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  • 51.
    Birgersson, Björn
    Stockholm University, Faculty of Science, Department of Zoology.
    Maternal investment in male and female offspring in the fallow deer1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, I investigate whether mothers of the polygynous fallow deer, Dama dama, bias their investment towards male offspring. I aim to answer the specific questions: (i) how is offspring fitness related to maternal investment?; (ii) do male fawns grow faster than female fawns during the period of maternal investment, and if so, why?; (iii) are male fawns more costly to raise than female fawns?; (iv) do fallow deer mothers adjust the sex of their offspring in relation to their ability to invest resources? To answer these questions I have collected and analysed data on reproduction of an enclosed fallow deer population and also performed an experimental study in which the level of investment was controlled for.

    Heavier mothers gave birth earlier and to larger offspring which grew at a faster rate. Pre-winter body mass of fawns was also found to affect sub-adult body mass in both sexes indicating that maternal investment influences offspring adult body size and, presumably, their fitness. The effect of pre-winter body mass on sub-adult body mass was stronger in male than in female fawns. Male pre-winter body mass was also constantly higher than female pre-winter body mass. Presumably, this is because male reproductive success varies more with body size than does female reproductive success and, hence, there has been stronger selection for early growth in males than in females. Male fawns grew faster than female fawns both before and after birth, independent of their birth date, but there were no behavioral differences between the two sexes. Furthermore, the faster male growth could not be explained by mothers in better condition (heavier mothers) producing male offspring and mothers in poorer condition producing females.

    When male and female fawns were given exactly the same amount and quality of milk by bottle-raising them, the difference in weight gain between bottle- and mother raised male fawns was significantly larger than between bottle- and mother-raised female fawns during the time when they solely consumed milk. It was also evident that bottle-raised male fawns suck harder and acquired milk at a more rapid rate than female fawns. These results suggest that male fawns receive more milk from their mothers than female fawns do.

    Mothers with sons accumulated less body mass than mothers with daughters during the period from late pregnancy to the end of lactation which gives additional support for the conclusion that male fawns receive more milk from their mothers. The higher energetic cost of raising a male was also translated into a higher reproductive cost, as indicated by later birth date and lower pre-winter mass of offspring the following year. Pre-winter body mass the first year is related to adult body mass and, most likely, to reproductive success in fallow deer. Consequently, the higher milk production and the corresponding higher energetic cost of raising sons do affect the mother's future offspring's chances to reproduce and, thus, support theories of male-biased maternal investment.

  • 52.
    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.

  • 53. 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.

  • 54.
    Björkman, Christer
    et al.
    Swedish University for Agricultural Sciences.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Pettersson, Mats
    Swedish University for Agricultural Sciences.
    Body Size2009In: Encyclopedia of Insects / [ed] Vincent H. Resh, Ring T. Cardé, Amsterdam: Elsevier/Academic Press , 2009, 2, p. 114-116Chapter in book (Other academic)
  • 55.
    Björkman, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Nutrient dynamics in the North Pacific subtropical gyre: phosphorus fluxes in the upper oligotrophic ocean1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the contemporary North Pacific subtropical gyre (NPSG) the extant microbial community is based on prokaryotic cells with the cyanobacterium Prochlorococcus dominating the phototrophic component. The prevalence of dinitrogen (N2) fixing organisms, such as Trichodesmium spp., appears to have relieved the ecosystem from its historically perceived nitrogen (N) limited state. It is thus conceivable that phosphorus (P) or trace elements such as iron (Fe) may be important factors in the regulation of primary and secondary productivity in these nutrient impoverished habitats. In a system under P control, determining the underlying mechanisms driving the P flux among its different compartments will be important in predicting ecosystem productivity and food web interactions.

    The papers presented herein were aimed at addressing dissolved organic matter (DOM) dynamics with specific objectives to investigate the P pool fluxes in the NPSG. These included assessment of P uptake and turnover rates, estimation of the bioavailable P (BAP) pool concentrations, dissolved organic phosphorus (DOP) and dissolved organic carbon (DOC) production, bioavailability of selected P compounds to natural assemblages of microorganisms and the role of dissolved nucleotides in the oligotrophic marine environment.

    At Station ALOHA the production of DOC could be nearly 50% of the net CO2 fixed into biomass. DOP production ranged from 0.6-2.5 nM d-1, equivalent to 10-40% of net P incorporation. Uptake rates and turnover times of P were approximately an order of magnitude higher in the coastal region compared to the open ocean habitats at about 40-80 nM P d-1, and 0.8-2.5 d respectively. The size of the BAP pool frequently exceeded the soluble reactive phosphorus (SRP) pool sometimes by a factor of two. There was a pronounced difference in microbial preference for the known P substrates tested. Although orthophosphate (Pi) was always the most readily available substrate nucleotides had the highest bioavailability of the P compounds tested. A large but variable percentage of P from the tested compounds accumulated outside the cells as SRP, indicating an efficient regeneration of Pi from some substrates.

    Dissolved and particulate adenosine triphosphate (ATP) and guanosine triphosphate (GTP) pools were dynamic and varied on temporal and spatial scales. The dissolved pools were frequently larger than their corresponding particulate fractions. Dissolved ATP uptake and production rates appeared to be in balance and the estimated turnover time for this DOP pool constituent, 1-2 days. Considering the high bioavailability and Pi regeneration from nucleotides, the potentially large dissolved nucleotide and nucleic acid pool, and a high P flux through ATP relative to bulk DOP, it is plausible that a substantial part of the P flux in the upper oligotrophic ocean revolves around the nucleic acid pool and its derivatives.

