1,720,984 research outputs found
Data for: Anti-predator phenotype in crucian carp altered by a psychoactive drug
No full textPredator-inducible defences constitute a widespread form of adaptive phenotypic plasticity, and such defences have recently been suggested linked with the neuroendocrine system. The neuroendocrine system is a target of endocrine disruptors, such as psychoactive pharmaceuticals, which are common aquatic contaminants. We hypothesized that exposure to an antidepressant pollutant, fluoxetine, influences the physiological stress response in our model species, crucian carp, affecting its behavioural and morphological responses to predation threat. We examined short- and long-term effects of fluoxetine and predator exposure on behaviour and morphology in crucian carp. 17 days of exposure to a high dose of fluoxetine (100 µg L-1), resulted in a shyer phenotype, regardless of the presence/absence of a pike predator, but this effect disappeared after long-term exposure. Fluoxetine effects on morphological plasticity was context dependent as a low dose (1 µg L-1) only influenced crucian carp body shape in pike presence. A high dose of fluoxetine strongly influenced body shape regardless of predator treatment. Our results highlight that environmental pollution by pharmaceuticals could disrupt physiological regulation of ecologically important inducible defences.Funding provided by: VetenskapsrådetCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100004359Award Number: 621-2014-524
Defence on Demand : A physiological perspective on phenotypic plasticity in anti-predator traits
Get PDFAlmost all species face some degree of predation risk, and, hence, evolution has produced a plethora of anti-predator defences. However, anti-predator strategies require resources, and the prevailing risk of becoming prey is influenced by many factors and rarely constant across time and space. Evolution has therefore favoured the development of phenotypic plasticity in anti-predator defences. The capacity of a single genotype to fine-tune its phenotype according to the prevailing risk of predation results in a closer phenotype-environment match in the mercurial environments of the natural world. Interest in the ecology and evolution of inducible defences has progressed the development of its theoretical underpinnings, along with empirical tests of theoretical predictions. Inter-individual differences in the expression of inducible traits are nowadays understood ubiquitous, and this intriguing variation holds possibility to bridge our current knowledge gap on the proximate, physiological mechanisms underlying inducible morphological defence regulation. In this thesis, I address unanswered questions on the proximate, physiological processes behind phenotypic plasticity in morphological defences. I first examine classic resource-allocation trade-offs to search for hidden physiological costs coupled with perceived predation risk and investment into a morphological defence. I further employ a recent hypothesis of physiological stress being the mechanism driving morphological defence regulation. To test my predictions, I have used a well-established model system for the study of inducible morphological defences, the crucian carp (Carassius carassius). I show that innate immune functions are altered by predator exposure, and that the defence against pathogens is correlated with the morphological defence against larger-sized enemies (predators). Second, from a series of laboratory experiments and field studies, I demonstrate support for the hypothesis of stress physiology being involved in plastic defence expression, and that crucian carp display clear sexual dimorphism in the anti-predator phenotype. I suggest that this is due to sex-specific trade-off dynamics, where females invest more into reproduction, resulting in less resources for anti-predator protection. Finally, I present novel trait changes (changes in body colour, diel activity and eye morphology) in response to non-lethal predation risk that may act in synergy to produce an integrated anti-predator phenotype. In summary, my results illustrate a potential causality from the vertebrate stress axis to the regulation of morphological defence expression. Further, my thesis highlights variation and complexity on the route to producing optimal anti-predator phenotypes under competing demands from other interests
Åtgärdsprogram för mal : (Siluris glanis)
