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  • 1.
    Almbro, Maria
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Kullberg, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Impaired escape flight ability in butterflies due to low flight muscle ratio prior to hibernation2008In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 211, no 1, p. 24-28Article in journal (Refereed)
  • 2.
    Birse, Ryan T.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Söderberg, Jeannette A. E.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Luo, Jiangnan
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Winther, Åsa M. E.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Nässel, Dick R.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Regulation of insulin-producing cells in the adult Drosophila brain via the tachykinin peptide receptor DTKR2011In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 214, p. 4201-4208Article in journal (Refereed)
    Abstract [en]

    Drosophila insulin-like peptides (DILPs) play important hormonal roles in the regulation of metabolic carbohydrates and lipids, but also in reproduction, growth, stress resistance and aging. In spite of intense studies of insulin signaling in Drosophilag the regulation of DILP production and release in adult fruit flies is poorly understood. Here we investigated the role of Drosophila tachykinin-related peptides (DTKs) and their receptors, DTKR and NKD, in the regulation of brain insulin-producing cells (IPCs) and aspects of DILP signaling. First, we show DTK-immunoreactive axon terminations close to the presumed dendrites of the IPCs, and DTKR immunolabeling in these cells. Second, we utilized targeted RNA interference to knock down expression of the DTK receptor, DTKR, in IPCs and monitored the effects on Dilp transcript levels in the brains of fed and starved flies. Dilp2 and Dilp3, but not Dilp5, transcripts were significantly affected by DTKR knockdown in IPCs, both in fed and starved flies. Both Dilp2 and Dilp3 transcripts increased in fed flies with DTKR diminished in IPCs whereas at starvation the Dilp3 transcript plummeted and Dilp2 increased. We also measured trehalose and lipid levels as well as survival in transgene flies at starvation. Knockdown of DTKR in IPCs leads to increased lifespan and a faster decrease of trehalose at starvation but has no significant effect on lipid levels. Finally, we targeted the IPCs with RNAi or ectopic expression of the other DTK receptor, NKD, but found no effect on survival at starvation. Our results suggest that DTK signaling, via DTKR, regulates the brain IPCs.

  • 3. Bisch-Knaden, Sonja
    et al.
    Carlsson, Mikael A.
    Stockholm University, Faculty of Science, Department of Zoology.
    Sugimoto, Yuki
    Schubert, Marco
    Missbach, Christine
    Sachse, Silke
    Hansson, Bill S.
    Olfactory coding in five moth species from two families2012In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 215, no 9, p. 1542-1551Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to determine what impact phylogeny and life history might have on the coding of odours in the brain. Using three species of hawk moths (Sphingidae) and two species of owlet moths (Noctuidae), we visualized neural activity patterns in the antennal lobe, the first olfactory neuropil in insects, evoked by a set of ecologically relevant plant volatiles. Our results suggest that even between the two phylogenetically distant moth families, basic olfactory coding features are similar. But we also found different coding strategies in the moths' antennal lobe; namely, more specific patterns for chemically similar odorants in the two noctuid species than in the three sphingid species tested. This difference demonstrates the impact of the phylogenetic distance between species from different families despite some parallel life history traits found in both families. Furthermore, pronounced differences in larval and adult diet among the sphingids did not translate into differences in the olfactory code; instead, the three species had almost identical coding patterns.

  • 4.
    Buechel, Séverine D.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Noreikiene, Kristina
    DeFaveri, Jacquelin
    Toli, Elisavet
    Kolm, Niclas
    Stockholm University, Faculty of Science, Department of Zoology.
    Merilä, Juha
    Variation in sexual brain size dimorphism over the breeding cycle in the three-spined stickleback2019In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 222, no 7, article id UNSP jeb194464Article in journal (Refereed)
    Abstract [en]

    Snapshot analyses have demonstrated dramatic intraspecific variation in the degree of brain sexual size dimorphism (SSD). Although brain SSDis believed to be generated by the sex-specific cognitive demands of reproduction, the relative roles of developmental and population-specific contributions to variation in brain SSD remain little studied. Using a common garden experiment, we tested for sex-specific changes in brain anatomy over the breeding cycle in three-spined stickleback (Gasterosteus aculeatus) sampled from four locations in northern Europe. We found that the male brain increased in size (ca. 24%) significantly more than the female brain towards breeding, and that the resulting brain SSD was similar (ca. 20%) for all populations over the breeding cycle. Our findings support the notion that the stickleback brain is highly plastic and changes over the breeding cycle, especially in males, likely as an adaptive response to the cognitive demands of reproduction (e.g. nest construction and parental care). The results also provide evidence to suggest that breeding-related changes in brain size may be the reason for the widely varying estimates of brain SSD across studies of this species, cautioning against interpreting brain size measurements from a single time point as fixed/static.