  • 56. Bohlin, Titti
    et al.
    Gamberale-Stille, Gabriella
    Stockholm University, Faculty of Science, Department of Zoology.
    Merilaita, Sami
    Exnerova, Alice
    Stys, Pavel
    Tullberg, Birgitta S.
    Stockholm University, Faculty of Science, Department of Zoology.
    The detectability of the colour pattern in the aposematic firebug, Pyrrhocoris apterus: an image-based experiment with human 'predators'2012In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 105, no 4, p. 806-816Article in journal (Refereed)
    Abstract [en]

    Crypsis and aposematism are often regarded as two opposite protective strategies. However, there is large variation in prey appearance within both strategies. In this article, we investigated the conspicuousness of the aposematic red-and-black firebug, Pyrrhocoris apterus, by presenting images of natural and digitally manipulated phenotypes in their natural habitat on a computer screen to human predators, and comparing the detection times. We asked whether the natural colour pattern can be made more or less conspicuous by rearranging the spatial distribution of colour elements. Hence, we created a phenotype in which the black colour elements were moved to the body outline to test for a possible disruptive effect. In the black and red manipulations, we removed one of the two colours, creating two uniform colour variants. We found that some of our manipulations increased, but none reduced, the detection time significantly; this indicates that the naturally coloured firebug is highly conspicuous. The detection time varied among backgrounds and there was a significant relationship between detection time and chromatic similarity between the bug and the background for the natural and black phenotypes. Although background colour composition has an important effect on the signal, we argue that the coloration of P. apterus has evolved for high conspicuousness.

  • 57.
    Bonet, James
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Ulefors, Sven-Olof
    Viklund, Bert
    Stockholm University, Faculty of Science, Department of Zoology.
    Pape, Thomas
    Species richness estimations of the megadiverse scuttle fly genus Megaselia (Diptera Phoridae) in a wildfire-affected hemiboreal forest2011In: Insect Science, ISSN 1672-9609, E-ISSN 1744-7917, Vol. 18, no 3, p. 325-348Article in journal (Refereed)
    Abstract [en]

    The species richness of the scuttle fly (Diptera: Phoridae) genus Megaselia was estimated by various non-parametric estimators from EstimateS, Species Prediction And Diversity Estimation (SPADE) and Ws2m, based on material from a Swedish hemiboreal forest area recently affected by major wildfires, Tyresta National Park and Nature Reserve (TNPNR), south of Stockholm. A total of 21 249 individuals were collected in Malaise traps, of which males constituted 16 976 and females 4 273. The analysed dataset represents 37 samples containing 18 549 specimens sorted into 330 species (184 described, 146 are either undescribed or of unsettled taxonomic status). It was not possible to estimate the total species richness using all samples due to heterogeneity caused by inclusion of different communities and temporal incoherencies between samples within and between years. Even with material obtained from a sampling program that was not designed for species richness estimates, it was possible to obtain reliable results when sample heterogeneity was minimized. By dividing the data into community-specific datasets - for bog, forest and wildfire - it was possible to obtain asymptotic curves for the smaller of the two wildfire datasets. A total estimate of 357-439 (95% CI) was attained by using the smaller wildfire dataset and adding the 85 unique species from the samples not included in the estimation analysis. TNPNR has one of the richest known scuttle fly communities in Europe, consisting of almost 50% of the currently named Megaselia species; 48 of these species are reported as new records for Sweden in this study.

  • 58. Borg, O.
    et al.
    Wille, M.
    Kjellander, P.
    Bergvall, Ulrika A.
    Stockholm University, Faculty of Science, Department of Zoology. Swedish University of Agricultural Sciences, Sweden.
    Lindgren, P.-E.
    Chirico, J.
    Lundkvist, Å.
    Expansion of spatial and host range of Puumala virus in Sweden: an increasing threat for humans?2017In: Epidemiology and Infection, ISSN 0950-2688, E-ISSN 1469-4409, Vol. 145, no 8, p. 1642-1648Article in journal (Refereed)
    Abstract [en]

    Hantaviruses are globally distributed and cause severe human disease. Puumala hantavirus (PUUV) is the most common species in Northern Europe, and the only hantavirus confirmed to circulate in Sweden, restricted to the northern regions of the country. In this study, we aimed to further add to the natural ecology of PUUV in Sweden by investigating prevalence, and spatial and host species infection patterns. Specifically, we wanted to ascertain whether PUUV was present in the natural reservoir, the bank vole (Myodes glareolus) further south than Dalälven river, in south-central Sweden, and whether PUUV can be detected in other rodent species in addition to the natural reservoir. In total, 559 animals were collected at Grimsö (59°43'N; 15°28'E), Sala (59°55'N; 16°36'E) and Bogesund (59°24'N; 18°14'E) in south-central Sweden between May 2013 and November 2014. PUUV ELISA-reactive antibodies were found both in 2013 (22/295) and in 2014 (18/264), and nine samples were confirmed as PUUV-specific by focus reduction neutralization test. Most of the PUUV-specific samples were from the natural host, the bank vole, but also from other rodent hosts, indicating viral spill-over. Finally, we showed that PUUV is present in more highly populated central Sweden.