No full textÅtgärdsprogrammet syftar till att förbättra malens (Siluris glanis) överlevnad i landet. Det är ett vägledande, men ej legalt bindande, aktionsprogram. Malen är Sveriges största sötvattensfisk. Den största mal som fångats i Sverige var 3,6 meter lång och vägde uppskattningsvis 180 kg. Malen vandrade in till Sverige under Ancylus-perioden, när Östersjön var ett varmt och sött innanhav. Malen lever i sjöar och flodmiljöer. Den är allätare och kan utöver fisk även äta groddjur, gnagare, fåglar, kräftor, insekter, maskar och blötdjur. Malen är revirhävdande, framför allt under lektiden. För sin reproduktion är den beroende av varmt vatten samt vattenväxter och strandnära vegetation. Hanen bygger ett bo bland vegetation och rötter dit honan lockas för lek. Hanen vaktar sedan äggen tills de kläckts. Ungarna växer upp i skydd av vegetationen. I Sverige var arten mer spridd förr, men förändringar i markanvändningen från 1800-talets mitt, med exempelvis sjösänkningar och anläggande av vattenkraftverk, har minskat förekomsten. Idag finns malen endast kvar i fyra ursprungliga områden: Båvenområdet, Emån, övre delen av Helge å och nedre delen av Helge å. Utöver dessa är mal känd från ett fåtal andra sjöar, varav de flesta är illegala utsättningar. Hotbilden är idag fragmentering och isolerade bestånd då många vattendrag och sjösystem är påverkade av vattenkraft och andra dämmen, vilka hindrar malen från att sprida sig till fler och större områden. Sjösänkningar, rensningar av vattendrag och annan verksamhet har inneburit och innebär än idag att lämpliga lekmiljöer och uppväxtområden försvunnit. Genetiska undersökningar visar att malpopulationerna i Sverige har låg genetisk variation och att det troligtvis är få individer som deltar i leken, vilket talar för att antalet lekhabitat är en begränsande faktor idag. I den svenska rödlistan från 2015 klassas malen som Sårbar (VU). Malen är fredad från fiske enligt 2 kap. 5 § i förordningen (1994:1716) om fisket, vattenbruket och fiskenäringen. Målet med programmet är att förstärka bestånden genom åtgärdande av vandringshinder samt översyn och anpassning av reglering. Andra viktiga åtgärder är olika biotopförbättrande åtgärder, exempelvis gynnade av strandnära vegetation och test av konstgjorda leknästen. Utöver detta finns ett stort fokus på förbättrat kunskapsunderlag och informationsspridning. De åtgärder som förutsätts finansieras av Havs- och vattenmyndighetens medel för genomförande av åtgärdsprogram för hotade arter beräknas totalt uppgå till 5 875 000kr under programmets giltighetsperiod 2017– 2021.This action program aims to improve the status of the European catfish (Siluris glanis) in Sweden. It is an indicative, but not legally binding, action program. The European catfish migrated to Swedish lake and river environments during the Ancylus lake period, an era when the temperature was higher than today. The species is the largest freshwater fish in Sweden with a record measuring 3.6 meters standard length and an estimated weight of about 180 kg. It is considered to be nocturnal and an opportunistic predator eating both fish and other freshwater organisms, such as amphibians, birds, crayfishes, insects, worms and molluscs. The species require relatively high water temperatures to spawn, which means it is not reproducing every year in Swedish waters. The European catfish is listed as Vulnerable (VU) on the Swedish red list. Four natural populations exist, all located in the southeast of Sweden, in the water systems Nyköpingsån (lake Båven), Emån, the upper part of Helge å and the lower part of Helge å. Additional records are known from a few other lakes, all results of illegal releases. The main reason for the decline is destruction of suitable habitat, such as large lowland rivers with a natural river environment. These habitats have been severely affected by human interference from the 19th century onwards, such as drainage of wetlands, water regulation, diversion of water, and physical impact on shore and bottom habitats. Genetic studies show that the populations in Sweden are genetically unique, but have low genetic variation indicating that the number of spawning individual is low, possibly due to lack of suitable spawning habitats. The European catfish is protected from fishing in Sweden. Other important measures is to make suitable habitats available by review and adjustments of legislation and water regulations in force. Also to improve the biotopes, for example promote the access to suitable spawning habitats and experiments with artificial nests. In addition, there is a great focus on an improved knowledge base and dissemination of information. The cost for the conservation measures, to be funded from Swedish Agency for Marine and Water Management allocation for action plans is estimated at 580 000 € during the period 2017-2021
Åtgärdsprogram för mal [Elektronisk resurs] : (Siluris glanis)
