| 1. |
- Nylund, Göran M., 1974, et al.
(författare)
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Increased resistance towards generalist herbivory in the new range of a habitat-forming seaweed
- 2012
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Ingår i: Ecosphere. - 2150-8925. ; 3:12, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Interactions between plants and their biotic environment can drastically change during range- expansion and result in rapid adaptive evolution of plant traits. According to the influential evolution of increased competitive ability (EICA) hypothesis escape from specialist natural enemies will lead to a reduction in defense levels, but the way in which generalist consumers in the new ranges affect the evolution of plant defenses remains poorly understood. We conducted a four month controlled environment experiment to examine if the high densities of the generalist herbivore Idotea baltica in the Baltic Sea have selected for increased grazer-resistance in Fucus vesiculosus, a North Atlantic seaweed that has expanded into large parts of the brackish Baltic Sea. Genetic analysis using microsatellites showed that the sampled populations are genetically distinct, which strongly suggests that traits under divergent selection may readily diverge and populations evolve local adaptations. Feeding trials and measurements of defense metabolites, i.e., phlorotannins, showed that F. vesiculosus from the Baltic Sea was least preferred and contained more than 50% higher constitutive levels of phlorotannins than conspecifics in the North Sea (Skagerrak), while algae from the Öresund, one of the sounds connecting the Baltic Sea to the Skagerrak, had intermediate resistance levels both in terms of grazer preference and phlorotannin levels. These results suggest that the higher grazing pressure on F. vesiculosus expanded into the Baltic Sea has resulted in the evolution of increased resistance towards generalist grazing.
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| 2. |
- Pereyra, Ricardo T., 1974, et al.
(författare)
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Isolation and characterization of nuclear microsatellite loci in the northern shrimp, Pandalus borealis
- 2012
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Ingår i: Conservation Genetics Resources. - : Springer Science and Business Media LLC. - 1877-7252 .- 1877-7260. ; 4:1, s. 109-112
-
Tidskriftsartikel (refereegranskat)abstract
- We developed and characterized 20 microsatellite primer loci for the northern shrimp Pandalus borealis. All 20 loci were polymorphic with number of alleles ranging from 3 to 36 and with observed heterozygosity between 0.04 and 0.93. In addition, we tested the utility of these markers in three related shrimp species, P. montagui, Atlantopandalus propinqvus and Dichelopandalus bonnieri. These new markers will prove useful in the identification of stock structure and hence, assessment of the commercially important species P. borealis.
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| 3. |
- Alfonso, B., et al.
(författare)
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Tracing genetic variation of Gelidium canariense (Rhodophyta) based on new and historical collections
- 2023
-
Ingår i: Phycologia. - 0031-8884. ; 62:4, s. 383-390
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Tidskriftsartikel (refereegranskat)abstract
- Genetic sequencing of herbarium specimens provides invaluable information on species genetic history. However, several factors hinder the extraction of high-quality DNA from long-term preserved specimens. Our goal was to study the genetic variability of the endemic and habitat-forming macroalga Gelidium canariense over the last 40 years using the mitochondrial intergenic marker cox2-3 spacer. We also studied the genetic diversity at the mesoscale (<100 km), i.e. between two localities on the north coast of Tenerife and at the macroscale (>100 km) using specimens collected on the island of La Palma. We found the presence of the same haplotype at the same location for the last 40 years. This haplotype also coincided within populations of Puerto de la Cruz and Garachico (Tenerife Island) and between populations of different islands (Tenerife and La Palma). This study provides a baseline (i.e. extraction method, PCR protocol for cox2-3 spacer molecular marker, level of DNA degradation of herbarium samples) of the genetic characterization of G. canariense that can be used in future molecular studies to better understand the distribution of genetic diversity in this vulnerable species.
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| 4. |
- Ardehed, Angelica, et al.
(författare)
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Complex spatial clonal structure in the macroalgae Fucus radicans with both sexual and asexual recruitment
- 2015
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 5:19, s. 4233-4245
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Tidskriftsartikel (refereegranskat)abstract
- In dioecious species with both sexual and asexual reproduction, the spatial distribution of individual clones affects the potential for sexual reproduction and local adaptation. The seaweed Fucus radicans, endemic to the Baltic Sea, has separate sexes, but new attached thalli may also form asexually. We mapped the spatial distribution of clones (multilocus genotypes, MLGs) over macrogeographic (>500km) and microgeographic (<100m) scales in the Baltic Sea to assess the relationship between clonal spatial structure, sexual recruitment, and the potential for natural selection. Sexual recruitment was predominant in some areas, while in others asexual recruitment dominated. Where clones of both sexes were locally intermingled, sexual recruitment was nevertheless low. In some highly clonal populations, the sex ratio was strongly skewed due to dominance of one or a few clones of the same sex. The two largest clones (one female and one male) were distributed over 100-550km of coast and accompanied by small and local MLGs formed by somatic mutations and differing by 1-2 mutations from the large clones. Rare sexual events, occasional long-distance migration, and somatic mutations contribute new genotypic variation potentially available to natural selection. However, dominance of a few very large (and presumably old) clones over extensive spatial and temporal scales suggested that either these have superior traits or natural selection has only been marginally involved in the structuring of genotypes.
