| 1. |
- Andersson, Måns Sverker, et al.
(författare)
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A partly coverable badge signalling avian virus resistance
- 2006
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Ingår i: Acta Zoologica. ; :87, s. 71-76
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: We investigated whether the sexually selected forehead patch of the collared flycatcher Ficedula albicollis is an honest badge of status indicating quality expressed as immunological response. We used both manual measurements and digital measurements, the latter based on photographs. Badge-size data were collected during the mating period and during the nestling feeding period to capture trait plasticity. Concomitant with first sample collection, birds were inoculated with a novel antigen. Antibody response was strongly and positively correlated with badge expression during the mating period and with the increase in badge expression during the mating period as compared with outside this period. The results support the Hansen and Rohwer theory of coverable badges, are consistent with the immunocompetence handicap hypothesis and with the good genes model suggesting that, on a population level, the expression of secondary sexual traits should be an honest signal positively associated with traits that are beneficial for survival. The results also suggest that manual measurements of this type of secondary sexual trait are sufficiently exact.
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| 2. |
- Boström, Jannika E., et al.
(författare)
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Ultra-Rapid Vision in Birds
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively), which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey.
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| 3. |
- de Jong, Johnny, et al.
(författare)
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Activity Pattern and Correlation between Bat and Insect Abundance at Wind Turbines in South Sweden
- 2021
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Ingår i: Animals. - : MDPI AG. - 2076-2615. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary:& nbsp;Wind power is an important energy system in the global transition towards renewable energy. As new wind farms are erected in increasing numbers, they will have an impact on many organisms, e.g., through habitat changes and collision mortalities. In this study, we measure bat activity, insect abundance, and weather conditions to test the hypothesis that insect abundance attracts bats to wind turbines because of feeding opportunities. We found that the relationship between insect abundance and bat activity was relatively weak, providing some support for the feeding-attraction hypothesis. However, we also found a strong correlation between bat passes and weather conditions. This suggests that stop-regulation based on weather conditions might be a solution to avoid collisions. However, this study highlights some of the problems with defining the limits for stop-regulation, as bat activity may be high also at relatively high wind speeds and low temperatures.& nbsp;We present data on species composition and activity of bats during two years at three different wind- turbines, located in south Sweden, both at the base and nacelle height. To test the hypothesis that bats are attracted to wind turbines because of feeding opportunities, insects were sampled at nacelle height at one wind turbine using a suction trap, simultaneously as bat activity were measured. At this wind turbine, we also compared two different technical systems for ultrasound recordings and collect meteorological data. The variation in bat activity was high between nights and between wind turbines. In addition to the expected open-air foraging species (Pipistrellus, Nyctalus, Vespertilio and Eptesicus), some individuals of unexpected species (Myotis, Barbastella, and Plecotus) were found at nacelle height. There was a weak but significant positive relation between bat activity and insect abundance, so the hypothesis could not be rejected, suggesting there might be other factors than insect abundance explaining the frequency of bat visits at the nacelle. We found a strong correlation between bat passes and weather conditions. A reasonable way to mitigate collisions is with stop-regulation. However, this study highlights some of the problems with defining the limits for stop-regulation based on weather conditions.
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| 4. |
- de Jong, Johnny, et al.