  • 59.
    Bornestaf, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology.
    Mechanisms in the photoperiodic control of reproduction in the three-spined stickleback, Gasterosteus aculeatus2000Doctoral thesis, comprehensive summary (Other academic)
  • 60. Boström, Jannika E.
    et al.
    Kullberg, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Åkesson, Susanne
    Northern magnetic displacements trigger endogenous fuelling responses in a naive bird migrant2012In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 66, no 5, p. 819-821Article in journal (Refereed)
    Abstract [en]

    In a previous study, we found that juvenile northern wheatears (Oenanthe oenanthe) exposed to a magnetic displacement to the west of their natural migration route increased their body mass. The total intensity and inclination used for the western displacement may also have been interpreted as northern compared to the experimental site (stronger total field intensity and steeper inclination angle). In order to investigate whether the fuelling response was a response to an unexpected magnetic field or specific to the northern magnetic field, we conducted a new experiment. Juvenile wheatears from the same study population were magnetically displaced to southwestern magnetic fields, exposing the birds to unexpected magnetic combinations, but eliminating the possible effect of a northern magnetic field. A control group was kept in the local geomagnetic field in Sweden for comparison. There was no difference in body mass increase between treatments, suggesting that the fuelling response previously found was not a simple response to an unexpected magnetic field, but rather a specific response to the northern magnetic field. Juvenile wheatears may have developed a fuelling response to northern magnetic fields in order to enable a successful flight towards the migration goal.

  • 61. Breidbach, Olaf
    et al.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Crustacean cardioactive peptide-immunoreactive neurons in the ventral nerve cord and the brain of the meal beetle Tenebrio molitor during postembryonic development1991In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 265, no 1, p. 129-144Article in journal (Refereed)
    Abstract [en]

    By use of an antiserum against the crustacean cardioactive peptide (CCAP) several types of bilaterally symmetrical neurons were mapped quantitatively in the ventral nerve cord and brain of Tenebrio molitor. The general architecture of these neurons was reconstructed. From the suboesophageal to the 7th abdominal ganglia 2 types of neurons showed a repetitive organization of contralateral projection patterns in each neuromere. The first type had few branches in the central neuropil and a distinct peripheral projection. The 2nd type was characterized by an elaborate central branching pattern, which included ascending and descending processes. Some of its peripheral branches supplied peripheral neurohaemal areas. In the protocerebrum, 10 CCAP-immunoreactive neurons occurred with projections into the superior median protocerebrum and the tritocerebrum. Immunopositive neurons were mapped in larvae, pupae and adults. All types of identified neurons persisted throughout metamorphosis, maintaining their essential structural and topological characteristics. The CCAP-immunoreactive neurons of T. molitor were compared with those described for Locusta migratoria. Putative structural homologies of subsets of neurons in both species are discussed.

  • 62.
    Breidbach, Olaf
    et al.
    Institute of Applied Zoology, University of Bonn, Germany.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Proctolin-immunoreactive neurons persist during metamorphosis of an insect: A developmental study of the ventral nerve cord of Tenebrio molitor(Coleoptera)1989In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 257, no 1, p. 217-225Article in journal (Refereed)
    Abstract [en]

    Proctolin-immunoreactive neurons in all neuromers of the ventral nerve cord of Tenebrio molitor L. have been quantitatively demonstrated and mapped throughout metamorphosis. Each neuromer contains an anterior and a posterior group of neurons with light and dark staining properties as revealed by peroxidase-antiperoxidase labeling. Serial homologous subsets of dark staining neurons with central and peripheral projections have been identified and found to persist during morphogenetic changes from the larva to the adult. Most neurons maintain their topological and structural characteristics throughout metamorphosis. The identified proctolin-immunoreactive neurons exhibit structures similar to those described in other insect species; some may correspond known motoneurons.

  • 63.
    Brick, Olle
    Stockholm University, Faculty of Science, Department of Zoology.
    Risk assessment and contest behaviour in the Cichlid fish Nannacara anomala2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The risk of predation is an important factor for our understanding of animal behaviour in general. This thesis investigates the influence of predation risk on fighting behaviour in the cichlid fish Nannacara anomala. According to game theoretical models, a fighting animal should base its decisions during a fight on its fighting ability in relation to the opponent and on the value of the contested resource. The result of the present thesis suggests that fighting N. anomala males engaged in escalated fighting are likely to be vulnerable to predation due to impaired vigilance. The presence of a model fish predator made the males reluctant to perform mouth wrestling and the intensity of mouth wrestling decreased significantly compared to undisturbed fights. When I used predation risk as a cost of fighting, the variability among fights increased. In some fights, the use of low intensity behaviour elements increased in the presence of a model fish predator in accordance with the previous findings on vigilance. Other fights escalated to mouth wrestling in a way resembling undisturbed fights, suggesting a difference among contestants in what behaviour they prefer to use when there is an increased risk of predation. The study showed that fish classified as 'bold' towards a model fish predator escalated significantly faster to mouth wrestling and performed significantly more agonistic behaviour in the presence of a model fish predator compared with fish that had been classified as 'cautious'. 'Bold' pairs also escalated significantly faster to mouth wrestling compared to 'cautious' pairs when the model fish predator was absent. In agreement with theoretical predictions, fights between N. anomala males contained significantly more costly behavioural acts in the presence of a female compared to fights in the absence of a female. Despite the presence of a female, the variability among fights increased significantly when predation risk increased, suggesting that increased risk of predation is not accepted even in fights about a valuable resource in this species. The study also showed that the probability for the lighter fish to win increased in the presence of a female and when predation risk was high. In fights over a valuable resource, other asymmetries besides relative body weight are likely to become important and increased risk of predation may impair assessment of relative fighting ability or the contestants may differ in risk assessment. A difference among contestants in what behaviour they prefer to use, clearly expressed when predation risk increase, may be an additional factor explaining some of the variability among fights found in many studies.