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| 5. |
- Ardehed, Angelica, et al.
(författare)
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Divergence within and among Seaweed Siblings (Fucus vesiculosus and F. radicans) in the Baltic Sea
- 2016
-
Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Closely related taxa provide significant case studies for understanding evolution of new species but may simultaneously challenge species identification and definition. In the Baltic Sea, two dominant and perennial brown algae share a very recent ancestry. Fucus vesiculosus invaded this recently formed postglacial sea 8000 years ago and shortly thereafter Fucus radicans diverged from this lineage as an endemic species. In the Baltic Sea both species reproduce sexually but also recruit fully fertile new individuals by asexual fragmentation. Earlier studies have shown local differences in morphology and genetics between the two taxa in the northern and western Bothnian Sea, and around the island of Saaremaa in Estonia, but geographic patterns seemin conflict with a single origin of F. radicans. To investigate the relationship between northern and Estonian distributions, we analysed the genetic variation using 9 microsatellite loci in populations from eastern Bothnian Sea, Archipelago Sea and the Gulf of Finland. These populations are located in between earlier studied populations. However, instead of bridging the disparate genetic gap between N-W Bothnian Sea and Estonia, as expected from a simple isolation-by-distance model, the new populations substantially increased overall genetic diversity and showed to be strongly divergent from the two earlier analysed regions, showing signs of additional distinct populations. Contrasting earlier findings of increased asexual recruitment in low salinity in the Bothnian Sea, we found high levels of sexual reproduction in some of the Gulf of Finland populations that inhabit extremely low salinity. The new data generated in this study supports the earlier conclusion of two reproductively isolated but very closely related species. However, the new results also add considerable genetic and morphological complexity within species. This makes species separation at geographic scales more demanding and suggests a need for more comprehensive approaches to further disentangle the intriguing relationship and history of the Baltic Sea fucoids.
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| 6. |
- Berdan, Emma L, 1983, et al.
(författare)
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A metabarcoding analysis of the wrackbed microbiome indicates a phylogeographic break along the North Sea-Baltic Sea transition zone
- 2023
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Ingår i: Environmental Microbiology. - 1462-2912. ; 25:9, s. 1659-73
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Tidskriftsartikel (refereegranskat)abstract
- Sandy beaches are biogeochemical hotspots that bridge marine and terrestrial ecosystems via the transfer of organic matter, such as seaweed (termed wrack). A keystone of this unique ecosystem is the microbial community, which helps to degrade wrack and re-mineralize nutrients. However, little is known about this community. Here, we characterize the wrackbed microbiome as well as the microbiome of a primary consumer, the seaweed fly Coelopa frigida, and examine how they change along one of the most studied ecological gradients in the world, the transition from the marine North Sea to the brackish Baltic Sea. We found that polysaccharide degraders dominated both microbiomes, but there were still consistent differences between wrackbed and fly samples. Furthermore, we observed a shift in both microbial communities and functionality between the North and Baltic Sea driven by changes in the frequency of different groups of known polysaccharide degraders. We hypothesize that microbes were selected for their abilities to degrade different polysaccharides corresponding to a shift in polysaccharide content in the different seaweed communities. Our results reveal the complexities of both the wrackbed microbial community, with different groups specialized to different roles, and the cascading trophic consequences of shifts in the near shore algal community.
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| 7. |
- Dahl, Mikael, 1976, et al.
(författare)
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Fine-scale spatial genetic structure and clonal distribution of the cold-water coral Lophelia pertusa
- 2012
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Ingår i: Coral Reefs. - : Springer Science and Business Media LLC. - 0722-4028 .- 1432-0975. ; 31:4, s. 1135-1148
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Tidskriftsartikel (refereegranskat)abstract
- Determining the spatial genetic structure within and among cold-water coral populations is crucial to understanding population dynamics, assessing the resilience of cold-water coral communities and estimating genetic effects of habitat fragmentation for conservation. The spatial distribution of genetic diversity in natural populations depends on the species' mode of reproduction, and coral species often have a mixed strategy of sexual and asexual reproduction. We describe the clonal architecture of a cold-water coral reef and the fine-scale population genetic structure (< 35 km) of five reef localities in the NE Skagerrak. This study represents the first of this type of analysis from deep waters. We used thirteen microsatellite loci to estimate gene flow and genotypic diversity and to describe the fine-scale spatial distribution of clonal individuals of Lophelia pertusa. Within-population genetic diversity was high in four of the five reef localities. These four reefs constitute a genetic cluster with asymmetric gene flow that indicates metapopulation dynamics. One locality, the Sacken reef, was genetically isolated and depauperate. Asexual reproduction was found to be a highly important mode of reproduction for L. pertusa: 35 genetic individuals were found on the largest reef, with the largest clone covering an area of nearly 300 m(2).
