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  • 151.
    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.

  • 152.
    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.

  • 153.
    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.

  • 154.
    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.

  • 155.
    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.

  • 156. 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

  • 157. 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.

  • 158.
    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)
  • 159.
    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.

  • 160.
    Gotthard, Karl
    Stockholm University.
    Life history analysis of growth strategies in temperate butterflies1999Doctoral thesis, comprehensive summary (Other academic)
  • 161. 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.

  • 162. 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.

  • 163.
    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.

  • 164.
    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)
  • 165.
    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)
  • 166.
    Hagman, Mattias
    et al.
    Universutyof Sydney.
    Pape, Tomas
    Schulte, Rainer
    Flesh fly myiasis in Peruvian poison frogs genus Epipedobates (Anura, Dendrobatidae)2005In: Phyllomedusa, ISSN 1519-1397, Vol. 4, no 1, p. 69-73Article in journal (Refereed)
  • 167.
    Hagman, Mattias
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Shine, Richard
    Species-specific communication systems in an introduced toad compared with native frogs in Australia2009In: Chemoecology, ISSN 0937-7409, E-ISSN 1423-0445, Vol. 19, no 4, p. 211-217Article in journal (Refereed)
    Abstract [en]

    Novel approaches to control invasive species are urgently needed. Cane toads (Bufo marinus) are large, highly toxic anurans that are spreading rapidly through tropical Australia. Injured toad larvae produce an alarm pheromone that elicits rapid avoidance by conspecifics but not by frog larvae. Experiments in outdoor ponds show that repeated exposure to the pheromone reduced toad tadpole survival rates (by >50%) and body mass at metamorphosis (by 20%). The alarm pheromone did not induce tadpoles to seek shelter, but accelerated ontogenetic differentiation. Perhaps reflecting mortality of weaker individuals during larval life, growth rates post-metamorphosis were higher in animals emerging from the pheromone exposure treatment than from the control treatment. Nonetheless, body size differentials established at metamorphosis persisted through the first 8 days of post-metamorphic life. We will need substantial additional research before evaluating whether the alarm pheromone provides a way to reduce cane toad recruitment in nature, but our field trials are encouraging in this respect.

  • 168. Hall, Susanna
    Moult strategies in relation to migration in long-distance migrants2003Doctoral thesis, comprehensive summary (Other academic)
  • 169.
    Hallgren, Stefan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Kitambi, Satish-Srinivas
    Karolinska Institutet.
    Cloning, sequencing and In situ localisation of guppy brain aromatase, cyp19bManuscript (Other academic)
    Abstract [en]

    Oestrogens are biosynthesised by cytochrome p450-aromatase (Cyp19). Brain oestrogens serve several important functions of which nerve protection, cell proliferation, nerve development and behaviour control are a few. Teleost brain aromatase activity is exceptionally high (between 100-1000 times) compared to mammals and birds. We have successfully cloned and sequenced a 950 bp long partial fragment of the guppy CYP19B gene (PrCyp19b) derived from adult brain mRNA. Sequence alignment of translated amino acid sequence shows PrCYP19b having high sequence similarity to teleost brain aromatase. Anatomical distribution of PrCYP19b expression in adult guppy brains was studied using in situ-hybridisation with an antisense riboprobe synthesised from the cloned PrCYP19b gene. Expression of brain aromatase appeared at ventricular surfaces of the ventral telencephalic zones and the pre-optic area, in the hypothalamus, the pituitary gland, optic tectum and the cerebellum. This pattern is similar to previously reported distribution of brain aromatase in other teleosts. Measurement of brain aromatase activity in telencephalon, mesencephalon/diencephalon and rhombencephalon revealed female guppies producing the most oestrogens in mesencephalon/diencephalon, whereas males produces the most oestrogens in both telencephalon and mesencephalon/diencephalon. This indicates that brain oestrogen production is sexually dimorphic in the guppy and may serve different functions in the two genders.

  • 170.
    Hallgren, Stefan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Linderoth, Maria
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Olsén, Håkan
    Södertörns högskola.
    Inhibition of cytochrome p450 brain aromatase reduces two male specific sexual behaviours in the male Endler guppy (Poecilia reticulata)2006In: General and Comparative Endocrinology, ISSN 0016-6480, Vol. 147, no 3, p. 323-328Article in journal (Refereed)
    Abstract [en]

    In mammalian and avian vertebrate groups, androgens act as controlling agents on male aggression and courtship behaviour by their conversion to oestrogens by cytochrome P450 aromatase in well-defined brain regions. Despite the fact that bony fishes have exceptionally high brain aromatase activity, little is known about it’s possible regulatory effects on the reproductive behaviours of teleosts. In this study, Endler guppy males (Poecilia reticulata) were subjected to 26–29 days of 24-h exposure to two different concentrations (15 and 100 μg/L) of the aromatase inhibitor fadrozole in the water. Compared with the control males, two of three courtship activities in males exposed to the higher concentration were reduced when they were paired with receptive stimulus females. Reduction in brain aromatase activity was confirmed in both exposed groups with the use of the tritiated water assay.

  • 171.
    Hallgren, Stefan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Olsén, Håkan
    Södertörns högskola.
    Effects on Guppy brain aromatase activity following short-term steroid and 4-Nonyl phenol exposures2010In: Environmental Toxicology, ISSN 1520-4081, E-ISSN 1522-7278, Vol. 25, no 3, p. 261-271Article in journal (Refereed)
    Abstract [en]

    Brain oestrogen production, performed by the enzyme aromatase, can be disrupted/affected in teleost fish exposed to endocrine disruptors found in polluted aquatic environments. The guppy (Poecilia reticulata) was previously studied and confirmed to suffer negative effects on reproductive behaviours following inhibition of the brain aromatase reaction. Here Adult guppies (Poecilia reticulata) of both genders were subjected to known endocrine disruptors: the androgen androstenedione (A), the synthetic oestrogen 17α-ethynylestradiol (EE2) and the oestrogenic surfactant 4-nonylphenol (NP), at high (50 μg/L) and at environmentally relevant concentrations (10 ng/L EE2, 5 μg/L NP and 0.7 μg/L A) for two weeks followed by measurements of brain aromatase activity (bAA). In the adult males, bAA was stimulated by A and EE2 at 50 μg/L. Female activity was also stimulated by the higher oestrogenic treatment. At environmentally relevant concentrations only the EE2 treatment affected bAA, and only in males. The alkylphenolic substance NP produced no effect in either of the experiments, not on males nor females. The results indicate that short-term steroid treatments have stimulatory effects on guppy brain aromatase even at concentrations that can be found in the environment. We thus suggest bAA of adult guppies to be a suitable bioindicator of endocrine disruptors.

