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  • 151.
    Envall, Ida
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Gustavsson, Lena M.
    Erseus, Christer
    Genetic and chaetal variation in Nais worms (Annelida, Clitellata, Naididae)2012In: Zoological Journal of the Linnean Society, ISSN 0024-4082, E-ISSN 1096-3642, Vol. 165, no 3, p. 495-520Article in journal (Refereed)
    Abstract [en]

    The genus Nais is a group of oligochaetous clitellates, common in eutrophic freshwater habitats. About 30 species are described. Species identification is based primarily on chaetal characters, which are often subtle, inconsistent, and even overlapping between nominal species. We investigated the correlation between genetic variation and chaetal morphology in this genus. Eighty-one individuals from Europe, North America, and China were included in the study. Seventy-five of these were preserved as vouchers. They were scrutinized with regard to chaetal morphology, and ten different morphotypes were identified. Three molecular markers, two mitochondrial (the COI gene and 16S rDNA) and one nuclear (the ITS region), were used to establish the genetic lineages in the material. Genetic variation was found to be largely congruent with chaetal character patterns. However, at least nine separately evolving lineages (all supported by mitochondrial as well as nuclear data) correspond to at most six nominal species. Four morphotypes/lineages are recognized as Nais barbata, Nais christinae, Nais elinguis, and Nais stolci, respectively, whereas five, or possibly more, lineages represent a morphological continuum covering the variation of the Nais communis/variabilis complex. Thus, cryptic speciation is revealed. Our results indicate that a taxonomic revision of the genus will be needed in the future.

  • 152.
    Envall, Ida
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Källersjö, Mari
    Erséus, Christer
    University of Gothenburg.
    Molecular evidence for the non-monophyletic status of Naidinae (Annelida, Clitellata, Tubificidae)2006In: Molecular Phylogenetics and Evolution, ISSN 1055-7903, E-ISSN 1095-9513, Vol. 40, no 2, p. 570-584Article in journal (Refereed)
    Abstract [en]

    Naidinae (former Naididae) is a group of small aquatic clitellate annelids, common worldwide. In this study, we evaluated the phylogenetic status of Naidinae, and examined the phylogenetic relationships within the group. Sequence data from two mitochondrial genes (12S rDNA and 16S rDNA), and one nuclear gene (18S rDNA), were used. Sequences were obtained from 27 naidine species, 24 species from the other tubificid subfamilies, and five outgroup taxa. New sequences (in all 108) as well as GenBank data were used. The data were analysed by parsimony and Bayesian inference. The tree topologies emanating from the different analyses are congruent to a great extent. Naidinae is not found to be monophyletic. The naidine genus Pristina appears to be a derived group within a clade consisting of several genera (Ainudrilus, Epirodrilus, Monopylephorus, and Rhyacodrilus) from another tubificid subfamily, Rhyacodrilinae. These results demonstrate the need for a taxonomic revision: either Ainudrilus, Epirodrilus, Monopylephorus, and Rhyacodrilus should be included within Naidinae, or Pristina should be excluded from this subfamily. Monophyly of four out of six naidine genera represented by more than one species is supported: Chaetogaster, Dero, Paranais, and Pristina, respectively

  • 153.
    Ericson, Gunilla
    Stockholm University, Faculty of Science, Department of Zoology.
    ³²P-postlabelling analysis of DNA adducts in fish as a biomarker of genotoxic exposure1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The 32P-postlabelling assay was used for analysis of hydrophobic DNA adducts in fish as a biomarker of genotoxic exposure. DNA adducts were analysed in perch (Perca fluviatilis) and northern pike (Esox lucius), two relatively stationary fish species which are common in Swedish freshwater systems and along the Baltic coast. Experimental studies on time-course, dose-response and persistence of DNA adducts in liver and extrahepatic tissues of pike were performed in the laboratory. DNA adducts were readily formed in pike exposed to carcinogenic model substances. Oral exposure gave rise to higher adduct levels in both liver and intestine compared to intraperitoneal exposure. Following repeated oral exposure, adduct levels increased in a dose-related manner in liver, gills, brain and intestine, with highest levels in the intestine. No significant decrease in total adduct levels was observed in liver, gills and brain during a 78-day period after the last exposure, while adduct levels in intestine decreased to one third of the maximum value. DNA adducts in the intestine are probably removed due to a high cell turnover rate in this tissue, and may thus represent ongoing or relatively recent exposure.

    Perch and pike from minimally polluted sites were analysed at several occasions, including during the reproductive season for perch, with the results showing no detectable adducts, or very low levels. No adducts related to spawning season were detected in unexposed female or male perch.

    In a field investigation carried out in a pollution gradient of polycyclic aromatic hydrocarbons leading away from an aluminium smelter, adduct levels in liver and kidney were correlated to distance from the suspected point source and to contaminant levels in the sediment. Adduct levels in gills, spleen, blood and brain were also elevated in perch from the site closest to the smelter compared to the outermost site. Increased adduct levels in these tissues were correlated to effects on higher biological organisation levels, i.e. hepatocellular degeneration and decreased growth rate at the two innermost sites, and decreased spleen somatic index at the innermost site. Adduct levels were also increased in perch from a river with creosote-contaminated bottom sediments, indicating that potentially genotoxic compounds in the sediment were bioavailable to the fish. Exposure of perch in the laboratory to a solvent extract prepared from the contaminated sediment resulted in adduct patterns which closely resembled those obtained from field captured perch, thus verifying the origin of the genotoxic substances. Furthermore, increased DNA adduct levels in liver and intestine of feral fish from coastal waters receiving bleached kraft pulp mill effluents were detected.

    The results show that 32P-postlabelling analysis of hydrophobic DNA adducts in feral perch and pike can be used as a sensitive biomarker of exposure to potentially genotoxic compounds in the aquatic environment. Adduct levels in liver and several extrahepatic tissues were positively correlated to exposure concentrations. Levels of aromatic/hydrophobic DNA adducts in unexposed perch and pike can be considered as practically zero. DNA adducts thus exhibit a wide range in response, from almost zero in unexposed fish to high levels in exposed fish, which is desirable for a good biomarker.

  • 154.
    Eriksson, Maertha
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Carlsson, Mikael A.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Insect brain plasticity: effects of olfactory input on neuropil size2019In: Royal Society Open Science, E-ISSN 2054-5703, Vol. 6, no 8, article id 190875Article in journal (Refereed)
    Abstract [en]

    Insect brains are known to express a high degree of experience-dependent structural plasticity. One brain structure in particular, the mushroom body (MB), has been attended to in numerous studies as it is implicated in complex cognitive processes such as olfactory learning and memory. It is, however, poorly understood to what extent sensory input per se affects the plasticity of the mushroom bodies. By performing unilateral blocking of olfactory input on immobilized butterflies, we were able to measure the effect of passive sensory input on the volumes of antennal lobes (ALs) and MB calyces. We showed that the primary and secondary olfactory neuropils respond in different ways to olfactory input. ALs show absolute experience-dependency and increase in volume only if receiving direct olfactory input from ipsilateral antennae, while MB calyx volumes were unaffected by the treatment and instead show absolute age-dependency in this regard. We therefore propose that cognitive processes related to behavioural expressions are needed in order for the calyx to show experience-dependent volumetric expansions. Our results indicate that such experience-dependent volumetric expansions of calyces observed in other studies may have been caused by cognitive processes rather than by sensory input, bringing some causative clarity to a complex neural phenomenon.