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| 8. |
- De Wit, Pierre, 1978, et al.
(författare)
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A decade of progress in marine evolutionary biology
- 2022
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Ingår i: Evolutionary Applications. - : Wiley. - 1752-4571. ; 16:2, s. 193-201
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This article summarizes the Evolutionary Applications Special Issue, “A decade of progress in Marine Evolutionary Biology.” The globally connected ocean, from its pelagic depths to its highly varied coastlines, inspired Charles Darwin to develop the theory of evolution during the voyage of the Beagle. As technology has developed, there has been a dramatic increase in our knowledge about life on our blue planet. This Special Issue, composed of 19 original papers and seven reviews, represents a small contribution to the larger picture of recent research in evolutionary biology, and how such advancements come about through the connection of researchers, their fields, and their knowledge. The first European network for marine evolutionary biology, the Linnaeus Centre for Marine Evolutionary Biology (CeMEB), was developed to study evolutionary processes in the marine environment under global change. Though hosted by the University of Gothenburg in Sweden, the network quickly grew to encompass researchers throughout Europe and beyond. Today, more than a decade after its foundation, CeMEB's focus on the evolutionary consequences of global change is more relevant than ever, and knowledge gained from marine evolution research is urgently needed in management and conservation. This Special Issue, organized and developed through the CeMEB network, contains contributions from all over the world and provides a snapshot of the current state of the field, thus forming an important basis for future research directions.
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| 9. |
- De Wit, Pierre, 1978, et al.
(författare)
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Spatial genetic structure in a crustacean herbivore highlights the need for local considerations in Baltic Sea biodiversity management
- 2020
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Ingår i: Evolutionary Applications. - : Wiley. - 1752-4563 .- 1752-4571. ; 13:5, s. 974-990
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Tidskriftsartikel (refereegranskat)abstract
- Incorporating species' eco-evolutionary responses to human-caused disturbances remains a challenge in marine management efforts. A prerequisite is knowledge of geographic structure and scale of genetic diversity and connectivity—the so-called seascape genetic patterns. The Baltic Sea is an excellent model system for studies linking seascape genetics with effects of anthropogenic stress. However, seascape genetic patterns in this area are only described for a few species and are completely unknown for invertebrate herbivores, which constitute a critical part of the ecosystem. This information is crucial for sustainable management, particularly under future scenarios of rapid environmental change. Here, we investigate the population genetic structure among 31 locations throughout the Baltic Sea, of which 45% were located in marine protected areas, in one of the most important herbivores of this region, the isopod crustacean Idotea balthica, using an array of 33,774 genome-wide SNP markers derived from 2b-RAD sequencing. In addition, we generate a biophysical connectivity matrix for I. balthica from a combination of oceanographic current models and estimated life history traits. We find population structure on scales of hundreds of kilometers across the Baltic Sea, where genomic patterns in most cases closely match biophysical connectivity, indicating passive transport with oceanographic currents as an important mean of dispersal in this species. We also find a reduced genetic diversity in terms of heterozygosity along the main salinity gradient of the Baltic Sea, suggesting periods of low population size. Our results provide crucial information for the management of a key ecosystem species under expected changes in temperature and salinity following global climate change in a marine coastal area. © 2019 The Authors. Evolutionary Applications published by John Wiley & Sons Ltd.
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| 10. |
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| 11. |
- Gardeström, J., et al.
(författare)
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Characterization of six microsatellite loci in the Baltic blue mussel Mytilus trossulus and cross-species amplification in North Sea Mytilus edulis
- 2008
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Ingår i: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 9:4, s. 1003-1005
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Tidskriftsartikel (refereegranskat)abstract
- The blue mussel Mytilus trossulus occurs in the Pacific and in the North Atlantic. We developed and characterized six microsatellite loci for Baltic M. trossulus. Seventeen microsatellite loci were screened, of which six were polymorphic. The number of alleles among 50 individuals ranged from 3 to 13 and the observed and expected heterozygosity were 0.09-0.46 and 0.34-0.86, respectively. The loci were also tested for cross amplification in M. edulis, in which four of the six microsatellite loci were successfully amplified.
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| 12. |
- Henriksson, Simon, 1997, et al.