  • 172.
    Hallgren, Stefan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Olsén, Håkan
    Södertörns högskola.
    Impacts of synthetic oestrogen and antioestrogen treatments on courtship and mating behaviours in male guppies (Poecilia reticulata)Manuscript (Other academic)
    Abstract [en]

    Understanding the neuroendocrinological mechanisms behind reproductive behaviour is fundamental when studying endocrine disruption. Neuroestrogen production is a key step in the activation of reproductive behaviours among vertebrates. The actions of estrogens are transmitted through estrogen receptors (ERs) in distinct brain nuclei. Here we report alterations in reproductive behaviours in guppy males following 55-day food treatments with the antiestrogen fulvestrant (ICI) and the synthetic oestrogen 17α-ethinylestradiol (EE2). Male courtship and mating attempts were severely reduced in EE2 treated males after both 27-30 and 41-55 days of treatment when paired with females. ICI treatment gave a significant reduction in the frequency of sigmoid display behaviour after 27-30 days of treatment, and an almost 2.5-fold increase in gonopodium thrusting after 41-55 days of treatment. ICI treated males also decreased their frequency in successful mating attempts in comparison to the control males. The neurological effects of ICI were confirmed by Real Time-PCR analysis for brain aromatase and ERα gene expression. ICI treatment suppressed aromatase expression to 64% and stimulated ERα gene expression by over 300%. These results indicate that oestrogen action via ERs may play an important role for the complete display of male courtship and mating behaviour in the guppy. The results also suggest that local steroids are involved in regulating brain aromatase expression and that the negative effects of EE2 on sexual behaviour are linked via endocrine disruption of gonadal function.

  • 173.
    Halonen, Juha
    Stockholm University.
    Adipocyte ion channels and metabolic control2002Doctoral thesis, comprehensive summary (Other academic)
  • 174. Harzsch, Steffen
    et al.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology.
    Beltz, Barbara S
    Development of pigment-dispersing hormone-immunoreactive neurons in the American lobster: homology to the insect circadian pacemaker system?2009In: Cell and tissue research, ISSN 1432-0878, Vol. 335, no 2, p. 417-29Article in journal (Refereed)
    Abstract [en]

    We have examined the development of pigment-dispersing hormone (PDH)-immunoreactive neurons in embryos of the American lobster Homarus americanus Milne Edwards, 1837 (Decapoda, Reptantia, Homarida) by using an antiserum against beta-PDH. This peptide is detectable in the terminal medulla of the eyestalks and the protocerebrum where PDH immunoreactivity is present as early as 20% of embryonic development. During ontogenesis, an elaborate system of PDH-immunoreactive neurons and fibres develops in the eyestalks and the protocerebrum, whereas less labelling is present in the deuto- and tritocerebrum and the ventral nerve cord. The sinus gland is innervated by PDH neurites at hatching. This pattern of PDH immunoreactivity has been compared with that found in various insect species. Neurons immunoreactive to pigment-dispersing factor in the medulla have been shown to be a central component of the system that generates the circadian rhythm in insects. Our results indicate that, in view of the position of the neuronal somata and projection patterns of their neurites, the immunolabelled medulla neurons in insects have homologous counterparts in the crustacean eyestalk. Since locomotory and other activities in crustaceans follow distinct circadian rhythms comparable with those observed in insects, we suggest that PDH-immunoreactive medulla neurons in crustaceans are involved in the generation of these rhythms.

  • 175.
    Hasnat, Md. Abul
    Stockholm University, Faculty of Science, Department of Biology Education. Sher-e-Bangla Agricultural University, Bangladesh.
    Reproductive Potential Difference of Artificially Inseminated and Naturally Mated Honey Bee Queens (Apis mellifera L.)2018Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    Apis mellifera L. is the only commercially cultivated bee species in Bangladesh nowadays and has been practicing for migratory beekeeping since 1990. Notably, without taking initiatives to improve the bee stocks, intensified beekeeping has been making the species vulnerable to different threats of diseases, pests and inbreeding depression. Reproductive potentiality of the queens has been declining severely. The investigation was carried out to diagnose present problems regarding reproductive potentiality of the queen bees and finding out the possible solutions. Firstly, 56 numbers of naturally mated queens (Apis mellifera L.) were collected from problematic and non-problematic hives from three districts of Bangladesh. Samples were weighed, body length and thorax width were measured, and dissected to study spermathecae appearance. Average queen body weight (160.75±3.65 mg) was found much lower than the earlier studies in different countries. Moreover, 32.33% spermathecae of the queens were found poor in appearance. Again, 3 different queen rearing and mating procedures were applied in 12 replications each: naturally mated queen (NM), grafted and naturally mated queen (GNM) and grafted and artificially inseminated queen (AIQ). NM and GNM queens were allowed to mate naturally where AIQ queens were inseminated artificially in the laboratory. Interestingly, GNM (196.65±3.13 mg) and AIQ(196.55±2.41 mg) queens were significantly heavier than the NM (159.07±6.94 mg) queens. Likewise, their spermathecae radius, respective workers, drones, brood occupation area showed much better strength than the NM queens, though, latency period of AIQ queens were higher. Since grafted queens were reared with good larvae and implemented in artificial queen cups with increased brood support, hence that could make the queens heavier and reproductively more potential, whereas NM queens were left to grow naturally and found less potential. The findings will encourage beekeepers for practicing grafting procedure as the better queen rearing procedure in field condition. However, the procedure of AIQ queens also could be used for stock improvement and bee research because of its control mating system.