  • 5.
    Cannon, Barbara
    et al.
    Stockholm University, Faculty of Science, The Wenner-Gren Institute .
    Nedergaard, Jan
    Stockholm University, Faculty of Science, The Wenner-Gren Institute .
    Nonshivering thermogenesis and its adequate measurement in metabolic studies2011In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 214, no Pt 2, p. 242-53Article in journal (Refereed)
    Abstract [en]

    Alterations in nonshivering thermogenesis are presently discussed as being both potentially causative of and able to counteract obesity. However, the necessity for mammals to defend their body temperature means that the ambient temperature profoundly affects the outcome and interpretation of metabolic experiments. An adequate understanding and assessment of nonshivering thermogenesis is therefore paramount for metabolic studies. Classical nonshivering thermogenesis is facultative, i.e. it is only activated when an animal acutely requires extra heat (switched on in minutes), and adaptive, i.e. it takes weeks for an increase in capacity to develop. Nonshivering thermogenesis is fully due to brown adipose tissue activity; adaptation corresponds to the recruitment of this tissue. Diet-induced thermogenesis is probably also facultative and adaptive and due to brown adipose tissue activity. Although all mammals respond to injected/infused norepinephrine (noradrenaline) with an increase in metabolism, in non-adapted mammals this increase mainly represents the response of organs not involved in nonshivering thermogenesis; only the increase after adaptation represents nonshivering thermogenesis. Thermogenesis (metabolism) should be expressed per animal, and not per body mass [not even to any power (0.75 or 0.66)]. A 'cold tolerance test' does not examine nonshivering thermogenesis capacity; rather it tests shivering capacity and endurance. For mice, normal animal house temperatures are markedly below thermoneutrality, and the mice therefore have a metabolic rate and food consumption about 1.5 times higher than their intrinsic requirements. Housing and examining mice at normal house temperatures carries a high risk of identifying false positives for intrinsic metabolic changes; in particular, mutations/treatments that affect the animal's insulation (fur, skin) may lead to such problems. Correspondingly, true alterations in intrinsic metabolic rate remain undetected when metabolism is examined at temperatures below thermoneutrality. Thus, experiments with animals kept and examined at thermoneutrality are likely to yield an improved possibility of identifying agents and genes important for human energy balance.

  • 6.
    Chung, J S
    et al.
    Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA.
    Wilcockson, D C
    Zmora, N
    Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA.
    Zohar, Y
    Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA.
    Dircksen, H
    Stockholm University, Faculty of Science, Department of Zoology.
    Webster, S G
    Identification and developmental expression of mRNAs encoding crustacean cardioactive peptide (CCAP) in decapod crustaceans.2006In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 209, no Pt 19, p. 3862-72Article in journal (Refereed)
    Abstract [en]

    Full-length cDNAs encoding crustacean cardioactive peptide (CCAP) were isolated from several decapod (brachyuran and astacuran) crustaceans: the blue crab Callinectes sapidus, green shore crab Carcinus maenas, European lobster Homarus gamarus and calico crayfish Orconectes immunis. The cDNAs encode open reading frames of 143 (brachyurans) and 139-140 (astacurans) amino acids. Apart from the predicted signal peptides (30-32 amino acids), the conceptually translated precursor codes for a single copy of CCAP and four other peptides that are extremely similar in terms of amino acid sequence within these species, but which clearly show divergence into brachyuran and astacuran groups. Expression patterns of CCAP mRNA and peptide were determined during embryonic development in Carcinus using quantitative RT-PCR and immunohistochemistry with whole-mount confocal microscopy, and showed that significant mRNA expression (at 50% embryonic development) preceded detectable levels of CCAP in the developing central nervous system (CNS; at 70% development). Subsequent CCAP gene expression dramatically increased during the late stages of embryogenesis (80-100%), coincident with developing immunopositive structures. In adult crabs, CCAP gene expression was detected exclusively in the eyestalk, brain and in particular the thoracic ganglia, in accord with the predominance of CCAP-containing cells in this tissue. Measurement of expression patterns of CCAP mRNA in Carcinus and Callinectes thoracic ganglia throughout the moult cycle revealed only modest changes, indicating that previously observed increases in CCAP peptide levels during premoult were not transcriptionally coupled. Severe hypoxic conditions resulted in rapid downregulation of CCAP transcription in the eyestalk, but not the thoracic ganglia in Callinectes, and thermal challenge did not change CCAP mRNA levels. These results offer the first tantalising glimpses of involvement of CCAP in environmental adaptation to extreme, yet biologically relevant stressors, and perhaps suggest that the CCAP-containing neurones in the eyestalk might be involved in adaptation to environmental stressors.

