| 1. |
- Aastrup, Christian, et al.
(författare)
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Size and immune function as predictors of predation risk in nestling and newly fledged jackdaws
- 2023
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Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472. ; 198, s. 73-84
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Tidskriftsartikel (refereegranskat)abstract
- Prey choice by predators may be based on the potential prey's condition, for example resulting in substandard individuals running a higher risk of being predated. Over 5 years, we studied young jackdaws, Corvus monedula, to determine whether size and innate baseline immune function may predict predation risk by goshawks, Accipiter gentilis, during the nestling and early fledging phases. We measured body mass, wing length, tarsus length and four innate immune indices two to four times when nestlings were 12–29 days old. To determine which individuals had been predated during the nestling phase and shortly after fledging, we searched for metal rings of the jackdaws in the only goshawk territory close to the jackdaw colony. Nestling mortality before 12 days of age was entirely due to starvation, whereas between 12 days of age and fledging, mortality was mainly due to predation. Nestlings with smaller size (mass, wing, tarsus) and low lysis titre and haptoglobin concentrations were at a higher risk of being predated before fledging. Directly after fledging, individuals with short wings were preferentially predated, with no effects of body mass, tarsus length or any of the four immune indices measured at day 29 (i.e. shortly before fledging). That lower immune function and smaller size predict predation risk in nestlings may reflect that these individuals are of poor quality and/or lag behind in development. We hypothesize that hunger makes these nestlings sit closest to the entrance hole and hence become the first to be predated. For fledglings, our results suggest that poor flight ability makes individuals with short wings the easiest targets for avian predators.
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| 2. |
- Abolfathi, Bela, et al.
(författare)
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The Fourteenth Data Release of the Sloan Digital Sky Survey : First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment
- 2018
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Ingår i: Astrophysical Journal Supplement Series. - : IOP Publishing Ltd. - 0067-0049 .- 1538-4365. ; 235:2
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Tidskriftsartikel (refereegranskat)abstract
- The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014-2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V.
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| 3. |
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| 4. |
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| 5. |
- Andersson, Arne, et al.
(författare)
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Ottenby fågelstation : Årsrapport 1999
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Decenniets, seklets och milleniets sista år blev ett år av stora förändringar vid Ottenby fågelstation. Deföregående tre-fyra åren hade präglats av mycket dålig ekonomi och därtill personalproblem. Under 1998blev situationen akut. Som ett första led i att förbättra situationen ombildades Ottenbykommittén (avSveriges Ornitologiska Förening satt att sköta fågelstationen) under hösten 1998. Den störstaförändringen blev sedan att Jan Pettersson, platschef sedan 1978, sades upp. Därtill kom uppsägning,pensionering, dödsfall (se nedan) och sedan tidigare överflyttade tjänster till OFAB, vilket innebar detatt den “fast” anställda personalstyrkan, som 1992 var 7 personer, reducerades till noll!Ottenbykommittén har nu fått en mycket mer aktiv roll i stationens arbete. Olika verksamhetsdelar haridentifierats och ledamöterna har getts olika ansvarsområden.Kommittén bestod under året av :Åke Lindström (ordförande)Christian Hjort (sekreterare, utlandsverksamheten)Dennis Kraft (ekonomi)Arne Andersson (datafrågor)Dennis Hasselquist (samordning av ansökningar)Anders Hedenström (forskningssamordnare)Niclas Jonzén (personal)Lars Lindell (SOF:s styrelse).Aktiviteterna inom dessa olika områden redovisas nedan och här skallbara de generella linjerna i arbetet läggas fram.Tvivelsutan förbättrades arbetsklimatet för den ideellt