(författare)
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Mixed origin of juvenile Atlantic cod (Gadus morhua) along the Swedish west coast
- 2023
-
Ingår i: Ices Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 80:1, s. 145-157
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Tidskriftsartikel (refereegranskat)abstract
- Cryptic population structure in exploited fishes poses a major challenge for fisheries management. In Atlantic cod, sympatric ecotypes are well-known, for instance off the coast of northern Norway. Recently, two sympatric cod ecotypes have also been documented in the Skagerrak and Kattegat, where adult cod has declined dramatically. One ecotype has an apparent offshore origin and displays a more migratory lifestyle than the other, which is generally resident at the coast throughout its life. To investigate their relative abundances along the Swedish west coast, juvenile cod were collected at high spatial resolution along the coast and genetically assigned to ecotypes. The results reveal large proportions of the coastal ecotype in the southern Kattegat, oresund, and inshore Swedish Skagerrak, whereas the offshore ecotype dominates in offshore areas. A regression model comparison suggests that differences in bottom depth, rather than distance from the open sea, explain the heterogeneous spatial distribution of the two ecotypes. In addition, the two ecotypes display genetic differences suggesting adaptation to different environments. The results underline that successful fisheries management requires identification and consideration of locally adapted sympatric ecotypes.
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| 13. |
- Johannesson, Kerstin, 1955, et al.
(författare)
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FREQUENT CLONALITY IN FUCOIDS (FUCUS RADICANS AND FUCUS VESICULOSUS; FUCALES, PHAEOPHYCEAE) IN THE BALTIC SEA
- 2011
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Ingår i: Journal of Phycology. - : Wiley. - 0022-3646 .- 1529-8817. ; 47:5, s. 990-998
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Tidskriftsartikel (refereegranskat)abstract
- Asexual reproduction by cloning may affect the genetic structure of populations, their potential to evolve, and, among foundation species, contributions to ecosystem functions. Macroalgae of the genus Fucus are known to produce attached plants only by sexual recruitment. Recently, however, clones of attached plants recruited by asexual reproduction were observed in a few populations of Fucus radicans Bergstrom et L. Kautsky and F. vesiculosus L. inside the Baltic Sea. Herein we assess the distribution and prevalence of clonality in Baltic fucoids using nine polymorphic microsatellite loci and samples of F. radicans and F. vesiculosus from 13 Baltic sites. Clonality was more common in F. radicans than in F. vesiculosus, and in both species it tended to be most common in northern Baltic sites, although variation among close populations was sometimes extensive. Individual clonal lineages were mostly restricted to single or nearby locations, but one clonal lineage of F. radicans dominated five of 10 populations and was widely distributed over 550 x 100 km of coast. Populations dominated by a few clonal lineages were common in F. radicans, and these were less genetically variable than in other populations. As thalli recruited by cloning produced gametes, a possible explanation for this reduced genetic variation is that dominance of one or a few clonal lineages biases the gamete pool resulting in a decreased effective population size and thereby loss of genetic variation by genetic drift. Baltic fucoids are important habitat-forming species, and genetic structure and presence of clonality have implications for conservation strategies.
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| 14. |
- Johannesson, Kerstin, 1955, et al.
(författare)
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Phenotypic variation in sexually and asexually recruited individuals of the Baltic Sea endemic macroalga Fucus radicans : in the field and after growth in a common-garden
- 2012
-
Ingår i: BMC Ecology. - : Springer Science and Business Media LLC. - 1472-6785. ; 12, s. 2-
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Most species of brown macroalgae recruit exclusively sexually. However, Fucus radicans, a dominant species in the northern Baltic Sea, recruits new attached thalli both sexually and asexually. The level of asexual recruitment varies among populations from complete sexual recruitment to almost (> 90%) monoclonal populations. If phenotypic traits have substantial inherited variation, low levels of sexual activity will decrease population variation in these traits, which may affect function and resilience of the species. We assessed the level of inherited variation in nine phenotypic traits by comparing variation within and among three monoclonal groups and one group of unique multilocus genotypes (MLGs) sampled in the wild.RESULTS: Of the nine phenotypic traits, recovery after freezing, recovery after desiccation, and phlorotannin content showed substantial inherited variation, that is, phenotypic variation in these traits were to a large extend genetically determined. In contrast, variation in six other phenotypic traits (growth rate, palatability to isopod grazers, thallus width, distance between dichotomies, water content after desiccation and photochemical yield under ambient conditions) did not show significant signals of genetic variation at the power of analyses used in the study. Averaged over all nine traits, phenotypic variation within monoclonal groups was only 68% of the variation within the group of different MLGs showing that genotype diversity does affect the overall level of phenotypic variation in this species.CONCLUSIONS: Our result indicates that, in general, phenotypic diversity in populations of Fucus radicans increases with increased multilocus genotype (MLG) diversity, but effects are specific for individual traits. In the light of Fucus radicans being a foundation species of the northern Baltic Sea, we propose that increased MLG diversity (leading to increased trait variation) will promote ecosystem function and resilience in areas where F. radicans is common, but this suggestion needs experimental support.