  • 176.
    Hedlund, Johanna
    Stockholm University, Faculty of Science, Department of Zoology.
    Climate change effects on migratory birds and on the ecology and behaviour of the willow warbler (Phylloscopus trochilus)2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Recent global climate change is influencing the behaviour and ecology of species worldwide. Birds are typical systems to study in this context, as they are often migratory and thus subjected to a variety of environmental effects. This thesis employs the use of long-term ringing records, field observations, historical maps and historical volunteer observations with the aim of describing behavioural and ecological responses of birds to the current environmental change. An investigation into the spring arrival, reproduction and autumn departure in willow warblers (Phylloscopus trochilus) breeding at a southern study site in Sweden (65°N 18°E) showed that all three phenological events had advanced in parallel. Thus birds arrive earlier, start breeding earlier and leave Sweden earlier, with the breeding period staying the same in length. By teasing apart the migratory responses of different individuals, it became clear that particularly early arriving males and early departing juveniles had advanced migration. However, willow warblers migrating past a northern study site in Sweden (65°N 23°E) displayed no change in autumn departure. When migration in the two regionally separate populations were analyzed in relation to climatic variables, the results indicated that foremost a combined effect of growing season onset and the North Atlantic Oscillation influenced migratory timing, and only in individuals that had advanced migration. As growing season onset had advanced at both regions, but only elicited migratory change in southern willow warblers, it is proposed that intra-specific difference between populations prepare them differently to climate change. Willow warblers breeding at northern latitudes were also displaying absence of an otherwise common behaviour of the species: philopatry. It is suggested that the climate induced change in onset of the growing season, coupled with an increase in available territories, could have enabled a southern influx of dispersal-prone birds adopting a less philopatric breeding behaviour. Availability of territories was also studied in southern Sweden, in relation to 100 years of land use change and future climate change effects on forestry. The mass-conversion of grazed forest into coniferous sylvicultures that has occurred in Sweden 1900-2013 was shown to have negatively affected territory availability for willow warblers. The second most common bird species in Sweden, the chaffinch (Fringilla coelebs), was however shown to be largely unaffected. In a future scenario where rising temperatures will increase growth rates of trees, harvest rotation will be faster and both sylvicultures and logged areas will increase in coverage, favouring both species. Thus commonness in terms of landscape and species occurrence has altered historically and is dynamically linked. Historic perspectives were also applied to observations of spring arrival of 14 migratory bird species. A relative comparison of two data sets, collected over 140 years, revealed that short-distance migrants have changed their spring arrival more than long-distance migrants in southern Sweden. In conclusion, the results of this thesis provide insights into climate change effects on avian behaviour and ecology, document unique observations and contribute with a great spectrum of knowledge, from exact details on responses by individual birds, through long-term changes in populations to historical perspectives on shifts in entire landscapes

  • 177.
    Hedlund, Johanna S. U.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Kullberg, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology.
    Fransson, Thord
    Long-term phenological shifts and intra-specific differences in migratory change in the willow warbler Phylloscopus trochilus2015In: Journal of Avian Biology, ISSN 0908-8857, E-ISSN 1600-048X, Vol. 46, no 1, p. 97-106Article in journal (Refereed)
    Abstract [en]

    Climate change can influence many aspects of avian phenology and especially migratory shifts and changes in breeding onset receive much research interest in this context. However, changes in these different life-cycle events in birds are often investigated separately and by means of ringing records of mixed populations. In this long-term study on the willow warbler Phylloscopus trochilus, we investigated timing of spring and autumn migration in conjunction with timing of breeding. We made distinction among individuals with regard to age, sex, juvenile origin and migratory phase. The data set comprised 22-yr of ringing records and two temporally separated data sets of egg-laying dates and arrival of the breeding population close to the ringing site. The results reveal an overall advancement consistent in most, but not all, phenological events. During spring migration, early and median passage of males and females became earlier by between 4.4 to 6.3 d and median egg-laying dates became earlier by 5 d. Male arrival advanced more, which may lead to an increase in the degree of protandry in the future. Among breeding individuals, only female arrival advanced in timing. In autumn, adults and locally hatched juvenile females did not advanced median passage, but locally hatched juvenile males appeared 4.2 d earlier. Migrating juvenile males and females advanced passage both in early and median migratory phase by between 8.4 to 10.1 d. The dissimilarities in the response between birds of different age, sex and migratory phase emphasize that environmental change may elicit intra-specific selection pressures. The overall consistency of the phenological change in spring, autumn and egg-laying, coupled with the unchanged number of days between median spring and autumn migration in adults, indicate that the breeding area residence has advanced seasonally but remained temporally constant.

  • 178.
    Heidel-Fischer, Hanna
    et al.
    Department of Entomology, Max Planck Institute for Chemical Ecology.
    Freitak, Dalial
    Department of Entomology, Max Planck Institute for Chemical Ecology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Soderlind, Lina
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Vogel, Heiko
    Department of Entomology, Max Planck Institute for Chemical Ecology.
    Nylin, Soren
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Phylogenetic relatedness and host plant growth form influence gene expression of the polyphagous comma butterfly (Polygonia c-album).2009In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 10, no 1, p. 506-Article in journal (Refereed)
    Abstract [en]

    ABSTRACT: BACKGROUND: The mechanisms that shape the host plant range of herbivorous insect are to date not well understood but knowledge of these mechanisms and the selective forces that influence them can expand our understanding of the larger ecological interaction. Nevertheless, it is well established that chemical defenses of plants influence the host range of herbivorous insects. While host plant chemistry is influenced by phylogeny, also the growth forms of plants appear to influence the plant defense strategies as first postulated by Feeny (the "plant apparency" hypothesis). In the present study we aim to investigate the molecular basis of the diverse host plant range of the comma butterfly (Polygonia c-album) by testing differential gene expression in the caterpillars on three host plants that are either closely related or share the same growth form. RESULTS: In total 120 differentially expressed genes were identified in P. c-album after feeding on different host plants, 55 of them in the midgut and 65 in the restbody of the caterpillars. Expression patterns could be confirmed with an independent method for 14 of 27 tested genes. Pairwise similarities in upregulation in the midgut of the caterpillars were higher between plants that shared either growth form or were phylogenetically related. No known detoxifying enzymes were found to be differently regulated in the midgut after feeding on different host plants. CONCLUSIONS: Our data suggest a complex picture of gene expression in response to host plant feeding. While each plant requires a unique gene regulation in the caterpillar, both phylogenetic relatedness and host plant growth form appear to influence the expression profile of the polyphagous comma butterfly, in agreement with phylogenetic studies of host plant utilization in butterflies.