  • 7.
    Corral-López, Alberto
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Kotrschal, Alexander
    Stockholm University, Faculty of Science, Department of Zoology.
    Kolm, Niclas
    Stockholm University, Faculty of Science, Department of Zoology.
    Selection for relative brain size affects context-dependent male preference for, but not discrimination of, female body size in guppies2018In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 221, no 12, article id jeb175240Article in journal (Refereed)
    Abstract [en]

    Understanding what drives animal decisions is fundamental in evolutionary biology, and mate choice decisions are arguably some of the most important in any individual's life. As cognitive ability can impact decision making, elucidating the link between mate choice and cognitive ability is necessary to fully understand mate choice. To experimentally study this link, we used guppies (Poecilia reticulata) artificially selected for divergence in relative brain size and with previously demonstrated differences in cognitive ability. A previous test in our female guppy selection lines demonstrated the impact of brain size and cognitive ability on information processing during female mate choice decisions. Here, we evaluated the effect of brain size and cognitive ability on male mate choice decisions. Specifically, we investigated the preference of large-brained, small-brained and non-selected guppy males for female body size, a key indicator of female fecundity in this species. For this, male preference was quantified in dichotomous choice tests when presented with dyads of females with small, medium and large body size differences. All types of males showed a preference for larger females but no effect of brain size was found in the ability to discriminate between differently sized females. However, we found that non-selected and large-brained males, but not small-brained males, showed a context-dependent preference for larger females depending on the difference in female size. Our results have two important implications. First, they provide further evidence that male mate choice also occurs in a species in which secondary sexual omamentation is present only in males. Second, they show that brain size and cognitive ability have important effects on individual variation in mating preference and sexually selected traits.

  • 8.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Department of Functional Morphology.
    Insect ion transport peptides are derived from alternatively spliced genes and differentially expressed in the central and peripheral nervous system.2009In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 212, no Pt 3, p. 401-12Article in journal (Refereed)
    Abstract [en]

    Insect ionic and fluid homeostasis relies upon the Malpighian tubules (MT) and different hindgut compartments. Primary urine formed in MTs is finally modified by ion, solute and water reabsorptive processes primarily in the hindgut under the control of several large peptide hormones. One of these, the ion transport peptide (ITP), is a chloride transport-stimulating and acid secretion-inhibiting hormone similar to crustacean hyperglycaemic hormones (CHHs). In locusts, moths and fruit flies, ITP together with the slightly longer ITPL isoforms, inactive in hindgut bioassays, arise by alternative splicing from very similar itp genes. ITP and ITPL are differentially distributed in (1) pars lateralis/retrocerebral complex neurosecretory cells (NSCs) containing both splice forms, (2) interneurons with either one of the splice forms, (3) hindgut-innervating abdominal ITP neurons (in Drosophila only), and (4) intrinsic, putative sensory NSCs in peripheral neurohaemal perisympathetic/perivisceral organs or transverse nerves (usually containing ITPL). Both splice forms occur as hormones released into the haemolymph in response to feeding or stress stimuli. ITPL mainly released from the peripheral NSCs is discussed as a competitive inhibitor (as established in vitro) of ITP action on yet to be identified hindgut ITP receptors. Furthermore, some evidence has been provided for possible ecdysis-related functions of ITP and/or ITPL in moths. The comparative data on the highly similar gene, precursor and primary structures and similar differential distributions in insect and crustacean NSCs suggest that CHH/ITP and ITPL neuropeptide-producing cells and their gene products share common phylogenetic ancestry.

  • 9.
    Dircksen, Heinrich
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Burdzik, S.
    Sauter, A.
    Keller, R.
    Two orcokinins and the novel octapeptide orcomyotropin in the hindgut of the crayfish Orconectes limosus: identified myostimulatory neuropeptides originating together in neurones of the terminal abdominal ganglion2000In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 203, no 18, p. 2807-2818Article in journal (Refereed)
    Abstract [en]

    The tridecapeptides Asn(13)-orcokinin and Val(13)-orcokinin, two known members of the orcokinin neuropeptide family native to crustaceans, and a novel octapeptide, orcomyotropin, FDAFTTGFamide, have been identified from extracts of hindguts of the crayfish Orconectes limosus using an isolated hindgut contractility bioassay, high-performance liquid chromatography, microsequencing and mass spectrometry. All three peptides display strong inotropic actions on crayfish hindguts. Orcomyotropin showed higher potency than the two orcokinins. Threshold concentration was approximately 5 x 10(-12)mol l(-1)versus 10(-10)mol l(-1) for the two orcokinins. An approximately fivefold increase in contraction amplitude was observed with 10(-9)mol l(-1) orcomyotropin and 10(-7)mol l(-1) of the orcokinins. Asn(13)- and Val(13)-orcokinin did not differ significantly with regard to their biological effects. Semi-isolated crayfish hearts and locust oviducts did not respond to the three peptides. Immunocytochemistry using antisera against Asn(13)-orcokinin and orcomyotropin showed that these neuropeptides are co-localized in approximately 80-90 neurones of the terminal abdominal ganglion that have been shown to innervate the entire hindgut muscularis via the intestinal nerve. The neurones form elaborate terminal branches preferentially on longitudinal hindgut muscles. Orcomyotropin is a novel crustacean member of the GF-amide family of myotropic and/or allatotropic neuropeptides from annelids, molluscs and insects.