  • 155.
    Erlandsson, Rasmus
    Stockholm University, Faculty of Science, Department of Zoology.
    Spatial and temporal population dynamics in the mountain tundra – mesopredator and prey2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    It is well known that competition, predation and fluctuating food resources can have strong effect on individual fitness and population dynamics. The complexity of natural systems can make it complicate to disentangle those processes, but environments with relatively simple food webs, and strong cyclic population dynamics offer contrasting conditions resembling experimental treatments. This thesis concerns the spatial and temporal implications of fluctuations in small rodent abundance on two trophic levels in a highly cyclic ecosystem, the Scandinavian mountain tundra. The first two chapters focus on plant biomass and spatiotemporal distribution in the Norwegian lemming (Lemmus lemmus), while the three last papers focus on the direct and indirect effects of small rodent fluctuations and territory quality on reproductive success, juvenile survival and group living in a lemming specialist mesopredator, the arctic fox (Vulpes lagopus). By developing, validating and applying a novel application of aerial photos for remote sensing of plant biomass (Chapter I), we found that food availability predicted lemming distribution during population peaks, but that they were more habitat specific during increase years when intraspecific competition was lower (Chapter II). Arctic fox reproduction is tightly connected to small rodent abundance but the effects of geographical variation in food availability is less well known. We used 17 years of population surveys of an arctic fox subpopulation in mid Sweden (Helagsfjällen) to investigate potential effects. During small rodent increase years, we found that arctic fox litter sizes were smaller in territories of intermediate plant productivity, compared to both more and less productive territories (Chapter III). This could be an effect of limited food availability together with increased presence of red foxes (Vulpes vulpes), a stronger and potentially lethal competitor. However, when small rodents peaked, and competition would be expected to decrease, we saw no effect of territory productivity. Based on a smaller data set concerning juvenile summer survival, we found that the mortality rate among juveniles born by first time breeding arctic fox females were more sensitive to low small rodent prey abundance (Chapter IV). We explain it with an increased predation pressure from top-predators that switch from small rodents to alternative prey when small rodents decline, as suggested by an observed positive effect on juvenile survival by adult presence on den sites. Arctic foxes are socially flexible, and several adults can share a den with the resident pair, potentially increasing juvenile survival and help in territorial defence. Returning to the 17-year data set, we tested the Resource Dispersion Hypothesis predicting that increased resource availability should increase group size (Chapter V). We found support for this prediction as group living increased during the small rodent peak phase. However, it remained unexpectedly high during the decrease phase, when resources are scarce. This could however be related to increased predation pressure, and an increasing benefit of group living.

  • 156.
    Erlandsson, Rasmus
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Wallén, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Märkningen av fjällrävar förutsättning för effektiv och långsiktig forskning2015In: Härjedalen, ISSN 1103-9426, no 27 augustiArticle in journal (Other (popular science, discussion, etc.))
  • 157.
    Espeland, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology.
    Irestedt, Martin
    Swedish Museum of Natural History, Molecular Systematics Laboratory.
    Johanson, Kjell Arne
    Swedish Museum of Natural History, Entomology department.
    Åkerlund, Monika
    Swedish Museum of Natural History, Research Department.
    Bergh, Jan-Erik
    Dalarna University College.
    Källersjö, Mari
    Swedish Museum of Natural History, Molecular Systematics Laboratory.
    Dichlorvos exposure impedes extraction and amplification of DNA from insects in museum collections2010In: Frontiers in Zoology, ISSN 1742-9994, E-ISSN 1742-9994, Vol. 7, no 2, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Background: The insecticides dichlorvos, paradichlorobenzene and naphthalene have been commonly used to eradicate pest insects from natural history collections. However, it is not known how these chemicals affect the DNA of the specimens in the collections. We thus tested the effect of dichlorvos, paradichlorobenzene and naphthalene on DNA of insects (Musca domestica) by extracting and amplifying DNA from specimens exposed to insecticides in two different concentrations over increasing time intervals.

    Results: The results clearly show that dichlorvos impedes both extraction and amplification of mitochondrial and nuclear DNA after relatively short time, whereas paradichlorobenzene and naphthalene do not.

    Conclusion: Collections treated with paradichlorobenzene and naphthalene, are better preserved concerning DNA, than those treated with dichlorvos. Non toxic pest control methods should, however, be preferred due to physical damage of specimens and putative health risks by chemicals.

  • 158.
    Espeland, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology.
    Johanson, Kjell Arne
    A new species of Goera Stephens: 1829 (Goeridae Trichoptera) from the Solomon Islands2011In: Aquatic Insects, ISSN 0165-0424, E-ISSN 1744-4152, Vol. 33, no 2, p. 185-189Article in journal (Refereed)
    Abstract [en]

    Male and female of Goera pitisopai sp. nov. from the Solomon Islands are illustrated and described based on recently collected material. This is the first species of the family Goeridae reported from the Solomon Islands, and the sixth from the Australasian region.

  • 159.
    Espeland, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology.
    Johanson, Kjell Arne
    Swedish Museum of Natural History, Entomology department.
    The diversity and radiation of the largest monophyletic animal group on New Caledonia (Trichoptera: Ecnomidae: Agmina)2010In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 23, no 10, p. 2112-2122Article in journal (Refereed)
    Abstract [en]

    In area, New Caledonia is the smallest of the world's 25 official biodiversity hotspots, but in many taxonomic groups, the island has the highest concentration of species on earth, particularly so in the freshwater insect order Trichoptera. This study aims at applying molecular data and morphology for estimating the real species diversity of the genus Agmina on New Caledonia and investigating potential effects of ultramafic rock substrate on diversification. A dated molecular phylogeny was applied to study diversity and diversification related to geological substrate using the dispersal-extinction-cladogenesis model, diva and Bayesian ancestral character reconstruction. More than 47 species (> 63%) were unknown to science. Initial radiation occurred on ultramafic substrate followed by several independent dispersal events to nonultramafic substrate. The rate of shift from ultramafic to nonultramafic substrate was significantly higher than the rate of shift in the opposite direction, indicating a possible cost associated with living on ultramafic substrate.