(författare)
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Aktivitet av fladdermöss och insekter vid ett vindkraftverk
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det är väl dokumenterat att fladdermöss kan kollidera med vindkraftverk och det är viktigt att kartlägga de bakomliggande faktorerna för att minska risken för kollisioner. Det finns ett antal hypoteser som kan förklara varför fladdermöss kan förekomma vid vindkraftverkens rotorblad. En av dessa, som testas i den här studien, är att vindkraftverken attraherar insekter, och att fladdermössen nyttjar denna resurs för födosök. För att testa hypotesen placerades en insektsfälla vid nacellen på ett vindkraftverk i Småland, tillsammans med en mikrofon som registrerar fladdermusljud. Insektsfällan var en sugfälla som endast fångade insekter under natten, och utan att attrahera insekterna. Fångst av insekter och registrering av fladdermusljud gjordes under perioden 28 juni till 3 november, 2017. Samtidigt registrerades väderleksvariabler som temperatur, vindhastighet, vindriktning och nederbörd. Registrering av fladdermöss gjordes även under perioden 1 juli till 31 oktober 2018.Resultatet visar att det finns en korrelation mellan fladdermusaktiviteten och insektsabundansen. Det finns också signifikanta korrelationer mellan fladdermusaktivitet, temperatur och vindhastighet, liksom mellan insektsabundans och vindhastighet. Den negativa korrelationen mellan antal insekter och vindhastighet var ganska stark. Övriga korrelationer är dock ganska svaga och variationen var stor både när det gäller fladdermusaktivitet och insektsabundans. Sambanden mellan fladdermusaktivitet och väderlek tycks inte vara linjära. Fladdermusaktiviteten minskar när temperaturen sjunker under 10 grader och när vindhastigheten är större än 12 m/s. Vi kan också konstatera att det inte fanns någon korrelation mellan fladdermusaktiviteten på marken och aktiviteten uppe vid nacellen. Olika fladdermustaxa hade sin maximala aktivitet vid nacellen under olika tidpunkter, men med ett visst överlapp.Resultatet från studien ger stöd åt hypotesen att fladdermössen förekommer vid nacellen av vindkraftverken för födosök, men eftersom sambandet är så svagt, och variationen så stor ligger det nära till hands att anta att det finns fler faktorer inblandade, alternativt att fladdermössen är ganska dåliga på att prediktera insektsförekomsten. Ett sätt att minska dödligheten för fladdermöss i ett konfliktområde skulle kunna vara att minska vindkraftverkens attraktion av insekter (ljud, färg, belysning mm). Ett annat sätt kan vara stoppreglering under vissa väderbetingelser, och under vissa tidsperioder. Om man väljer stoppreglering blir det viktigt att så bra som möjligt ringa in under vilka förutsättningar vindkraftverken bör stå stilla. Vår bedömning är att variationen när det gäller fladdermusförekomst och dess respons på väderfaktorer kan vara ganska stor i olika geografiska regioner och det är därför viktigt att upprepa den här typen av försök på flera platser.
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| 5. |
- Håstad, Olle, et al.
(författare)
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A vision physiological estimation of ultraviolet window marking visibility to birds
- 2014
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 2, s. e621-
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Tidskriftsartikel (refereegranskat)abstract
- Billions of birds are estimated to be killed in window collisions every year, worldwide. A popular solution to this problem may lie in marking the glass with ultraviolet reflective or absorbing patterns, which the birds, but not humans, would see. Elegant as this remedy may seem at first glance, few of its proponents have taken into consideration how stark the contrasts between ultraviolet and human visible light reflections or transmissions must be to be visible to a bird under natural conditions. Complicating matters is that diurnal birds differ strongly in how their photoreceptors absorb ultraviolet and to a lesser degree blue light. We have used a physiological model of avian colour vision to estimate the chromatic contrasts of ultraviolet markings against a natural scene reflected and transmitted by ordinary window glass. Ultraviolets markings may be clearly visible under a range of lighting conditions, but only to birds with a UVS type of ultraviolet vision, such as many passerines. To bird species with the common VS type of vision, ultraviolet markings should only be visible if they produce almost perfect ultraviolet contrasts and are viewed against a scene with low chromatic variation but high ultraviolet content.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Håstad, Olle, 1971-
(författare)
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Plumage Colours and the Eye of the Beholder : The Ecology of Colour and its Perception in Birds
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Virtually all diurnal birds have tetrachomatic vision based on four different colour receptors. As a result, birds are potentially able to perceive their environment in twice as many colours as humans and four times as many colours compared to most other mammals, which are dichromatic. In addition to the spectrum visible to humans, birds are able to detect ultraviolet (UV) light. Signals with a UV component have been shown to be important to birds both in foraging and colour signalling. Because of the superior colour discrimination of the avian eye, UV sensitivity, but especially owing to its tetrachromacy, we cannot know what birds look like to those that matter, i.e. other birds.In my thesis I describe a new molecular method with which it is possible to identify the vision system of birds only using a small amount of DNA, without the need to keep or sacrifice the animal. It thereby facilitates large screenings, including rare and endangered species. The method has been used to increase the number of species with identified vision system type from 19 to 66. I show that raptors and songbirds have different vision systems, giving songbirds the possibility of a secret channel for colour signalling, and that male songbirds in coniferous forest take advantage of this to be significantly more cryptic to raptors than to females songbirds. I show that gulls have gained a vision system enabling them to detect the UV signals of fish when the fish swim close to the surface.Even though we tend to be rather self-satisfied with the quality of our colour vision, we are colour-blind when compared to birds. My work shows that human colour vision is inadequate for judging animal coloration, and that there is much more going on in bird colour signalling than meets our eye.