  • 10. el Jundi, Basil
    et al.
    Baird, Emily
    Stockholm University, Faculty of Science, Department of Zoology.
    Byrne, Marcus J.
    Dacke, Marie
    The brain behind straight-line orientation in dung beetles2019In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 222, article id jeb192450Article, review/survey (Refereed)
    Abstract [en]

    For many insects, celestial compass cues play an important role in keeping track of their directional headings. One well-investigated group of celestial orientating insects are the African ball-rolling dung beetles. After finding a dung pile, these insects detach a piece, form it into a ball and roll it away along a straight path while facing backwards. A brain region, termed the central complex, acts as an internal compass that constantly updates the ball-rolling dung beetle about its heading. In this review, we give insights into the compass network behind straight-line orientation in dung beetles and place it in the context of the orientation mechanisms and neural networks of other insects. We find that the neuronal network behind straight-line orientation in dung beetles has strong similarities to the ones described in path-integrating and migrating insects, with the central complex being the key control point for this behavior. We conclude that, despite substantial differences in behavior and navigational challenges, dung beetles encode compass information in a similar way to other insects.

  • 11. Fenkes, Miriam
    et al.
    Fitzpatrick, John L.
    Stockholm University, Faculty of Science, Department of Zoology.
    Ozolina, Karlina
    Shiels, Holly A.
    Nudds, Robert L.
    Sperm in hot water: direct and indirect thermal challenges interact to impact on brown trout sperm quality2017In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 220, no 14, p. 2513-2520Article in journal (Refereed)
    Abstract [en]

    Climate change alters the thermal habitat of aquatic species on a global scale, generating novel environmental challenges during all life stages, including reproduction. Changes in water temperature profoundly influence the performance of ectothermic aquatic organisms. This is an especially crucial issue for migratory fish, because they traverse multiple environments in order to reproduce. In externally fertilizing migratory fish, gametes are affected by water temperature indirectly, within the reproductive organ in which they are produced during migration, as well as directly, upon release into the surrounding medium at the spawning grounds. Both direct (after release) and indirect (during production) thermal impacts on gamete quality have been investigated, but never in conjunction. Here, we assessed the cumulative influence of temperature on brown trout, Salmo trutta, sperm quality during sperm production (male acclimation temperature) as well as upon release (sperm activation water temperature) on two consecutive dates during the brown trout spawning season. Early in the season, warm acclimation of males reduced their fertilization probability (lower sperm velocity) when compared with cold-acclimated males, especially when the activation water temperature was also increased beyond the thermal optimum (resulting in a lower proportion of motile sperm with lower velocity). Later in the season, sperm quality was unaffected by acclimation temperature and thermal sensitivity of sperm was reduced. These results give novel insights into the complex impacts of climate change on fish sperm, with implications for the reproduction and management of hatchery and wild trout populations in future climate scenarios.

  • 12.
    Fong, Stephanie
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Buechel, Séverine D.
    Stockholm University, Faculty of Science, Department of Zoology.
    Boussard, Annika
    Stockholm University, Faculty of Science, Department of Zoology.
    Kotrschal, Alexander
    Stockholm University, Faculty of Science, Department of Zoology.
    Kolm, Niclas
    Stockholm University, Faculty of Science, Department of Zoology.
    Plastic changes in brain morphology in relation to learning and environmental enrichment in the guppy (Poecilia reticulata)2019In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 222, no 10, article id UNSP jeb200402Article in journal (Refereed)
    Abstract [en]

    Despite the common assumption that the brain is malleable to surrounding conditions mainly during ontogeny, plastic neural changes can occur also in adulthood. One of the driving forces responsible for alterations in brain morphology is increasing environmental complexity that may demand enhanced cognitive abilities (e.g. attention, memory and learning). However, studies looking at the relationship between brain morphology and learning are scarce. Here, we tested the effects of both learning and environmental enrichment on neural plasticity in guppies (Poecilia reticulata), by means of either a reversal-learning test or a spatial-learning test. Given considerable evidence supporting environmentally induced plastic alterations, two separate control groups that were not subjected to any cognitive test were included to account for potential changes induced by the experimental setup alone. We did not find any effect of learning on any of our brain measurements. However, we found strong evidence for an environmental effect, where fish given access to the spatial-learning environment had larger relative brain size and optic tectum size in relation to those exposed to the reversal-learning environment. Our results demonstrate the plasticity of the adult brain to respond adaptively mainly to environmental conditions, providing support for the environmental enhancement theory.