  • 179. Helander, B.
    et al.
    Axelsson, J.
    Borg, Hans
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Holm, Karin
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Bignert, A.
    Ingestion of lead from ammunition and lead concentrations in white-tailed sea eagles (Haliaeetus albicilla) in Sweden2009In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 407, no 21, p. 5555-5563Article in journal (Refereed)
    Abstract [en]

    In this study we show for the first time that lead poisoning from ammunition is a significant mortality factor for white-tailed sea eagle (WSE) (Holiaeetus albicilla) in Sweden. We analyzed 118 WSEs collected between 1981 and 2004 from which both liver and kidney samples could be taken. A total of 22% of all eagles examined had elevated (>6 mu g/g d.w.) lead concentrations, indicating exposure to leaded ammunition. and 14% of the individuals had either liver or kidney lead concentrations diagnostic of lethal lead poisoning (>20 mu g/g d.w.). Lead concentrations in liver and kidney were significantly correlated. In individuals with lead levels <6 mu g/g, concentrations were significantly higher in kidney than in liver; in individuals with lead levels >20 mu g/g, concentrations were significantly higher in liver. The lead isotope ratios indicate that the source of lead in individuals with lethal concentrations is different from that of individuals exhibiting background concentrations of lead (<6 mu g/g d.w.) There were no significant sex or age differences in lead concentrations. A study from the Baltic reported in principle no biomagnification of lead, but background lead concentrations in WSE liver in this study were still four to >10 times higher than concentrations reported for Baltic fish from the same time period. in contrast to other biota there was no decrease in lead concentrations in WSE over the study period. The proportion of lead poisoned WSE remained unchanged over the study period, including two years after a partial ban of lead shot was enforced in 2002 for shallow wetlands. The use of lead in ammunition poses a threat to all raptors potentially feeding on shot game or offal. The removal of offal from shot game and alternatives to leaded ammunition needs to be implemented in order to prevent mortality from lead in raptors and scavengers.

  • 180. Hellqvist, Anna
    The brain-pituitary-gonadal axis and gonadotropic hormones in the three-spined stickleback, Gasterosteus aculeatus2003Doctoral thesis, comprehensive summary (Other academic)
  • 181.
    Hellström, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Helander, Björn
    Naturhistoriska riksmuseet.
    A preliminary overview of monitoring for raptors in Sweden2012In: Acrocephalus, ISSN 0351-2851, Vol. 33, no 154/155, p. 277-282Article in journal (Refereed)
    Abstract [en]

    Swedish diurnal raptor and owl monitoring is to a large extent based on species specific projects with long-standing traditions, migration counts at specific migration hot-spots, and a nation-wide bird survey. The best-known and longlived projects are the Peregrine Falcon Falco peregrinus and White-tailed Eagle Haliaeetus albicilla projects, which continue to make important contributions to the knowledge about effects of environmental pollutants in wild birds. For many diurnal birds of prey, trend estimation is based on the long time series (1973–) of migration counts at Falsterbo in southernmost Sweden, whereas possibilities to detect population trends in most owl species are still relatively low. New protocols, however, are being developed to better incorporate night active-birds such as owls in the Swedish Bird Survey. Much raptor monitoring data is being collected by volunteers. Sweden has several valuable networks for bird monitoring in general, although special efforts could be directed towards better coordination and publication of the on-going raptor work within a common framework. Potential threats (e.g. forestry, wind power development, train collisions, declining prey populations, pollutants) and their effects on raptor populations should preferably also be included in monitoring protocols to a higher extent than at present.

  • 182.
    Henriksson, Oskar
    Stockholm University, Faculty of Science, Department of Zoology. Södertörns högskola.
    Genetic connectivity of fish in the Western Indian Ocean2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    An almost unbroken fringing reef runs along the east coast of Africa, the lagoon inside the reef is the foundation of almost all artisanal fisheries. It is a low-tech fishery conducted by many people. Some areas can have up to 19 fishermen per square kilometer. High fishing pressures, coupled with declining fish stocks has led to changes in mean size and reproductive age of many exploited species. There is a vital and urgent need for scientifically based management systems, including the utilization of genetic information to guide management practices.

    This thesis aims to investigate the presence of genetic structures in the western Indian Ocean. In order to do that we first investigated the historical patterns of connectivity throughout the region (paper I). In papers II and III we focused on local scale connectivity in Kenya and Tanzania and finally in paper IV we investigate the large-scale contemporary gene flow throughout the Western Indian Ocean. In paper III we also investigate the temporal genetic variation at one site and compare it to the small-scale genetic variation along a stretch of the Kenyan coastline. Some overall conclusions that can be drawn from my body of work are: there are genetic structures present in the western Indian Ocean even though the apparent lack of physical barriers. Major oceanic currents aid evolutionary dispersal patterns. A single geographic site need not be genetically homogenous or temporally stable. Island sites are genetically more homogenous than mainland sites.

    In conclusion, there are clear and distinct genetic structures present especially in Siganus sutor, the most targeted fish for the artisanal fishery in East Africa.

  • 183.
    Henriksson, Oskar
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology. Södertörns högskola.
    Larsson, Josefine
    Södertörns högskola.
    Grahn, Mats
    Södertörns högskola.
    Temporal genetic variability of landed Siganus sutor reveals a mixed stock fishery in coastal KenyaManuscript (preprint) (Other academic)
    Abstract [en]

    Artisanal fisheries in Kenya have been in decline since the 1980’s and are currently managed by gear restriction and no take zones. The fishery is a mixed species fishery but the Shoemaker spinefoot (Siganus sutor) comprise a large portion of the total catches. The sustainable use of these resources is dependent on informed assessment and management of the harvested species. In Kenya there is a lack of critical information about landings, fish stock productivity and genetic stock structure, and there is no knowledge of populations size or genetic variation of S. sutor. In this study we used the molecular marker, AFLP to investigate the genetic variation within and between sites of S. sutor landed along the 200 km coast of Kenya. We compared the spatial genetic variation among sites with the within site temporal genetic variation from a single site, adjacent to a number of spawning aggregations. Our results show that the there is genetic variation among the sites (spatial variation) and that the temporal genetic variation with in a six week period was about 1/5 of the spatial genetic variation. We believe these findings to be an important aspect to considered for both future scientific research as well as management.

