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1.
  • Lee, Marcus, et al. (författare)
  • Low-latitude zooplankton pigmentation plasticity in response to multiple threats
  • 2019
  • Ingår i: Royal Society Open Science. - : The Royal Society Publishing. - 2054-5703. ; 6:7
  • Tidskriftsartikel (refereegranskat)abstract
    • Crustacean copepods in high-latitude lakes frequently alter their pigmentation facultatively to defend themselves against prevailing threats, such as solar ultraviolet radiation ( UVR) and visually oriented predators. Strong seasonality in those environments promotes phenotypic plasticity. To date, no one has investigated whether low-latitude copepods, experiencing continuous stress from UVR and predation threats, exhibit similar inducible defences. We here investigated the pigmentation levels of Bahamian 'blue hole' copepods, addressing this deficit. Examining several populations varying in predation risk, we found the lowest levels of pigmentation in the population experiencing the highest predation pressure. In a laboratory experiment, we found that, in contrast with our predictions, copepods from these relatively constant environments did show some changes in pigmentation subsequent to the removal of UVR; however, exposure to water from different predation regimes induced minor and idiosyncratic pigmentation change. Our findings suggest that low-latitude zooplankton in inland environments may exhibit reduced, but non-zero, levels of phenotypic plasticity compared with their high-latitude counterparts.
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2.
  • Bergström, G, et al. (författare)
  • The Swedish CArdioPulmonary BioImage Study: objectives and design.
  • 2015
  • Ingår i: Journal of Internal Medicine. - : Wiley-Blackwell Publishing Ltd. - 1365-2796 .- 0954-6820. ; 278:6, s. 645-659
  • Tidskriftsartikel (refereegranskat)abstract
    • Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.
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3.
  • Hansen, Joan H., et al. (författare)
  • Ecological Consequences of Animal Migration : Prey Partial Migration Affects Predator Ecology and Prey Communities
  • Ingår i: Ecosystems. - : Springer. - 1432-9840 .- 1435-0629. ; 23:2, s. 292-306
  • Tidskriftsartikel (refereegranskat)abstract
    • Patterns of animal migration and the ecological forces that shape them have been studied for centuries. Yet ecological impacts caused by the migration, such as altered predator–prey interactions and effects on community structure, remain poorly understood. This is to a large extent due to the scarcity of naturally replicated migration systems with negative controls, that is, ecosystems without migration. In this study, we tested whether partial migration of certain species within the overall prey community affects foraging ecology of top predators and thereby alters energy pathways in food webs. We carried out the study in independent replicated freshwater lake systems, four with and four without opportunity for prey migration. Specifically, we compared predator foraging mode in lakes where cyprinid prey fish perform seasonal partial migrations into connected streams with lakes lacking migratory opportunities for prey fish. We found clear seasonal bottom-up effects of prey migration on predators, including changes in size structure and total biomass of ingested prey, size-specific changes in littoral versus pelagic origin of diet, and a higher degree of feast-and-famine for predators in systems with migratory prey. Our analyses further showed that partially migratory prey species constitute a larger part of the prey community in systems that allow migration. Hence, prey migrations have important implications for predator foraging ecology and may cause seasonal shifts in the importance of their supporting energy pathways. We suggest that such bottom-up effects of partial migration may be a widespread phenomenon both in aquatic and in terrestrial ecosystems.
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4.
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5.
  • Hulthén, Kaj, et al. (författare)
  • A predation cost to bold fish in the wild
  • Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Studies of predator-mediated selection on behaviour are critical for our understanding of the evolution and maintenance of behavioural diversity in natural populations. Consistent individual differences in prey behaviour, especially in the propensity to take risks ("boldness"), are widespread in the animal kingdom. Theory predicts that individual behavioural types differ in a cost-benefit trade-off where bolder individuals benefit from greater access to resources while paying higher predation-risk costs. However, explicitly linking predation events to individual behaviour under natural conditions is challenging and there is currently little data from the wild. We assayed individual behaviour and electronically tagged hundreds of fish (roach, Rutilus rutilus) before releasing them into their lake of origin, thereby exposing them to predation risk from avian apex predators (cormorants, Phalacrocorax carbo). Scanning for regurgitated tags at the cormorant roosting site provided data on individual predation events. We found that fish with higher boldness have a greater susceptibility to cormorant predation compared to relatively shy, risk-averse individuals. Our findings hereby provide unique and direct evidence of behavioural type-dependent predation vulnerability in the wild, i.e. that there is a predation cost to boldness, which is critical for our understanding of the evolution and maintenance of behavioural diversity in natural populations.
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6.
  • Nilsson, Per Anders, 1968-, et al. (författare)
  • Species integrity enhanced by a predation cost to hybrids in the wild
  • 2017
  • Ingår i: Biology Letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 13:7, s. 1-4
  • Tidskriftsartikel (refereegranskat)abstract
    • Species integrity can be challenged, and even eroded, if closely related species can hybridize and produce fertile offspring of comparable fitness to that of par- ental species. The maintenance of newly diverged or closely related species therefore hinges on the establishment and effectiveness of pre- and/or post- zygotic reproductive barriers. Ecological selection, including predation, is often presumed to contribute to reduced hybrid fitness, but field evidence for a predation cost to hybridization remains elusive. Here we provide proof-of- concept for predation on hybrids being a postzygotic barrier to gene flow in the wild. Cyprinid fishes commonly produce fertile, viable hybrid offspring and therefore make excellent study organisms to investigate ecological costs to hybrids. We electronically tagged two freshwater cyprinid fish species (roach Rutilus rutilus and bream Abramis brama) and their hybrids in 2005. Tagged fish were returned to their lake of origin, exposing them to natural predation risk from apex avian predators (great cormorant, Phalacrocorax carbo). Scanning for regurgitated tags under cormorant roosts 3–4 years later ident- ified cormorant-killed individual fish and allowed us to directly test for a predation cost to hybrids in the wild. Hybrid individuals were found significantly more susceptible to cormorant predation than individuals from either parental species. Such ecological selection against hybrids contributes to species integrity, and can enhance species diversification.