  • 13. Gmeiner, Florian
    et al.
    Kolodziejczyk, Agata
    Stockholm University, Faculty of Science, Department of Zoology.
    Yoshii, Taishi
    Rieger, Dirk
    Nässel, Dick R.
    Stockholm University, Faculty of Science, Department of Zoology.
    Helfrich-Förster, Charlotte
    GABA(B) receptors play an essential role in maintaining sleep during the second half of the night in Drosophila melanogaster2013In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 216, no 20, p. 3837-3843Article in journal (Refereed)
    Abstract [en]

    GABAergic signalling is important for normal sleep in humans and flies. Here we advance the current understanding of GABAergic modulation of daily sleep patterns by focusing on the role of slow metabotropic GABA(B) receptors in the fruit fly Drosophila melanogaster. We asked whether GABA(B)-R2 receptors are regulatory elements in sleep regulation in addition to the already identified fast ionotropic Rdl GABA(A) receptors. By immunocytochemical and reporter-based techniques we show that the pigment dispersing factor (PDF)-positive ventrolateral clock neurons (LNv) express GABA(B)-R2 receptors. Downregulation of GABA(B)-R2 receptors in the large PDF neurons (l-LNv) by RNAi reduced sleep maintenance in the second half of the night, whereas sleep latency at the beginning of the night that was previously shown to depend on ionotropic Rdl GABA(A) receptors remained unaltered. Our results confirm the role of the l-LNv neurons as an important part of the sleep circuit in D. melanogaster and also identify the GABA(B)-R2 receptors as the thus far missing component in GABA-signalling that is essential for sleep maintenance. Despite the significant effects on sleep, we did not observe any changes in circadian behaviour in flies with downregulated GABA(B)-R2 receptors, indicating that the regulation of sleep maintenance via l-LNv neurons is independent of their function in the circadian clock circuit.

  • 14.
    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.

  • 15.
    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.

  • 16.
    Herbert-Read, J. E.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Uppsala University, Sweden.
    Ward, A. J. W.
    Sumpter, D. J. T.
    Mann, R. P.
    Escape path complexity and its context dependency in Pacific blue-eyes (Pseudomugil signifer)2017In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 220, no 11, p. 2076-2081Article in journal (Refereed)
    Abstract [en]

    The escape paths prey animals take following a predatory attack appear to be highly unpredictable - a property that has been described as 'protean behaviour'. Here, we present a method of quantifying the escape paths of individual animals using a path complexity approach. When individual fish (Pseudomugil signifer) were attacked, we found that a fish's movement path rapidly increased in complexity following the attack. This path complexity remained elevated (indicating a more unpredictable path) for a sustained period (at least 10 s) after the attack. The complexity of the path was context dependent: paths were more complex when attacks were made closer to the fish, suggesting that these responses are tailored to the perceived level of threat. We separated out the components of speed and turning rate changes to determine which of these components contributed to the overall increase in path complexity following an attack. We found that both speed and turning rate measures contributed similarly to an individual's path complexity in absolute terms. Overall, our work highlights the context-dependent escape responses that animals use to avoid predators, and also provides a method for quantifying the escape paths of animals.

  • 17.
    Herbert-Read, James E.
    Stockholm University, Faculty of Science, Department of Zoology. Uppsala University, Sweden.
    Understanding how animal groups achieve coordinated movement2016In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 219, no 19, p. 2971-2983Article, review/survey (Refereed)
    Abstract [en]

    Moving animal groups display remarkable feats of coordination. This coordination is largely achieved when individuals adjust their movement in response to their neighbours' movements and positions. Recent advancements in automated tracking technologies, including computer vision and GPS, now allow researchers to gather large amounts of data on the movements and positions of individuals in groups. Furthermore, analytical techniques from fields such as statistical physics now allow us to identify the precise interaction rules used by animals on the move. These interaction rules differ not only between species, but also between individuals in the same group. These differences have wide-ranging implications, affecting how groups make collective decisions and driving the evolution of collective motion. Here, I describe how trajectory data can be used to infer how animals interact in moving groups. I give examples of the similarities and differences in the spatial and directional organisations of animal groups between species, and discuss the rules that animals use to achieve this organisation. I then explore how groups of the same species can exhibit different structures, and ask whether this results from individuals adapting their interaction rules. I then examine how the interaction rules between individuals in the same groups can also differ, and discuss how this can affect ecological and evolutionary processes. Finally, I suggest areas of future research.

  • 18.
    Kahsai, Lily
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Martin, Jean-René
    CNRS .
    Winther, Åsa M E
    Stockholm University, Faculty of Science, Department of Zoology.
    Neuropeptides in the Drosophila central complex in modulation of locomotor behavior2010In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 213, p. 2256-2265Article in journal (Refereed)
    Abstract [en]