  • 160.
    Espmark, Yngve
    Stockholm University.
    Mother-young relations and development of behaviour in roe deer (Capreolus capreolus L.)1969Doctoral thesis, monograph (Other academic)
  • 161.
    Fang Kullander, Fang
    Stockholm University, Faculty of Science, Department of Zoology.
    Phylogeny and species diversity of the South and Southeast Asian cyprinid genus Danio Hamilton (Teleostei, Cyprinidae)2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Danio Hamilton, in the wide sense, consists of 66 nominal species, of which about 45 are valid. Four species, viz. D. kakhienensis, D. laoensis, D. shanensis and D. browni, were revalidated in papers revising the genus. Six species were found to be new to science: Danio maetaengensis from northern Thailand; D. kyathit from northern Myanmar; D. apopyris, D. acrostomus and D. leptos form northern Laos; and D. roseus from northeastern Thailand and northwestern Laos. Daniops myersi was confirmed to be a junior synonym of D. laoensis.

    Three species groups have been recognized among Danio (s. l.) species based mainly on colour pattern and other morphological characters: the striped danios, the barred danios and the Danio dangila species group. The striped danios differ from barred danios in having more branched dorsal-fin rays, a complete lateral line, two pairs of short barbels and a P stripe extending to the end of the caudal-fin rays (instead of the P stripe being confined to the caudal peduncle).

    A few characters common to both striped and barred danios but absent in the Danio dangila species group are, e. g., a cleithral spot immediately behind the gill-opening and a skin groove on the supraorbital shelf. A phylogenetic analysis shows that Danio is paraphyletic. Two monophyletic groups can be recognized within the non-monophyletic genus Danio, one comprising only the Danio dangila species group, and the other including all the striped and barred danios. The first group thus represents the genus Danio (s. str.), and the latter a distinct genus Devario, with the type species D. devario. The monophyly of Danio is strongly supported, and its sister group is Esomus. Chela and Inlecypris are closely related to each other, and they form the sister group of Devario. Brachydanio is confirmed to be a junior synonym of Danio (s. str.). Danio erythromicron is excluded from both Danio (s. str.) and Devario. Its generic status is pending further study. The phylogenetic relationships of Sundadanio axelrodi and Danionella translucida to Danio (s. str.) and Devario remain unresolved. 

  • 162.
    Favati, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Løvlie, Hanne
    Personality predicts social dominance in male domestic fowl2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 7, article id e103535Article in journal (Refereed)
    Abstract [en]

    Individuals in social species commonly form dominance relationships, where dominant individuals enjoy greater access to resources compared to subordinates. A range of factors such as sex, age, body size and prior experiences has to varying degrees been observed to affect the social status an individual obtains. Recent work on animal personality (i.e. consistent variation in behavioural responses of individuals) demonstrates that personality can co-vary with social status, suggesting that also behavioural variation can play an important role in establishment of status. We investigated whether personality could predict the outcome of duels between pairs of morphologically matched male domestic fowl (Gallus gallus domesticus), a species where individuals readily form social hierarchies. We found that males that more quickly explored a novel arena, or remained vigilant for a longer period following the playback of a warning call were more likely to obtain a dominant position. These traits were uncorrelated to each other and were also uncorrelated to aggression during the initial part of the dominance-determining duel. Our results indicate that several behavioural traits independently play a role in the establishment of social status, which in turn can have implications for the reproductive success of different personality types.

  • 163. Felton, Adam
    et al.
    Lindbladh, Matts
    Elmberg, Johan
    Felton, Annika M.
    Andersson, Erik
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Sekercioglu, Cagan H.
    Collingham, Yvonne
    Huntley, Brian
    Projecting impacts of anthropogenic climatic change on the bird communities of southern Swedish spruce monocultures: will the species poor get poorer?2014In: Ornis Fennica, ISSN 0030-5685, Vol. 91, no 1, p. 1-13Article in journal (Refereed)
    Abstract [en]

    The potential impact of climatic change on bird species' distributions in Europe was recently modeled for several scenarios of projected late 21st century climate. The results indicate mean range shifts of hundreds of kilometres north for many of European bird species. Here we consider the implications from such distributional shifts for the bird communities of Norway spruce (Picea abies) monocultures in southern Sweden, a forest type likely to remain prevalent due to forestry, despite climate change. Our assessment led us to three key findings. First, the monocultures offer suitable habitat to only two bird species projected to extend their breeding distribution northwards into southern Sweden this century. Second, species richness was projected to decline overall, which would accentuate the depauperate nature of these stands. Third, all conifer-associated arboreal granivores and three of four conifer-associated arboreal insectivores were projected not to occur, reducing both the functional richness and functional redundancy. We discuss caveats related to our approach, including the potential for bioclimatic projections - used in this study - to be hampered by the artificial retention of dominant vegetation. We also discuss the implications of our results for avian biodiversity in what is today the most prevalent forest type in southern Sweden and in many other regions of Europe.

  • 164.
    Fernholm, Bo
    Stockholm University.
    Pituitary and ovary of the Atlantic hagfish: an endocrinological investigation1972Doctoral thesis, comprehensive summary (Other academic)
  • 165.
    Fernö, Anders
    Stockholm University.
    Aggressive behaviour between territorial cichlid fish and its regulation1986Doctoral thesis, comprehensive summary (Other academic)
  • 166.
    Forkman, Björn
    Stockholm University, Faculty of Science, Department of Zoology.
    The gathering and use of information in foraging1993Doctoral thesis, comprehensive summary (Other academic)
  • 167.
    Forsberg, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Reproductive biology of some Pierid butterflies1988Doctoral thesis, comprehensive summary (Other academic)
  • 168.
    Fransson, Thord
    Stockholm University, Faculty of Science, Department of Zoology.
    Time and energy in long-distance bird migration1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Long-distance seasonal migration is energetically demanding and time consuming. For example, some passerine birds are on migration during six months of the year, travel more than 10 000 km and make use of many fuelling sites. Migration requires many different decisions, and an individual bird will face a variety of situations. This thesis investigates how long-distance migratory passerine birds use time and energy under different circumstances.

    In a comparison of Sylvia warblers, it was shown that more northern populations within species spend shorter time at breeding grounds and have a higher speed during autumn migration. Higher overall speed was also shown in species undertaking longer migrations. This indicates that selection has favoured a behaviour that will economise time during long-distance migration. Results from the last part of the spring migration in the Ortolan Bunting Emberiza hortulana indicate that early arrival is important in males while females might take other considerations into account. Willow Warbler Phylloscopus trochilus males arriving at breeding sites following spring migration carried an overload of fuel, which might be important during the transition between migration and breeding. Since acquisition of this reserve probably delayed their arrival, it also indicates that an individual's future activities have to be considered at some stages of migration.

