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  • 1.
    Abreu-Vieira, Gustavo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut.
    Regulation and measurement of brown adipose tissue blood flow2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Brown adipose tissue (BAT) is an organ specialized in macromolecule combustion in order to produce heat. Because of its high capacity to dissipate energy, it is currently among the best hopes for future treatments of obesity and diabetes. BAT is permeated by a vast capillary network that delivers blood rich in oxygen and nutrients to supply the high metabolic needs of the tissue. At the same time, metabolites, carbon dioxide and warm blood are drained back into systemic circulation. Blood flow is in fact a limiting factor for thermogenesis. Therefore, understanding BAT blood flow regulation is a crucial step for describing the tissue function. This thesis aims to summarize anatomical descriptions, to discuss the methodological evolution of the field, and to synthetize what we have learned about mechanistic regulation of BAT blood flow during the last half century. Manuscript I introduces a new method (high-resolution laser-doppler imaging) for the measurement of BAT blood flow, and gives mechanistic insights about its physiological regulation. Manuscript II focuses on the influence of bombesin receptor subtype-3 on the neurological control of body temperature and thermogenesis.

  • 2.
    Ackefors, Hans
    Stockholms universitet.
    Studies on the ecology of the zooplankton fauna in the Baltic proper1971Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 3.
    Ackefors, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    The evolution of a worldwide shrimp industry2009Ingår i: World Aquaculture, ISSN 1041-5602, Vol. 40, nr 3, s. 46-55Artikel i tidskrift (Refereegranskat)
  • 4. Aguirre, A. A.
    et al.
    Angerbjörn, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Tannerfeldt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Mörner, T.
    Health evaluation of arctic fox (Alopex lagopus) cubs in Sweden2000Ingår i: Journal of Zoo and Wildlife Medicine, Vol. 31, nr 1, s. 36-40Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hematologic. serum biochemistry, and serum cortisol reference ranges were established and tonsil/rectal bacterial and fecal parasite examinations were performed on 21 wild arctic fox (Alopex lagopus) cubs during July 1996. Several of the hematologic and serum biochemistry values fell within normal ranges for other wild canids or domestic dogs of the same age class. Serum alanine transaminase and creatine phosphokinase values were significantly higher in the youngest cubs. Proteus vulgaris and Escherichia coli were isolated from both tonsilar and rectal swabs of several cubs in all dens. The most common gastrointestinal parasite ova were Toxascaris leonina (59%), Isospora spp. (52%), Uncinaria stenocephala (33%), and Capillaria spp. (26%). Prevalence of T. leonina differed significantly between dens and between age groups. Hematologic and serum biochemistry values and degree of parasitism may be indicators of health, stress, and nutritional status of arctic foxes.

  • 5. Aguirre, A. Alonso
    et al.
    Principe, B.
    Tannerfeldt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Mörner, Torsten
    Field anesthesia of wild arctic fox (Alopex lagopus) cubs in the Swedish lapland using medetomidine-ketamine-atipamezole2000Ingår i: Journal of Zoo and Wildlife Medicine, Vol. 31, nr 2, s. 244-246Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A safe and effective anesthetic regime for use in arctic fox (Alopex lagopus) cubs was developed. During July 1996, six free-ranging 6-8-wk-old cubs were captured near their den in Vindelfjallen Nature Reserve, Sweden. Medetomidine and ketamine HCl, followed by atipamezole, were selected for the anesthetic trial because of the well-documented safety and efficacy of this drug combination in a broad range of species. The dosage regimen used was 50 mu g/kg medetomidine combined with 2.5 mg/kg ketamine followed by reversal with 250 mu g/kg atipamezole. induction was rapid, with a mean induction time of 1 min and 32 sec (range: 58-150 sec). The cubs were anesthetized for a mean time of 18 +/- 5 min (range: 13-25 min). Serially recorded heart rate, respiratory rate, temperature, and pulse oximetry were stable throughout the anesthetic period for all cubs. Anesthetic depth was suitable for safe handling and minor clinical procedures, including venipuncture. Following atipamezole, all cubs were standing within 12 +/- 7 min (range: 5-24 min) and fully recovered at 27 +/- 5 min (range: 19-36 min). This information will be useful for future captive breeding and management programs involving the endangered arctic fox.

  • 6. Ah-King, Malin
    Phylogenetic analyses of parental care evolution2003Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 7.
    Ahlbert, Inga-Britt
    Stockholms universitet.
    Organization of the cone cells in the retinae of some teleosts in relation to their feeding habits1975Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 8. Ahola, Virpi
    et al.
    Lehtonen, Rainer
    Somervuo, Panu
    Salmela, Leena
    Koskinen, Patrik
    Rastas, Pasi
    Valimaki, Niko
    Paulin, Lars
    Kvist, Jouni
    Wahlberg, Niklas
    Tanskanen, Jaakko
    Hornett, Emily A.
    Ferguson, Laura C.
    Luo, Shiqi
    Cao, Zijuan
    de Jong, Maaike A.
    Duplouy, Anne
    Smolander, Olli-Pekka
    Vogel, Heiko
    McCoy, Rajiv C.
    Qian, Kui
    Chong, Wong Swee
    Zhang, Qin
    Ahmad, Freed
    Haukka, Jani K.
    Joshi, Aruj
    Salojarvi, Jarkko
    Wheat, Christopher W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Grosse-Wilde, Ewald
    Hughes, Daniel
    Katainen, Riku
    Pitkanen, Esa
    Ylinen, Johannes
    Waterhouse, Robert M.
    Turunen, Mikko
    Vaharautio, Anna
    Ojanen, Sami P.
    Schulman, Alan H.
    Taipale, Minna
    Lawson, Daniel
    Ukkonen, Esko
    Makinen, Veli
    Goldsmith, Marian R.
    Holm, Liisa
    Auvinen, Petri
    Frilander, Mikko J.
    Hanski, Ilkka
    The Glanville fritillary genome retains an ancient karyotype and reveals selective chromosomal fusions in Lepidoptera2014Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, s. 4737-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Previous studies have reported that chromosome synteny in Lepidoptera has been well conserved, yet the number of haploid chromosomes varies widely from 5 to 223. Here we report the genome (393 Mb) of the Glanville fritillary butterfly (Melitaea cinxia; Nymphalidae), a widely recognized model species in metapopulation biology and eco-evolutionary research, which has the putative ancestral karyotype of n = 31. Using a phylogenetic analyses of Nymphalidae and of other Lepidoptera, combined with orthologue-level comparisons of chromosomes, we conclude that the ancestral lepidopteran karyotype has been n = 31 for at least 140 My. We show that fusion chromosomes have retained the ancestral chromosome segments and very few rearrangements have occurred across the fusion sites. The same, shortest ancestral chromosomes have independently participated in fusion events in species with smaller karyotypes. The short chromosomes have higher rearrangement rate than long ones. These characteristics highlight distinctive features of the evolutionary dynamics of butterflies and moths.