    The central complex is one of the most prominent neuropils in the insect brain. It has been implicated in the control of locomotor activity and is considered as a pre-motor center. Several neuropeptides are expressed in circuits of the central complex, and thus may be modulators of locomotor behavior. Here we have investigated the roles of two different neuropeptides, Drosophila tachykinin (DTK) and short neuropeptide F (sNPF), in aspects of locomotor behavior. In the Drosophila brain, DTK and sNPF are expressed in interneurons innervating the central complex. We have directed RNA interference (RNAi) towards DTK and sNPF specifically in different central complex neurons. We also expressed a temperature-sensitive dominant negative allele of the fly ortholog of dynamin called shibire(ts1), essential in membrane vesicle recycling and endocytosis, to disrupt synaptic transmission in central complex neurons. The spontaneous walking activity of the RNAi- or shibire(ts1)-expressing flies was quantified by video tracking. DTK-deficient flies displayed drastically increased center zone avoidance, suggesting that DTK is involved in the regulation of spatial orientation. In addition, DTK deficiency in other central complex neurons resulted in flies with an increased number of activity-rest bouts. Perturbations in the sNPF circuit indicated that this peptide is involved in the fine regulation of locomotor activity levels. Our findings suggest that the contribution of DTK and sNPF to locomotor behavior is circuit dependent and associated with particular neuronal substrates. Thus, peptidergic pathways in the central complex have specific roles in the fine tuning of locomotor activity of adult Drosophila.

  • 19.
    Kivela, Sami M.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Lehmann, Philipp
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Do respiratory limitations affect metabolism of insect larvae before moulting? An empirical test at the individual level2016In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 219, no 19, p. 3061-3071Article in journal (Refereed)
    Abstract [en]

    Recent data suggest that oxygen limitation may induce moulting in larval insects. This oxygen-dependent induction of moulting (ODIM) hypothesis stems from the fact that the tracheal respiratory system of insects grows primarily at moults, whereas tissue mass increases massively between moults. This may result in a mismatch between oxygen supply and demand at the end of each larval instar because oxygen demand of growing tissues exceeds the relatively fixed supply capacity of the respiratory system. The ODIM hypothesis predicts that, within larval instars, respiration and metabolic rates of an individual larva first increase with increasing body mass but eventually level off once the supply capacity of the tracheal system starts to constrain metabolism. Here, we provide the first individual-level test of this key prediction of the ODIM hypothesis. We use a novel methodology where we repeatedly measure respiration and metabolic rates throughout the penultimate- and final-instar larvae in the butterfly Pieris napi. In the penultimate instar, respiration and metabolic rates gradually decelerated along with growth, supporting the ODIM hypothesis. However, respiration and metabolic rates increased linearly during growth in the final instar, contradicting the prediction. Moreover, our data suggest considerable variation among individuals in the association between respiration rate and mass in the final instar. Overall, the results provide partial support for the ODIM hypothesis and suggest that oxygen limitation may emerge gradually within a larval instar. The results also suggest that there may be different moult induction mechanisms in larva-to-larva moults compared with the final metamorphic moult.

  • 20. Kivela, Sami M.
    et al.
    Viinamaki, Sonja
    Keret, Netta
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Hohtola, Esa
    Valimaki, Panu
    Elucidating mechanisms for insect body size: partial support for the oxygen-dependent induction of moulting hypothesis2018In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 221, no 2, article id UNSP jeb166157Article in journal (Refereed)
    Abstract [en]

    Body size is a key life history trait, and knowledge of its mechanistic basis is crucial in life history biology. Such knowledge is accumulating for holometabolous insects, whose growth is characterised and body size affected by moulting. According to the oxygen-dependent induction of moulting (ODIM) hypothesis, moult is induced at a critical mass at which oxygen demand of growing tissues overrides the supply from the tracheal respiratory system, which principally grows only at moults. Support for the ODIM hypothesis is controversial, partly because of a lack of proper data to explicitly test the hypothesis. The ODIM hypothesis predicts that the critical mass is positively correlated with oxygen partial pressure (P-O2) and negatively with temperature. To resolve the controversy that surrounds the ODIM hypothesis, we rigorously test these predictions by exposing penultimate-instar Orthosia gothica (Lepidoptera: Noctuidae) larvae to temperature and moderate P-O2 manipulations in a factorial experiment. The relative mass increment in the focal instar increased along with increasing P-O2, as predicted, but there was only weak suggestive evidence of the temperature effect. Probably owing to a high measurement error in the trait, the effect of P-O2 on the critical mass was sex specific; high P-O2 had a positive effect only in females, whereas low P-O2 had a negative effect only in males. Critical mass was independent of temperature. Support for the ODIM hypothesis is partial because of only suggestive evidence of a temperature effect on moulting, but the role of oxygen in moult induction seems unambiguous. The ODIM mechanism thus seems worth considering in body size analyses.

  • 21. Kivelä, Sami M.
    et al.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Lehmann, Philipp
    Stockholm University, Faculty of Science, Department of Zoology.
    Developmental plasticity in metabolism but not in energy reserve accumulation in a seasonally polyphenic butterfly2019In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 222, no 13, article id jeb202150Article in journal (Refereed)
    Abstract [en]

    The evolution of seasonal polyphenisms (discrete phenotypes in different annual generations) associated with alternative developmental pathways of diapause (overwintering) and direct development is favoured in temperate insects. Seasonal life history polyphenisms are common and include faster growth and development under direct development than in diapause. However, the physiological underpinnings of this difference remain poorly known despite its significance for understanding the evolution of polyphenisms. We measured respiration and metabolic rates through the penultimate and final larval instars in the butterfly Pieris napi and show that directly developing larvae grew and developed faster and had a higher metabolic rate than larvae entering pupal diapause. The metabolic divergence appeared only in the final instar, that is, after induction of the developmental pathway that takes place in the penultimate instar in P. napi. The accumulation of fat reserves during the final larval instar was similar under diapause and direct development, which was unexpected as diapause is predicted to select for exaggerated reserve accumulation. This suggests that overwinter survival in diapause does not require larger energy reserves than direct development, likely because of metabolic suppression in diapause pupae. The results, nevertheless, demonstrate that physiological changes coincide with the divergence of life histories between the alternative developmental pathways, thus elucidating the proximate basis of seasonal life history polyphenisms.