  • 64.
    Brodin, Anders
    Stockholm University, Faculty of Science.
    Time aspects on food hoarding in the willow tit: an evolutionary perspective1994Doctoral thesis, comprehensive summary (Other academic)
  • 65.
    Brodin, Yngve
    et al.
    Department of Popular Biology, Evolutionary Centre Uppsala University.
    Andersson, Mathias H
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    The marine splash midge Telmatogonjaponicus (Diptera; Chironomidae)—extreme and alien?2009In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 11, no 6, p. 1311-1317Article in journal (Refereed)
    Abstract [en]

    We found all developmental stages of the midge offshore windmills near the major Swedish seaport Kalmar in the southern Baltic Sea. This might be the first record of an insect species really inhabiting the offshore areas of the Baltic Sea. A thorough analysis of previous findings of the species, its history in Europe and its ecology indicates that Telmatogeton japonicus (Chironomidae) onT. japonicus quite likely is an alien species in Europe introduced from the Pacific Ocean. Shipping is probably the vector, as all records in the Baltic Sea and several from the Eastern Atlantic Sea are near major seaports. Our analysis further suggests that be both advantageous and disadvantageous to native species in the Baltic Sea. T. japonicus should be kept under observation within monitoring programmes as it might expand its distribution as a result of the construction of new windmills in the Baltic Sea and elsewhere in European marine and brackish water habitats.

  • 66.
    Brooke-Jones, Megan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gáliková, Martina
    Stockholm University, Faculty of Science, Department of Zoology.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology.
    Cyanobacterial Neurotoxin Beta-Methyl-Amino-l-Alanine Affects Dopaminergic Neurons in Optic Ganglia and Brain of Daphnia magna2018In: Toxins, ISSN 2072-6651, E-ISSN 2072-6651, Vol. 10, no 12, article id 527Article in journal (Refereed)
    Abstract [en]

    The non-proteinogenic amino acid beta-methyl-amino-l-alanine (BMAA) is a neurotoxin produced by cyanobacteria. BMAA accumulation in the brain of animals via biomagnification along the food web can contribute to the development of neurodegenerative diseases such as Amyotrophic lateral sclerosis/Parkinsonism dementia complex (ALS/PDC), the latter being associated with a loss of dopaminergic neurons. Daphnia magna is an important microcrustacean zooplankton species that plays a key role in aquatic food webs, and BMAA-producing cyanobacteria often form part of their diet. Here, we tested the effects of BMAA on putative neurodegeneration of newly identified specific dopaminergic neurons in the optic ganglia/brain complex of D. magna using quantitative tyrosine-hydroxylase immunohistochemistry and fluorescence cytometry. The dopaminergic system was analysed in fed and starved isogenic D. magna adults incubated under different BMAA concentrations over 4 days. Increased BMAA concentration showed significant decrease in the stainability of dopaminergic neurons of D. magna, with fed animals showing a more extreme loss. Furthermore, higher BMAA concentrations tended to increase offspring mortality during incubation. These results are indicative of ingested BMAA causing neurodegeneration of dopaminergic neurons in D. magna and adversely affecting reproduction. This may imply similar effects of BMAA on known human neurodegenerative diseases involving dopaminergic neurons.

  • 67. Bruun, Hans Henrik
    et al.
    Österdahl, Sofia
    Moen, Jon
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Distinct patterns in alpine vegetation around dens of the Arctic fox2005In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 28, no 1, p. 81-87Article in journal (Refereed)
    Abstract [en]

    The arctic fox Alopex lugopus excavates its dens in gravely ridges and hillocks, and creates a local environment quite distinct from the surrounding tundra or heath landscape. In northern Sweden, the vegetation of 18 dens of the arctic fox was investigated, as well as reference areas off the dens but in geologically and topographically similar locations. The species composition showed considerable differences between den and reference areas, with grasses and forbs occurring more abundantly on the dens, and evergreen dwarf-shrubs occurring more in reference areas. The effect of the foxes' activities is thought to be either through mechanical soil disturbance, or through nutrient enrichment via scats, urine, and carcasses. This was expected to result in differences in plant traits with key functional roles in resource acquisition and regeneration, when comparing dens with reference areas. We hypothesised that the community mean of specific leaf area (SLA) would differ if nutrient enrichment was the more important effect, and that seed weight, inversely proportional to seed number per ramet and hence dispersal ability, would differ if soil disturbance was the more important effect. Specific leaf area showed a significant difference, indicating nutrient enrichment to be the most important effect of the arctic fox on the vegetation on its dens. Arctic foxes act as ecosystems engineers on a small scale, maintaining niches for relatively short-lived nutrient demanding species on their dens in spite of the dominance of long-lived ericaceous dwarf-shrubs in the landscape matrix. Thus, foxes contribute to the maintenance of species richness on the landscape level.

  • 68.
    Bukontaite, Rasa
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History.
    Evolution of the Biodiversity Hotspot of Madagascar from the Eye of Diving Beetles: Phylogeny, colonization and speciation2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dytiscidae, contains numerous endemic and non-endemic species on Madagascar. Their evolutionary history is largely unknown on the island. Herein, I use analyses to infer phylogenetic relationship among groups of diving beetles, with a focus on the subfamily Dytiscinae and endemic species in two other groups of Dytiscidae. Paper I represents the first phylogenetic reconstruction focusing on the tribe Aciliini based on molecular data. Several commonly used molecular markers, as well as a new marker for Hydradephagan beetles, were evaluated in this study. Our analyses suggest that six genera within Aciliini are monophyletic. The most basal clades with Neotropical and Afrotropical taxa suggest a possible Gondwanan origin. Evaluation of gene fragments indicated CAD to be the most informative marker. Paper II focuses on colonization and radiation events of large bodied endemic diving beetles of the tribes Cybistrini and Hydaticini on Madagascar. Colonization events were inferred from dated phylogenetic trees and ancestral biogeographical reconstructions. Our results suggest both multiple colonizations, and out-of-Madagascar dispersal events, mostly during the Miocene and Oligocene. In paper III, we revised the Rhantus species of Madagascar. We used both molecular and morphological data to evaluate species hypothesis and emphasized the value of Manjakatompo – one of the last remaining fragments of central highland forests. In Paper IV we reconstruct the phylogeny and use Species Distribution Modelling for the endemic genus Pachynectes in Madagascar. Our sampling has discovered that the species diversity of Pachynectes is at least three times higher than previously believed. It seems that allopatric speciation was the main driver, which led to the diversity of Pachynectes. Our results suggest that climatic gradients and the five main biomes were a better predictor than watershed systems in explaining the distribution pattern and speciation between sister species. 