  • 184.
    Henshaw, Ian
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Fransson, Thord
    Naturhistoriska riksmuseet, Ringmärkningscentralen.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Jenni-Eiermann, Susanne
    Swiss ornithological Institute.
    Kullberg, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Information from the geomagnetic field triggers a reduced adrenocortical response in a migratory bird2009In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 212, p. 2902-2907Article in journal (Refereed)
    Abstract [en]

    Long-distance migrants regularly pass ecological barriers, like the Sahara desert, where extensive fuel loads are necessary for a successful crossing. A central question is how inexperienced migrants know when to put on extensive fuel loads. Beside the endogenous rhythm, external cues have been suggested to be important. Geomagnetic information has been shown to trigger changes in foraging behaviour and fuel deposition rate in migratory birds. The underlying mechanism for these adjustments, however, is not well understood. As the glucocorticoid hormone corticosterone is known to correlate with behaviour and physiology related to energy regulation in birds, we here investigated the effect of geomagnetic cues on circulating corticosterone levels in a long-distance migrant. Just as in earlier studies, juvenile thrush nightingales (Luscinia luscinia) caught during autumn migration and exposed to the simulated geomagnetic field of northern Egypt increased food intake and attained higher fuel loads than control birds experiencing the ambient magnetic field of southeast Sweden. Our results further show that experimental birds faced a reduced adrenocortical response compared with control birds, thus for the first time implying that geomagnetic cues trigger changes in hormonal secretion enabling appropriate behaviour along the migratory route.

  • 185.
    Henshaw, Ian
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Fransson, Thord
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Lind, Johan
    Stockholm University, Faculty of Science, Department of Zoology. Stockholm University, Faculty of Humanities, Centre for Cultural Evolution.
    Vallin, Adrian
    Stockholm University, Faculty of Science, Department of Zoology.
    Kullberg, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology.
    Food intake and fuel deposition in a migratory bird is affected by multiple as well as single-step changes in the magnetic field2008In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 211, p. 649-653Article in journal (Refereed)
    Abstract [en]

    Recent studies have shown that migratory thrush nightingales (Luscinia luscinia) experimentally treated with multiple changes of the magnetic field simulating a journey to their target stopover area in northern Egypt, increased fuel deposition as expected in preparation to cross the Sahara desert. To investigate the significance of food intake on the body mass changes observed, in the work described here we analysed food intake of the nightingales under study in those earlier experiments. Furthermore, to study whether a single change in the magnetic field directly to northern Egypt is sufficient to provide information for fuelling decisions, we performed a new experiment, exposing thrush nightingales trapped in Sweden, directly to a magnetic field of northern Egypt. Our results show that an experimentally induced magnetic field of northern Egypt, close to the barrier crossing, triggers the same response in fuel deposition as experiments with multiple changes of the magnetic field simulating a migratory journey from Sweden to Egypt, suggesting that migratory birds do not require successive changes in field parameters to incorporate magnetic information into their migratory program. Furthermore, irrespective of experimental set up (single or multiple changes of the magnetic field parameters) increase in food intake seems to be the major reason for the observed increase in fuelling rate compared with control birds, suggesting that geomagnetic information might trigger hormonal changes in migratory birds enabling appropriate fuelling behaviour during migration.

  • 186. Hermann, Christiane
    et al.
    Saccon, Rachele
    Senthilan, Pingkalai R.
    Domnik, Lilith
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Yoshii, Taishi
    Helfrich-Foerster, Charlotte
    The circadian clock network in the brain of different Drosophila species2013In: Journal of Comparative Neurology, ISSN 0021-9967, E-ISSN 1096-9861, Vol. 521, no 2, p. 367-388Article in journal (Refereed)
    Abstract [en]

    Comparative studies on cellular and molecular clock mechanisms have revealed striking similarities in the organization of the clocks among different animal groups. To gain evolutionary insight into the properties of the clock network within the Drosophila genus, we analyzed sequence identities and similarities of clock protein homologues and immunostained brains of 10 different Drosophila species using antibodies against vrille (VRI), PAR-protein domain1 (PDP1), and cryptochrome (CRY). We found that the clock network of both subgenera Sophophora and Drosophila consists of all lateral and dorsal clock neuron clusters that were previously described in Drosophila melanogaster. Immunostaining against CRY and the neuropeptide pigment-dispersing factor (PDF), however, revealed species-specific differences. All species of the Drosophila subgenus and D. pseudoobscura of the Sophophora subgenus completely lacked CRY in the large ventrolateral clock neurons (lLNvs) and showed reduced PDF immunostaining in the small ventrolateral clock neurons (sLNvs). In contrast, we found the expression of the ion transport peptide (ITP) to be consistent within the fifth sLNv and one dorsolateral clock neuron (LNd) in all investigated species, suggesting a conserved putative function of this neuropeptide in the clock. We conclude that the general anatomy of the clock network is highly conserved throughout the Drosophila genus, although there is variation in PDF and CRY expression. Our comparative study is a first step toward understanding the organization of the circadian clock in Drosophila species adapted to different habitats.