  • 22. Klepsatel, Peter
    et al.
    Nagaraj Girish, Thirnahalli
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Gáliková, Martina
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Slovak Academy of Sciences, Slovakia.
    Reproductive fitness of Drosophila is maximised by optimal developmental temperature2019In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 222, no 10, article id 202184Article in journal (Refereed)
    Abstract [en]

    Whether the character of developmental plasticity is adaptive or non-adaptive has often been a matter of controversy. Although thermal developmental plasticity has been studied in Drosophila for several traits, it is not entirely clear how it affects reproductive fitness. We, therefore, investigated how developmental temperature affects reproductive performance (early fecundity and egg-to-adult viability) of wild-caught Drosophila melanogaster. We have tested competing hypotheses on the character of developmental thermal plasticity using a full factorial design with three developmental and adulthood temperatures within the natural thermal range of this species. To account for potential intraspecific differences, we examined flies from tropical (India) and temperate (Slovakia) climate zones. Our results show that flies from both populations raised at intermediate developmental temperature (25°C) have comparable or higher early fecundity and fertility at all tested adulthood temperatures, while lower (17°C) or higher developmental temperatures (29°C) did not entail any advantage under the tested thermal regimes. Importantly, the superior thermal performance of flies raised at 25°C is apparent even after taking two traits positively associated with reproductive output into account – body size and ovariole number. Thus, in Drosophila melanogaster, development at a given temperature does not necessarily provide any advantage at this thermal environment in terms of reproductive fitness. Our findings strongly support the optimal developmental temperature hypothesis which claims that at different thermal environments the highest fitness is achieved when an organism is raised at its optimal developmental temperature.

  • 23.
    Lehmann, Philipp
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Pruisscher, Peter
    Stockholm University, Faculty of Science, Department of Zoology.
    Kostal, Vladimir
    Moos, Martin
    Simek, Petr
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Agren, Rasmus
    Varemo, Leif
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Metabolome dynamics of diapause in the butterfly Pieris napi: distinguishing maintenance, termination and post-diapause phases2018In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 221, no 2, article id UNSP jeb169508Article in journal (Refereed)
    Abstract [en]

    Diapause is a deep resting stage facilitating temporal avoidance of unfavourable environmental conditions, and is used by many insects to adapt their life cycle to seasonal variation. Although considerable work has been invested in trying to understand each of the major diapause stages (induction, maintenance and termination), we know very little about the transitions between stages, especially diapause termination. Understanding diapause termination is crucial for modelling and predicting spring emergence and winter physiology of insects, including many pest insects. In order to gain these insights, we investigated metabolome dynamics across diapause development in pupae of the butterfly Pieris napi, which exhibits adaptive latitudinal variation in the length of endogenous diapause that is uniquely well characterized. By employing a time-series experiment, we show that the whole-body metabolome is highly dynamic throughout diapause and differs between pupae kept at a diapause-terminating (low) temperature and those kept at a diapause-maintaining (high) temperature. We showmajor physiological transitions through diapause, separate temperature-dependent from temperature-independent processes and identify significant patterns of metabolite accumulation and degradation. Together, the data show that although the general diapause phenotype (suppressed metabolism, increased cold tolerance) is established in a temperature-independent fashion, diapause termination is temperature dependent and requires a cold signal. This revealed several metabolites that are only accumulated under diapause-terminating conditions and degraded in a temperature-unrelated fashion during diapause termination. In conclusion, our findings indicate that some metabolites, in addition to functioning as cryoprotectants, for example, are candidates for having regulatory roles as metabolic clocks or time-keepers during diapause.

