SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "hsv:(NATURVETENSKAP) hsv:(Biologiska vetenskaper) "

Sökning: hsv:(NATURVETENSKAP) hsv:(Biologiska vetenskaper)

  • Resultat 1-10 av 463
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Alho, Jussi S., et al. (författare)
  • Increasing melanism along a latitudinal gradient in a widespread amphibian : local adaptation, ontogenic or environmental plasticity?
  • 2010
  • Ingår i: BMC Evolutionary Biology. - 1471-2148 .- 1471-2148. ; 10, s. 317-
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundThe thermal benefits of melanism in ectothermic animals are widely recognized, but relatively little is known about population differentiation in the degree of melanism along thermal gradients, and the relative contributions of genetic vs. environmental components into the level of melanism expressed. We investigated variation in the degree of melanism in the common frog (Rana temporaria; an active heliotherm thermoregulator) by comparing the degree of melanism (i) among twelve populations spanning over 1500 km long latitudinal gradient across the Scandinavian Peninsula and (ii) between two populations from latitudinal extremes subjected to larval temperature treatments in a common garden experiment.ResultsWe found that the degree of melanism increased steeply in the wild as a function of latitude. Comparison of the degree of population differentiation in melanism (PST) and neutral marker loci (FST) revealed that the PST > FST, indicating that the differences cannot be explained by random genetic drift alone. However, the latitudinal trend observed in the wild was not present in the common garden data, suggesting that the cline in nature is not attributable to direct genetic differences.ConclusionsAs straightforward local adaptation can be ruled out, the observed trend is likely to result from environment-driven phenotypic plasticity or ontogenetic plasticity coupled with population differences in age structure. In general, our results provide an example how phenotypic plasticity or even plain ontogeny can drive latitudinal clines and result in patterns perfectly matching the genetic differences expected under adaptive hypotheses. 
  •  
2.
  • Dessborn, Lisa, 1976-, et al. (författare)
  • Pike predation affects breeding success and habitat selection of ducks
  • 2011
  • Ingår i: Freshwater Biology. - : Wiley: 12 months. - 0046-5070 .- 1365-2427. ; 56:3, s. 579-589
  • Tidskriftsartikel (refereegranskat)abstract
    • 1. Fish and ducks often belong to the same local food web, and several studies indicate that there is a general negative effect of fish on breeding ducks. This pattern has so far been addressed mainly within the framework of competition for common invertebrate prey, while predation by large fish as a force behind settlement and abundance patterns in ducks remains largely unknown. This is the first study to address the effect of fish predation on breeding ducks, isolated from that of competition, and the first experiment to explore the ability of ducks to identify and avoid lakes with high risk of fish predation. 2. We used a before-after control-impact design and 11 naturally fishless lakes. Waterfowl on the lakes were surveyed during the breeding season of 2005. Large adult pike (Esox lucius) were added to two lakes in early spring 2008, and waterfowl surveys were repeated on all 11 lakes. 3. Pike introduction did not affect the number of pairs on lakes during the nesting season in any of three focal duck species (mallard Anas platyrhynchos, teal Anas crecca, and goldeneye Bucephala clangula). During the brood-rearing season, however, there was a decrease in duck days in teal and goldeneye in lakes with pike, with similar trends observed in mallard. The number of goldeneye ducklings was also significantly lower in lakes with pike. We were unable to determine whether the response was attributable to direct pike predation or to broods leaving experimental lakes, but in either case, our study demonstrates high fitness costs for ducks breeding on lakes with pike. 4. The apparent inability of nesting ducks to detect pike and the clear fitness implications may influence the annual recruitment of ducks on a larger scale as pike are both common and widespread. Vegetation complexity and food abundance are likely to be of overriding importance when breeding ducks are choosing a nesting site. As pike have a strong influence on breeding birds, relying on vegetation and cues of food abundance, while ignoring indicators of predation risk from fish, could lead to lakes with pike acting as an ecological trap.