No full textÅtgärdsprogrammet syftar till att förbättra malens (Siluris glanis) överlevnad i landet. Det är ett vägledande, men ej legalt bindande, aktionsprogram. Malen är Sveriges största sötvattensfisk. Den största mal som fångats i Sverige var 3,6 meter lång och vägde uppskattningsvis 180 kg. Malen vandrade in till Sverige under Ancylus-perioden, när Östersjön var ett varmt och sött innanhav. Malen lever i sjöar och flodmiljöer. Den är allätare och kan utöver fisk även äta groddjur, gnagare, fåglar, kräftor, insekter, maskar och blötdjur. Malen är revirhävdande, framför allt under lektiden. För sin reproduktion är den beroende av varmt vatten samt vattenväxter och strandnära vegetation. Hanen bygger ett bo bland vegetation och rötter dit honan lockas för lek. Hanen vaktar sedan äggen tills de kläckts. Ungarna växer upp i skydd av vegetationen. I Sverige var arten mer spridd förr, men förändringar i markanvändningen från 1800-talets mitt, med exempelvis sjösänkningar och anläggande av vattenkraftverk, har minskat förekomsten. Idag finns malen endast kvar i fyra ursprungliga områden: Båvenområdet, Emån, övre delen av Helge å och nedre delen av Helge å. Utöver dessa är mal känd från ett fåtal andra sjöar, varav de flesta är illegala utsättningar. Hotbilden är idag fragmentering och isolerade bestånd då många vattendrag och sjösystem är påverkade av vattenkraft och andra dämmen, vilka hindrar malen från att sprida sig till fler och större områden. Sjösänkningar, rensningar av vattendrag och annan verksamhet har inneburit och innebär än idag att lämpliga lekmiljöer och uppväxtområden försvunnit. Genetiska undersökningar visar att malpopulationerna i Sverige har låg genetisk variation och att det troligtvis är få individer som deltar i leken, vilket talar för att antalet lekhabitat är en begränsande faktor idag. I den svenska rödlistan från 2015 klassas malen som Sårbar (VU). Malen är fredad från fiske enligt 2 kap. 5 § i förordningen (1994:1716) om fisket, vattenbruket och fiskenäringen. Målet med programmet är att förstärka bestånden genom åtgärdande av vandringshinder samt översyn och anpassning av reglering. Andra viktiga åtgärder är olika biotopförbättrande åtgärder, exempelvis gynnade av strandnära vegetation och test av konstgjorda leknästen. Utöver detta finns ett stort fokus på förbättrat kunskapsunderlag och informationsspridning. De åtgärder som förutsätts finansieras av Havs- och vattenmyndighetens medel för genomförande av åtgärdsprogram för hotade arter beräknas totalt uppgå till 5 875 000kr under programmets giltighetsperiod 2017– 2021.This action program aims to improve the status of the European catfish (Siluris glanis) in Sweden. It is an indicative, but not legally binding, action program. The European catfish migrated to Swedish lake and river environments during the Ancylus lake period, an era when the temperature was higher than today. The species is the largest freshwater fish in Sweden with a record measuring 3.6 meters standard length and an estimated weight of about 180 kg. It is considered to be nocturnal and an opportunistic predator eating both fish and other freshwater organisms, such as amphibians, birds, crayfishes, insects, worms and molluscs. The species require relatively high water temperatures to spawn, which means it is not reproducing every year in Swedish waters. The European catfish is listed as Vulnerable (VU) on the Swedish red list. Four natural populations exist, all located in the southeast of Sweden, in the water systems Nyköpingsån (lake Båven), Emån, the upper part of Helge å and the lower part of Helge å. Additional records are known from a few other lakes, all results of illegal releases. The main reason for the decline is destruction of suitable habitat, such as large lowland rivers with a natural river environment. These habitats have been severely affected by human interference from the 19th century onwards, such as drainage of wetlands, water regulation, diversion of water, and physical impact on shore and bottom habitats. Genetic studies show that the populations in Sweden are genetically unique, but have low genetic variation indicating that the number of spawning individual is low, possibly due to lack of suitable spawning habitats. The European catfish is protected from fishing in Sweden. Other important measures is to make suitable habitats available by review and adjustments of legislation and water regulations in force. Also to improve the biotopes, for example promote the access to suitable spawning habitats and experiments with artificial nests. In addition, there is a great focus on an improved knowledge base and dissemination of information. The cost for the conservation measures, to be funded from Swedish Agency for Marine and Water Management allocation for action plans is estimated at 580 000 € during the period 2017-2021.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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