    Whitethroats Sylvia communis with access to food ad libitum at the start of autumn migration increased their fuel deposition rate and departed with a larger fuel load. At the feeder, no correlation between fuel deposition rate and departure fuel load was found, which is theoretically expected for birds minimising time on migration. Juvenile birds in post-juvenile moult attained a much higher stable body mass at the feeder than under natural conditions. Before departure they abruptly increased their gross food intake by about 70% resulting in a period of body mass gain. Whitethroat behaviour at the feeder agreed with predictions in a finite-distance model for time-minimisation during migration, in which birds take the total migratory distance into account. However, both the compensatory increase in migration speed in late birds that was found in several Sylvia warblers, and the higher departure fuel loads found in late Whitethroats at the feeder indicate that early birds also take other considerations than time-minimisation into account.

    The effect of increased fuel load on the take-off ability under a simulated predator attack in Blackcaps Sylvia atricapilla, was shown to be much less than previously shown for other species. The large fuel loads that often exist, and the intense foraging normally combined with fuelling, will probably still place them at increased risk of predation during migration. In a simulated stopover situation, Blackcaps with an imminent risk of predation initially increase their food intake and fuelling rate compared with a control group. The pattern of night activity indicated that they also choose to leave earlier and with a lower fuel load than birds in the control group. This clearly shows that stopover behaviour can be adjusted to perceived predation risk.

    Evolution is expected to favour a behaviour where survival is maximised during migration. However, it is not always possible to maximise behaviour and performance in all respect simultaneously. It is suggested that the optimal migration strategy may be to minimise overall mortality risk, achieved through a balance between consequences of arrival time, starvation risk and exposure to predation during migration

  • 169.
    Fransson, Thord
    et al.
    Naturhistoriska Riksmuseet.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Johansson, Patrik
    Sveriges geologiska undersökningar.
    Kullberg, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology.
    Lind, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Valllin, Adrian
    Stockholm University, Faculty of Science, Department of Zoology.
    Magnetic cues trigger extensive refuelling2001In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 414, p. 35-36Article in journal (Refereed)
  • 170.
    Fredriksson, Gunnar
    Stockholm University.
    Thyroid-like systems in endostyles: a study on morphology, function and evolution in "primitive" chordates1988Doctoral thesis, comprehensive summary (Other academic)
  • 171.
    Fredriksson, Magnus J.
    Stockholm University.
    β-adrenergic stimulation of VEGF gene expression: intracellular signalling pathways2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the present study, the intracellular signalling pathway mediating ß-adrenergic stimulation of the expression of the vascular endothelial growth factor (VEGF) gene was investigated.

    VEGF is an activator of angiogenesis, the formation of new blood vessels, and is considered to be a major regulator of both physiologically and pathologically related angiogenesis, as well as being essential for development of the vascular system. At the outset of the present investigation, it was already known that several factors - such as hypoxia, certain growth factors and phorbol esters - were potent stimulators of Vegf expression; however, it was unknown whether activation of ß-adrenergic receptors could influence the expression of the VEGF gene. Thus, to investigate this issue, cultured primary brown adipocytes, which express ß-adrenergic receptors, were isolated from mouse brown adipose tissue and used as a model system. The present cell system is here thought of as a relevant model for elucidation of angiogenesis-related processes - such as regulation of Vegf expression - since brown adipose tissue is a highly vascularised tissue, demonstrating high angiogenesis activity during tissue recruitment which is induced as a response to cold exposure or norepinephrine stimulation.

    With Ucp1-ablated mice - the brown adipocytes of which were demonstrated to lack the capacity for adrenergically induced oxygen consumption (thermogenesis) - results were obtained that provide support for the idea that the physiological activator of ß-adrenergic receptors, norepinephrine, is the factor that directly mediates physiological stimulation of Vegf expression in brown adipose tissue during recruitment, i.e. without involvement of hypoxic conditions being generated in the tissue.

    It was demonstrated that norepinephrine-induced activation of ß-adrenergic receptors mediates a potent stimulation of Vegf expression in brown adipocytes. For elucidation of the intracellular signalling factors activated via the ß-receptors, differentiated brown adipocytes, which possess ß3-adrenergic receptors, were used. It was found that for mediation of the ß-adrenergic signal, high intracellular levels of cAMP, and subsequent activation of PKA, are the exclusive mediating pathway for adrenergic stimulation; involvement of other adrenergic signalling mechanisms were excluded. In connection with investigations of PKA-mediated signalling via ß3-adrenergic receptors, the PKA inhibitor H89 was used and it was concluded that it functioned as intended - to abolish ß3-adrenergically induced Vegf and Ucp1 expression and thermogenesis by PKA inhibition - and did not act as a ß3-adrenergic antagonist.

    Further, adrenergic activation of the Erk1/2 MAP kinase signalling pathway in brown adipocytes was elucidated and shown to proceed through Src tyrosine kinases. ß-Adrenergic activation of Src, via a cAMP/PKA-mediated pathway, was demonstrated to partially mediate ß-adrenergic stimulation of Vegf expression, without dependence on further mediation via the downstream-acting Erk1/2, thus indicating a branch-point in the ß-adrenergically activated Src-Erk1/2 signalling cascade which further connects to the VEGF gene.

    In conclusion, the present investigation has provided further insight into the mechanisms by which stimulation of Vegf expression can be mediated, and has contributed information on the involvement of ß-adrenergic receptors in this process.

  • 172. Freeberg, Todd M.
    et al.
    Krama, Tatjana
    Vrublevska, Jolanta
    Krams, Indrikis
    Kullberg, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology.
    Tufted titmouse (Baeolophus bicolor) calling and risk-sensitive foraging in the face of threat2014In: Animal Cognition, ISSN 1435-9448, E-ISSN 1435-9456, Vol. 17, no 6, p. 1341-1352Article in journal (Refereed)
    Abstract [en]

    Individuals often produce alarm or mobbing calls when they detect a threat such as a predator. Little is known about whether such calling is affected by the facial orientation of a potential threat, however. We tested for an effect of facial orientation of a potential threat on tufted titmice, Baeolophus bicolor, a songbird that uses chick-a-dee calls in a variety of social contexts. In two studies, a human observer wore an animal mask that either faced or faced away from the focal bird(s). In Study 1, focal birds were individual titmice captured in a walk-in trap, and the observer stood near the trapped bird. In Study 2, focal birds were titmouse flocks utilizing a feeding station and the observer stood near the station. In both studies, calling behavior was affected by mask orientation. In Study 2, foraging and agonistic behavior were also affected. Titmice can therefore perceive the facial orientation of a potential threat, and this perception affects different behavioral systems, including calling. Our results indicate sensitivity of titmice to the facial orientation of a potential predator in two quite different motivational contexts. This work suggests the possibility of strategic signaling by prey species depending upon the perceptual space of a detected predator.

