metabarcoding. Results showed a high similarity of microbiome samples taken from the left and right side of the same fish individuals, suggesting that fish skin microbiomes can be reliably assessed and characterized even using a single sample from a specific body site. The microbiome composition of fish skin differed markedly from the bacterioplankton communities in the surrounding water and was highly variable among individuals. No ASV was present in all samples, and the most prevalent phyla, Actinobacteria, Bacteroidetes, and Proteobacteria, varied in relative abundance among fish hosts. Microbiome composition was both individual- and population specific, with most of the variation explained by individual host. At the individual level, we found no diversification in microbiome composition between dorsal and ventral body sites, but the degree of intra-individual heterogeneity varied among individuals. To identify how genetic and phenotypic characteristics of fish hosts impact the rate and nature of intra-individual temporal dynamics of the skin microbiome, and thereby contribute to the host-specific patterns documented here, remains an important task for future research.
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