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| 15. |
- Johansson, Daniel, et al.
(författare)
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Reciprocal transplants support a plasticity-first scenario during colonisation of a large hyposaline basin by a marine macro alga
- 2017
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Ingår i: BMC Ecology. - : Springer Science and Business Media LLC. - 1472-6785. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Author(s).Background: Establishing populations in ecologically marginal habitats may require substantial phenotypic changes that come about through phenotypic plasticity, local adaptation, or both. West-Eberhard's "plasticity-first" model suggests that plasticity allows for rapid colonisation of a new environment, followed by directional selection that develops local adaptation. Two predictions from this model are that (i) individuals of the original population have high enough plasticity to survive and reproduce in the marginal environment, and (ii) individuals of the marginal population show evidence of local adaptation. Individuals of the macroalga Fucus vesiculosus from the North Sea colonised the hyposaline (≥2-3%) Baltic Sea less than 8000 years ago. The colonisation involved a switch from fully sexual to facultative asexual recruitment with release of adventitious branches that grow rhizoids and attach to the substratum. To test the predictions from the plasticity-first model we reciprocally transplanted F. vesiculosus from the original population (ambient salinity 24%) and from the marginal population inside the Baltic Sea (ambient salinity 4%). We also transplanted individuals of the Baltic endemic sister species F. radicans from 4 to 24%. We assessed the degree of plasticity and local adaptation in growth and reproductive traits after 6 months by comparing the performance of individuals in 4 and 24%. Results: Branches of all individuals survived the 6 months period in both salinities, but grew better in their native salinity. Baltic Sea individuals more frequently developed asexual traits while North Sea individuals initiated formation of receptacles for sexual reproduction. Conclusions: Marine individuals of F. vesiculosus are highly plastic with respect to salinity and North Sea populations can survive the extreme hyposaline conditions of the Baltic Sea without selective mortality. Plasticity alone would thus allow for an initial establishment of this species inside the postglacial Baltic Sea at salinities where reproduction remains functional. Since establishment, the Baltic Sea populations have evolved adaptations to extreme hyposaline waters and have in addition evolved asexual recruitment that, however, tends to impede local adaptation. Overall, our results support the "plasticity-first" model for the initial colonisation of the Baltic Sea by Fucus vesiculosus.
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| 16. |
- Kautsky, Lena, et al.
(författare)
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Rapid speciation in a newly opened postglacial marine environment, the Baltic Sea
- 2009
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 9:70
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Tidskriftsartikel (refereegranskat)abstract
- Background: Theory predicts that speciation can be quite rapid. Previous examples comprise a wide range of organisms such as sockeye salmon, polyploid hybrid plants, fruit flies and cichlid fishes. However, few studies have shown natural examples of rapid evolution giving rise to new species in marine environments. Results: Using microsatellite markers, we show the evolution of a new species of brown macroalga (Fucus radicans) in the Baltic Sea in the last 400 years, well after the formation of this brackish water body ~8–10 thousand years ago. Sympatric individuals of F. radicans and F. vesiculosus (bladder wrack) show significant reproductive isolation. Fucus radicans, which is endemic to the Baltic, is most closely related to Baltic Sea F. vesiculosus among north Atlantic populations, supporting the hypothesis of a recent divergence. Fucus radicans exhibits considerable clonal reproduction, probably induced by the extreme conditions of the Baltic. This reproductive mode is likely to have facilitated the rapid foundation of the new taxon. Conclusion: This study represents an unparalleled example of rapid speciation in a species-poor open marine ecosystem and highlights the importance of increasing our understanding on the role of these habitats in species formation. This observation also challenges presumptions that rapid speciation takes place only in hybrid plants or in relatively confined geographical places such as postglacial or crater lakes, oceanic islands or rivers.
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| 17. |
- Kinnby, Alexandra, 1990, et al.
(författare)
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Combining an Ecological Experiment and a Genome Scan Show Idiosyncratic Responses to Salinity Stress in Local Populations of a Seaweed
- 2020
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- Climate change-related effects threaten species worldwide; within-species populations may react differently to climate-induced stress due to local adaptation and partial isolation, particularly in areas with steep environmental gradients. Populations of the marine foundation seaweed Fucus vesiculosus are established over a steep salinity gradient at the entrance of the brackish water in the Baltic Sea (NE Atlantic). First, we analyzed the genetic differentiation among populations using thousands of genetic markers. Second, we measured the physiological tolerance to reduced salinity, a predicted effect of climate change in the study area, by measuring growth, phlorotannin (defense compounds) content, and maximum photochemical yield in tissue of the same individuals exposed to both current and projected future salinities. Our results show that despite short geographic distances (max 100 km), most populations were genetically well separated. Furthermore, populations responded very differently to a salinity decrease of four practical salinity units (psu) corresponding to projected future salinity. At the high salinity end of the gradient, some populations maintained growth at the cost of reduced phlorotannin production. However, at the low salinity end, mortality increased and growth was strongly reduced in one population, while a second population from similar salinity instead maintained growth and phlorotannin production. Among genetic markers that appeared as outliers (showing more genetic differentiation than the majority of loci), we found that four were associated with genes that were potential candidates for being under selection. One of these, a calcium-binding protein gene, also showed a significant genotype-phenotype relationship in the population where this genetic marker was variable. We concluded that local selection pressure, genetic affinity, and possibly also population history could explain the very different responses to reduced salinity among these populations, despite being from the same geographic area. Our results highlight the importance of local perspective in the management of species.