  • 9.
    Alm Bergvall, Ulrika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish University of Agricultural Sciences, Sweden.
    Svensson, Lisa
    Kjellander, Petter
    Vigilance adjustments in relation to long- and short term risk in wild fallow deer (Dama dama)2016Ingår i: Behavioural Processes, ISSN 0376-6357, E-ISSN 1872-8308, Vol. 128, s. 58-63Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The risk allocation hypothesis predicts that vigilance should be adjusted to the temporal variation in risk. We test this hypothesis in wild fallow deer exposed to short term (disturbance) and long term (presence of a fawn after parturition) changes in risk. We recorded the proportion, frequency and type of vigilance and size of used area before and after parturition, in GPS-collared wild female fallow deer. Vigilance was divided in two main groups: non-grazing vigilance and grazing vigilance. The latter group was divided into grazing vigilance while chewing and a grazing vigilance when chewing was interrupted. By recording external disturbance in form of passing cars, we were able to investigate if this altered the amount, and type of vigilance. We found that females increased the proportion and frequency of grazing vigilance stop chewing after parturition. The grazing vigilance chewing was unaffected, but non-grazing vigilance decreased. Disturbance increased the proportion grazing vigilance stop chewing to the same extent before and after parturition. We found a clear decrease in female home range size after parturition as a possible behavioural adjustment. The increase in grazing vigilance stop chewing after parturition is a rarely described but expected cost of reproduction.

  • 10.
    Almbro, Maria
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för etologi.
    Kullberg, Cecilia
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för etologi.
    Impaired escape flight ability in butterflies due to low flight muscle ratio prior to hibernation2008Ingår i: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 211, nr 1, s. 24-28Artikel i tidskrift (Refereegranskat)
  • 11.
    Almbro, Maria
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Kullberg, Cecilia
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Weight Loading and Reproductive Status Affect the Flight Performance of Pieris napi Butterflies2012Ingår i: Journal of insect behavior, ISSN 0892-7553, E-ISSN 1572-8889, Vol. 25, nr 5, s. 441-452Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Weight-induced mobility reductions can have dramatic fitness consequences and winged animals are especially sensitive to the trade-off between mass and locomotion. Data on how natural weight fluctuations influence a flying insect's ability to take off are scarce. We therefore quantified take-off flight ability in Pieris napi butterflies in relation to reproductive status. Take-off flight ability (velocity and take-off angle) under suboptimal temperature conditions was recorded with a 3D-tracking camera system and was predicted to decrease with relatively larger weight loads. Our results show that relatively larger weight loads generally reduce flight speed in male butterflies and lower take-off angles in females. However, despite having a lower wing loading, mated male butterflies flew slower than unmated males. Our study suggests that retention of weight loads associated with reproduction impairs insect flight performance.

  • 12.
    Andersson, Anastasia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Laikre, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Bergvall, Ulrika A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish University of Agricultural Sciences, Sweden.
    Two shades of boldness: novel object and anti-predator behavior reflect different personality dimensions in domestic rabbits2014Ingår i: Journal of ethology, ISSN 0289-0771, E-ISSN 1439-5444, Vol. 32, nr 3, s. 123-136Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is increasingly common to quantify and describe behavioral variation in domestic and wild animals in terms of personality. Correlating behavioral traits are referred to as personality dimensions or factors and different dimensions have been reported in different species. Boldness is a well-described personality dimension in several species, although some issues remain unclear. Previous models of boldness include both novelty and risk taking, but recent studies indicate that these types of behaviors may reflect separate personality dimensions. In this study, we developed a behavioral test battery for domestic rabbits, and recorded behaviors of 61 individuals in four different situations (novel object, novel arena, social, and predator interactions). We used domestic rabbits as a model because behavioral variation in rabbits has rarely been quantified in terms of personality dimensions, although rabbit behavior is described. We also wanted to investigate behavioral variation in a Swedish rabbit breed of conservation concern - the Gotland rabbit. Factor analysis of the behavioral test measures suggested three personality dimensions: exploration, boldness, and anxiety. Novel object scores clustered in the exploration and boldness factors, whereas scores associated with predator interactions were explained by anxiety, indicating that novel object and anti-predator behavior reflect different personality dimensions in rabbits.

  • 13.
    Andersson, Ulf
    Stockholms universitet, Naturvetenskapliga fakulteten, Wenner-Grens institut, Avdelningen för fysiologi.
    On the biosynthesis of ATP synthase1998Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 14.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gigantism in Island Populations of Wood Mice (Apodemus) in Europe1986Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 47, nr 1, s. 47-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many rodents have large body sizes on islands, and there are many hypotheses that try to explain this observed pattern. Using body size data on Apodemus in Europe as an example, I try to evaluate the main hypotheses. These can be divided in four different categories. 1) Hypotheses assuming climatic differences between islands and mainland: no trend in body size on islands in the Mediterranean, in Britain or in the Baltic area is observed. 2) Hypotheses based on island size: no trend is observed in the data analysed. 3) Hypotheses based on distance to mainland: no general effect is found, although there is an effect in the British material. 4) Hypotheses based on faunistic differences: consistent relationships are found in all areas. A. sylvaticus shows larger body size when lacking competition from A. flavicollis or Clethrionomys glareolus or when predation is absent. A. flavicollis is larger when predators are lacking, and smaller when no competitors are present. This is in agreement with character displacement theory

  • 15.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Reproduction of Mountain Hares (Lepus-Timidus) in Relation to Density and Physical Condition1986Ingår i: Journal of Zoology, Vol. 208, nr 4, s. 559-568Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Population estimates of Mountain hares were done on three islands off the west coast of Sweden. Three different relative measures of hare reproduction were negatively related to density. Most of this relationship was accounted for through a positive correlation with body condition. However, there was no significant density trend in litter size or number of litters. The start of the reproductive season each year was related to mean air temperature during spring, so when spring was early so was conception.

  • 16.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The Effect of Red Fox Predation on Mountain Hare Populations on Islands1986Ingår i: Mammal Review, ISSN 0305-1838, E-ISSN 1365-2907, Vol. 16, nr 3-4, s. 198-198Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The population dynamics of Mountain Hares on islands have been monitored during 10 years. In some years Red Foxes have been present on some islands. The intensity of predation on the hares is given from the reduction of the known hare densities, and from the foxes’ diet (scat analysis). The effect of predation on the hare populations was found to be density dependent, but also dependent on the alternative food available.

    [Complete text from journal]

  • 17.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The Evolution of Body Size in Mammals on Islands - Some Comments1985Ingår i: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 125, nr 2, s. 304-309Artikel i tidskrift (Refereegranskat)
  • 18.
    Angerbjörn, Anders
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Arvidson, Bengt
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Erik
    Strömgren, Lasse
    The Effect of Winter Food on Reproduction in the Arctic Fox, Alopex-Lagopus - a Field Experiment1991Ingår i: Journal of Animal Ecology, Vol. 60, nr 2, s. 705-714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    (1) The population of arctic foxes in Fennoscandia is very small and has been so for around 60 years in spite of total protection for over half a century. The reasons why the arctic fox population has not increased to its former size are unknown. The population numbers fluctuate highly in relation to vole numbers. There is also very high interannual variation in reproduction among arctic foxes. (2) To determine the effect of winter food availability on reproductive success, we carried out a feeding experiment. The study area is situated above the treeline from an altitude of 700 m to mountains of 1600 m in Swedish Lapland. We added food (reindeer and moose carcasses) to dens during the winter months, January-April 1985-89. To determine the effect of this extra food on reproduction, we made inventories at both food-manipulated dens and control dens. These inventories of dens took place during July so we could check not only if dens were occupied, but also whether a litter was born and assess the number of cubs appearing outside the den. (3) The proportion of occupied dens in the experimental group was significantly higher than in the control group. The number of cubs at weaning in the food-manipulated dens was also higher than in control dens in each year. However, no effect on litter size was found. (4) From these results we conclude that the larger number of cubs produced in dens with extra winter food shows that reproduction under present dietary poor conditions was limited by available food. Many canid species show this close relation between reproduction and food availability, with pregnancy rates and litter sizes declining with the abundance of the main food.

  • 19.
    Angerbjörn, Anders
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Börjesson, Patrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Brandberg, K.
    Stable isotope analysis of harbour porpoises and their prey from the Baltic and Kattegat/Skagerrak Seas2006Ingår i: Marine Biology Research, ISSN 1745-1000, E-ISSN 1745-1019, Vol. 2, nr 6, s. 411-419Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The by-caught harbour porpoises in commercial fisheries have raised concerns over their conservation status in the Baltic region. One important aspect for management purposes is porpoise movements within the region. We measured stable isotopes in cod, herring and hagfish, species that are important prey for harbour porpoises in the Baltic region. Bone collagen in fish from the marine Kattegat/Skagerrak was significantly enriched in C-13 compared with collagen in fish from the brackish Baltic Sea. However, despite the isotopic variation seen in their prey, we found no difference in C-13 in harbour porpoise collagen from the two areas. In fact, only eight of 24 porpoises had isotope signatures corresponding to those estimated for the diet in the area where they were caught. Our general conclusion is that porpoises move between the Baltic and Kattegat/Skagerrak Seas. Future studies are needed to evaluate the magnitude of these movements.

  • 20.
    Angerbjörn, Anders
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Hjernquist, B.
    A Rapid Summer Decline in a Mountain Hare Population on an Island1984Ingår i: Acta Theriologica, ISSN 0001-7051, E-ISSN 2190-3743, Vol. 29, nr 1-10, s. 63-75Artikel i tidskrift (Refereegranskat)
  • 21.
    Angerbjörn, Anders
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Pehrson, A.
    Factors Influencing Winter Food Choice by Mountain Hares (Lepus-Timidus L) on Swedish Coastal Islands1987Ingår i: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 65, nr 9, s. 2163-2167Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In mainland areas, mountain hares seem unable to survive on a single browse species. However, mountain hares on islands off the west coast of Sweden rely almost entirely on a plain heather diet during winter. Herein, we give as a possible explanation for this phenomenon that the high concentration of sodium in the heather in the coastal areas can buffer the high sodium excretion otherwise observed in hares feeding on heather under experimental conditions. Furthermore, hares selected heather with the highest nitrogen and phosphorus contents. We argue that the pattern of food choice exhibited by the hares in the coastal area is to be expected in homogenous habitats where hares rely on one dominant food species. In heterogenous habitats, the possibility of food selection on a nutritional level is to a considerable extent overridden by effects of digestibility and concentration of secondary compounds in the different food plants available.

  • 22.
    Angerbjörn, Anders
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Tannerfeldt, M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Bjärvall, A.
    Ericson, M.
    From, J.
    Noren, E.
    Dynamics of the Arctic Fox Population in Sweden1995Ingår i: Annales Zoologici Fennici, Vol. 32, nr 1, s. 55-68Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Arctic fox populations fluctuate widely with the abundance of prey, i.e. lemmings and voles (Arvicolinae). We have investigated the patterns and mechanisms of these fluctuations in arctic fox numbers through den inventories during 20 years (1974-1993) in Sweden. Time series analyses confirmed a four-year cyclicity in both arctic fox numbers and litter size. However, the different geographical regions were not in synchrony. The fox population in the southern parts of the distribution range has shown regular peaks during the whole period, whereas those in the northern and middle parts of Sweden have declined since 1982. In the northernmost county, also litter sizes have decreased. These differences coincided with an absence of vole and lemming peaks in the north. Experimental feeding confirmed that food availability had a direct impact on breeding success and litter size, thereby limiting the population. We conclude that the total number of arctic foxes in Sweden in 1994 is as low as 40-80 animals.

  • 23.
    Angerbjörn, Anders
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Tannerfeldt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Erlinge, S.
    Predator-prey relationships: Arctic foxes and lemmings1999Ingår i: Journal of Animal Ecology, Vol. 68, nr 1, s. 34-49Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. The number of breeding dens and litter sizes of arctic foxes Alopex lagopus were recorded and the diet of the foxes was analysed during a ship-based expedition to 17 sites along the Siberian north coast. At the same time the cyclic dynamics of coexisting lemming species were examined. 2. The diet of arctic foxes was dominated by the Siberian lemming Lemmus sibiricus (on one site the Norwegian lemming L. lemmus), followed by the collared lemming Dicrostonyx torquatus. 3. The examined Lemmus sibiricus populations were in different phases of the lemming cycle as determined by age profiles and population densities. 4. The numerical response of arctic foxes to varying densities of Lemmus had a time lag of 1 year, producing a pattern of limit cycles in lemming-arctic fox interactions, Arctic fox litter sizes showed no time lag, but a linear relation to Lemmus densities. We found no evidence for a numerical response to population density changes in. Dicrostonyx. 5. The functional or dietary response of arctic foxes followed a type II curve for Lemmus, but a type III response curve for Dicrostonyx. 6. Arctic foxes act as resident specialist for Lemmus and may increase the amplitude and period of their population cycles. For Dicrostonyx, on the other hand, arctic foxes act as generalists which suggests a capacity to dampen oscillations.

  • 24.
    Angerbjörn, Anders
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Tannerfeldt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Lundberg, Håkan
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Geographical and temporal patterns of lemming population dynamics in Fennoscandia2001Ingår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 24, nr 3, s. 298-308Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is a long-lasting debate in ecology on cyclicity, synchrony and time lags of lemming population fluctuations. We have analysed 137 yr of previously published population data on the Norwegian lemming Lemmus lemmus in ten geographic regions of Fennoscandia. The dominating pattern was synchronous 4-yr cycles. There was no support for the hypothesis of a north-south gradient in cycle length. However. we found periods of prolonged interruptions in the cyclicity, which were more common in northern areas. Wa found a high degree of synchrony between regions. with only a weak relationship to distance, The observed pattern in lemming population dynamics was more consistent with effects from extrinsic factors, such as climate. than intrinsic factors. such as dispersal.

  • 25.
    Ankar, Sven
    Stockholms universitet.
    The soft bottom ecosystem of the northern Baltic proper with special reference to the macrofauna1977Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 26. Antonopoulou, Efthimia
    et al.
    Swanson, Penny
    Borg, Bertil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Effects of aromatase inhibitors and different doses of testosterone on gonadotropins in one year old male Atlantic salmon (Salmo salar).2009Ingår i: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, ISSN 1531-4332, Vol. 153, nr 4, s. 408-16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effects of different doses of testosterone (T), the aromatase inhibitors 1,4,6-androstatriene-3,17-dione (ATD) and 4-hydroxy-4-androstene-3,17-dione (4OH), and the combined treatment of T and ATD on luteinizing hormone (LH) and follicle-stimulating hormone (FSH) at the onset of puberty in juvenile Atlantic salmon males were investigated. T always increased pituitary LH. Also, ATD increased pituitary LH, though to a lesser extent than T. However, ATD combined with T diminished pituitary LH levels compared to T alone, indicating an aromatase-dependent positive feedback of T on LH in immature males. 4OH, which was less effective than ATD as an aromatase inhibitor, increased LH content. ATD treatment resulted in increased pituitary FSH levels, similar to those of mature controls. Positive effects of ATD on plasma FSH were found, indicating the presence of an aromatase-dependent negative feedback. The 4OH effects on FSH levels were inconsistent. T exerted both positive and negative effects on pituitary FSH and testes growth, depending on dose and season, with the positive effects being more pronounced with the low doses and the negative effects with the high doses. The treatment of T combined with ATD did not affect the positive effect of T alone on pituitary and plasma FSH, indicating the presence of an aromatase-independent positive feedback on FSH. There was a positive correlation between FSH and gonadosomatic index, especially during summer when gonadal development occurs.

  • 27.
    Arnbom, Tom
    Stockholms universitet, Naturvetenskapliga fakulteten.
    Maternal investment in male and female offspring in the southern elephant seal1994Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 28.
    Aronsson, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gamberale-Stille, Gabriella
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Colour and pattern similarity in mimicry: evidence for a hierarchical discriminative learning of different components2012Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 84, nr 4, s. 881-887Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many aposematic species combine their bright colours with a black pattern that produces internal contrasts. Studies have shown that birds often pay attention to some parts of a signalling pattern and disregard others, which could be of importance in Batesian mimicry, where a palatable species copies the visual appearance of a distasteful model in order to deceive predators. We used domestic chicks, Gallus gallus domesticus, and artificial prey signals to investigate whether predators use different warning colour components for discrimination depending on the degree of information about prey quality they convey. This study supports earlier findings of the importance of colour for discrimination among prey but also provides evidence that other less associable signal properties such as internal patterning, when holding valuable discriminatory information, can be used to assess prey quality in a hierarchical manner. The results also suggest that, in certain circumstances, the presence of a palatable mimic can have positive effects on learning, resulting in 'super-Mullerian' effects. We propose that the degree of selection for perfect mimicry may be dependent on the proportion of well-educated predators in the population.

  • 29.
    Aronsson, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gamberale-Stille, Gabriella
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Evidence of signaling benefits to contrasting internal color boundaries in warning coloration2013Ingår i: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 24, nr 2, s. 349-354Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It has been suggested that the common existence of regular patterning in aposematic prey animals makes them stand out from the background, improving detection and recognition. Another suggestion is that internal patterns could have a similar positive effect on predator aversion learning as prey-to-background contrast. We used wild caught blue tits (Cyanistes caeruleus) and artificial prey signals to investigate if internal color boundaries, pattern regularity and pattern symmetry affect learning. Birds in different treatments were trained, on a complex background, to discriminate between artificial prey with different nonrewarding color stimuli with a black pattern and rewarding stimuli without a black pattern, followed by a generalization test. This study provides evidence of learning benefits to internally contrasting patterns as the striped prey stimuli were learned faster than the unstriped. Also, we found no beneficial effects of pattern regularity and symmetry. The birds generalized more between prey with different black patterns than to the profitable prey, suggesting that color is of foremost importance. The generalization test also showed a greater avoidance of striped than that of unstriped prey, suggesting some attention on patterns. Thus, internal patterning may affect signal salience and in some circumstances benefit prey due to both a faster avoidance learning and generalization behavior.

  • 30.
    Aronsson, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för etologi.
    Gamberale-Stille, Gabriella
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för etologi.
    Importance of internal pattern contrast and contrast against the background in aposematic signals.2009Ingår i: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 20, nr 6, s. 1356-1362Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aposematic color patterns that signal prey unprofitability are suggested to work best when there is high contrast within the animal color pattern or between the animal and its background. Studies show that prey contrast against the background increases the signal efficiency. This has occasionally been extended to also explain the presence of internal patterns. We used domestic chicks, Gallus gallus domesticus, to investigate the relative importance for avoidance learning of within-prey pattern contrast and prey contrast against the background. In a series of trials, birds were first trained to avoid artificially made aposematic mealworms that were plain red or red with black stripes, and to discriminate them from palatable brown mealworms, on either a red or a brown background. Second, we investigated how the birds generalized between striped and nonstriped prey. The chicks showed faster avoidance learning when the basic color of the aposematic prey (red) contrasted with the background color (brown). However, there was no similar effect of internal pattern contrast. The generalization test showed a complete generalization between the nonstriped and the striped prey. We conclude that contrasting internal patterns do not necessarily affect predator avoidance learning the same way as shown for prey-to-background contrast in aposematic prey.

  • 31.
    Audehm, Uwe
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Trube, Anke
    Institute of Zoophysiology, University of Bonn, Germany.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Patterns and projections of crustacean cardioactive-peptide-immunoreactive neurons of the terminal ganglion of crayfish.1993Ingår i: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 272, nr 3, s. 473-485Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three distinct clusters of crustacean cardioactive-peptide-immunoreactive neurones occur in the terminal abdominal ganglion of the crayfish species Orconectes limosus, Astacus leptodactylus, Astacus astacus and Procambarus clarkii, as revealed by immunocytochemistry of whole-mount preparations and sections. They exhibit similar topology and projection patterns in all four studied species. An anterior ventral lateral and a posterior lateral cluster contain one small, strongly stained perikaryon and two large, less intensely stained perikarya, each showing contralateral projections. A posterior medial lateral cluster of up to six cells also contains these two types of perikarya. Whereas the small type perikarya belong to putative interneurones, the large type perikarya give rise to extensive neurohaemal plexuses in perineural sheaths of the third roots of the fifth abdominal ganglia, the connectives, the dorsal telson nerves, the ganglion itself, its roots and arteriolar supply. Thin fibres from these plexuses reach newly discovered putative neurohaemal areas around the hindgut and anus via the intestinal and the anal nerves, and directly innervate the phasic telson musculature. A comparison with earlier investigations of motoneurones and segmentation indicates that these three cell groups containing putative neurosecretory neurones may be members of at least three neuromeres in this ganglion. Crustacean cardioactive peptide released from these neurones may participate in the neurohumoral and modulatory control of different neuronal and muscle targets, thereby exceeding its previously established hindgut and heart excitatory effects.

  • 32.
    Audusseau, Hélène
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Effect of climate and land use on niche utilization and distribution of nettle-feeding  butterflies2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Mänsklig påverkan på klimat och markanvändning har orsakat en dramatisk förlust av biologisk mångfald. Effekten av dessa förändringar på lokal och regional nivå är dock komplex, och kräver integrativa strategier för att kunna förstå och förutsäga förändringar, på individ-, art- och samhällsnivå. Experimentella studier har utforskat arters plastiska och evolutionära respons till främst abiotiska förändringar, och observationsdata har använts för att modellera skiften i fenologi och utbredning som en konsekvens av klimatförändringar. Trots detta är det fortfarande mycket kvar att förstå för att kunna förutsäga hur miljöförändringar ska påverka arters respons på olika rumsliga och tidsliga skalor. Denna avhandling undersöker i vilken utsträckning arters specifika livshistoria och artinteraktioner kan förklara deras ekologiska och evolutionära respons på miljöförändringar.

    För att angripa detta har jag fokuserat på ett samhälle av fjärilar i Sverige (Vanessa cardui, Polygonia c-album, Aglais urticae, Aglais io, Araschnia levana) som alla lever på brännässla (Urtica dioica). Den tillgängliga kunskapen om dessa arters biologi samt deras korta livscykler gör det möjligt att undersöka deras svar på förändringar över korta tidsskalor, vilket gör dem till ett lämpligt studiesystem. Huvudslutsatsen från denna avhandling är att för att beskriva hur en art svarar på en förändring måste man ta hänsyn till variation i livshistorieegenskaper och artinteraktioner. Till exempel har den ökade användningen av kemiska gödningsmedel förändrat näringstillgången även i naturliga ekosystem, vilket gynnar växtarter som är kapabla att växa under höga näringsnivåer, som brännässla. Variation i växternas näringsinnehåll kommer i sin tur att påverka herbivorerna som äter av dem, och artikel II visar att skillnader mellan fjärilsarter i hur de svarar på variation i näringstillgång till stor del beror på specialiseringsgrad och voltinism (antal generationer per år). Livshistorieegenskaper avgör således hur arter kommer att svara på förändringar i klimat och markanvändning, men sådana miljöförändringar påverkar i sin tur också evolution av livshistorieegenskaperna (artikel I & III). Slutligen, förändringar i utbredning som ett resultat av klimatförändring kommer även att påverka den lokala sammansättningen av interagerande arter (resurser, predatorer, konkurrenter). Ett exempel på detta är hur den relativt nyliga koloniseringen av södra Sverige av A. levana har förändrat nischerna hos de inhemska arterna A. urticae och A. io (artikel IV).

  • 33.
    Axén, Annkristin H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Behaviour of Lycaenid butterfly larvae in their mutualistic interactions with ants2001Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Interspecific mutualism often involves partners trading different kinds of services. The cost and benefits of the trade may differ from one interaction to the next, or fluctuate over time in a single interaction, due to factors both internal and external to the mutualism itself. Aspects of partner quality, such as a partner's ability to provide services and its need for the services obtained in return, are likely to be particularly important. As a consequence of such variation, one might expect strategies of adjusting investments to the characteristics of the partner and to other circumstances, in a way that increases the benefit received and/or decreases the investment necessary to obtain the benefit. Lycaenid butterfly larvae often interact mutualistically with ants, which they reward with nutritious secretions in return for being protected from parasitoids and predators. The larvae also have other means of influencing ants, such as a pair of eversible tentacular organs, which emit volatile substances that attract and alert ants. Both participants in the interaction can readily modify their mutualistic investments over very short periods of time. My aim in this thesis has been to investigate strategies individual larvae could use to change the cost-benefit relationship of the interaction in a way that increases their returns. For this purpose I have manipulated factors that might influence the outcome of the mutualism for lycaenids and observed their response, both as tentacle signalling and in the form of investment in secretions. Examples of factors I have investigated are the level of ant attendance, the need for protection, and the species of the attending ants. I have also investigated the effect of group size and companion quality in a gregarious lycaenid species. I have found that larvae react to such changed circumstances by varying their behaviour, either acting to increase the number of attending ants when better protection is likely to be needed or reducing the costly secretion when adequate protection is already available. My overall conclusion is that lycaenid larvae have a series of adaptations that serve to efficiently regulate the number of protecting ants and that much of the variability I have observed can be interpreted in this way.

  • 34. Baba, Yuki G.
    et al.
    Walters, Richard J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Miyashita, Tadashi
    Host-dependent differences in prey acquisition between populations of a kleptoparasitic spider Argyrodes kumadai (Araneae Theridiidae)2007Ingår i: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 32, nr 1, s. 38-44Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. A kleptoparasitic spider, Argyrodes kumadai, is known to use phylogenetically unrelated host species in different regions - Cyrtophora moluccensis (Araneidae) in south-west Japan and Agelena silvatica (Agelenidae) in north-east Japan. The work reported here examined whether differences in host characters affect prey acquisition of A. kumadai. 2. Field surveys showed that prey-biomass capture rate of Argyrodes was significantly higher in populations parasitising Cyrtophora than in populations parasitising Agelena. Although Argyrodes appeared to catch fewer prey within Cyrtophora webs, they were able to feed upon substantially larger prey. 3. Differences in prey-biomass capture rate were found to reflect differences in host traits rather than regional differences in potential prey availability. Individuals in populations parasitising Cyrtophora were observed to acquire prey via a number of foraging tactics that included stealing wrapped food bundles, feeding upon prey remains and, in the case of large prey items, feeding together with the host. In contrast, individuals in populations parasitising Agelena were only ever observed to feed upon small prey items ignored by its host. 4. This variability in prey acquisition between kleptoparasite populations reflected different opportunities for feeding within their respective host webs - opportunities that were primarily determined by the foraging behaviour of the host. One key trait associated with host foraging behaviour was host-web structure, namely the presence/absence of a retreat.

  • 35.
    Barth, Lukas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Tannerfeldt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Are Norwegian lemmings Lemmus lemmus avoided by arctic Alopex lagopus or red foxes Vulpes vulpes? A feeding experiment2000Ingår i: Wildlife Biology, Vol. 6, nr 2, s. 101-109Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Arctic fox Alopex lagopus and red fox Vulpes vulpes are close relatives with similar niche demands in the Holarctic. Where they are sympatric, they compete for territories, dens and food. Seat analyses from Fennoscandia have shown different proportions of lemmings and voles in the diets of the two fox species suggesting food partitioning. However, it was not clear if this was due to different food preferences or distinct habitat use. Since the arctic fox is an endangered species in Fennoscandia, it is important to know whether the superior, north spreading red fox can oust it from the tundra habitat, or if food specialisation may prevent displacement. In a feeding experiment at the Lycksele Zoo in northern Sweden, we compared the food preferences of two arctic and two red foxes. Our results show that the four individuals responded similarly to a variety of food items, and particularly that the two species were not distinct in their food preferences concerning lemmings and voles. However, the foxes had considerable individual predilections. Therefore, in the wild, the unequal proportions of lemmings and voles found in seats may reflect different habitat use for hunting.

  • 36.
    Bartosiewicz, Laszlo
    et al.
    Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur, Osteoarkeologiska forskningslaboratoriet.
    Lisk, Elicia
    Mammalian Remains2018Ingår i: Quedem Reports, E-ISSN 0793-4289, Vol. 10, s. 83-117Artikel, recension (Refereegranskat)
  • 37.
    Becedas, Luisa
    Stockholms universitet, Naturvetenskapliga fakulteten.
    Xenobiotic-conjugating enzymes in rat ovary: hormonal regulation of UDP-glucuronosyltransferase and glutathione transferase and release of mutagenic metabolites by granulosa cells1997Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 38. Becnel, Jaime
    et al.
    Johnson, Oralee
    Luo, Jiangnan
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Nässel, Dick R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Nichols, Charles D.
    The Serotonin 5-HT(7)Dro Receptor Is Expressed in the Brain of Drosophila, and Is Essential for Normal Courtship and Mating2011Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, nr 6, s. e20800-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The 5-HT(7) receptor remains one of the less well characterized serotonin receptors. Although it has been demonstrated to be involved in the regulation of mood, sleep, and circadian rhythms, as well as relaxation of vascular smooth muscles in mammals, the precise mechanisms underlying these functions remain largely unknown. The fruit fly, Drosophila melanogaster, is an attractive model organism to study neuropharmacological, molecular, and behavioral processes that are largely conserved with mammals. Drosophila express a homolog of the mammalian 5-HT(7) receptor, as well as homologs for the mammalian 5-HT(1A), and 5-HT(2), receptors. Each fly receptor couples to the same effector pathway as their mammalian counterpart and have been demonstrated to mediate similar behavioral responses. Here, we report on the expression and function of the 5-HT(7)Dro receptor in Drosophila. In the larval central nervous system, expression is detected postsynaptically in discreet cells and neuronal circuits. In the adult brain there is strong expression in all large-field R neurons that innervate the ellipsoid body, as well as in a small group of cells that cluster with the PDF-positive LNvs neurons that mediate circadian activity. Following both pharmacological and genetic approaches, we have found that 5-HT(7)Dro activity is essential for normal courtship and mating behaviors in the fly, where it appears to mediate levels of interest in both males and females. This is the first reported evidence of direct involvement of a particular serotonin receptor subtype in courtship and mating in the fly.

  • 39.
    Bengtsson, Tore
    Stockholms universitet.
    β-adrenergic receptors: Genes and Expression1998Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 40.
    Beramendi, Ana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Peron, Samantha
    Casanova, Gabriela
    Reggiani, Carlo
    Cantera, Rafael
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Neuromuscular junction in abdominal muscles of Drosophila melanogaster during adulthood and aging2007Ingår i: Journal of Comparative Neurology, ISSN 0021-9967, E-ISSN 1096-9861, Vol. 501, nr 4, s. 498-508Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The neuromuscular junction (NMJ) of Drosophila melanogaster has been established as a productive model for the study of synaptogenesis, synaptic plasticity, vesicle recycling, and other synaptic functions in embryos and larvae. It also has potential for the study of long-term plasticity during adult life and degenerative processes associated with aging. Here we provide a detailed description of the morphology and ultrastructure of the NMJ on abdominal dorsal longitudinal muscles throughout adult life from eclosion to senescence. In contrast to the case in the larva, the predominant type of terminals in these muscles in the adult fly consists of only two or three branches with tightly packed synaptic boutons. We observed qualitative and quantitative changes as mean bouton size increased gradually during adulthood, and the largest boutons were present in the old fly. The length of nerve branches first increased and thereafter decreased gradually during most of adult life. Branch diameter also decreased progressively, but branch number did not change. The subsynaptic reticulum became progressively thinner, and “naked” boutons were found in old flies. Ultrastructural traits gave indications of an age-associated increment in autophagy, larger synaptic vesicles, and impaired endocytosis. We propose that NMJ aging in the fly correlates with impaired endocytosis and membrane dynamics. This view finds a functional correlate in flies carrying a temperature-sensitive mutation in shibire that reversible blocks endocytosis; age significantly reduces the time required for complete paralysis and increases the time of recovery, thus confirming the age-dependent alteration in vesicle dynamics.

  • 41.
    Berger, David
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Friberg, Magne
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gotthard, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Divergence and ontogenetic coupling of larval behaviour and thermal reaction norms in three closely related butterflies2011Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 278, nr 1703, s. 313-320Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Genetic trade-offs such as between generalist-specialist strategies can be masked by changes in compensatory processes involving energy allocation and acquisition which regulation depends on the state of the individual and its ecological surroundings. Failure to account for such state dependence may thus lead to misconceptions about the trade-off structure and nature of constraints governing reaction norm evolution. Using three closely related butterflies, we first show that foraging behaviours differ between species and change remarkably throughout ontogeny causing corresponding differences in the thermal niches experienced by the foraging larvae. We further predicted that thermal reaction norms for larval growth rate would show state-dependent variation throughout development as a result of selection for optimizing feeding strategies in the respective foraging niches of young and old larvae. We found substantial developmental plasticity in reaction norms that was species-specific and reflected the different ontogenetic niche shifts. Any conclusions regarding constraints on performance curves or species-differentiation in thermal physiology depend on when reaction norms were measured. This demonstrates that standardized estimates at single points in development, or in general, allow variation in only one ecological dimension, may sometimes provide incomplete information on reaction norm constraints.

  • 42.
    Berger, David
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Uppsala University, Sweden.
    Olofsson, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Friberg, Magne
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. University of California Santa Cruz, USA.
    Karlsson, Bengt
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Wiklund, Christer
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gotthard, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Intraspecific variation in body size and the rate of reproduction in female insects- adaptive allometry or biophysical constraint?2012Ingår i: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 81, nr 6, s. 1244-1258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. A high rate of reproduction may be costly if ecological factors limit immediate reproductive output as a fast metabolism compromises own future survival. Individuals with more reserves need more time and opportunity to realize their reproductive potential. Theory therefore predicts that the reproductive rate, defined as the investment in early reproduction in proportion to total potential, should decrease with body size within species. 2. However, metabolic constraints on body size- and temperature-dependent biological rates may impede biophysical adaptation. Furthermore, the sequential manner resources that are allocated to somatic vs. reproductive tissue during ontogeny may, when juveniles develop in unpredictable environments, further contribute to non-adaptive variation in adult reproductive rates. 3. With a model on female egg laying in insects, we demonstrate how variation in body reserves is predicted to affect reproductive rate under different ecological scenarios. Small females always have higher reproductive rates but shorter lifespans. However, incorporation of female host selectivity leads to more similar reproductive rates among female size classes, and oviposition behaviour is predicted to co-evolve with reproductive rate, resulting in small females being more selective in their choice and gaining relatively more from it. 4. We fed simulations with data on the butterfly Pararge aegeria to compare model predictions with reproductive rates of wild butterflies. However, simulated reproductive allometry was a poor predictor of that observed. Instead, reproductive rates were better explained as a product of metabolic constraints on rates of egg maturation, and an empirically derived positive allometry between reproductive potential and size. However, fitness is insensitive to moderate deviations in reproductive rate when oviposition behaviour is allowed to co-evolve in the simulations, suggesting that behavioural compensation may mitigate putative metabolic and developmental constraints. 5. More work is needed to understand how physiology and development together with compensatory behaviours interact in shaping reproductive allometry. Empirical studies should evaluate adaptive hypotheses against proper null hypotheses, including prediction from metabolic theory, preferentially by studying reproductive physiology in combination with behaviour. Conversely, inferences of constraint explanations on reproductive rates must take into consideration that adaptive scenarios may predict similar allometric exponents.

  • 43.
    Berggren, Per
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Stocks, status and survival of harbour porpoises (Phocoena phocoena) in Swedish waters1995Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 44.
    Berggren, Per
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Coles, Phil
    Whales and dolphins: a field guide to marine mammals of East Africa2009Bok (Övrigt vetenskapligt)
  • 45.
    Bergman, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Fjärilar, revirslagsmål och parningsframgång2009Ingår i: Schedula Ranae, nr 1, s. 12-13Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 46.
    Bergman, Martin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Olofsson, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Wiklund, Christer
    Contest outcome in a territorial butterfly: the role of motivation2010Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 277, nr 1696, s. 3027-3033Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In many butterfly species, males compete over areas advantageous for encountering females. Rules for contest settlement are, however, largely unknown and neither morphological nor physiological traits can reliably predict the contest outcome. Here, we test the hypothesis that contests are settled in accordance with a motivation asymmetry. We staged contests between males of Pararge aegeria and after removing the resident, the non-resident was allowed (i) either to interact with a non-receptive female for 30 min (n = 30) or (ii) to spend 30 min alone in the cage (n = 30), after which the initial resident was reintroduced. The results show that males that had interacted with a female had a higher probability of becoming dominant and reversing contest outcome. Moreover, males that were faster to take over a vacant territory when the resident was removed were more likely to become dominant. Here, we show for the first time, to our knowledge, that frequent encounters with a mated female can increase male motivation to persist in a territorial contest in a butterfly. Further, we suggest that variation in intrinsic motivation reflects male eagerness to take over vacant territory. This study indicates that variation in resource value and motivational asymmetries are important for settling contests in butterflies.

  • 47.
    Bergman, Martin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Wiklund, Christer
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Territorialitet hos dagfjärilar2011Ingår i: Fauna & Flora, Vol. 106, nr 1, s. 20-25Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 48.
    Bergström, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Oviposition site preferences of the threatened butterfly Parnassius mnemosyne: implications for conservation2005Ingår i: Journal of Insect Conservation, ISSN 1366-638X, E-ISSN 1572-9753, Vol. 9, nr 1, s. 21-27Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent studies on the threatened clouded apollo butterfly, Parnassius mnemosyne, have identified suitable habitats on a large scale. More detailed knowledge on specific habitat requirements of ovipositing females is still needed. Some earlier observations suggest that females just drop their eggs without discrimination. This study suggests that females can be rather choosy in their oviposition site selection and that they actively search for oviposition sites with suitable vegetation structure. By identifying factors influencing female oviposition, such as distance to shrub, valuable knowledge is generated for restoration plans considered in the study area. This stresses the importance of proper management of extant habitats in order to prevent local extinctions of P. mnemosyne and it also highlights the need for data on specific oviposition requirements in butterfly conservation.

  • 49.
    Bergvall, Ulrika A
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Development of feeding selectivity and consistency in food choice over5 years in fallow deer2009Ingår i: Behavioural Processes, ISSN 0376-6357, E-ISSN 1872-8308, Vol. 80, s. 140-146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to better understand the development and maintenance of feeding selectivity, several feedingexperimentswere performed with fallowdeer (Damadama L.). In experiments performed when the fawnswere between tenand 27 days old, itwas found that all fawnsshowedpreferences for sucrose but aversionstowards tannic acid and ascorbic acid.However, differences in selectivity towards tannic acidwere presentalready before the fawns became functional ruminants and these individual differences lasted 5 years.Moreover, individuals that ingested overall less tannic acid, searched more thoroughly between foodsources. When the foraging behaviour was compared with age (11–41 days old and 65–97 days old), itwas found that the time a fawn spent eating, increased with age, and the time spent on exploration,smelling and tasting plants decreased with age. Furthermore, the fawns increased their intake of grassand herbs, while the intake of soil and dead plant material decreased with age.

  • 50.
    Bergvall, Ulrika A.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Co, Michelle
    Bergström, Roger
    Sjöberg, Per J. R.
    Waldebäck, Monica
    Turner, Charlotta
    Anti-browsing effects of birch bark extract on fallow deer2013Ingår i: European Journal of Forest Research, ISSN 1612-4669, E-ISSN 1612-4677, Vol. 132, nr 5-6, s. 717-725Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A major problem within forest industry is unwanted browsing on seedlings from mammalian herbivores. The aim of this study was to evaluate the effects of birch bark extracts as repellents towards fallow deer. Birch bark was extracted in a conventional way with ethanol as solvent at ambient temperature and with a new method, liquid CO2 extraction. An analysis of the ethanol-extracted birch bark showed that it contained large amounts of terpenoids, of which the most abundant was betulin. In seven different treatment trials, we used 15 individually handled fallow deer. To investigate the binary taste preferences, birch bark extract was added to food and presented in two bowls in typical two-choice tests. We found that the amount of a food type consumed during a trial and the number of shifts between food bowls were dependent on the amount of the birch extract the food contained. Concentrations of above 1 % by dry weight of birch extract acted as a repellent. In addition, such concentrations produced shorter feeding bouts by a greater willingness to change bowls. Therefore, our conclusion is that birch bark extract acts as a repellent towards fallow deer and is therefore likely to act as a repellent against other deer species. In addition, we show that birch bark extract produced by the new and more environmentally sustainable method employing liquid CO2 mixed with ethanol has the same repellent effect as the traditional ethanol extraction.

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