  • 187. Hermann-Luibl, Christiane
    et al.
    Yoshii, Taishi
    Senthilan, Pingkalai R.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology.
    Helfrich-Förster, Charlotte
    The Ion Transport Peptide Is a New Functional Clock Neuropeptide in the Fruit Fly Drosophila melanogaster2014In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 34, no 29, p. 9522-9536Article in journal (Refereed)
    Abstract [en]

    The clock network of Drosophila melanogaster expresses various neuropeptides, but a function in clock-mediated behavioral control was so far only found for the neuropeptide pigment dispersing factor (PDF). Here, we propose a role in the control of behavioral rhythms for the ion transport peptide (ITP), which is expressed in the fifth small ventral lateral neuron, one dorsal lateral neuron, and in only a few nonclock cells in the brain. Immunocytochemical analyses revealed that ITP, like PDF, is most probably released in a rhythmic manner at projection terminals in the dorsal protocerebrum. This rhythm continues under constant dark conditions, indicating that ITP release is clock controlled. ITP expression is reduced in the hypomorph mutant ClkAR, suggesting that ITP expression is regulated by CLOCK. Using a genetically encoded RNAi construct, we knocked down ITP in the two clock cells and found that these flies show reduced evening activity and increased nocturnal activity. Overexpression of ITP with two independent timeless-GAL4 lines completely disrupted behavioral rhythms, but only slightly dampened PER cycling in important pacemaker neurons, suggesting a role for ITP in clock output pathways rather than in the communication within the clock network. Simultaneous knockdown (KD) of ITP and PDF made the flies hyperactive and almost completely arrhythmic under constant conditions. Under light-dark conditions, the double-KD combined the behavioral characteristics of the single-KD flies. In addition, it reduced the flies' sleep. We conclude that ITP and PDF are the clock's main output signals that cooperate in controlling the flies' activity rhythms.

  • 188.
    Herron, David
    Stockholm University, Faculty of Science, The Wenner-Gren Institute.
    Brown adipose tissue recruitment in-vivo and in-vitro1992Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Brown adipose tissue recruitment was studied in the newborn hamster and in brown adipocyte precursor cell cultures.

    In the newborn hamster, the development of the thermogenic potential of brown adipose tissue was followed by estimating the amount of the uncoupling protein thermogenin by the binding of GDP to the mitochondria. Between the ages of 12 and 20 days, GDP Binding to isolated mitochondria rose sharply, indicating a dramatic increase in the thermogenic potential of brown adipose tissue during this period. This increase in thermogenic potential correlated well with morphological observations on the development of the tissue. It was concluded that in the perinatal hamster, brown adipose tissue recruits at a relatively late stage and that the recruited tissue probably contributes to the attainment of homeothermy in this species. The mechanisms which regulate this recruitment remain largely unknown.

    Brown adipocyte precursor cells, isolated as part of a stromal-vascular fraction derived from the brown adipose tissue of rat and mouse, were grown in culture. Various aspects of the recruitment process in brown adipose tissue were studied with these cell culture systems. Chronically raising cyclic-AMP levels with cholera toxin accelerated the differentation of rat brown adipocyte precursor cells, measured as enhanced levels of cytochrome £-oxidase and lipoprotein lipase mRNAs, and decreased levels of actin mRNA. A 35 kDa protein, of unknown identity, was also induced by this treatment.

    The cellular recruitment of thermogenin was studied in differentiating mouse brown adipocyte precursor cells. Thermogenin was expressed at low levels, if at all, in untreated cultures. Short-term norepinephrine treatment dramatically increased thermogenin mRNA and protein levels in the differentiating cells. Induction by norepinephrine was maximal in the period around confluence. Pharmacological characterization suggested that the norepinephrine signal was transduced mainly through ß-receptors (ß3-subtype), but transduction through aj-receptors was also involved. The newly synthesized thermogenin was incorporated into the mitochondria. Degradation studies suggested the existence of two pools of thermogenin.

    Thus, brown adipose tissue recruitment was studied in-vivo and invitro. The in-vitro studies on brown adipocyte cell cultures substantiate a central role for norepinephrine in the regulation of the recruitment process.

  • 189. Herzke, D.
    et al.
    Nygard, T.
    Berger, Urs
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Huber, S.
    Rov, N.
    Perfluorinated and other persistent halogenated organic compounds in European shag (Phalacrocorax aristotelis) and common eider (Somateria mollissima) from Norway: A suburban to remote pollutant gradient2009In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 408, no 2, p. 340-348Article in journal (Refereed)
    Abstract [en]

    Samples of two marine bird species, European shag (Phalacrocorax aristotelis) and common eider (Somateria mollissima) sampled at a remote coastal site in Norway were analysed for POPs and PFCs. Additionally samples of common eider were analysed from two other locations in Norway, representing a gradient from "densely populated" to "remote". The variety, concentration and distribution of lipophilic POPs in comparison to PFCs were investigated. PCBs were the dominating group of contaminants in the analysed egg samples. Shag eggs had median sum PCBs levels of 4580 ng/g l.w. in 2004. Six different PBDE congeners could be detected in the shag eggs. BDE 47 and 100 were the main contributors with 24 and 27 ng/g l.w. respectively, sum PBDEs was 90 ng/g l.w. Relatively high concentrations of chlordanes were found witha total sum of 903 ng/g l.w. Of other OCs, toxaphene 26 and 52 together (sum 657 ng/g l.w.) and HCB (165 ng/g l.w.) were contributing majorly to the egg burden. Sum HCHs were low; only 54 ng/g l.w. PFOS was the main PFC in egg, plasma and liver samples. Similar median levels of 29,32 and 27 ng/g w.w. were observed. PFOSA, PFHxS, and PFDcA were observed additionally in all shag samples at minor concentrations with the exception of elevated levels observed in liver for PFOSA and PFDcA with median levels of 7.6 and 7.9 ng/g w.w., respectively. In common eider eggs, the POP concentrations decreased up to 1/8th along the sampled spatial gradient from suburban to remote. of the 9 detected PFCs, PFOS dominated all samples by one order of magnitude, followed by PFOA. Sum PFC concentrations were twice as high at the two fjord sites compared to the remote site. Shorter chained PFCAs like PFOA and PFNA could be detected in the eider eggs whilst being absent in shag eggs.