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| 18. |
- Kinnby, Alexandra, 1990, et al.
(författare)
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Factors affecting formation of adventitious branches in the seaweeds Fucus vesiculosus and F. radicans
- 2019
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Ingår i: Bmc Ecology. - : Springer Science and Business Media LLC. - 1472-6785. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIn the brackish Baltic Sea, shedding of adventitious branches is central to asexual recruitment of new thalli in the brown algae Fucus vesiculosus and F. radicans. To test which factors influence the formation of adventitious branches in brackish and in more marine conditions, we sampled 29 Fucus sites in the Baltic Sea (salinity 3-11) and 18 sites from the Danish straits, Kattegat, Skagerrak, and the North Sea (salinity 15-35). Separately for each area, we used structural equation modelling to determine which of eight predictor factors (phosphate, nitrate, chlorophyll-a (as a proxy for turbidity), temperature, salinity, oxygen, grazing pressure, and thallus area) best explained observed numbers of adventitious branches.ResultsIn more marine waters, high yearly average values of phosphate, salinity and turbidity had positive effects on the formation of adventitious branches. In brackish-waters, however, high numbers of adventitious branches were found in areas with low yearly average values of temperature, salinity and oxygen. Grazing intensity had no significant effect in either of the two study areas, contrasting findings from studies in other areas. In areas with both sexually and asexually reproducing Fucus individuals, clones had on average more adventitious branches than unique genotypes, although there was strong variation among clonal lineages.ConclusionThis study is the first to investigate multiple potential drivers of formation of adventitious branches in natural populations of Fucus. Our results suggest that several different factors synergistically and antagonistically affect the growth of adventitious branches in a complex way, and that the same factor (salinity) can have opposing effects in different areas.
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| 19. |
- Knutsen, H., et al.
(författare)
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Does population genetic structure support present management regulations of the northern shrimp (Pandalus borealis) in Skagerrak and the North Sea?
- 2015
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Ingår i: Ices Journal of Marine Science. - : Oxford University Press (OUP). - 1054-3139 .- 1095-9289. ; 72:3, s. 863-871
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Tidskriftsartikel (refereegranskat)abstract
- Population structuring in the northern shrimp (Pandalus borealis) in the North Sea area (including Fladen and Skagerrak) was studied by microsatellite DNA analyses. Screening 20 sample locations in the open ocean and Skagerrak fjords for nine loci revealed low, but significant genetic heterogeneity. The spatial genetic structure among oceanic samples of Skagerrak and the eastern North Sea was weak and non-significant, consistent with the current management regime of one single stock. However, Skagerrak fjord samples generally displayed elevated levels of genetic differentiation, and significantly so in several pairwise comparisons with other fjords and oceanic samples. Although the Skagerrak fjord populations are of less economic value, some of them are regulated separately (e.g. the Gullmarsfjord) and local stocks may prove important to uphold genetic variability and biocomplexity in a changing environment.
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| 20. |
- Milec, Leona, et al.
(författare)
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Double-edged sword of desalination: Decreased growth and increased grazing endanger range-margin Fucus populations
- 2022
-
Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981. ; 547
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Tidskriftsartikel (refereegranskat)abstract
- Coastal ecosystems worldwide are facing intense and diverse pressures caused by anthropogenic climate change, which compromises physiological tolerance of organisms, as well as causes shifts in their biotic interactions. Within-species genetic variation plays an important role in persistence of populations under such changes by providing building blocks for adaptation. The brackish-water Baltic Sea is predicted to experience a significant desalination by the end of this century. The Baltic Sea is dominated, in terms of biomass, by a few species with locally adapted populations, making it a suitable model for studying shifting biotic interactions under changing abiotic conditions. We exposed two foundation species of brown algae, Fucus vesiculosus and Fucus radicans, to end-of-the-century projected salinity together with grazing pressure in experimental tanks. We measured growth, grazing and phlorotannin content and compared these traits between the current and projected future salinity conditions, between Fucus species, and between high and low genotypic diversity groups. Grazing, phlorotannin content and growth of both F. radicans and F. vesiculosus all showed genotypic variation. Future decreased salinity hampered growth of F. vesiculosus irrespective of genotypic diversity of the experimental population. Furthermore, the growth response to desalination showed variation among genotypes. F. radicans was more susceptible to grazing than F. vesiculosus, and, in the high genetic diversity group of the latter, grazing was higher in the future than in current salinity. Climate change induced hyposalinity will thus challenge Fucus populations at their range margins in the Baltic Sea both because of the growth deterioration and changes in grazing. Differences between the species in these responses indicate a better ability of F. radicans to cope with the changing environment. Our results emphasize the complexity of biotic interactions in mediating the climate change influences as well as the importance of genetic diversity in coping with climate change.