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| 10. |
- Håstad, Olle, 1971-, et al.
(författare)
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Ultraviolet photopigment sensitivity and ocular media transmittance in gulls, with an evolutionary perspective
- 2009
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Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 195:6, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- Gulls (Laridae excluding Sternidae) appear to be the only shorebirds (Charadriiformes) that have a short wavelength sensitive type 1 (SWS1) cone pigment opsin tuned to ultraviolet (UV) instead of violet. However, the apparent UV-sensitivity has only been inferred indirectly, via the interpretation that the presence of cysteine at the key amino acid position 90 in the SWS1 opsin confers UV sensitivity. Unless the cornea and the lens efficiently transmit UV to the retina, gulls might in effect be similar to violet-sensitive birds in spectral sensitivity even if they have an ultraviolet sensitive (UVS) SWS1 visual pigment. We report that the spectral transmission of the cornea and lens of great black-backed Larus marinus and herring gulls L. argentatus allow UV-sensitivity, having a λ value, 344 nm, similar to the ocular media of UV sensitive birds. By molecular sequencing of the second α-helical transmembrane region of the SWS1 opsin gene we could also infer that 15 herring gulls and 16 yellow-legged gulls L. michahellis, all base-pair identical, are genetically UV-sensitive.
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| 11. |
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| 12. |
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| 13. |
- Lisney, Thomas J., et al.
(författare)
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Behavioural assessment of flicker fusion frequency in chicken Gallus gallus domesticus
- 2011
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Ingår i: Vision Research. - : Elsevier BV. - 0042-6989 .- 1878-5646. ; 51:12, s. 1324-1332
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Tidskriftsartikel (refereegranskat)abstract
- To interact with its visual environment, an organism needs to perceive objects in both space and time. High temporal resolution is hence important to the fitness of diurnally active animals, not least highly active aerial species such as birds. However, temporal resolution, as assessed by flicker fusion frequency (FFF; the stimulus frequency at which a flickering light stimulus can no longer be resolved and appears continuous) or critical flicker fusion frequency (CFF; the highest flicker fusion frequency at any light intensity) has rarely been assessed in birds. In order to further our understanding of temporal resolution as a function of light intensity in birds we used behavioural experiments with domestic chickens (Gallus gallus domesticus) from an old game breed 'Gammalsvensk dvarghona' (which is morphologically and behaviourally similar to the wildtype ancestor, the red jungle fowl, G. gallus), to generate an 'Intensity/FFF curve' (I/FFF curve) across full spectrum light intensities ranging from 0.2 to 2812 cd m(-2). The I/FFF curve is double-branched, resembling that of other chordates with a duplex retina of both rods and cones. Assuming that the branches represent rod and cone mediated responses respectively, the break point between them places the transition between scotopic and photopic vision at between 0.8 and 1.9 cd m(-2). Average FFF ranged from 19.8 Hz at the lowest light intensity to a CFF 87.0 Hz at 1375 cd m(-2). FFF dropped slightly at the highest light intensity. There was some individual variation with certain birds displaying CFFs of 90-100 Hz. The FFF values demonstrated by this non-selected breed appear to be considerably higher than other behaviourally derived FFF values for similar stimuli reported for white and brown commercial laying hens, indicating that the domestication process might have influenced temporal resolution in chicken.
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| 14. |
- Lisney, Thomas J., et al.