  • 24.
    Lehmann, Philipp
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Pruisscher, Peter
    Stockholm University, Faculty of Science, Department of Zoology.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Carlsson, Mikael
    Stockholm University, Faculty of Science, Department of Zoology.
    Käkelä, Reijo
    Tang, Patrik
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Wheat, Christopher W.
    Stockholm University, Faculty of Science, Department of Zoology.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Energy and lipid metabolism during direct and diapause development in a pierid butterfly2016In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 219, no 19, p. 3049-3060Article in journal (Refereed)
    Abstract [en]

    Diapause is a fundamental component of the life-cycle in the majority of insects living in environments characterized by strong seasonality. The present study addresses poorly understood associations and trade-offs between endogenous diapause duration, thermal sensitivity of development, energetic cost of development and cold tolerance. Diapause intensity, metabolic rate trajectories and lipid profiles of directly developing and diapausing animals were studied using pupae and adults of Pieris napi butterflies from a population for which endogenous diapause is well studied. Endogenous diapause was terminated after 3 months and termination required chilling. Metabolic and postdiapause development rates increased with diapause duration, while the metabolic cost of postdiapause development decreased, indicating that once diapause is terminated development proceeds at a low rate even at low temperature. Diapausing pupae had larger lipid stores than the directly developing pupae and lipids constituted the primary energy source during diapause. However, during diapause lipid stores did not decrease. Thus, despite lipid catabolism meeting the low energy costs of the diapausing pupae, primary lipid store utilization did not occur until the onset of growth and metamorphosis in spring. In line with this finding, diapausing pupae contained low amounts of mitochondria-derived cardiolipins, which suggests a low capacity for fatty acid β-oxidation. While ontogenic development had a large effect on lipid and fatty acid profiles, only small changes in these were seen during diapause. The data therefore indicate that the diapause lipidomic phenotype is built early, when pupae are still at high temperature, and retained until diapause post-diapause development.

  • 25. Phlippen, M K
    et al.
    Webster, S G
    Chung, J S
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Ecdysis of decapod crustaceans is associated with a dramatic release of crustacean cardioactive peptide into the haemolymph.2000In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 203, no Pt 3, p. 521-36Article in journal (Refereed)
    Abstract [en]

    On the basis of detailed analyses of morphological characteristics and behavioural events associated with ecdysis in a crab (Carcinus maenas) and a crayfish (Orconectes limosus), a comprehensive substaging system has been introduced for the ecdysis stage of the moult cycle of these decapod crustaceans. In a remarkably similar stereotyped ecdysis sequence in both species, a passive phase of water uptake starting with bulging and rupture of thoracoabdominal exoskeletal junctions is followed by an active phase showing distinct behavioural changes involved in the shedding of the head appendages, abdomen and pereiopods. Together with an enzyme immunoassay for crustacean cardioactive peptide (CCAP), the substaging has been used to demonstrate a large, rapid and reproducible peak in haemolymph CCAP levels (increases of approximately 30-fold in the crab and more than 100-fold in the crayfish compared with intermoult titres) during the later stages of active ecdysis. We suggest that the release of CCAP (accumulated in late premoult) from the crab pericardial organs or the crayfish ventral nerve cord accounts for many of the changes in behaviour and physiology seen during ecdysis and that this neurohormone is likely to be of critical importance in crustaceans and other arthropods.

  • 26. Wilson, S. K.
    et al.
    Adjeroud, M.
    Bellwood, D. R.
    Berumen, M. L.
    Booth, D.
    Bozec, Y. -Marie
    Chabanet, P.
    Cheal, A.
    Cinner, J.
    Depczynski, M.
    Feary, D. A.
    Gagliano, M.
    Graham, N. A. J.
    Halford, A. R.
    Halpern, B. S.
    Harborne, A. R.
    Hoey, A. S.
    Holbrook, S. J.
    Jones, G. P.
    Kulbiki, M.
    Letourneur, Y.
    De Loma, T. L.
    McClanahan, T.
    McCormick, M. I.
    Meekan, M. G.
    Mumby, P. J.
    Munday, P. L.
    Öhman, Marcus C.
    Stockholm University, Faculty of Science, Department of Zoology.
    Pratchett, M. S.
    Riegl, B.
    Sano, M.
    Schmitt, R. J.
    Syms, C.
    Crucial knowledge gaps in current understanding of climate change impacts on coral reef fishes2010In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 213, no 6, p. 894-900Article in journal (Refereed)
    Abstract [en]

    Expert opinion was canvassed to identify crucial knowledge gaps in current understanding of climate change impacts on coral reef fishes. Scientists that had published three or more papers on the effects of climate and environmental factors on reef fishes were invited to submit five questions that, if addressed, would improve our understanding of climate change effects on coral reef fishes. Thirty-three scientists provided 155 questions, and 32 scientists scored these questions in terms of: (i) identifying a knowledge gap, (ii) achievability, (iii) applicability to a broad spectrum of species and reef habitats, and (iv) priority. Forty-two per cent of the questions related to habitat associations and community dynamics of fish, reflecting the established effects and immediate concern relating to climate-induced coral loss and habitat degradation. However, there were also questions on fish demographics, physiology, behaviour and management, all of which could be potentially affected by climate change. Irrespective of their individual expertise and background, scientists scored questions from different topics similarly, suggesting limited bias and recognition of a need for greater interdisciplinary and collaborative research. Presented here are the 53 highest-scoring unique questions. These questions should act as a guide for future research, providing a basis for better assessment and management of climate change impacts on coral reefs and associated fish communities.

1 - 26 of 26
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