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| 21. |
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| 22. |
- Pereyra, Ricardo T., 1974, et al.
(författare)
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Clones on the run: The genomics of a recently expanded partially clonal species
- 2023
-
Ingår i: Molecular Ecology. - 0962-1083. ; 32:15, s. 4209-23
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Tidskriftsartikel (refereegranskat)abstract
- Why species that in their core areas mainly reproduce sexually become enriched with clones in marginal populations ("geographic parthenogenesis") remains unclear. Earlier hypotheses have emphasized that selection might promote clonality because it protects locally adapted genotypes. On the other hand, it also hampers recombination and adaptation to changing conditions. The aim of the present study was to investigate the early stages of range expansion in a partially clonal species and what drives an increase in cloning during such expansion. We used genome-wide sequencing to investigate the origin and evolution of large clones formed in a macroalgal species (Fucus vesiculosus) during a recent expansion into the postglacial Baltic Sea. We found low but persistent clonality in core populations, while at range margins, large dominant clonal lineages had evolved repeatedly from different sexual populations. A range expansion model showed that even when asexual recruitment is less favourable than sexual recruitment in core populations, repeated bottlenecks at the expansion front can establish a genetically eroded clonal wave that spreads ahead of a sexual wave into the new area. Genetic variation decreases by drift following repeated bottlenecks at the expansion front. This results in the emerging clones having low expected heterozygosity, which corroborated our empirical observations. We conclude that Baker's Law (clones being favoured by uniparental reproductive assurance in new areas) can play an important role during range expansion in partially clonal species, resulting in a complex spatiotemporal mosaic of clonal and sexual lineages that might persist during thousands of generations.
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| 23. |
- Pereyra, Ricardo T., 1974, et al.
(författare)
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Parallel speciation or long-distance dispersal? : Lessons from seaweeds (Fucus) in the Baltic Sea
- 2013
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26:8, s. 1727-1737
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Tidskriftsartikel (refereegranskat)abstract
- Parallel evolution has been invoked as a forceful mechanism of ecotype and species formation in many animal taxa. However, parallelism may be difficult to separate from recently monophyletically diverged species that are likely to show complex genetic relationships as a result of considerable shared ancestral variation and secondary hybridization in local areas. Thus, species' degrees of reproductive isolation, barriers to dispersal and, in particular, limited capacities for long-distance dispersal will affect demographical structures underlying mechanisms of divergent evolution. Here, we used nine microsatellite DNA markers to study intra- and interspecific genetic diversity of two recently diverged species of brown macroalgae, Fucus radicans (L. Bergstrom & L. Kautsky) and F.vesiculosus (Linnaeus), in the Baltic Sea. We further performed biophysical modelling to identify likely connectivity patterns influencing the species' genetic structures. For each species, we found intraspecific contrasting patterns of clonality incidence and population structure. In addition, strong genetic differentiation between the two species within each locality supported the existence of two distinct evolutionary lineages (F-ST=0.15-0.41). However, overall genetic clustering analyses across both species' populations revealed that all populations from one region (Estonia) were more genetically similar to each other than to their own taxon from the other two regions (Sweden and Finland). Our data support a hypothesis of parallel speciation. Alternatively, Estonia may be the ancestral source of both species, but is presently isolated by oceanographic barriers to dispersal. Thus, a limited gene flow in combination with genetic drift could have shaped the seemingly parallel structure.
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| 25. |
- Rafajlović, Marina, 1983, et al.