  • 190. Hjalmarsson, Anna Emilia
    et al.
    Bukontaite, Rasa
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Ranarilalatiana, Tolotra
    Randriamihaja, Jacquelin Herisahala
    Bergsten, Johannes
    Taxonomic revision of Madagascan Rhantus (Coleoptera, Dytiscidae, Colymbetinae) with an emphasis on Manjakatompo as a conservation priority2013In: ZooKeys, ISSN 1313-2989, E-ISSN 1313-2970, no 350, p. 21-45Article in journal (Refereed)
    Abstract [en]

    We review the diving-beetle genus Rhantus Dejean of Madagascar (Coleoptera, Dytiscidae, Colymbetinae) based on museum collection holdings and recently collected expedition material. Both morphology and DNA is used to test species boundaries, in particular whether newly collected material from the Tsaratanana mountains in the north represent a new species or are conspecific with Rhantus manjakatompo Pederzani and Rocchi 2009, described based on a single male specimen from the central Ankaratra mountains. DNA of the holotype of R. manjakatompo was successfully extracted in a non-destructive way and sequenced. The general mixed Yule coalescent model applied to an ultrametric tree constructed from mitochondrial cytochrome c oxidase subunit I (COI) sequence data delimited three species. Morphological characters supported the same species unambiguously. We therefore recognise three species of Rhantus to occur in Madagascar: R. latus (Fairmaire, 1869), R. bouvieri Regimbart, 1900 and R. manjakatompo Pederzani and Rocchi, 2009. All three species are endemic to Madagascar and restricted to the highlands of the island. Rhantus stenonychus Regimbart, 1895, syn. n., is considered a junior synonym of R. latus. We designate lectotypes for R. bouvieri and R. goudoti Sharp, 1882, the latter a junior synonym of R. latus. We provide descriptions, a determination key, SEM-images of fine pronotal and elytral structures, distribution maps, habitus photos, and illustrations of male genitalia and pro-and mesotarsal claws. We discuss the role of the Manjakatompo forest as a refugium for Madagascan Rhantus diversity and other endemics of the montane central high plateau.

  • 191.
    Holm, Gisela
    Stockholm University, Faculty of Science.
    The three-spined stickleback, Gasterosteus aculeatus L., in ecotoxicological test systems1994Doctoral thesis, comprehensive summary (Other academic)
  • 192.
    Holmberg, Lovisa
    Stockholm University, Faculty of Science, Department of Zoology.
    The eukaryotic ribosome: a chemical and enzymatic footprinting analysis of the structure and function of ribosomal RNA1995Doctoral thesis, comprehensive summary (Other academic)
  • 193.
    Hurd, Peter L.
    Stockholm University, Faculty of Science, Department of Zoology.
    Game theoretical perspectives on conflict and biological communication1997Doctoral thesis, comprehensive summary (Other academic)
  • 194.
    Hájková, Lucie
    Stockholm University.
    The dynamic microfilament system: cellular organization of actin and profilin and their association with cell signalling1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Active shape changes and movement of whole cells, and translocations within cells are essential to life. For instance, during embryogenesis cell migration is a central theme. Wound healing depends on increased and directed motile activity of several cell types. Platelets change their shape dramatically during blood clotting and restoration of blood flow. Cells of the immune system extravasate (leave blood vessels) and migrate to sites of infection, where they carry out their defense reactions etc. Furthermore, increased motile activity is one of the hallmarks of malignant tumor cells.

    All these movements are carried out by a system of muscle proteins. They are present in all our cells, in fact in all eukaryotic cells. The proteins actin and myosin play central roles in this system. They form superstructures inside the cell, converting chemical energy into movements. In non-muscle cells, they are part of a highly dynamic system called the microfilament system, where the basic component are filaments formed from actin. Microfilaments are particularly concentrated beneath the plasma membrane, where they are linked, directly or indirectly, to transmembrane proteins - receptors, adhesion proteins, and ion channels. The dynamic activity of the microfilament system is based on the ability the cell has to change the system, both with respect to organization and activity, and it does so in response to the interactions that it has with the immediate surroundings.

    The protein profilin is one of the crucial components in the regulation of the microfilament system. It binds to actin and controls its polymerizability. In addition to that, it appears to be an important link between the transmembrane signalling and the mechanisms that polymerize actin into filaments.

    This thesis deals with the role of profilin in vivo. It reports on the localization of profilin in cells and describes the effects of microinjecting normal and mutant profilins, and a chemically crosslinked profilin:actin complex into cells. The results strengthen the view that profilin plays a role in the activation of the microfilament system, and provides evidence that the profilin:actin complex is the precursor for filament formation and that dissociation of the complex is a crucial step in the polymerization reaction. The thesis also describes effects on the microfilament system by microinjection of antibodies against two isoforms of PI3-kinase, an enzyme that is involved in the metabolism of a particular type of phospholipid present in the plasma membrane and linked to the control of the microfilament system.

  • 195.
    Hössjer, Ola
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics.
    Jorde, Per Erik
    Ryman, Nils
    Stockholm University, Faculty of Science, Department of Zoology.
    Quasi equilibrium approximations of the fixation index under neutrality: The finite and infinite island models2013In: Theoretical Population Biology, ISSN 0040-5809, E-ISSN 1096-0325, Vol. 84, p. 9-24Article in journal (Refereed)
    Abstract [en]

    The fixation index FST and the coefficient of gene differentiation GST are analyzed for the finite island model under short time spans, ignoring mutations. Dividing the reproduction cycle into the three steps–gamete formation, fertilization, and migration–we develop a new approach for computing quasi equilibrium formulas for FST (and GST). Our formulas generalize earlier ones and reveal that the equilibrium value of FST is influenced not only by the migration rate and local effective population size, Ne, but also by the local census size N, particularly so when the migration rate is high. The order of migration and fertilization is found to have a smaller effect on FST. A major advantage compared to previous approaches is that stochastic allele frequency of migrants is easily accommodated, thereby avoiding underestimation of FST for large migration rates.

  • 196.
    Israelsson, Olle
    Stockholm University, Faculty of Science, Department of Zoology.
    Xenoturbella2000Doctoral thesis, comprehensive summary (Other academic)
  • 197.
    Jakobsson, Staffan
    Stockholm University, Faculty of Science, Department of Zoology.
    Target organs for androgens in two teleost fishes, Atlantic salmon, Salmo salar, and three-spined stickleback, Gasterosteus aculeatus1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The major androgen in male teleost fishes is 11-ketotestosterone (11KT) and not testosterone (T) as in mammals. 11KT has often been found to be more effective than T in stimulating teleost male secondary sexual characters (SSC's). The main aim of this thesis was to investigate how androgens, in particular 11KT, act on target organs in teleost fishes.