(författare)
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Using electroretinograms to assess flicker fusion frequency in domestic hens Gallus gallus domesticus
- 2012
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Ingår i: Vision Research. - : Elsevier BV. - 0042-6989 .- 1878-5646. ; 62, s. 125-133
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Tidskriftsartikel (refereegranskat)abstract
- The assessment of flicker fusion frequency (FFF), the stimulus frequency at which a flickering light stimulus can no longer be resolved and appears continuous, and critical flicker fusion frequency (CFF; the highest frequency at any light intensity that an observer can resolve flicker) are useful methods for comparing temporal resolution capabilities between animals. Behavioural experiments have found that average CFFs in domestic chickens (Gallus gallus domesticus) are in the range of ca. 75-87 Hz, measured in response to full spectrum (i.e. white light plus UV) stimuli. In order to examine whether the chicken retina is able to detect flicker at higher frequencies, we used electroretinograms (ERGs) to assess FFF/CFF in adult hens from two commercial genotypes, Lohmann Selected Leghorns (LSLs) and Lohmann Browns (LBs). ERGs were recorded in response to flickering light at ten full spectrum light intensities ranging from 0.7 to 2740 cd m(-2). Two methods were used to determine FFF/CFF from the ERG recordings and these methods yielded very similar results, with average FFF ranging from ca. 20 Hz at 0.7 cd m(-2) to an average CFF of ca. 105 Hz at 2740 cd m(-2). In some individuals, CFFs of 118-119 Hz were recorded. The Intensity/FFF (I/FFF) curves are double-branched with a break point representing the rod-cone transition occurring between 2.5 and 5.9 cd m(-2). No significant differences in the I/FFF curves were found between the two genotypes. At stimulus light intensities >250 cd m(-2), the ERG-derived FFF and CFF values are all higher than those from behavioural studies using the same stimuli. Although hens do not appear to be able to consciously perceive flicker above approximately 90 Hz, the finding that the ERG responses are able to remain in phase with light flickering at frequencies >100 Hz means that the retinae of domestic poultry housed in artificial light conditions may be able to resolve flicker from fluorescent lamps. As range of detrimental effects have been reported in humans as a result of exposure to such "invisible flicker", the possibility exists that flicker from fluorescent lamps also acts as stressor in domesticated birds.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Rubene, Diana, et al.
(författare)
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The presence of UV wavelengths improves the temporal resolution of the avian visual system
- 2010
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 213:19, s. 3357-3363
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Tidskriftsartikel (refereegranskat)abstract
- The ability to perceive rapid movement is an essential adaptation in birds, which are involved in rapid flight, pursuing prey and escaping predators. Nevertheless, the temporal resolution of the avian visual systems has been less well explored than spectral sensitivity. There are indications that birds are superior to humans in their ability to detect movement, as suggested by higher critical flicker frequencies (CFFs). It has also been implied, but not properly tested, that properties of CFF, as a function of light intensity, are affected by the spectral composition of light. This study measured CFF in the chicken, Gallus gallus L., using four different light stimuli - white, full-spectrum (white with addition of UV), yellow (590 nm) and UV (400 nm) - and four light intensity levels, adjusted to relative cone sensitivity. The results showed significantly higher CFF values for full-spectrum compared with white light, as well as a steeper rate of increase with intensity. The presence of UV wavelengths, previously demonstrated to affect mate choice and foraging, appears to be important also for detection of rapid movement. The yellow and UV light stimuli yielded rather similar CFFs, indicating no special role for the double cone in flicker detection.
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| 19. |
- Rudh, Andreas, et al.
(författare)
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Rapid population divergence linked with co-variation between coloration and sexual display in strawberry poison frogs
- 2011
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 65:5, s. 1271-1282
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Tidskriftsartikel (refereegranskat)abstract
- The likelihood of speciation is assumed to increase when sexually selected traits diverge together with ecologically important traits. According to sexual selection theory, the evolution of exaggerated display behavior is driven by increased mating success, but limited by natural selection, for example, through predation. However, the evolution of aposematic coloration (i.e., an ecologically important trait) could relieve the evolution of exaggerated display behavior from the bound of predation, resulting in joint divergence in aposematic coloration and sexual display behavior between populations. We tested this idea by examining conspicuousness, using color contrasts between individuals and their native backgrounds, and sexual display of 118 males from genetically diverged populations of the Strawberry poison frog, Dendrobates pumilio. Our results show that the level of conspicuousness of the population predicts the sexual display behavior of males. Males from conspicuous populations used more exposed calling sites. We argue that changes in aposematic coloration may rapidly cause not only postmating isolation due to poorly adapted hybrids, but also premating isolation through shifts in mating behaviors.
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| 20. |
- Victorsson, Jonas, et al.
