| 1. |
- Caesar, Sofia, et al.
(författare)
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Diversity and relatedness enhance survival in colour polymorphic grasshoppers
- 2010
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:5
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Tidskriftsartikel (refereegranskat)abstract
- Evolutionary theory predicts that different resource utilization and behaviour by alternative phenotypes may reduce competition and enhance productivity and individual performance in polymorphic, as compared with monomorphic, groups of individuals. However, firm evidence that members of more heterogeneous groups benefit from enhanced survival has been scarce or lacking. Furthermore, benefits associated with phenotypic diversity may be counterbalanced by costs mediated by reduced relatedness, since closely related individuals typically are more similar. Pygmy grasshoppers (Tetrix subulata) are characterized by extensive polymorphism in colour pattern, morphology, behaviour and physiology. We studied experimental groups founded by different numbers of mothers and found that survival was higher in low than in high density, that survival peaked at intermediate colour morph diversity in high density, and that survival was independent of diversity in low density where competition was less intense. We further demonstrate that survival was enhanced by relatedness, as expected if antagonistic and competitive interactions are discriminately directed towards non-siblings. We therefore also performed behavioural observations and staged encounters which confirmed that individuals recognized and responded differently to siblings than to non-siblings. We conclude that negative effects associated with competition are less manifest in diverse groups, that there is conflicting selection for and against genetic diversity occurring simultaneously, and that diversity and relatedness may facilitate the productivity and ecological success of groups of interacting individuals.
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| 2. |
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| 3. |
- Drake, Henrik, Docent, 1979-, et al.
(författare)
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Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield
- 2021
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Ingår i: Communications Earth & Environment. - : Springer Nature. - 2662-4435. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- Earth’s crust contains a substantial proportion of global biomass, hosting microbial life up to several kilometers depth. Yet, knowledge of the evolution and extent of life in this environment remains elusive and patchy. Here we present isotopic, molecular and morphological signatures for deep ancient life in vein mineral specimens from mines distributed across the Precambrian Fennoscandian shield. Stable carbon isotopic signatures of calcite indicate microbial methanogenesis. In addition, sulfur isotope variability in pyrite, supported by stable carbon isotopic signatures of methyl-branched fatty acids, suggest subsequent bacterial sulfate reduction. Carbonate geochronology constrains the timing of these processes to the Cenozoic. We suggest that signatures of an ancient deep biosphere and long-term microbial activity are present throughout this shield. We suggest that microbes may have been active in the continental igneous crust over geological timescales, and that subsurface investigations may be valuable in the search for extra-terrestrial life.
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| 5. |
- Forsman, Anders, 1962-, et al.
(författare)
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Rapid evolution of fire melanism in replicated populations of pygmy grasshoppers
- 2011
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 65:9, s. 2530-2540
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Tidskriftsartikel (refereegranskat)abstract
- Evolutionary theory predicts an interactive process whereby spatiotemporal environmental heterogeneity will maintain genetic variation, while genetic and phenotypic diversity will buffer populations against stress and allow for fast adaptive evolution in rapidly changing environments. Here, we study color polymorphism patterns in pygmy grasshoppers (Tetrix subulata) and show that the frequency of the melanistic (black) color variant was higher in areas that had been ravaged by fires the previous year than in nonburned habitats, that, in burned areas, the frequency of melanistic grasshoppers dropped from ca. 50% one year after a fire to 30% after four years, and that the variation in frequencies of melanistic individuals among and within populations was genetically based on and represented evolutionary modifications. Dark coloration may confer a selective benefit mediated by enhanced camouflage in recently fire-ravaged areas characterized by blackened visual backgrounds before vegetation has recovered. These findings provide rare evidence for unusually large, extremely rapid adaptive contemporary evolution in replicated natural populations in response to divergent and fluctuating selection associated with spatiotemporal environmental changes.
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| 6. |
- Forsman, Anders, et al.
(författare)
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Variation in founder groups promotes establishment success in the wild
- 2012
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 279:1739, s. 2800-2806
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Tidskriftsartikel (refereegranskat)abstract
- Environmental changes currently pose severe threats to biodiversity, and reintroductions and translocations are increasingly used to protect declining populations and species from extinction. Theory predicts that establishment success should be higher for more variable groups of dissimilar individuals. To test this ‘diversity promotes establishment’ hypothesis, we introduced colour polymorphic pygmy grasshoppers (Tetrix subulata) to different sites in the wild. The number of descendants found at the release sites the subsequent year increased with increasing number of colour morphs in the founder group, and variation in founder groups also positively affected colour morph diversity in the established populations. Since colour morphs differ in morphology, physiology, behaviour, reproductive life history and types of niche used, these findings demonstrate that variation among individuals in functionally important traits promotes establishment success under natural conditions, and further indicate that founder diversity may contribute to evolutionary rescue and increased population persistence.
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| 7. |
- Karlsson Good, Magnus, 1988-, et al.
(författare)
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Increasing the accessibility to internet-based cognitive behavioural therapy for depression : A single-blind randomized controlled trial of condensed versus full-text versions
- 2023
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Ingår i: Internet Interventions. - : Elsevier. - 2214-7829. ; 34
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Tidskriftsartikel (refereegranskat)abstract
- Background: Research shows that internet-based cognitive behavioural therapy (iCBT) is an effective treatment for depression. However, little is known about how the length of the text material in iCBT affects outcomes. Objective: The aim of this study was to test whether a condensed iCBT version for depression would be noninferior to the existing full-text version in reducing depressive symptoms at post-treatment. We also wanted to test non-inferiority for secondary outcomes and explore reading speed and ADHD symptoms as potential moderators. Method: A single-blind randomized controlled trial was conducted (N = 267) comparing two versions of guided iCBT for depression; full-text (around 60,000 words) and condensed (around 30,000 words, with the option to listen to the text). Estimated between-group effect sizes and their confidence intervals for depression, anxiety and quality of life, were compared to a pre-determined non-inferiority margin (ES = 0.4). Moderation analyses of reading speed and ADHD symptoms were conducted. Results: The condensed version of iCBT was non-inferior to the full-text version on post-treatment measures for depressive symptoms (95 % CI = - 0.42-0.24), anxiety symptoms (95 % CI = - 0.24-0.32), and quality of life (95 % CI = - 0.09-0.49). Non-inferiority was inconclusive for depressive symptoms at the one-year follow-up (95 % CI = - 0.60-0.47). There was no significant moderation effects of reading speed (p = 0.06) or ADHD symptoms (p = 0.11) on depressive symptoms. Conclusion: These results indicate that a condensed version of iCBT for depression is as effective at treating depression as the full-text version. By shortening texts, iCBT may be made available to more people. Due to unequal dropout rates between the groups, these results are preliminary and need to be replicated.
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