  •  
3.
  • Elmberg, Johan, et al. (författare)
  • Within-season sequential density dependence regulates breeding success in mallards Anas platyrhynchos
  • 2005
  • Ingår i: Oikos. - 0030-1299 .- 1600-0706. ; 108, s. 582-590
  • Tidskriftsartikel (refereegranskat)abstract
    • Density dependence in vital rates is a key issue in population ecology but remains largely unexplored experimentally. We studied breeding success, lake use, and prey availability in wild mallards Anas platyrhynchos on small nemoral lakes in a replicated, two-year cross-over experiment in which pair density was increased. The number of wild mallards that settled on lakes prior to introductions of extra pairs did not differ between control and introduction years. Introductions led to a lake-level reduction in the number of broods observed. However, the number of stage 2/ (almost fledged) ducklings did not differ between treatments, nor did lake utilization by nonbreeding adults, broods and ducklings. Prey resource availability differed greatly among lakes, but it did not correlate with breeding success. Partialling out the possible effect of food competition from wild adult nonbreeding mallards did not change this conclusion. Our study demonstrates sequential density dependence in breeding success; introductions caused a decrease in brood number, but despite fewer broods a similar number of nearly fledged ducklings were produced. We suggest that predation and/or lake change of broods soon after hatching created these patterns. We conclude that using a single and late measure of breeding success such as fledged birds can mask regulatory processes. Implications of density dependence and its relation to individual reproductive success are understood better if breeding success is decomposed into nest success, duckling survival and fledgling survival.
  •  
4.
  • Gillman, Anna, et al. (författare)
  • Oseltamivir-Resistant Influenza A (H1N1) Virus Strain with an H274Y Mutation in Neuraminidase Persists without Drug Pressure in Infected Mallards
  • 2015
  • Ingår i: Applied and Environmental Microbiology. - : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 81:7, s. 2378-2383
  • Tidskriftsartikel (refereegranskat)abstract
    • Influenza A virus (IAV) has its natural reservoir in wild waterfowl and emerging human IAVs often contain gene segments from avian viruses. The active drug metabolite of oseltamivir (oseltamivir carboxylate (OC)), stockpiled as Tamiflu® for influenza pandemic preparedness, is not removed by conventional sewage treatment and has been detected in river water. There, it may there exert evolutionary pressure on avian IAV in waterfowl, resulting in development of resistant viral variants. A resistant avian IAV can circulate among wild birds only if resistance does not restrict viral fitness and if the resistant virus can persist without continuous drug pressure. In this in vivo Mallard (Anas platyrhynchos) study we tested if an OC-resistant avian IAV strain (A(H1N1)/NA-H274Y) could retain resistance while drug pressure was gradually removed. Successively infected Mallards were exposed to decreasing levels of OC, and fecal samples were analyzed for neuraminidase sequence and phenotypic resistance. No reversion to wild-type virus was observed during the experiment, which included 17 days of viral transmission in 10 ducks exposed to OC concentrations below resistance induction levels. We conclude that resistance in avian IAV, induced by OC exposure of the natural host, can persist in absence of the drug. Thus, there is a risk that human pathogenic IAVs that evolve from IAVs circulating among wild birds may contain resistance mutations. An oseltamivir resistant pandemic IAV would be a substantial public health threat. Therefore, our observations underscore the need for prudent oseltamivir use, upgraded sewage treatment and resistance surveillance of IAV in wild birds.
  •  
5.