  • 69.
    Bukontaite, Rasa
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Ranarilalatiana, Tolotra
    Randriamihaja, Jacquelin Herisahala
    Bergsten, Johannes
    In or Out-of-Madagascar?-Colonization Patterns for Large-Bodied Diving Beetles (Coleoptera: Dytiscidae)2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 3, article id e0120777Article in journal (Refereed)
    Abstract [en]

    High species diversity and endemism within Madagascar is mainly the result of species radiations following colonization from nearby continents or islands. Most of the endemic taxa are thought to be descendants of a single or small number of colonizers that arrived from Africa sometime during the Cenozoic and gave rise to highly diverse groups. This pattern is largely based on vertebrates and a small number of invertebrate groups. Knowledge of the evolutionary history of aquatic beetles on Madagascar is lacking, even though this species-rich group is often a dominant part of invertebrate freshwater communities in both standing and running water. Here we focus on large bodied diving beetles of the tribes Hydaticini and Cybistrini. Our aims with this study were to answer the following questions 1) How many colonization events does the present Malagasy fauna originate from? 2) Did any colonization event lead to a species radiation? 3) Where did the colonizers come from-Africa or Asia- and has there been any out-of-Madagascar event? 4) When did these events occur and were they concentrated to any particular time interval? Our results suggest that neither in Hydaticini nor in Cybistrini was there a single case of two or more endemic species forming a monophyletic group. The biogeographical analysis indicated different colonization histories for the two tribes. Cybistrini required at least eight separate colonization events, including the non-endemic species, all comparatively recent except the only lotic (running water) living Cybister operosus with an inferred colonization at 29 Ma. In Hydaticini the Madagascan endemics were spread out across the tree, often occupying basal positions in different species groups. The biogeographical analyses therefore postulated the very bold hypothesis of a Madagascan origin at a very deep basal node within Hydaticus and multiple out-of-Madagascar dispersal events. This hypothesis needs to be tested with equally intense taxon sampling of mainland Africa as for Madagascar.

  • 70.
    Burreau, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    On the uptake and biomagnification of PCBs and PBDEs in fish and aquatic food chains2001Doctoral thesis, comprehensive summary (Other academic)
  • 71.
    Böcking, Detlef
    et al.
    Institute of Zoophysiology, University of Bonn, Germany.
    Dircksen, Heinrich
    Institute of Zoophysiology, University of Bonn, Germany.
    Keller, Rainer
    Institute of Zoophysiology, University of Bonn, Germany.
    The crustacean neuropeptides of the CHH/MIH/GIH family: Structures and biological activities.2002In: The Crustacean Nervous System. / [ed] Konrad Wiese, Heidelberg: Springer , 2002, p. 84-97Chapter in book (Other academic)
  • 72.
    Börjesson, Patrik
    Stockholm University.
    Geographical variation and resource use in harbour porpoises2002Doctoral thesis, comprehensive summary (Other academic)
  • 73.
    Campenni, Marco
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Istituto Superiore di Sanità, Italy.
    Manciocco, Arianna
    Vitale, Augusto
    Schino, Gabriele
    Exchanging Grooming, But not Tolerance and Aggression in Common Marmosets (Callithrix jacchus)2015In: American Journal of Primatology, ISSN 0275-2565, E-ISSN 1098-2345, Vol. 77, no 2, p. 222-228Article in journal (Refereed)
    Abstract [en]

    In this study, we investigated the reciprocal exchanges of grooming, tolerance and reduced aggression in common marmosets (Callithrix jacchus), a cooperatively breeding primate whose groups are typically characterized by uniformly high genetic relatedness and high interdependency between group members. Both partner control and partner choice processes played a role in the reciprocal exchanges of grooming. In contrast, we did not find any evidence of reciprocity between grooming and tolerance over a preferred food source or between grooming and reduced aggression. Thus, reciprocity seems to play a variable role in the exchange of cooperative behaviors in marmosets. Am. J. Primatol. 77:222-228, 2015.

  • 74. Campos, Bruno
    et al.
    Rivetti, Claudia
    Kress, Timm
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Barata, Carlos
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Depressing antidepressant: Fluoxetine affects serotonin neurons causing adverse reproductive responses in Daphnia magna2016In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, no 11, p. 6000-6007Article in journal (Refereed)
    Abstract [en]

    Selective serotonin reuptake inhibitors (SSRIs) are widely used antidepressants. As endocrine disruptive contaminants in the environment, SSRIs affect reproduction in aquatic organisms. In the water flea Daphnia magna, SSRIs increase offspring production in a food ration-dependent manner. At limiting food conditions, females exposed to SSRIs produce more but smaller offspring, which is a maladaptive life-history strategy. We asked whether increased serotonin levels in newly identified serotonin-neurons in the Daphnia brain mediate these effects. We provide strong evidence that exogenous SSRI fluoxetine selectively increases serotonin-immunoreactivity in identified brain neurons under limiting food conditions thereby leading to maladaptive offspring production. Fluoxetine increases serotonin-immunoreactivity at low food conditions to similar maximal levels as observed under high food conditions and concomitantly enhances offspring production. Sublethal amounts of the neurotoxin 5,7-dihydroxytryptamine known to specifically ablate serotonin-neurons markedly decrease serotonin-immunoreactivity and offspring production, strongly supporting the effect to be serotonin-specific by reversing the reproductive phenotype attained under fluoxetine. Thus, SSRIs impair serotonin-regulation of reproductive investment in a planktonic key organism causing inappropriately increased reproduction with potentially severe ecological impact.