  • 173. Freitas, André
    et al.
    Peña, Carlos
    Stockholm University, Faculty of Science, Department of Zoology. Zoologisk ekologi.
    Description of genus Guaianaza for "Euptychia" pronophila (Lepidoptera: Nymphalidae: Satyrinae) with a description of the immature stages2006In: Zootaxa, ISSN 1175-5326, E-ISSN 1175-5334, Vol. 1163, p. 49-59Article in journal (Refereed)
    Abstract [en]

    The satyrine Euptychia pronophila Butler (Nymphalidae) was described in 1867 in the “catch-all” genus Euptychia, but was recently treated as incertae sedis. A DNA-based cladistic analysis confirms that it belongs to the Euptychiina, as sister to Forsterinaria and closely related to Taygetis, Posttaygetis, Parataygetis, Pseudodebis, and Harjesia. Although immature morphology also suggests that this species is closely related to Forsterinaria, none of the adult morphological synapomorphies for the genera in the aforementioned clade occur in E. pronophila, a highly autapomorphic species. Because we were unable to place it with confidence in an established genus, the monotypic satyrine genus Guaianaza Freitas & Peña New Genus is described, with Euptychia pronophila Butler as the type species

  • 174.
    Friberg, Magne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Aalberg Haugen, Inger M.
    Stockholm University, Faculty of Science, Department of Zoology.
    Dahlerus, Josefin
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Asymmetric life-history decision-making in butterfly larvae2011In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 165, no 2, p. 301-310Article in journal (Refereed)
    Abstract [en]

    In temperate environments, insects appearing in several generations in the growth season typically have to decide during the larval period whether to develop into adulthood, or to postpone adult emergence until next season by entering a species-specific diapause stage. This decision is typically guided by environmental cues experienced during development. An early decision makes it possible to adjust growth rate, which would allow the growing larva to respond to time stress involved in direct development, whereas a last-minute decision would instead allow the larva to use up-to-date information about which developmental pathway is the most favourable under the current circumstances. We study the timing of the larval pathway decision-making between entering pupal winter diapause and direct development in three distantly related butterflies (Pieris napi, Araschnia levana and Pararge aegeria). We pinpoint the timing of the larval diapause decision by transferring larvae from first to last instars from long daylength (inducing direct development) to short daylength conditions (inducing diapause), and vice versa. Results show that the pathway decision is typically made in the late instars in all three species, and that the ability to switch developmental pathway late in juvenile life is conditional; larvae more freely switched from diapause to direct development than in the opposite direction. We contend that this asymmetry is influenced by the additional physiological preparations needed to survive the long and cold winter period, and that the reluctance to make a late decision to enter diapause has the potential to be a general trait among temperate insects.

  • 175.
    Friberg, Magne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Uppsala universitet.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Heterospecific courtship, minority effects and niche separation between cryptic butterfly species2013In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 26, no 5, p. 971-979Article in journal (Refereed)
    Abstract [en]

    Species interacting in varied ecological conditions often evolve in different directions in different local populations. The butterflies of the cryptic Leptidea complex are sympatrically distributed in different combinations across their Eurasian range. Interestingly, the same species is a habitat generalist in some regions and a habitat specialist in others, where a sibling species has the habitat generalist role. Previous studies suggest that this geographically variable niche divergence is generated by local processes in different contact zones. By varying the absolute and relative densities of Leptidea sinapis and Leptidea juvernica in large outdoor cages, we show that female mating success is unaffected by conspecific density, but strongly negatively affected by the density of the other species. Whereas 80% of the females mated when a conspecific couple was alone in a cage, less than 10% mated when the single couple shared the cage with five pairs of the other species. The heterospecific courtships can thus affect the population fitness, and for the species in the local minority, the suitability of a habitat is likely to depend on the presence or absence of the locally interacting species. If the local relative abundance of the different species depends on the colonization order, priority effects might determine the ecological roles of interacting species in this system.

  • 176.
    Friberg, Magne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology. Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Nya rön om skogs- och ängsvitvingar: Vem är vem i fjärilsvärlden?2009In: Flora och Fauna, Vol. 104, no 1, p. 12-17Article, review/survey (Other (popular science, discussion, etc.))
  • 177. Fridberg, Gunnar
    Morphological studies on the caudal neurosecretory system in teleosts and elasmobranchs.1963Doctoral thesis, comprehensive summary (Other academic)
  • 178.
    Gale, Charles C.
    Stockholm University.
    Hypothalamic control of the pituitary gland during lactation and thermoregulation1964Doctoral thesis, comprehensive summary (Other academic)
  • 179.
    Gamberale-Stille, Gabriella
    Stockholm University, Faculty of Science, Department of Zoology.
    On the evolution and function of aposematic coloration2000Doctoral thesis, comprehensive summary (Other academic)
  • 180.
    Gamberale-Stille, Gabriella
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Balogh, Alexandra C. V.
    Stockholm University, Faculty of Science, Department of Zoology.
    Tullberg, Birgitta S.
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    FEATURE SALTATION AND THE EVOLUTION OF MIMICRY2012In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 66, no 3, p. 807-817Article in journal (Refereed)
    Abstract [en]

    In Batesian mimicry, a harmless prey species imitates the warning coloration of an unpalatable model species. A traditional suggestion is that mimicry evolves in a two-step process, in which a large mutation first achieves approximate similarity to the model, after which smaller changes improve the likeness. However, it is not known which aspects of predator psychology cause the initial mutant to be perceived by predators as being similar to the model, leaving open the question of how the crucial first step of mimicry evolution occurs. Using theoretical evolutionary simulations and reconstruction of examples of mimicry evolution, we show that the evolution of Batesian mimicry can be initiated by a mutation that causes prey to acquire a trait that is used by predators as a feature to categorize potential prey as unsuitable. The theory that species gain entry to mimicry through feature saltation allows us to formulate scenarios of the sequence of events during mimicry evolution and to reconstruct an initial mimetic appearance for important examples of Batesian mimicry. Because feature-based categorization by predators entails a qualitative distinction between nonmimics and passable mimics, the theory can explain the occurrence of imperfect mimicry.