arbetandepersonalen på fågelstationen och glädjande nog var tillströmningen storav arbetsvilliga ungdomar. Stationen blev på många sätt öppnare, inteminst mot fågelskådarleden. Fler personer besökte stationen och pådetta sätt kan många fler känna sig delaktiga och trivas. Nackdelen äratt det rent praktiskt blir svårare att driva verksamheten med mångamänniskor närvarande och relativt stor omsättning på personer.Genom mycket hård åtstramning på utgiftssidan kunde ett förväntat rejält underskott i budgeten vändastill en liten vinst. Alla inblandade skall ha stor ära av detta eftersom både stora som små uppoffringarkrävts för att styra ekonomin rätt. Den lilla vinsten användes till att börja täcka det underskott somunder många år ackumulerats. Även om det nu känns som att vi har en god kontroll över den löpandeekonomin så måste vi på lång sikt hitta fler finansieringskällor till stationens verksamhet. Det är tillexempel mycket otillfredsställande att vi nu inte har någon heltidsanställd personal, något som på siktmåste lösas.Fågelstationens gamla dröm om att ha en egen filial söder om Sahara gick i uppfyllelse under 1999 meden månads försöksverksamhet i Nigeria under våren. Denna slog väl ut på alla sätt och verksamhetenskall nu intensifieras under 2000.Datahanteringen fick sig en rejäl skjuts framåt under året och kan vi bara snart förnya maskinparken finnsgrunden för en smidig och effektiv datahantering vid stationen. Detta kommer att underlätta bådeutåtriktad verksamhet (Internet) och eget analysarbete.Ottenby Försäljnings AB (OFAB), som drivit den affärsmässiga delen av stationens verksamhet sedan1995, fortsatte sin verksamhet parallellt med fågelstationens ideella verksamhet. Genom verksamheten iNaturum och restaurang Fågel Blå svarar OFAB för en viktig del av fågelstationens publika aktiviteter.Det är av stor vikt för framtiden att behålla och utveckla det goda samarbetet mellan fågelstationen ochOFAB.Figur 1. Åke LindströmFigur 2. Patrik Rhönnstad, platschef 1999Kontinuiteten i det praktiska arbetet på stationen blev naturligtvis något lidande av att den rutineradepersonalen försvunnit. Situationen hjälptes dock upp signifikant av att OFABs personal fanns på plats(Håkan och Annika Lundkvist, Gösta Friberg) samt att nye platschefen och många av de ideelltarbetande hade erfarenhet från tidigare år.
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| 6. |
- Arlt, D, et al.
(författare)
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Breeding synchrony does not affect extra-pair paternity in great reed warblers
- 2004
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Ingår i: Behaviour. - : Brill. - 1568-539X .- 0005-7959. ; 141:7, s. 863-880
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Tidskriftsartikel (refereegranskat)abstract
- Breeding synchrony is hypothesised to influence the occurrence and frequency of extra-pair fertilisations (EPFs) in birds irrespective of the social mating system. The two proposed hypotheses make opposite predictions. (1) Synchronous breeding leads to a lower frequency of EPFs because males face a trade-off between mate guarding and obtaining additional matings via extra-pair copulations (EPCs) ('guarding constraint' hypothesis). (2) Synchronous breeding promotes EPFs because females are able to compare displaying males simultaneously, which provides them with more reliable cues for extra-pair mate choice ('mate assessment' hypothesis). In a study of great reed warblers (Acrocephalus arundillaceus) from 1987-1998, annual breeding was asynchronous and the frequency of EPFs was rather low (extra-pair young occurring in 6.4% of the broods). Within this population, however, there was no relationship between the frequency of EPFs and breeding synchrony, thus not favouring any of the two hypotheses. Contrary to assumptions of the hypotheses, mate guarding did not seem to constrain males from engaging in EPCs (disfavouring the 'guarding constraint' hypothesis), and females seem to have repeated opportunities to compare males irrespective of breeding synchrony (disfavouring the 'mate assessment' hypothesis). Our results suggest that breeding synchrony is not an important factor influencing patterns of EPFs in great reed warblers. The low frequency of EPFs may instead be explained by the socially polygynous mating system, where females are less constrained in their choice of a social male.
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| 7. |
- Arlt, D, et al.
(författare)
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Observation of a ZZW female in a natural population: implications for avian sex determination
- 2004
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 271:S4, s. 249-251
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Tidskriftsartikel (refereegranskat)abstract
- Avian sex determination is chromosomal; however, the underlying mechanisms are not yet understood. There is no conclusive evidence for either of two proposed mechanisms: a dominant genetic switch or a dosage mechanism. No dominant sex-determining gene on the female-specific W chromosome has been found. Birds lack inactivation of one of the Z chromosomes in males, but seem to compensate for a double dose of Z-linked genes by other mechanisms. Recent studies showing female-specific expression of two genes may support an active role of the W chromosome. To resolve the question of avian sex determination the investigation of birds with a 2A: ZZW or 2A: Z0 genotype would be decisive. Here, we report the case of an apparent 2A: ZZW great reed warbler (Acrocephalus arundinaceus) female breeding in a natural population, which was detected using Z-linked microsatellites. Our data strongly suggest a role of W-linked genes in avian sex determination.
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| 8. |
- Asghar, Muhammad, et al.
(författare)
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Cellular aging dynamics after acute malaria infection : A 12-month longitudinal study
- 2018
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Ingår i: Aging Cell. - : Wiley. - 1474-9718 .- 1474-9726. ; 17:1, s. 12702-12702
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Tidskriftsartikel (refereegranskat)abstract
- Accelerated cellular aging and reduced lifespan have recently been shown in birds chronically infected with malaria parasites. Whether malaria infection also affects cellular aging in humans has not been reported. Here, we assessed the effect of a single acute Plasmodium falciparum malaria infection on cellular aging dynamics in travelers prospectively followed over one year in Sweden. DNA and RNA were extracted from venous blood collected at the time of admission and repeatedly up to one year. Telomere length was measured using real-time quantitative PCR, while telomerase activity and CDKN2A expression were measured by reverse transcriptase (RT)-qPCR. Our results show that acute malaria infection affects cellular aging as reflected by elevated levels of CDKN2A expression, lower telomerase activity, and substantial telomere shortening during the first three months postinfection. After that CDKN2A expression declined, telomerase activity increased and telomere length was gradually restored over one year, reflecting that cellular aging was reversed. These findings demonstrate that malaria infection affects cellular aging and the underlying cellular mechanism by which pathogens can affect host cellular aging and longevity need to be elucidated. Our results urge the need to investigate whether repeated malaria infections have more pronounced and long-lasting effects on cellular aging and lifespan (similarly to what was observed in birds) in populations living in malaria endemic areas.
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| 9. |
- Asghar, Muhammad, et al.
(författare)
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Parallel telomere shortening in multiple body tissues owing to malaria infection
- 2016
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 283:1836
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have shown associations between shorter telomere length in blood and weakened immune function, susceptibility to infections, and increased risk of morbidity and mortality. Recently, we have shown that malaria accelerates telomere attrition in blood cells and shortens lifespan in birds. However, the impact of infections on telomere attrition in different body tissues within an individual is unknown. Here, we tested whether malarial infection leads to parallel telomere shortening in blood and tissue samples from different organs. We experimentally infected siskins (Spinus spinus) with the avian malaria parasite Plasmodium ashfordi, and used real-time quantitative polymerase chain reaction (PCR) to measure telomere length in control and experimentally infected siskins. We found that experimentally infected birds showed faster telomere attrition in blood over the course of infection compared with control individuals (repeatedly measured over 105 days post-infection (DPI)). Shorter telomeres were also found in the tissue of all six major organs investigated (liver, lungs, spleen, heart, kidney, and brain) in infected birds compared with controls at 105 DPI. To the best of our knowledge, this is the first study showing that an infectious disease results in synchronous telomere shortening in the blood and tissue cells of internal organs within individuals, implying that the infection induces systemic stress. Our results have far-reaching implications for understanding how the short-term effects of an infection can translate into long-term costs, such as organ dysfunction, degenerative diseases, and ageing.
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