  • 75.
    Cantera, Rafael
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Developmental Neurobiology, IIBCE, Montevideo, Uruguay.
    Barrio, Rosa
    Do the Genes of the Innate Immune Response Contribute to Neuroprotection in Drosophila?2015In: Journal of Innate Immunity, ISSN 1662-811X, E-ISSN 1662-8128, Vol. 7, no 1, p. 3-10Article, review/survey (Refereed)
    Abstract [en]

    A profound debate exists on the relationship between neurodegeneration and the innate immune response in humans. Although it is clear that such a relation exists, the causes and consequences of this complex association remain to be determined in detail. Drosophila is being used to investigate the mechanisms involved in neurodegeneration, and all genomic studies on this issue have generated gene catalogues enriched in genes of the innate immune response. We review the data reported in these publications and propose that the abundance of immune genes in studies of neurodegeneration reflects at least two phenomena: (i) some proteins have functions in both immune and nervous systems, and (ii) immune genes might also be of neuroprotective value in Drosophila. This review opens this debate in Drosophila, which could thus be used as an instrumental model to elucidate this question.

  • 76.
    Cantera, Rafael
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Jose Ferreiro, Maria
    Maria Aransay, Ana
    Barrio, Rosa
    Global Gene Expression Shift during the Transition from Early Neural Development to Late Neuronal Differentiation in Drosophila melanogaster2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 5, article id e97703.Article in journal (Refereed)
    Abstract [en]

    Regulation of transcription is one of the mechanisms involved in animal development, directing changes in patterning and cell fate specification. Large temporal data series, based on microarrays across the life cycle of the fly Drosophila melanogaster, revealed the existence of groups of genes which expression increases or decreases temporally correlated during the life cycle. These groups of genes are enriched in different biological functions. Here, instead of searching for temporal coincidence in gene expression using the entire genome expression data, we searched for temporal coincidence in gene expression only within predefined catalogues of functionally related genes and investigated whether a catalogue's expression profile can be used to generate larger catalogues, enriched in genes necessary for the same function. We analyzed the expression profiles from genes already associated with early neurodevelopment and late neurodifferentiation, at embryonic stages 16 and 17 of Drosophila life cycle. We hypothesized that during this interval we would find global downregulation of genes important for early neuronal development together with global upregulation of genes necessary for the final differentiation of neurons. Our results were consistent with this hypothesis. We then investigated if the expression profile of gene catalogues representing particular processes of neural development matched the temporal sequence along which these processes occur. The profiles of genes involved in patterning, neurogenesis, axogenesis or synaptic transmission matched the prediction, with largest transcript values at the time when the corresponding biological process takes place in the embryo. Furthermore, we obtained catalogues enriched in genes involved in temporally matching functions by performing a genome-wide systematic search for genes with their highest expression levels at the corresponding embryonic intervals. These findings imply the use of gene expression data in combination with known biological information to predict the involvement of functionally uncharacterized genes in particular biological events.

  • 77.
    Carlberg, Ulf
    Stockholm University, Faculty of Science.
    The importance of being phosphorylated: regulation of eukaryotic protein synthesis by phosphorylation of elongation factor 21992Doctoral thesis, comprehensive summary (Other academic)
  • 78.
    Carlsson, Mikael A.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Enell, Lina E.
    Stockholm University, Faculty of Science, Department of Zoology.
    Nässel, Dick R.
    Stockholm University, Faculty of Science, Department of Zoology.
    Distribution of short neuropeptide F and its receptor in neuronal circuits related to feeding in larval Drosophila2013In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 353, no 3, p. 511-523Article in journal (Refereed)
    Abstract [en]

    Four forms of short neuropeptide F (sNPF1-4), derived from the gene snpf, have been identified in Drosophila and are known to act on a single G-protein-coupled receptor (sNPFR). Several functions have been suggested for sNPFs in Drosophila, including the regulation of feeding and growth in larvae, the control of insulin signalling and the modulation of neuronal circuits in adult flies. Furthermore, sNPF has been shown to act as a nutritional state-dependent neuromodulator in the olfactory system. The role of sNPF in the larval nervous system is less well known. To analyse sites of action of sNPF in the larva, we mapped the distribution of sNPF- and sNPFR-expressing neurons. In particular, we studied circuits associated with chemosensory inputs and systems involved in the regulation of feeding, including neurosecretory cell systems and the hypocerebral ganglion. We employed a combination of immunocytochemistry and enhancer trap and promoter Gal4 lines to drive green fluorescent protein. We found a good match between the distribution of the receptor and its ligand. However, several differences between the larval and adult systems were observed. Thus, neither sNPF nor its receptor was found in the olfactory (or other sensory) systems in the larva and cells producing insulin-like peptides did not co-express sNPFR, as opposed to results from adults. Moreover, sNPF was expressed in a subpopulation of Hugin cells (second-order gustatory neurons) only in adult flies. We propose that the differences in sNPF signalling between the developmental stages is explained by differences in their feeding behaviour.