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7.
  • Sha, Yongcui, et al. (författare)
  • Diel vertical migration of copepods and its environmental drivers in subtropical Bahamian blue holes
  • 2020
  • Ingår i: Aquatic Ecology. - : Springer. - 1386-2588 .- 1573-5125.
  • Tidskriftsartikel (refereegranskat)abstract
    • Diel vertical migration (DVM) is the most common behavioral phenomenon in zooplankton, and numerous studies have evaluated DVM under strong seasonality at higher latitudes. Yet, our understanding of the environmental drivers of DVM at low latitudes, where seasonal variation is less pronounced, remains limited. Therefore, we here examined patterns of vertical distribution in copepods in six subtropical Bahamian blue holes with different food web structure and tested the role of several key environmental variables potentially affecting this behavior. Day and night samplings showed that copepods generally performed DVM, characterized by downward migration to deeper depths during the day and upward migration to surface waters at night. Across all blue holes, the daytime vertical depth distribution of calanoid copepods correlated positively with both predation risk and depth of food resources (Chlorophyll a), but was less affected by ultraviolet radiation (UVR). A potential explanation is that since UVR is a continuous threat across seasons, zooplankton have established photoprotective pigmentation making them less vulnerable to this threat. The copepods also showed a size-structured depth segregation, where larger individuals were found at deeper depths during the day, which further strengthens the suggestion that predation is a major driver of DVM in these systems. Hence, in contrast to studies performed at higher latitudes, we show that despite the constant exposure to UVR, predator avoidance and food availability are the most pronounced drivers of copepod DVM at those low latitudes, suggesting that the main driver of DVM may vary among systems, but also systematically by latitude. 
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8.
  • Skov, Christian, et al. (författare)
  • Biomanipulating streams : a supplementary tool in lake restoration
  • Ingår i: Hydrobiologia. - : Springer. - 0018-8158 .- 1573-5117. ; 829:1, s. 205-216
  • Tidskriftsartikel (refereegranskat)abstract
    • Removal of cyprinid fish is a widely used biomanipulation tool to transform turbid shallow eutrophic lakes in north temperate regions into a clear water state. We here evaluate the removal of cyprinids from streams as a supplement to lake fishing. Since cyprinids often aggregate in high densities in lake inlet/outlet streams during winter migration, removal of fish in this space-confined habitat may be cost-efficient as compared to fish removal in the lake habitat. In two consecutive years, we annually removed up to 35% of the dominant cyprinids from an inlet stream to a lake and argue that this could easily be increased with a more targeted fishing effort. Concurrently, we monitored species- and length-specific variation in migration propensity, to explore how this relates to efficient fish removal. Smaller planktivores generally had a much higher migratory propensity than larger benthivores. Hence, stream fishing specifically targets species and size groups that are less efficiently controlled with traditional lake fishing methods. As a rule of thumb, stream fishing is most efficient when water temperature is 2–6°C. Prior to implementing fish removals from streams, the potential evolutionary consequences of the targeted removal of migratory phenotypes should be considered.
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9.
  • Bergström, Göran, 1964, et al. (författare)
  • The Swedish CArdioPulmonary BioImage Study: objectives and design.
  • 2015
  • Ingår i: Journal of internal medicine. - : Wiley-Blackwell Publishing Ltd. - 1365-2796 .- 0954-6820. ; 278:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.
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10.
  • Hansson, Lars-Anders, et al. (författare)
  • A lake as a microcosm: reflections on developments in aquatic ecology
  • 2013
  • Ingår i: Aquatic Ecology. - : Springer. - 1386-2588 .- 1573-5125. ; 47:2, s. 125-135
  • Tidskriftsartikel (refereegranskat)abstract
    • In the present study, we aim at relating Forbes' remarkable paper on "The lake as a microcosm", published 125 years ago, to the present status of knowledge in our own research group. Hence, we relate the observations Forbes made to our own microcosm, Lake Krankesjon in southern Sweden, that has been intensively studied by several research groups for more than three decades. Specifically, we focus on the question: Have we made any significant progress or did Forbes and colleagues blaze the trail through the unknown wilderness and we are mainly paving that intellectual road? We conclude that lakes are more isolated than many other biomes, but have, indeed, many extensions, for example, input from the catchment, fishing and fish migration. We also conclude that irrespective of whether lakes should be viewed as microcosms or not, the paper by Forbes has been exceptionally influential and still is, especially since it touches upon almost all aspects of the lake ecosystem, from individual behaviour to food web interactions and environmental issues. Therefore, there is no doubt that even if 125 years have passed, Forbes' paper still is a source of inspiration and deserves to be read. Hence, although aquatic ecology has made considerable progress over the latest century, Forbes might be viewed as one of the major pioneers and visionary scientists of limnology.
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