  • Hedenas, Henrik, et al. (författare)
  • Changes Versus Homeostasis in Alpine and Sub-Alpine Vegetation Over Three Decades in the Sub-Arctic
  • 2012
  • Ingår i: Ambio. - : Springer Verlag (Germany). - 0044-7447 .- 1654-7209. ; 41, s. 187-196
  • Tidskriftsartikel (refereegranskat)abstract
    • Plant species distributions are expected to shift and diversity is expected to decline as a result of global climate change, particularly in the Arctic where climate warming is amplified. We have recorded the changes in richness and abundance of vascular plants at Abisko, sub-Arctic Sweden, by re-sampling five studies consisting of seven datasets; one in the mountain birch forest and six at open sites. The oldest study was initiated in 1977–1979 and the latest in 1992. Total species number increased at all sites except for the birch forest site where richness decreased. We found no general pattern in how composition of vascular plants has changed over time. Three species, Calamagrostis lapponica, Carex vaginata and Salix reticulata, showed an overall increase in cover/frequency, while two Equisetum taxa decreased. Instead, we showed that the magnitude and direction of changes in species richness and composition differ among sites.
  •  
6.
  • Jönsson, K. Ingemar, 1959-, et al. (författare)
  • Environmental adaptations : radiation tolerance
  • 2019
  • Ingår i: Water bears. - : Springer. - 9783319957012 - 9783319957029 ; , s. 311-330
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
    • Several studies in different species have documented that tardigrades are among the most radiation-tolerant animals on Earth, surviving doses of ionizing radiation on the order of kGy. Both low-LET and high-LET radiation have been used with no apparent differences in the tolerance of the animals. Tolerance to ionizing radiation in tardigrades also seems to be independent of whether the animal has entered a dry anhydrobiotic state or is hydrated with normal activity. However, when exposed to UV radiation, desiccated tardigrades show a higher tolerance than hydrated animals. Recent studies in several species have shown that tardigrade embryos have considerably lower tolerance to ionizing radiation compared to adults, and embryos in the early stage of development are clearly more sensitive to radiation than those in the late developmental stage. The molecular mechanisms behind radiation tolerance in tardigrades are still largely unclear, but available evidence suggests that mechanisms related to both the avoidance of DNA damage and the repair of damage are involved.
  •  
7.
  • Jönsson, K. Ingemar, 1959-, et al. (författare)
  • Sexual patterns of prebreeding energy reserves in the common frog Rana temporaria along a latitudinal gradient
  • 2009
  • Ingår i: Ecography. - : Wiley-Blackwell. - 0906-7590 .- 1600-0587. ; 32:5, s. 831-839
  • Tidskriftsartikel (refereegranskat)abstract
    • The ability to store energy is an important life history trait for organisms facing long periods without energy income, and in particular for capital breeders such as temperate zone amphibians, which rely on stored energy during reproduction. However, large scale comparative studies of energy stores in populations with different environmental constraints on energy allocation are scarce. We investigated energy storage patterns in spring (after hibernation and before reproduction) in eight common frog (Rana temporaria) populations exposed to different environmental conditions along a 1600 km latitudinal gradient across Scandinavia (range of annual activity period 3-7 months). Analyses of lean body weight (eviscerated body mass), weight of fat bodies, liver weight, and liver fat content, showed that (i) post-hibernation/pre-breeding energy stores increased with increasing latitude in both sexes, (ii) males generally had larger energy reserves than females and (iii) the difference in energy stores between sexes decreased towards the north. Larger energy reserves towards the north can serve as a buffer against less predictable and/or less benign weather conditions during the short activity period, and may also represent a risk-averse tactic connected with a more pronounced iteroparous life history. In females, the continuous and overlapping vitellogenic activity in the north may also demand more reserves in early spring. The general sexual difference could be a consequence of the fact that, at the time of our sampling, females had already invested their energy into reproduction in the given year (i.e. their eggs were already ovulated), while the males' main reproductive activities (e.g. calling, mate searching, sexual competition) occurred later in the season.
  •  
8.