  • 79.
    Carlsson, Mikael A.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Schäpers, Alexander
    Stockholm University, Faculty of Science, Department of Zoology.
    Nässel, Dick R.
    Stockholm University, Faculty of Science, Department of Zoology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology.
    Organization of the olfactory system of Nymphalidae butterflies2013In: Chemical Senses, ISSN 0379-864X, E-ISSN 1464-3553, Vol. 38, no 4, p. 355-367Article in journal (Refereed)
    Abstract [en]

    Olfaction is in many species the most important sense, essential for food search, mate finding, and predator avoidance. Butterflies have been considered a microsmatic group of insects that mainly rely on vision due to their diurnal lifestyle. However, an emerging number of studies indicate that butterflies indeed use the sense of smell for locating food and oviposition sites. To unravel the neural substrates for olfaction, we performed an anatomical study of 2 related butterfly species that differ in food and host plant preference. We found many of the anatomical structures and pathways, as well as distribution of neuroactive substances, to resemble that of their nocturnal relatives among the Lepidoptera. The 2 species differed in the number of one type of olfactory sensilla, thus indicating a difference in sensitivity to certain compounds. Otherwise no differences could be observed. Our findings suggest that the olfactory system in Lepidoptera is well conserved despite the long evolutionary time since butterflies and moths diverged from a common ancestor.

  • 80. Carlström, Julia
    Bycatch, conservation and echolocation of harbour porpoises2003Doctoral thesis, comprehensive summary (Other academic)
  • 81. Carlström, Julia
    et al.
    Berggren, Per
    Stockholm University, Faculty of Science, Department of Zoology.
    Tregenza, Nick
    Spatial and temporal impact of pingers on porpoises2009In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 66, no 1, p. 72-82Article in journal (Refereed)
    Abstract [en]

     

    Bycatches are considered the most serious threat to harbour porpoises (Phocoena phocoena) and other small cetaceans worldwide. Pingers are used to reduce bycatch levels, but may also deter porpoises from critical habitats. We investigated the spatial and temporal responses of porpoises to simulated bottom-set nets equipped with periodically operating Dukane NetMark 1000 pingers. Echolocation rates were monitored by porpoise click train detectors (PODs) placed at and around the nets, and a shore-based observation team recorded surfacing positions and movements. Pinger sound significantly reduced the median echolocation encounter rate by 50%–100% at PODs placed up to 500 m and reduced the sighting rate up to 375 m from the simulated net. The average distance of approach increased by 300 m. When pingers were silent after being active for 24 h 50 min, the return time of porpoises was 6 h, in comparison with 2.5 h after pingers had been silent. During the study period of approximately 50 days, habituation was detectable at two of nine PODs. The results indicate that pingers affect porpoises at greater distances than previously observed. This confirms that pingers are an effective bycatch mitigation measure, but alternative solutions should be applied in ecologically important habitats and migration routes. An example is given from the Baltic region.

     

     

    Bycatches are considered the most serious threat to harbour porpoises and other small cetaceans worldwide.  Pingers are used to reduce bycatch levels, but may also deter porpoises from critical habitats.  We investigated the spatial and temporal responses of porpoises to simulated bottom set nets equipped with periodically operating Dukane NetMark 1000 pingers.  Echolocation rates were monitored by porpoise click train detectors (PODs) placed at and around the nets, and a shore-based observation team recorded surfacing positions and movements.  Pinger sound significantly reduced the median echolocation encounter rate by 50-100% at PODs placed up to 500m, and the sighting rate up to 375m from the simulated net.  The average distance of approach increased by 300m.  When pingers were silent after being active for 24h 50min, the return time of porpoises was 6h, in comparison to 2.5h after pingers had been silent.  During the study period of approximately 50 days, habituation was detectable at two of nine PODs.  The results indicate that pingers affect porpoises at greater distances than previously observed.  This confirms that pingers are an effective bycatch mitigation measure, but alternative solutions should be applied in ecologically important habitats and migration routes. An example is given from the Baltic region.

     

  • 82.
    Celorio-Mancera, Maria de la Paz
    et al.
    Max Planck Society.
    Heckel, David G.
    Vogel, Heiko
    Transcriptional analysis of physiological pathways in a generalist herbivore: responses to different host plants and plant structures by the cotton bollworm, Helicoverpa armigera2012In: Entomologia Experimentalis et Applicata, ISSN 0013-8703, E-ISSN 1570-7458, Vol. 144, no 1, p. 123-133Article in journal (Refereed)
    Abstract [en]

    The generalist cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), can consume host plants in more than 40 families, and often utilizes several tissues of a single plant. It is believed that generalists owe their success to the deployment of various members of multigene families of detoxification and digestive enzymes, a strategy that may also be responsible for rapid evolution of insecticide resistance. However, studies of generalist adaptations have been limited to specific genes or gene families, and an overview of how these adaptations are orchestrated at the transcriptional level is lacking. We used Drosophila melanogaster Meigen gene homology to H. armigera-expressed sequence tags to identify key groups of genes and pathways differentially regulated in the gut of fifth instars after 2 days of feeding on a variety of food sources. A series of microarray hybridizations was performed following two alternating loop designs, one comparing the gut gene expression upon feeding on various hosts (cotton, bean, tobacco, and chickpea) and two artificial diets (pinto bean and wheat germ-based), whereas the second design compared the gut expression toward feeding on various plant structures within cotton (leaf, square, and boll). The transcriptional responses toward bean and tobacco feeding treatments were more closely related in comparison with the rest of the diets, whereas the gene expression profiles toward cotton leaf and square-feeding were highly similar. We furthermore found significant changes in several pathways not directly responsible for detoxification mechanisms. Genes involved in primary and secondary metabolism, environmental information processing, and cellular processes were found to be differentially expressed. In addition, regulation of xenobiotic metabolism and the extracellular matrix-receptor pathways appeared differentially regulated across feeding treatments. Three cytochrome P450 genes – CYP6AE17, CYP6B6, and CYP9A17 – grouped as part of a xenobiotic metabolism pathway, were up-regulated in the bean-feeding treatment, and down-regulated in both tobacco and cotton-feeding treatments. CYP4L11, CYP4L5, and CYP4S13 were differentially expressed upon feeding on different cotton plant structures. The present work provides host plant and plant structure-specific transcriptional responses in a lepidopteran herbivore, including pathways and gene candidates for future studies of H. armigera physiology under a more integrative ecologically meaningful framework.