(författare)
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Insekters attraktion till färger och hinderbelysning på vindkraftverk : Slutrapport
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det är antagligen flera faktorer som bestämmer hur mycket insekter som finns tillgängliga för fladdermöss och fåglar vid vindkraftverk. I detta projekt testade vi om anlockningen av insekter påverkas av blinkfrekvensen eller färgsammansättningen hos vindkraftverkens hinderbelysningsljus eller av kraftverkens färg. Vi genomförde fyra försöksserier av insekters anlockning till nuvarande och alternativa blinkregimer och färger i en dubbelsidig försöksanordning på marknivå. Principen för försöksanordningen är att insekterna flyger mot den belysta eller färgade ytan om de upplever ytan som attraktiv. Insekter som kommer nära den belysta/färgade ytan samlas upp med en sugfälla. Den dubbelsidiga designen gör att vi provtar samma lokala insektsfauna och kontrollerar för väderförhållanden och andra miljöfaktorer.Resultaten från blinkförsöken visade att anlockningen av Diptera (tvåvingar, främst myggor) minskade om lampan var tänd kortare tid per minut än den nuvarande blinkregim som används vid hinderbelysning (40 blinkningar per minut med en duty cycle på 0.5). Vid 10 blinkningar per minut och en duty cycle på 0.03, vilket var den lägsta vi testade, så minskade anlockningen av insekter med 30 %. Resultatet varierade mellan olika insektsfamiljer och för Chironomidae (fjädermyggor) minskade anlockningen med hela 56 %. Blinkningens längd i den behandlingen är dock endast 0.2 s vilket knappast är förenligt med god flygsäkerhet. Detta resultat visar dock tydligt att det går att minska insektsanlockningen genom att ändra blinkregimen.Vi fann även att mindre förändringar av blinkregimen som bör kunna accepteras som tillräckligt säkra för luftfarten gav lägre anlockning av insekter. När vi minskade lampans duty cycle från 0.5 till 0.3 eller 0.1 men behöll 40 blinkningar per minut minskade antalet myggor som lockas till belysningen med mellan 6 % och 18 %. Att sänka antalet blinkningar till 20 per minut men behålla en duty cycle på 0.5 sänkte också anlockningen av myggor men endast med 6 %. Anlockningen av nattflygande fjärilar sänktes endast i två av våra tio testade blinkregimer. Antalet infångade fjärilar var dock få jämfört med antalet myggor (91 % av insekterna var myggor och endast 7 % var fjärilar). Om det är värt att förändra nuvarande blinkregim för att uppnå minskningar i anlockningen av insekter i storleksordningen 6 % till 18 % beror bland annat på om den minskningen kommer att leda till lägre fladdermusdödlighet. Att ta reda på detta kräver ytterligare studier.I ett ytterligare försök nattetid så testade vi anlockningen till LEDlampor som var framtagna för att så nära som möjligt motsvara en vit färg för människor medan de skulle vara så ”osynlig” som möjligt för insekterna. Med ”osynlig” menas att topparna i lampans färgspektrum, skulle så nära som möjligt, ligga i de ”dalar” som insekter har i sitt färgseende. Denna belysning skulle då kunna ersätta dagens hinderbelysning. Den ena färgen, gulblå, bestod av en blandning av gula och blå LED-lampor. Den andra färgen, blågrön bestod av en blandning av blå och gröna LED-lampor.Våra två testade LED-lampor fungerade inte alls som planerat. Tvärtom lockade båda lamporna till sig flera djur än kontrollen när vi analyserade hela insektsmaterialet tillsammans. Stövsländorna var den enda grupp som reagerade som förväntat och hos den ordningen så lockade den blågröna, lampan till sig 42 % färre djur än kontrollen. I analysen av de enskilda insektsfamiljerna så var det ingen skillnad på blågrön och kontrollen för nio av de tretton testade familjerna vilket i sig är intressant eftersom insekterna i dessa familjer då inte ser någon skillnad på vanligt vitt ljus och det vita ljus vi skapat med blåa och gröna LED-lampor. Vi avser att gå vidare i vår analys genom att beräkna det antal fotoner som respektive insektsgrupp uppfattade utifrån deras spektrala känsligheter, i de fall där dessa är kända. Vi hoppas med detta bättre förstå vilka ljusparametrar som avgör attraktionskraften för insekterna, men ur ett praktiskt perspektiv kan vi dra slutsatsen att den nuvarande ljussammansättningen är bra, och inte på ett enkelt sätt kan ändras för att radikalt minska antalet insekter.Vi genomförde också ett försök med anlockning till färger dagtid. Här testade vi dels färger som används idag och dels färger som skulle kunna ersätta dagens färger. Vi fann att den gula färg som används på vindkraftverk till havs lockar till sig flera insekter än den vita färg som är vanligast på vindkraftverk på land. Vi testade en orange färg som skulle kunna vara ett alternativ till den gula färgen men fann att den var lika dålig som den gula. Vi testade en grå färg som är tillåten idag och fann att den var något sämre än den vita färgen, den ökade anlockningen av myggor och flugor med 4 %. En ljust grön färg lockade till sig färre insekter än den vita färg som används idag men minskningen var liten (4 %). Lila har i en tidigare studie förts fram som ett alternativ som lockar till sig få insekter. Våra resultat motsäger detta och den lila färg vi testade ökade istället anlockningen av steklar. Den färg som minskade insektsanlockningen mest var rosa (12 % färre myggor och flugor). Detta resultat visar att det går att minska anlockningen genom att välja en lämplig färg. Att måla nederdelen av vindkraftverk rosa eller ljusgrönt skulle dock påverka synligheten för människor och är inte en lämplig åtgärd i alla miljöer. I miljöer där man har skog nära inpå kraftverken så skulle dock synligheten öka bara marginellt om man målar kraftverken upp till trädtoppshöjd.