  • Jönsson, K. Ingemar, 1959-, et al. (författare)
  • The fate of the TARDIS offspring : no intergenerational effects of space exposure
  • 2016
  • Ingår i: Zoological Journal of the Linnean Society. - 0024-4082 .- 1096-3642. ; 178:4, s. 924-930
  • Tidskriftsartikel (refereegranskat)abstract
    • In September 2007 tardigrades became the first animal in history to survive the combined effect of exposure to space vacuum, cosmic radiation and ultraviolet radiation in low Earth orbit. The main results from this experiment were reported in 2008, but some of the results have remained unpublished. Here we report that descendant generations of space-exposed tardigrades of the species Milnesium tardigradum did not show reduced performance. This indicates that individual tardigrades that survived the exposure to environmental extremes in space, and were able to reproduce, did not transfer any damage to later generations. Repair of environmentally induced damage may therefore follow a ‘make or break’ rule, such that a damaged animal either fails to repair all damage and dies, or repairs damage successfully and leaves no mutations to descendants. We also report that two additional tardigrade species, Echiniscus testudo and Ramazzottius oberhaeuseri, showed high survival after exposure to space vacuum and cosmic radiation within the TARDIS experiment.
  •  
9.
  • Nilsson, Charlotta, et al. (författare)
  • Element analysis of the eutardigrades Richtersius coronifer and Milnesium cf. asiaticum using Particle Induced X-ray Emission (PIXE)
  • 2013
  • Ingår i: Journal of limnology. - : Page Press. - 1129-5767 .- 1723-8633. ; 72:s1, s. 92-101
  • Tidskriftsartikel (refereegranskat)abstract
    • Semi-terrestrial tardigrades are well-known for their tolerance to a variety of environmental extremes, including desiccation, freezing and radiation. Despite several attempts to reveal the genetic and molecular mechanisms behind the resilience of tardigrades, it is still unknown how these animals are able to maintain the integrity of their cellular components under severe stress. Quantitative or qualitative changes in molecular compounds (e.g., carbohydrates, proteins) are expected, and have been the main line of research towards understanding the tolerance of tardigrades. In radiation tolerant bacteria, a tolerance mechanism based on manganese has been proposed. We evaluate this hypothesis in tardigrades and provide the first data on element composition in desiccated and non-desiccated specimens of two eutardigrade species, Richtersius coronifer and Milnesium cf. asiaticum. A focused 2 MeV proton microbeam was utilised to determine the elemental content, distributions and concentrations, using the ion beam analytical technique particle induced X-ray emission(PIXE). The presence of six elements – phosphorus, sulphur, chlorine, potassium, calcium and iron – were confirmed in all tardigrade specimens, at levels up to a few mg g–1. However, manganese was found in less than 10% of the analysed specimens, and in low amounts, thus our study provides no evidence for the manganese hypothesis. We also show that the distributions and/or concentrations of some elements differ between the two species as well as between the dehydrated and hydrated state. In particular, very low levels of iron were found in dehydrated M. cf. asiaticum. Our analysis shows that the PIXE technique is a useful tool for investigating questions on the distribution of elements both in dehydrated and hydrated tardigrades.
  •  
10.
  • Söderquist, Pär (författare)
  • Large-scale releases of native species : the mallard as a predictive model system
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Human alteration of natural systems, and its consequences are of great concern and the impact on global ecosystems is one of the biggest threats that biodiversity stands before. Translocations of invasive species, as well as intraspecific contingents with non-native genotypes, whether they are deliberate or unintentional, are one such alteration and its consequences are continuously being assessed. The mallard (Anas platyrhynchos) is the most numerous and widespread duck in the world and a flagship in wetland conservation. It is also an important game species which is heavily restocked for hunting purposes, especially in Europe where over three million ducklings are released every year. Because of its hunted status, its abundance, and the number of released individuals, it can serve as a model species to study effects of releases, both for conservation and restocking for hunting, on wild populations. In this thesis the status of the mallard was assessed in the Nordic countries and the effects of releases on the wild populations were studied by mining historical ringing data, comparing morphology of present-day wild, farmed, and historical mallards, and analyzing phylogeography of wild and farmed mallards in Europe. The status of the mallard population in the Nordic countries are generally good, however, a joint effort of European countries is needed to monitor and manage the population. A significant difference between wild and farmed mallards concerning longevity, migration, bill morphology and genetic structure was also found, together with signs of cryptic introgression of farmed genotypes in the wild population with potential fitness reduction as a result. The effect is however limited by that only a fraction of released farmed mallards reach the breeding season due to low survival. A natural captive environment is crucial to keep individuals wild-like with high survival rates after release. However, with an introgression of potentially maladapted farmed genotypes leading to a reduction in fitness, a low survival of released mallards would favor the wild population. A legislative change regarding obligation to report numbers, provenance, and release sites of farmed mallard should be considered, together with practical solutions of ringing and genetic monitoring of released mallards.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 463
Typ av publikation
tidskriftsartikel (316)
konferensbidrag (90)
bokkapitel (25)
rapport (10)
annan publikation (9)
doktorsavhandling (6)
visa fler...