(författare)
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Neutral processes forming large clones during colonization of new areas
- 2017
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 30:8, s. 1544-1560
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Authors. Journal of Evolutionary Biology Published by John Wiley & Sons ltd on Behalf of European Society for Evolutionary Biology. In species reproducing both sexually and asexually clones are often more common in recently established populations. Earlier studies have suggested that this pattern arises due to natural selection favouring generally or locally successful genotypes in new environments. Alternatively, as we show here, this pattern may result from neutral processes during species’ range expansions. We model a dioecious species expanding into a new area in which all individuals are capable of both sexual and asexual reproduction, and all individuals have equal survival rates and dispersal distances. Even under conditions that favour sexual recruitment in the long run, colonization starts with an asexual wave. After colonization is completed, a sexual wave erodes clonal dominance. If individuals reproduce more than one season, and with only local dispersal, a few large clones typically dominate for thousands of reproductive seasons. Adding occasional long-distance dispersal, more dominant clones emerge, but they persist for a shorter period of time. The general mechanism involved is simple: edge effects at the expansion front favour asexual (uniparental) recruitment where potential mates are rare. Specifically, our model shows that neutral processes (with respect to genotype fitness) during the population expansion, such as random dispersal and demographic stochasticity, produce genotype patterns that differ from the patterns arising in a selection model. The comparison with empirical data from a post-glacially established seaweed species (Fucus radicans) shows that in this case, a neutral mechanism is strongly supported.
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| 26. |
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| 27. |
- Rugiu, Luca, et al.
(författare)
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Gene regulatory response to hyposalinity in the brown seaweed Fucus vesiculosus
- 2020
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Rockweeds are among the most important foundation species of temperate rocky littoral shores. In the Baltic Sea, the rockweed Fucus vesiculosus is distributed along a decreasing salinity gradient from the North Atlantic entrance to the low-salinity regions in the north-eastern margins, thus, demonstrating a remarkable tolerance to hyposalinity. The underlying mechanisms for this tolerance are still poorly understood. Here, we exposed F. vesiculosus from two range-margin populations to the hyposaline (2.5 PSU - practical salinity unit) conditions that are projected to occur in the region by the end of this century as a result of climate change. We used transcriptome analysis (RNA-seq) to determine the gene expression patterns associated with hyposalinity acclimation, and examined the variation in these patterns between the sampled populations. Results Hyposalinity induced different responses in the two populations: in one, only 26 genes were differentially expressed between salinity treatments, while the other population demonstrated up- or downregulation in 3072 genes. In the latter population, the projected future hyposalinity induced an acute response in terms of antioxidant production. Genes associated with membrane composition and structure were also heavily involved, with the upregulation of fatty acid and actin production, and the downregulation of ion channels and alginate pathways. Changes in gene expression patterns clearly indicated an inhibition of the photosynthetic machinery, with a consequent downregulation of carbohydrate production. Simultaneously, energy consumption increased, as revealed by the upregulation of genes associated with respiration and ATP synthesis. Overall, the genes that demonstrated the largest increase in expression were ribosomal proteins involved in translation pathways. The fixation rate of SNP:s was higher within genes responding to hyposalinity than elsewhere in the transcriptome. Conclusions The high fixation rate in the genes coding for salinity acclimation mechanisms implies strong selection for them. The among-population differentiation that we observed in the transcriptomic response to hyposalinity stress suggests that populations of F. vesiculosus may differ in their tolerance to future desalination, possibly as a result of local adaptation to salinity conditions within the Baltic Sea. These results emphasise the importance of considering interspecific genetic variation when evaluating the consequences of environmental change.
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| 28. |
- Wennerström, Lovisa, et al.
(författare)
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Genetic biodiversity in the Baltic Sea: Species-specific patterns challenge management
- 2013
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Ingår i: Biodiversity and Conservation. - : Springer Science and Business Media LLC. - 0960-3115 .- 1572-9710. ; 22:13-14, s. 3045-3065
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Tidskriftsartikel (refereegranskat)abstract
- Information on spatial and temporal patterns of genetic diversity is a prerequisite to understanding the demography of populations, and is fundamental to successful management and conservation of species. In the sea, it has been observed that oceanographic and other physical forces can constitute barriers to gene flow that may result in similar population genetic structures in different species. Such similarities among species would greatly simplify management of genetic biodiversity. Here, we tested for shared genetic patterns in a complex marine area, the Baltic Sea. We assessed spatial patterns of intraspecific genetic diversity and differentiation in seven ecologically important species of the Baltic ecosystem-Atlantic herring (Clupea harengus), northern pike (Esox lucius), European whitefish (Coregonus lavaretus), three-spined stickleback (Gasterosteus aculeatus), nine-spined stickleback (Pungitius pungitius), blue mussel (Mytilus spp.), and bladderwrack (Fucus vesiculosus). We used nuclear genetic data of putatively neutral microsatellite and SNP loci from samples collected from seven regions throughout the Baltic Sea, and reference samples from North Atlantic areas. Overall, patterns of genetic diversity and differentiation among sampling regions were unique for each species, although all six species with Atlantic samples indicated strong resistence to Atlantic-Baltic gene-flow. Major genetic barriers were not shared among species within the Baltic Sea; most species show genetic heterogeneity, but significant isolation by distance was only detected in pike and whitefish. These species-specific patterns of genetic structure preclude generalizations and emphasize the need to undertake genetic surveys for species separately, and to design management plans taking into consideration the specific structures of each species. © 2013 The Author(s).
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