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| 21. |
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| 22. |
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| 23. |
- Wichman, Anette, et al.
(författare)
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Influence of Different Light Spectrums on Behaviour and Welfare in Laying Hens
- 2021
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Ingår i: Animals. - : MDPI AG. - 2076-2615. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Simple SummaryThis study investigated how different types of lighting affect laying hen behaviour and welfare. Amount and quality of light are important for birds to perform their natural behaviours, e.g., find food and water, recognise conspecifics and safely navigate their environment. The lighting used in poultry production facilities differs considerably from light conditions in the natural environment in which domestic fowl have evolved, which might have negative consequences for their welfare. This study examined whether light closely resembling natural daylight and light found in forest understory in Southeast Asia (ancestral habitat of jungle fowl) affected the behaviour of laying hens. The results revealed that birds had a preference for natural lighting in some situations. It is likely that these effects were due to the presence of ultraviolet light, which is known to be important for visual performance in birds. However, the differences were rather small, indicating that sufficient light intensity and other quality factors in the housing environment are more important in maintaining high welfare than the specific spectral composition of the light. This new knowledge can be used to improve the housing environment of domestic fowl by supplying artificial spectrums replicating natural lighting.Artificial commercial lighting used in animal production facilities can have negative influences on visual abilities, behaviour and welfare of domestic fowl. This study examined the effects of natural-derived light spectrums on behaviour, production and welfare of laying hens reared from hatching into adulthood. Comparisons were made of frequency of a range of behaviours associated with activity, aggression and comfort in birds kept in control light (commercial standard), daylight (full spectrum, including ultraviolet (UV) wavelengths and forest light (forest understorey, including UV). In addition, bird preferences for different lights, feather damage and egg production were monitored. The results showed that the behavioural repertoire of birds changed with age, while the effects of light treatment were subtle. Some evidence was found that birds preferred either daylight or forest light to control light, suggesting that inclusion of UV contributed to the preference. Daylight and forest light were associated with more active behaviours, and daylight with better plumage and later start of lay. Thus natural-like light may have beneficial effects on domestic fowl, but the differences between broad-spectrum light sources are rather small.
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| 24. |
- Zhang, Guojie, et al.
(författare)
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Comparative genomics reveals insights into avian genome evolution and adaptation
- 2014
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 346:6215, s. 1311-1320
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Tidskriftsartikel (refereegranskat)abstract
- Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits.
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| 25. |
- Ödeen, Anders, 1969-, et al.
(författare)
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Assessing the use of genomic DNA as a predictor of the maximum absorbance wavelength of avian SWS1 opsin visual pigments
- 2009
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Ingår i: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology. - : Springer Science and Business Media LLC. - 0340-7594 .- 1432-1351. ; 195:2, s. 167-173
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Tidskriftsartikel (refereegranskat)abstract
- Recently, in vitro mutation studies have made it possible to predict the wavelengths of maximum absorbance (λmax) of avian UV/violet sensitive visual pigments (SWS1) from the identity of a few key amino acid residues in the opsin gene. Given that the absorbance spectrum of a cone's visual pigment and of its pigmented oil droplet can be predicted from just the λmax, it may become possible to predict the entire spectral sensitivity of a bird using genetic samples from live birds or museum specimens. However, whilst this concept is attractive, it must be validated to assess the reliability of the predictions of λmax from opsin amino acid sequences. In this paper, we have obtained partial sequences covering three of the known spectral tuning sites in the SWS1 opsin and predicted λmax of all bird species for which the spectral absorbance has been measured using microspectrophotometry. Our results validate the use of molecular data from genomic DNA to predict the gross differences in λmax between the violet- and ultraviolet-sensitive subtypes of SWS1 opsin. Additionally, we demonstrate that a bird, the bobolink Dolichonyx oryzivorus L., can have more than one SWS1 visual pigment in its retina.
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