  • 181.
    Gamberale-Stille, Gabriella
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Söderlind, Lina
    Stockholm University, Faculty of Science, Department of Zoology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Host plant choice in the comma butterfly-larval choosiness may ameliorate effects of indiscriminate oviposition2014In: Insect Science, ISSN 1672-9609, E-ISSN 1744-7917, Vol. 21, no 4, p. 499-506Article in journal (Refereed)
    Abstract [en]

    In most phytophagous insects, the larval diet strongly affects future fitness and in species that do not feed on plant parts as adults, larval diet is the main source of nitrogen. In many of these insect host plant systems, the immature larvae are considered to be fully dependent on the choice of the mothers, who, in turn, possess a highly developed host recognition system. This circumstance allows for a potential mother-offspring conflict, resulting in the female maximizing her fecundity at the expense of larval performance on suboptimal hosts. In two experiments, we aimed to investigate this relationship in the polyphagous comma butterfly, Polygonia c-album, by comparing the relative acceptance of low- and medium-ranked hosts between females and neonate larvae both within individuals between life stages, and between mothers and their offspring. The study shows a variation between females in oviposition acceptance of low-ranked hosts, and that the degree of acceptance in the mothers correlates with the probability of acceptance of the same host in the larvae. We also found a negative relationship between stages within individuals as there was a higher acceptance of lower ranked hosts in females who had abandoned said host as a larva. Notably, however, neonate larvae of the comma butterfly did not unconditionally accept to feed from the least favorable host species even when it was the only food source. Our results suggest the possibility that the disadvantages associated with a generalist oviposition strategy can be decreased by larval participation in host plant choice.

  • 182.
    Ganning, Björn
    Stockholm University.
    Studies on Baltic rockpool ecosystems.1971Doctoral thesis, comprehensive summary (Other academic)
  • 183.
    Garpe, Kajsa C.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Yahya, Saleh A.S.
    Stockholm University, Faculty of Science, Department of Zoology.
    Lindahl, Ulf
    Stockholm University, Faculty of Science, Department of Zoology.
    Öhman, Marcus C.
    Stockholm University, Faculty of Science, Department of Zoology.
    Long-term effects of the 1998 coral bleaching event on reef fish assemblages2006In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 315, p. 237-247Article in journal (Refereed)
    Abstract [en]

    Coral bleaching events constitute compound disturbances often resulting in coral death as well as successive degradation of the reef framework. The 1997/1998 El Niño Southern Oscillation (ENSO) was the most severe on record and affected coral reefs worldwide. The present study examined the response of fish assemblages in plots of transplanted coral before and after the 1998 bleaching. Multidimensional scaling ordinations (MDS) demonstrate significant changes in assemblage composition related to habitat alteration. Within-site variability increased with disturbance, the increase being most apparent following substrate erosion. The differences in long-term responses as opposed to short-term responses were striking. Six mo after coral death, total abundance as well as taxonomic richness had increased at one of the sites, but not the other, whereas 6 yr later, both measures had decreased significantly at both sites. Functional groups, with documented affiliations with coral, were significantly influenced by the habitat alteration. Herbivore abundance increased as an immediate response to bleaching, but was subsequently decimated in eroded habitat. The loss of structural complexity had major detrimental effects on the entire fish community. In conclusion, we present evidence of severe and long-lasting secondary impacts of a catastrophic bleaching event, with no apparent recovery. The discrepancies between short-term and long-term responses underline the importance of long-term monitoring of fish assemblages following habitat alteration.

  • 184.
    Geijer, Christina K. A.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. University College London.
    Read, Andrew J.
    Mitigation of marine mammal bycatch in US fisheries since 19942013In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 159, p. 54-60Article in journal (Refereed)
    Abstract [en]

    Bycatch in fishing gear is one of the most pressing conservation issues facing marine mammals today. In the United States a formal regime to address bycatch of marine mammals was adopted in 1994 as Amendments to the Marine Mammal Protection Act (MMPA). This regime provides quantitative conservation goals and a transparent reporting system, allowing for a unique opportunity to assess the efficacy of bycatch mitigation within U.S. waters. In the present analysis, we compile bycatch estimates for each stock of U.S. marine mammals since 1994 to determine whether mitigation efforts under the Amendments have been successful in reducing bycatch. Bycatch trends were analysed on a national level, and for two regional case studies; harbor porpoises in the Gulf of Maine and common dolphins along the U.S. Pacific coast. The estimated annual marine mammal bycatch was 4356 (SE 424) and bycatch levels declined since the MMPA was amended. Harbor porpoise bycatch in the Gulf of Maine was, however, correlated with landings of cod, suggesting that effort controls in the fishery, rather than porpoise conservation measures, were responsible for initial bycatch reduction. Bycatch mitigation efforts were more successful in the Pacific, where higher levels of compliance with mitigation measures are known to occur. We conclude that the 1994 Amendments have in general been successful, but that implementation has not always translated into conservation success, as illustrated by the harbor porpoise case study. Further studies are required to determine factors that promote compliance and mitigation success within the MMPA framework.

  • 185.
    Gelang, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Cibois, A
    Museum Hist Nat, Geneva.
    Pasquet, E
    Museum Natl Hist, Paris.
    Olsson, U
    Göteborgs universitet.
    Alström, P
    SLU Uppsala.
    Ericson, Per
    Stockholm University, Faculty of Science, Department of Zoology.
    Phylogeny of babblers (Aves, Passeriformes): major lineages, family limits and classification2009In: Zoologica Scripta, ISSN 0300-3256, E-ISSN 1463-6409, Vol. 38, no 3, p. 225-236Article in journal (Refereed)
    Abstract [en]

    Babblers, family Timaliidae, have long been subject to debate on systematic position, family limits and internal taxonomy. In this study, we use five molecular regions to estimate the relationships among a large proportion of genera traditionally placed in Timaliidae. We find good support for five main clades within this radiation, and propose a new classification, dividing the babblers into the families Sylviidae and Timaliidae. Within the latter family, four subfamilies are recognized: Zosteropinae, Timaliinae, Pellorneinae and Leiothrichinae. Several taxa, previously not studied with molecular data, are phylogenetically placed within Sylviidae or Timaliidae. This is, however, not the case for the genus Pnoepyga, for which we propose the family name Pnoepygidae fam. n.

  • 186.
    Ghirlanda, Stefano
    Stockholm University, Faculty of Science, Department of Zoology.
    Towards a theory of stimulus control2001Doctoral thesis, monograph (Other academic)
    Abstract [en]

    If an animal performs a behaviour in response to a `familiar' stimulus, it is often found that the behaviour is elicited also by somewhat different, novel stimuli. It is said that behaviour `generalises' from familiar to novel stimuli. Studies of generalisation (or `stimulus control') are a valuable source of empirical knowledge and a powerful tool to evaluate theories of behaviour (since different theories often make different predictions about generalisation). Recently, the importance of generalisation for the evolution of communication systems has also been acknowledged, and stimulus control is now widely researched in evolutionary biology as well.

    Despite such extensive, and still growing empirical knowledge a comprehensive theory of generalisation is lacking. In this thesis, I first review empirical data in an attempt to establish a firm foundation for theoretical reasoning. Among the topics considered are the shape of generalisation gradients along different stimulus dimensions and response biases (peak-shift, supernormal stimulation). I then evaluate a number of theoretical models (both existing and novel ones), investigating their properties by computer simulations and formal mathematical analysis. One result is that models must take into account the information real nervous systems receive from the sense organs. Models that ignore the sense organs are found either unable to handle some phenomena or too vague to be tested concretely. Examples of concepts that are commonly used but often not precise enough are stimulus `elements' or `features', stimulus `similarity', `common elements of stimulation'. A further result is that, when sensory information is modelled realistically, very simple models can account for surprisingly many phenomena. These models have the form of simple artificial neural networks. Rather than being treated as `black-box' models, their computational principles are analysed and their abilities in realistic settings are determined. These models are judged superior to other popular models such as the Spence-Hull theory of gradient interaction and Shepard's theory of generalisation, because 1) they account for more data, 2) they are potentially biologically realistic, and 3) they follow the complete causal path from sensory information to behaviour.

    Finally, I consider how stimulus control theory can be applied to the study of human facial attractiveness. A model about how we form judgments of attractiveness is proposed. According to the model, facial beauty emerges from an interaction among memories of faces, in a way fully compatible with general knowledge about stimulus control. Many major findings about attractiveness are reproduced by the model, including preferences for certain symmetries, for moderate exaggerations of sexually dimorphic traits, and for average values of non-dimorphic traits. The model is also linked with a model of the ontogeny of sexual preferences. The resulting theory is potentially able to account for both uniformity and diversity of preferences within and between human populations. The theory provides a challenge to claims that sexual preferences arise from face-specific genetic adaptations evolved to detect quality cues in potential partners. Keywords: ethology, experimental psychology, learning, stimulus control, peak-shift, receiver bias.

  • 187. Gibbs, Melanie
    et al.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Van Dyck, Hans
    Phenotypic plasticity in butterfly morphology in response to weather conditions during development2011In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 283, no 3, p. 162-168Article in journal (Refereed)
    Abstract [en]

    In seasonal environments, phenotypic plasticity in response to gradual changes in environmental variables may result in the production of discrete seasonal morphs. Production of the appropriate seasonal morph at the correct time relies on individuals interpreting environmental cues during their development. The speckled wood butterfly Pararge aegeria (L.) has previously been shown to have developmental and phenotypic plasticity across seasons and space (habitats). Here, we examine the developmental sensitivity of different seasonal cohorts of female P. aegeria to changes in local weather conditions over time (1989–1999) and determine how such temporal climatic variation affects adult phenotype development. We observed trait- and cohort-specific changes of adult phenotype development in response to local temporal changes in temperature and rainfall levels. We discuss our findings using current life-history theory and consider the potential for changes in local weather conditions to influence population variability in butterfly morphology and performance

  • 188. Gibbs, Melanie
    et al.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Van Dyck, Hans
    Temperature, rainfall and butterfly morphology: does life history theory match the observed pattern?2011In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 34, no 2, p. 336-344Article in journal (Refereed)
    Abstract [en]

    Butterfly distribution and abundance is known to be influenced by temperature and rainfall. What is not clear, however, is how life history and flight morphological traits are affected by changes in local weather conditions. During the period 1989-1999, we explored the effects of ambient temperature and rainfall during larval development on adult phenotypic traits (body mass, forewing loading, forewing surface area and forewing length) in a Swedish population of the speckled wood butterfly Pararge aegeria. As different seasonal cohorts correspond to different developmental pathways (larval hibernating, pupal hibernating and directly developing), we analysed these morphological time series relative to developmental pathway. Phenotypic variation in response to the temperature and rainfall levels experienced during larval development differed in both magnitude and direction depending on the developmental pathway, and hence seasonal cohort, examined (i.e. there was a pathway-specific response). We suggest that through its developmental flexibility P. aegeria may be able to adjust to variation in weather conditions over time. Other less flexible species, however, may not be so fortunately buffered. To truly estimate the impact of climate change on biodiversity more fine-scale, local studies are required that examine the mechanisms underlying the response of species to climate change.

  • 189.
    Gilek, Michael
    Stockholm University, Faculty of Science, Department of Zoology.
    Bioaccumulation and cycling of hydrophobic organic contaminants by Baltic Sea blue mussels, Mytilus edulis L.1996Doctoral thesis, comprehensive summary (Other academic)
  • 190.
    Golozoubova, Valeria
    Stockholm University, Faculty of Science, The Wenner-Gren Institute.
    Cold-induced nonshivering thermogenesis: tissue origin, activation, recruitment2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two types of heat production, shivering and nonshivering thermogenesis, are activated in mammals in the cold. In small mammals, nonshivering thermogenesis becomes the main source of heat upon long-term cold exposure. Cold-induced nonshivering thermogenesis is adrenergically mediated, and the accepted measure of the development of this type of thermogenesis is the thermogenic response of the animal placed in a thermoneutral environment to the injection or infusion of norepinephrine. Brown adipose tissue is regarded as the main source of cold-induced, adrenergically-mediated nonshivering thermogenesis. However, other tissues (e.g. muscle or liver) have also been suggested to contribute to the process. Heat produced in brown adipose tissue is the result of the functioning of a specific protein, uncoupling protein-1 (UCP1). Several proteins structurally related to UCP1 (UCP2, UCP3 and others) have been described. The tissue distribution of the expression of these proteins is broader than that of UCP1 (found only in brown adipocytes), and one of the potential functions ascribed to these proteins was mediation of nonshivering thermogenesis in tissues and organs different from brown adipose tissue.

    In the present thesis, the sites and mechanisms of nonshivering thermogenesis are discussed. Using UCP1-ablated mice as a model system, we have shown that UCP1-dependent, brown adipose tissue-derived nonshivering thermogenesis is the one and only type of nonshivering thermogenesis induced in the cold. No substitution of a thermogenic process by UCP2, UCP3 or any other protein occurs in the cold-acclimated UCP1-ablated mice.

    The thermogenic response to injected norepinephrine was shown here to consist of two components: a pharmacological (non-inducible by cold-acclimation) and a physiological (developing as a result of cold exposure) component, and this response therefore cannot, per se, be used as a measure of available adaptive nonshivering thermogenesis. It is, however, a relevant measure of cold-inducible nonshivering thermogenesis, if the comparison is made between warm- and cold-acclimated animals.

    The processes leading to an increase of the thermogenic capacity of brown adipose tissue (recruitment) are discussed, and the mechanisms behind the acute thermogenic response to several substances (benidipine, carteolol and arotinolol in particular) are analysed.

    An attempt is also made to clarify the mechanisms underlying the cold intolerance observed in hypothyroidism, an effect possibly dependent on inadequate function of brown adipose tissue and UCP1 expression. Absence of nuclear thyroid hormone receptors also resulted in cold intolerance, but the reason for this was not a lack of UCP1 expression or function, but rather the inability to activate this function. Our results provide new insights into the regulation of UCP1 expression by thyroid hormones and into the reasons for the development of cold sensitivity in the hypothyroid state.

  • 191.
    Gotthard, Karl
    Stockholm University.
    Life history analysis of growth strategies in temperate butterflies1999Doctoral thesis, comprehensive summary (Other academic)
  • 192. Graham, Nicholas A. J.
    et al.
    Chabanet, Pascale
    Evans, Richard D.
    Jennings, Simon
    Letourneur, Yves
    MacNeil, M. Aaron
    McClanahan, Tim R.
    Öhman, Marcus C.
    Stockholm University, Faculty of Science, Department of Zoology.
    Polunin, Nicholas V. C.
    Wilson, Shaun K.
    Extinction vulnerability of coral reef fishes2011In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 14, no 4, p. 341-348Article in journal (Refereed)
    Abstract [en]

    P>With rapidly increasing rates of contemporary extinction, predicting extinction vulnerability and identifying how multiple stressors drive non-random species loss have become key challenges in ecology. These assessments are crucial for avoiding the loss of key functional groups that sustain ecosystem processes and services. We developed a novel predictive framework of species extinction vulnerability and applied it to coral reef fishes. Although relatively few coral reef fishes are at risk of global extinction from climate disturbances, a negative convex relationship between fish species locally vulnerable to climate change vs. fisheries exploitation indicates that the entire community is vulnerable on the many reefs where both stressors co-occur. Fishes involved in maintaining key ecosystem functions are more at risk from fishing than climate disturbances. This finding is encouraging as local and regional commitment to fisheries management action can maintain reef ecosystem functions pending progress towards the more complex global problem of stabilizing the climate.

  • 193.
    Grönwall, Olavi
    Stockholm University.
    Aspects of the food ecology of the red squirrel (Sciurus vulgaris L.)1982Doctoral thesis, comprehensive summary (Other academic)
  • 194. Gunnarsson, L.
    et al.
    Adolfsson-Erici, M.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Bjorlenius, B.
    Rutgersson, C.
    Forlin, L.
    Larsson, D.G.J.
    Comparison of six different sewage treatment processes-Reduction of estrogenic substances and effects on gene expression in exposed male fish2009In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 407, no 19, p. 5235-5242Article in journal (Refereed)
    Abstract [en]

    Treated sewage effluents often contain a mixture of estrogenic compounds in low concentrations. The total combined activity of these, however, may be sufficiently high to affect the reproduction of aquatic vertebrates. The introduction of advanced treatment technologies has been suggested as a way to remove micro-contaminants, including estrogenic substances. In this study, one municipal influent was treated with six different processes in parallel on a semi-large scale in order to assess their potential to reduce substances that could contribute to estrogenic effects in male fish. The effluent from a conventional, activated sludge treatment line was compared to a similarly treated effluent with a final sand-filtering step. The addition of ozonation (15 g O-3/m(3)). a moving bed biofilm reactor (MBBR) or both in combination was also evaluated. There was also a separate treatment line that was based on a membrane bioreactor. A small battery of hepatic estrogen-responsive genes was measured in the exposed fish using quantitative PCR. Concentrations of steroid estrogens and estrogenic phenols in the effluents were measured by GC-ECNI-MS. The ozonated effluents were the only tested effluents for which all measured biological effects in exposed fish were removed. Chemical data suggested that the MBBR technology was equally effective in removing the analyzed estrogens; however, elevated expression of estrogen-responsive genes suggested that some estrogenic substances were still present in the effluent. The membrane bioreactor removed most of the measured estrogens and it reduced the induction of the estrogen-responsive genes. However, fish exposed to this effluent had significantly enlarged livers. Given that the same influent was treated in parallel with a broad set of technologies and that the chemical analyses were combined with an in vivo assessment of estrogenic responses, this study provides valuable input into the assessment of advanced treatment processes for removing estrogenic substances.

  • 195.
    Gydemo, Rolf
    Stockholm University, Faculty of Science, Department of Zoology.
    Studies on reproduction and growth in the noble crayfish, Astacus astacus L.1989Doctoral thesis, comprehensive summary (Other academic)
  • 196.
    Gáliková, Martina
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology.
    Nässel, Dick R.
    Stockholm University, Faculty of Science, Department of Zoology.
    The thirsty fly: Ion transport peptide (ITP) is a novel endocrine regulator of water homeostasis in Drosophila2018In: PLOS Genetics, ISSN 1553-7390, E-ISSN 1553-7404, Vol. 14, no 8, article id e1007618Article in journal (Refereed)
    Abstract [en]

    Animals need to continuously adjust their water metabolism to the internal and external conditions. Homeostasis of body fluids thus requires tight regulation of water intake and excretion, and a balance between ingestion of water and solid food. Here, we investigated how these processes are coordinated in Drosophila melanogaster. We identified the first thirst-promoting and anti-diuretic hormone of Drosophila, encoded by the gene Ion transport peptide (ITP). This endocrine regulator belongs to the CHH (crustacean hyperglycemic hormone) family of peptide hormones. Using genetic gain- and loss-of-function experiments, we show that ITP signaling acts analogous to the human vasopressin and renin-angiotensin systems; expression of ITP is elevated by dehydration of the fly, and the peptide increases thirst while repressing excretion, promoting thus conservation of water resources. ITP responds to both osmotic and desiccation stress, and dysregulation of ITP signaling compromises the fly’s ability to cope with these stressors. In addition to the regulation of thirst and excretion, ITP also suppresses food intake. Altogether, our work identifies ITP as an important endocrine regulator of thirst and excretion, which integrates water homeostasis with feeding of Drosophila.

  • 197.
    Haage, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Bergvall, Ulrika A.
    Maran, Tiit
    Kiik, Kairi
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Situation and context impacts the expression of personality: The influence of breeding season and test context2013In: Behavioural Processes, ISSN 0376-6357, E-ISSN 1872-8308, Vol. 100, p. 103-109Article in journal (Refereed)
  • 198.
    Haage, Per
    Stockholm University.
    Studies on the Baltic Fucus macrofauna1976Doctoral thesis, comprehensive summary (Other academic)
  • 199.
    Hagelin, Lars-Olof
    Stockholm University.
    Studies on the development of the membranous labyrinth in lampreys, Lampetra fluviatilis Linné, Lampetra planeri Bloch and Petromyzon marinus Linné.1974Doctoral thesis, monograph (Other academic)
  • 200.
    Hagman, Mattias
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Kärvemo, Simon
    Elmberg, Johan
    Löwenborg, Kristin
    Stockholm University, Faculty of Science, Department of Zoology.
    Life at the edge: the nesting ecology of the world’s most northerly oviparous snake and its implications for conservation2013In: Reptiles in Research: Investigations of Ecology, Physiology and Behavior from Desert to Sea / [ed] William I. Lutterschmidt, New York: Nova Science Publishers, Inc., 2013, p. 247-264Chapter in book (Refereed)
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