forskningsöversikt (3)
samlingsverk (redaktörskap) (2)
bok (1)
recension (1)
visa färre...
Typ av innehåll
refereegranskat (306)
övrigt vetenskapligt/konstnärligt (82)
populärvet., debatt m.m. (75)
Författare/redaktör
Elmberg, Johan, 1960 ... (172)
Elmberg, Johan (97)
Pöysä, Hannu (73)
Nummi, Petri (66)
Sjöberg, Kjell (65)
Arzel, Céline (45)
visa fler...
Jönsson, K. Ingemar, ... (44)
Gunnarsson, Gunnar, ... (44)
Gunnarsson, Gunnar (44)
Guillemain, Matthieu (38)
Rehnstam-Holm, Ann-S ... (32)
Söderquist, Pär (24)
Waldenström, Jonas (20)
Dessborn, Lisa, 1976 ... (20)
Olsen, Björn (17)
Champagnon, Jocelyn (17)
Jonsson, Lars J. (14)
Lacoursière, Jean O. ... (12)
Collin, Betty, 1976- (11)
Latorre-Margalef, Ne ... (11)
Vought, Lena B. M. (11)
Dessborn, Lisa (9)
Czernekova, Michaela (9)
Harms-Ringdahl, Mats (8)
Godhe, Anna (8)
Hernroth, Bodil, 195 ... (8)
Gauthier-Clerc, Mich ... (8)
Holopainen, Sari (8)
Fox, Anthony D. (7)
Guillemain, M. (7)
Massez, Grégoire (7)
Halldén, Christer, 1 ... (7)
Herczeg, Gábor (6)
Jönsson, K. Ingemar (6)
Fouchier, Ron A. M. (6)
Björklund, Erland (5)
Lindström, Åke (5)
Emanuelsson, Urban (5)
Merilä, Juha (5)
Englund, Göran (5)
Lepley, Michel (5)
Legagneux, Pierre (5)
Karunasagar, Indrani (5)
Fransson, Thord (5)
Tassidis, Helena (5)
Clausen, Preben (5)
Osterhaus, Albert D. ... (5)
Guidetti, Roberto (5)
Rebecchi, Lorena (5)
Kreisinger, Jakub (5)
visa färre...
Lärosäte
Högskolan Kristianstad (462)
Sveriges Lantbruksuniversitet (20)
Lunds universitet (12)
Uppsala universitet (8)
Stockholms universitet (7)
Göteborgs universitet (5)
visa fler...
Umeå universitet (5)
Linnéuniversitetet (4)
Linköpings universitet (1)
Naturvårdsverket (1)
Högskolan i Skövde (1)
visa färre...
Språk
Engelska (328)
Svenska (125)
Finska (5)
Tyska (3)
Franska (1)
Norska (1)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (462)
Lantbruksvetenskap (12)
Samhällsvetenskap (6)
Medicin och hälsovetenskap (4)
Teknik (2)
Humaniora (1)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy