| 51. |
- Olofsson, Martin, 1980-, et al.
(författare)
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Bird attacks on a butterfly with marginal eyespots and the role of prey concealment against the background : Marginal eyespots can deflect bird attacks
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Small eyespots on butterflies have long been thought to deflect attacks and birds are presumptive drivers selecting for these patterns. However, evidence of this function is still ambiguous. Marginal eyespots typically consist of a UV-reflective white pupil, surrounded by one black and one yellowish ring. We have recently shown that blue tits attack such eyespots, but only under low light intensities with accentuated UV-levels. An increased salience of the eyespots relative to the rest of the butterfly probably explains this result. Possibly, a background against which the butterfly is concealed may deceive birds to making similar errors. We therefore presented speckled wood butterflies provided with eyespots (or controls without eyespots) to blue tits against two backgrounds, oak- and birch bark. Results show that (i) eyespots, independent of background, were effective in deflecting attacks, (ii) the time elapsed between a bird’s landing and attack was interactively dependent on background and whether the butterfly bore an eyespot and (iii) the speed at which a butterfly was attacked predicted the outcome, with faster birds being more prone to errors than slower birds. This underscores a speed-accuracy tradeoff in the predators and that background plays a role in the defensive qualities of marginal eyespots.
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| 52. |
- Olofsson, Martin, et al.
(författare)
-
Bird attacks on a butterfly with marginal eyespots and the role of prey concealment against the background
- 2013
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 109:2, s. 290-297
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Tidskriftsartikel (refereegranskat)abstract
- Small eyespots on butterflies have long been thought to deflect attacks, and birds are the presumptive drivers selecting for these patterns; however, evidence of this function is still ambiguous. Marginal eyespots typically consist of a UV-reflective white pupil, surrounded by one black and one yellowish ring. We have recently shown that Cyanistes caeruleus (blue tits) attack such eyespots, but only under low light intensities with accentuated UV levels: the increased salience of the eyespots relative to the rest of the butterfly probably explains this result. Possibly the background against which the butterfly is concealed may deceive birds to make similar errors. We therefore presented speckled wood butterflies decorated with eyespots (or controls without eyespots) to C.caeruleus against two backgrounds: oak and birch bark. Our results show that: (1) eyespots, independent of background, were effective in deflecting attacks; (2) the time elapsed between a bird landing and the attack was interactively dependent on the background and whether the butterfly bore an eyespot; and (3) the speed at which a butterfly was attacked predicted the outcome, with faster birds being more prone to errors than slower birds. This underscores a speedaccuracy trade-off in the predators, and that background plays a role in the defensive qualities of marginal eyespots.(c) 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 290297.
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| 53. |
- Olofsson, Martin, 1980-, et al.
(författare)
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Deimatic Display in the European Swallowtail Butterfly as a Secondary Defence against Attacks from Great Tits
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:10, s. e47092-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Many animals reduce the risk of being attacked by a predator through crypsis, masquerade or, alternatively, by advertising unprofitability by means of aposematic signalling. Behavioural attributes in prey employed after discovery, however, signify the importance of also having an effective secondary defence if a predator uncovers, or is immune to, the prey's primary defence. In butterflies, as in most animals, secondary defence generally consists of escape flights. However, some butterfly species have evolved other means of secondary defence such as deimatic displays/startle displays. The European swallowtail, Papilio machaon, employs what appears to be a startle display by exposing its brightly coloured dorsal wing surface upon disturbance and, if the disturbance continues, by intermittently protracting and relaxing its wing muscles generating a jerky motion of the wings. This display appears directed towards predators but whether it is effective in intimidating predators so that they refrain from attacks has never been tested experimentally. Methodology/Principal Findings: In this study we staged encounters between a passerine predator, the great tit, Parus major, and live and dead swallowtail butterflies in a two-choice experiment. Results showed that the dead butterfly was virtually always attacked before the live butterfly, and that it took four times longer before a bird attacked the live butterfly. When the live butterfly was approached by a bird this generally elicited the butterfly's startle display, which usually caused the approaching bird to flee. We also performed a palatability test of the butterflies and results show that the great tits seemed to find them palatable. Conclusions/Significance: We conclude that the swallowtail's startle display of conspicuous coloration and jerky movements is an efficient secondary defence against small passerines. We also discuss under what conditions predator-prey systems are likely to aid the evolution of deimatic behaviours in harmless and palatable prey.
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| 54. |
- Olofsson, Martin, 1980-, et al.
(författare)
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Eyespot display in the peacock butterfly triggers antipredator behaviors in naive adult fowl
- 2013
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Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 24:1, s. 305-310
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Tidskriftsartikel (refereegranskat)abstract
- Large conspicuous eyespots have evolved in multiple taxa and presumably function to thwart predator attacks. Traditionally, large eyespots were thought to discourage predator attacks because they mimicked eyes of the predators' own predators. However, this idea is controversial and the intimidating properties of eyespots have recently been suggested to Amply be a consequence of their conspicuousness. Some lepidopteran species include large eyespots in their antipredation repertoire. In the peacock butterfly, Mathis io, eyespots are typically hidden during rest and suddenly exposed by the butterfly when disturbed. Previous experiments have shown that small wild passerines are intimidated by this display. Here, we test whether eyespots also intimidate a considerably larger bird, domestic fowl, Gallus gallus domesticus, by staging interactions between birds and peacock butterflies that were sham-painted or had their eyespots painted oven Our results show that birds typically fled when peacock butterflies performed their display regardless of whether eyespots were visible or painted over. However, birds confronting butterflies with visible eyespots delayed their return to the butterfly, were more vigilant, and more likely to utter alarm calls associated with detection of ground-based predators, compared with birds confronting butterflies with eyespots painted over. Because production of alarm calls and increased vigilance are antipredation behaviors in the fowl, their reaction suggests that eyespots may elicit fear rather than just an aversion to conspicuous patterns. Our results, therefore, suggest that predators perceive large lepidopteran eyespots as belonging to the eyes of a potential predator.
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| 55. |
- Olofsson, Martin, 1980-, et al.
(författare)
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Marginal eyespots on butterfly wings deflect bird attacks under low light intensities with UV wavelengths
- 2010
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 5:5, s. e10798-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Predators preferentially attack vital body parts to avoid prey escape. Consequently, prey adaptations that make predators attack less crucial body parts are expected to evolve. Marginal eyespots on butterfly wings have long been thought to have this deflective, but hitherto undemonstrated function. METHODOLOGY/PRINCIPAL FINDINGS: Here we report that a butterfly, Lopinga achine, with broad-spectrum reflective white scales in its marginal eyespot pupils deceives a generalist avian predator, the blue tit, to attack the marginal eyespots, but only under particular conditions-in our experiments, low light intensities with a prominent UV component. Under high light intensity conditions with a similar UV component, and at low light intensities without UV, blue tits directed attacks towards the butterfly head. CONCLUSIONS/SIGNIFICANCE: In nature, birds typically forage intensively at early dawn, when the light environment shifts to shorter wavelengths, and the contrast between the eyespot pupils and the background increases. Among butterflies, deflecting attacks is likely to be particularly important at dawn when low ambient temperatures make escape by flight impossible, and when insectivorous birds typically initiate another day's search for food. Our finding that the deflective function of eyespots is highly dependent on the ambient light environment helps explain why previous attempts have provided little support for the deflective role of marginal eyespots, and we hypothesize that the mechanism that we have discovered in our experiments in a laboratory setting may function also in nature when birds forage on resting butterflies under low light intensities.
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| 56. |
- Olofsson, Martin, et al.
(författare)
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Winter predation on two species of hibernating butterflies: monitoring rodent attacks with infrared cameras
- 2011
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Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 81:3, s. 529-534
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Tidskriftsartikel (refereegranskat)abstract
- Documentation of predator attacks in nature is important for understanding how specific antipredator defences have evolved, but previous accounts have been mostly anecdotal. Therefore, we monitored predation on two closely related butterfly species, Aglais urticae and Inachis io, during winter hibernation. Butterflies were placed singly close to the floor on walls in dark, seminatural hibernation sites (e.g. unheated outhouses). We used motion-initiated infrared-sensitive cameras to record predator attacks on the butterflies. The antipredator attributes of the two species have two characteristics: during rest the butterflies reduce predators’ attention by mimicking leaves but they can suddenly change their guise by repeatedly flicking their wings. The wing flicking also produces hissing sounds and ultrasonic clicks and, furthermore, I. io, but not A. urticae, have large eyespots on the dorsal wing surface. The two butterfly species suffer from mouse predation during the winter and mice have been suggested as potential targets for the butterflies’ sound production. Results showed that (1) mice (Apodemus spp.) were important predators on butterflies, (2) I. io often survived attacks by wing-flicking behaviour, and (3) both species moved to less accessible positions after interactions with mice and other small mammalian predators, but I. io more often so. The successful predator evasion in darkness by I. io suggests a multimodal defence; in addition to the large eyespots, which intimidate birds, we suggest that the hissing and/or click sounds produced during wing flicking may have evolved as defence against rodent attacks
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| 57. |
- Pawelzik, Sven-Christian, et al.
(författare)
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Identification of Key Residues Determining Species Differences in Inhibitor Binding of Microsomal Prostaglandin E Synthase-1
- 2010
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 285:38, s. 29254-29261
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Tidskriftsartikel (refereegranskat)abstract
- Microsomal prostaglandin E synthase-1 (MPGES1) is induced during an inflammatory reaction from low basal levels by pro-inflammatory cytokines and subsequently involved in the production of the important mediator of inflammation, prostaglandin E-2. Nonsteroidal anti-inflammatory drugs prevent prostaglandin E-2 production by inhibiting the upstream enzymes cyclooxygenases 1 and 2. In contrast to these conventional drugs, a new generation of NSAIDs targets the terminal enzyme MPGES1. Some of these compounds potently inhibit human MPGES1 but do not have an effect on the rat orthologue. We investigated this interspecies difference in a rat/human chimeric form of the enzyme as well as in several mutants and identified key residues Thr-131, Leu-135, and Ala-138 in human MPGES1, which play a crucial role as gate keepers for the active site of MPGES1. These residues are situated in transmembrane helix 4, lining the entrance to the cleft between two subunits in the protein trimer, and regulate access of the inhibitor in the rat enzyme. Exchange toward the human residues in rat MPGES1 was accompanied with a gain of inhibitor activity, whereas exchange in human MPGES1 toward the residues found in rat abrogated inhibitor activity. Our data give evidence for the location of the active site at the interface between subunits in the homotrimeric enzyme and suggest a model of how the natural substratePGH(2), or competitive inhibitors of MPGES1, enter the active site via the phospholipid bilayer of the membrane.
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| 58. |
- Pizzari, Tommaso, et al.
(författare)
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Sophisticated sperm allocation in male fowl
- 2003
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 426:6962, s. 70-74
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Tidskriftsartikel (refereegranskat)abstract
- When a female is sexually promiscuous, the ejaculates of different males compete for the fertilization of her eggs; the more sperm a male inseminates into a female, the more likely he is to fertilize her eggs. Because sperm production is limited and costly, theory predicts that males will strategically allocate sperm (1) according to female promiscuity, (2) saving some for copulations with new females, and (3) to females producing more and/or better offspring. Whether males allocate sperm in all of these ways is not known, particularly in birds where the collection of natural ejaculates only recently became possible. Here we demonstrate male sperm allocation of unprecedented sophistication in the fowl Gallus gallus. Males show status-dependent sperm investment in females according to the level of female promiscuity; they progressively reduce sperm investment in a particular female but, on encountering a new female, instantaneously increase their sperm investment; and they preferentially allocate sperm to females with large sexual ornaments signalling superior maternal investment. Our results indicate that female promiscuity leads to the evolution of sophisticated male sexual behaviour.
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| 59. |
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| 60. |
- Redig, Josefine, et al.
(författare)
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Real-world cost-effectiveness of targeted therapy in metastatic renal cell carcinoma in Sweden : a population-based retrospective analysis
- 2019
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Ingår i: Cancer Management and Research. - Auckland : Dove medical press. - 1179-1322. ; 11, s. 1289-1297
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To explore cost-effectiveness of targeted therapies (TTs) in the treatment of metastatic renal cell carcinoma (mRCC) in a real-world context using a nationwide population-based approach.Methods: Data on patients diagnosed with mRCC between 2002 and 2012 were extracted from Swedish national health data registers. To facilitate comparisons of patients diagnosed before and after TT introduction to the market, three cohorts were derived: pre-TT introduction (preTT), patients diagnosed 2002-2005; early TT introduction (TTi), patients diagnosed 2006-2008; and late TT introduction (TTii), which was limited to patients diagnosed 2009-2010 to ensure availability of total health care resource utilization (HCRU) data. Patients were followed until end of 2012. The value of TTs across cohorts was estimated using mean HCRU costs per life-year (LY) gained. Data on HCRU were obtained through national health registers for dispensed medication and inpatient and outpatient care, and the associated costs were estimated using the Lin method to account for censoring. LYs gained were defined as the difference in mean survival over the study period.Results: The preTT, TTi, and TTii cohorts consisted of 1,366, 1,158, and 806 patients, respectively. Mean survival in years from mRCC diagnosis was 1.45 in the preTT cohort, 1.62 in the TTi cohort, and 1.83 in the TTii cohort. The respective mean total HCRU cost per patient over the study period was US$16,894, US$29,922, and US$30,037. The cost per LY gained per cohort was US$78,656 for TTi vs preTT, US$34,132 for TTii vs preTT, and US$523 for TTii vs TTi.Conclusion: Given common willingness-to-pay per LY gained thresholds, this study in a real-world population suggests the use of TTs in the Swedish mRCC population is increasingly cost-effective over time.
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