    Androgen binding was studied in three sexually dimorphic androgen target organs in teleosts, the kidney in the male three-spined stickleback, Gasterosteus aculeatus, which hypertrophies during the breeding season and produces a glue used in the building of a nest, the skin in male salmon, which increases in thickness during breeding season and finally the salmon heart, which increases in size during the breeding season. Binding of 11KT was detected in both the kidney and skin, two androgen dependent SSC's where 11KT has been found to be more effective than T. In contrast, only specific binding of T was found in the salmon heart, although 11KT and T are equally effective in stimulating heart growth. Thus, different androgen dependent target organs in fish appear to be controlled via different mechanisms.

    Specific binding of 11KT was detected in both tissue pieces and membrane fractions from the kidney of the stickleback and in the skin from Atlantic salmon, Salmo salar. The localisation of 11KT binding to membrane fractions suggests a different mechanism of action for 11KT than via traditional intracellular receptors.

    A specific binding of 11KT was found in the salmon brain membrane fraction, where tritiated 11KT could be displaced by unlabelled T and less effectively by 11KT. A specific binding of tritiated T was also detected in the brain membrane fraction, with T again being more effective than 11KT in displacement. T and 11-ketoandrostenedione (11KA, which is known to be extratesticulary converted to 11KT) administration can be to have similar effects on secretion of follicle stimulating hormone in summer. All these results are consistent with a shared action site for T and 11KT in the brain.

    Specific binding of T but not of 11KT could be detected in Atlantic salmon gill cytosolic and nuclear fractions. This suggests that the previously known impairment of androgens on salmon seawater adaptability could be due to a direct effect of androgens on the gills.

    The stickleback nest building glue was characterised and found to consist almost entirely of a major protein with an apparent molecular size of 203 kDa. It was named spiggin after the Swedish name for stickleback, spigg. Spiggin production could be induced by 11KT treatment and is so far the only protein known to be induced by 11KT.

  • 198.
    Jansson, Liselotte
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Enquist, Magnus
    Testing the receiver bias hypothesis empirically with “virtual evolution”2005In: Animal Behaviour, ISSN 1095-8282, Vol. 70, no 4, p. 865-875Article in journal (Refereed)
    Abstract [en]

    Many signals found in nature seem exaggerated, for instance in size or colour. According to the receiver bias hypothesis such signal features evolve as a consequence of nonfunctional response biases in receivers. In this study we tested this hypothesis using chickens, Gallus gallus domesticus, in a virtual evolution experiment testing the potentiality of receiver bias to drive the evolution of exaggerated signals. The chickens played the role of receivers that can respond to the preferred stimuli displayed by the sender on a peck-sensitive computer screen. The preferred stimulus was kept and evolved, in the direction specified by the chicken, before being introduced to the next chicken of the successive generation. The chickens were tested on signals changing in three dimensions: length, intensity and area. In all three cases, the signals became considerably exaggerated and beyond what was required for accurate discrimination. Our results support the hypothesis that response biases emerging in discrimination tasks are sufficient to cause the evolution of signal exaggeration

  • 199.
    Jansson, Liselotte
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Magnus, Enquist
    Receiver bias for colourful signals2003In: Animal Behaviour, ISSN 0003-3472, Vol. 66, no 5, p. 965-971Article in journal (Refereed)
    Abstract [en]

    Animals tend to respond more strongly to signals that are more colourful and such signals are also common in nature. This is the first study to explore experimentally the possibility that response biases arising in an animal's recognition mechanisms can explain these findings. We trained domestic fowls, Gallus gallus domesticus, to respond by pecking or not pecking to different colours displayed on a touch-sensitive computer screen. The colours changed in response to the birds' choices, which mimicked a simple evolutionary process. Discrimination training generated response biases for the colours more distinct from the nonrewarding colour. As a result the signals evolved towards distinct coloration. The biases developed in directions towards more intense and towards less intense colour, depending on the colour of the nonrewarding stimulus. The result may be applicable to all sorts of visual signals encountered during the same kind of experiences, that is, when one signal should be avoided and another should be approached

  • 200.
    Jansson, Mija
    Stockholm University, Faculty of Science, Department of Zoology.
    Assessing inbreeding and loss of genetic variation in canids, domestic dog (Canis familiaris) and wolf (Canis lupus), using pedigree data2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Genetic variation is necessary to maintain the ability of wild and domestic populations to genetically adapt to changed selective pressures. When relationships among individuals are known, conservation genetic management can be based on statistical pedigree analysis. Such approaches have traditionally focused on wild animal conservation breeding in captivity. In this thesis, I apply pedigree-based techniques to domestic and wild animal populations, focusing on two canids – the domestic dog and the wild wolf.

    Main objectives include to 1) develop a means for making any pedigree fit the input requirements of the software Population Management x (PMx) and to use this program to 2) investigate rate of inbreeding and loss of genetic variation in dog breeds, including possible correlations between recent inbreeding and health problems, 3) estimate effects on inbreeding of the 2010 hunt of the endangered Swedish wolf population, and to 4) evaluate the potential to genetically support this wolf population through cross-fostering releases of zoo bred pups from a conservation breeding program.

    Results include successfully developing the converter program mPed (Paper I) and applying both mPed and PMx to dog and wolf pedigrees. I found extensive loss of genetic variation and moderate rates of recent inbreeding in 26 dog breeds, but no major difference in these parameters between breeds classified as “healthy” vs. “unhealthy“ (Paper II). I found average inbreeding coefficients to more than double (from F=0.03 to 0.07) and founder genetic variation to decrease by c. 30 percent over the past few decades in traditional Swedish dog breeds identified as being of conservation concern (Paper IV). Hunting will make it less likely to reach genetically based Favourable Conservation Status criteria for the Swedish wild wolf population (Paper III), but release of zoo bred wolves through cross-fostering may potentially almost double founder genetic variation of this population (Paper V).

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