  • 83.
    Celorio-Mancera, Maria de la Paz
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Ytterberg, A. Jimmy
    Rutishauser, Dorothea
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Zubarev, Roman A.
    Effect of host plant and immune challenge on the levels of chemosensory and odorant-binding proteins in caterpillar salivary glands2015In: Insect Biochemistry and Molecular Biology, ISSN 0965-1748, E-ISSN 1879-0240, Vol. 61, p. 34-45Article in journal (Refereed)
    Abstract [en]

    More than half of the proteome from mandibular glands in caterpillars is represented by chemosensory proteins. Based on sequence similarity, these proteins are putative transporters of ligands to gustatory receptors in sensory organs of insects. We sought to determine whether these proteins are inducible by comparing, both qualitatively and quantitatively, the salivary (mandibular and labial) proteomes from caterpillars (Vanessa cardui) reared on different plants and artificial diet containing either bacteria or bacterial cell-walls. We included a treatment where the caterpillars were switched from feeding on artificial diet to plant material at some point in their development. Additionally, we evaluated the degree of overlap between the proteomes in the hemolymph-filled coelom and salivary glands of caterpillars reared on plant material. We found that the quality and quantity of the identified proteins differed clearly between hemolymph-filled coelome, labial and mandibular glands. Our results indicated that even after molting and two-day feeding on a new diet, protein production is affected by the previous food source used by the caterpillar. Candidate proteins involved in chemosensory perception by insects were detected: three chemosensory (CSPs) and two odorant-binding proteins (OBPs). Using the relative amounts of these proteins across tissues and treatments as criteria for their classification, we detected hemolymph- and mandibular gland-specific CSPs and observed that their levels were affected by caterpillar diet. Moreover, we could compare the protein and transcript levels across tissues and treatment for at least one CSP and one OBP. Therefore, we have identified specific isoforms for testing the role of CSPs and OBPs in plant and pathogen recognition. We detected catalase, immune-related protein and serine proteases and their inhibitors in high relative levels in the mandibular glands in comparison to the labial glands. These findings suggest that the mandibular glands of caterpillars may play an important role protecting the caterpillar from oxidative stress, pathogens and aiding in digestion. Contamination with hemolymph proteins during dissection of salivary glands from caterpillars may occur but it is not substantial since the proteomes from hemolymph, mandibular and labial glands were easily discriminated from each other by principal component analysis of proteomic data.

  • 84.
    Celorio-Mancera, Maria P.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Labavitch, John M.
    Salivary Gland Secretions of Phytophagous Arthropods2016In: Extracellular Composite Matrices in Arthropods / [ed] Ephraim Cohen, Bernard Moussian, Springer, 2016, p. 601-623Chapter in book (Refereed)
    Abstract [en]

    Thousands of arthropod species use plants as their main food source. Plants in turn are not completely passive towards arthropod herbivory. Arthropod saliva constitutes an important point of contact which initiates phytophagy and mediates chemical communication. Here we present a summary of those communications studying the constituents of arthropod saliva and their effect on plants. Particular attention has been dedicated to those reports identifying salivary gland genes and proteins in their entirety (transcriptomes and proteomes). The anatomy of salivary glands is highly variable and much of its complexity remains unstudied in various groups of phytophagous arthropods. Some important factors dictating the function of saliva in herbivory are the feeding strategy used by the arthropod, the developmental stage of the animal and the ecological niche in question. The function of many salivary components, such as the chemosensory proteins identified in arthropods, is still largely unknown. We consider the use of heterologous expression of these genes, chemoinformatic, molecular modeling and immunohistochemical studies to be of substantial importance for the elucidation of the functions of these genes as well as the functions of many other unknown proteins in arthropod systems. Additionally, the role of hemolymph proteins such as apolipophorins and storage proteins in saliva is unclear and therefore attention must be devoted to the understanding of protein movement in the arthropod body.

  • 85.
    Charlier, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Monitoring gene level biodiversity - aspects and considerations in the context of conservation2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objectives of this thesis relate to questions needed to be addressed in the context of genetic monitoring for implementing the Convention on Biological Diversity for the gene level. Genetic monitoring is quantifying temporal changes in population genetic metrics. Specific goals of this thesis include i) synthesizing existing information relevant to genetic monitoring of Swedish species, ii) providing a genetic baseline for the Swedish moose, iii) evaluating the relative performance of nuclear versus organelle genetic markers for detecting population divergence, iv) actually monitoring the genetic composition, structure, level of variation, and effective population size (Ne) and assessing the relation between Ne and the actual number of individuals for an unexploited brown trout population.

    The concept of conservation genetic monitoring is defined and Swedish priority species for such monitoring are identified; they include highly exploited organisms such as moose, salmonid fishes, Norway spruce, Atlantic cod, and Atlantic herring. Results indicate that the Swedish moose might be more genetically divergent than previously anticipated and appears to be divided into at least three different subpopulations, representing a southern, a central, and a northern population.

    The relative efficiency of nuclear and organelle markers depends on the relationship between the degree of genetic differentiation at the two types of markers. In turn, this relates to how far the divergence process has progressed.

    For the monitored brown trout population no indication of systematic change of population structure or allele frequencies was observed over 30 years. Significant genetic drift was found, though, translating into an overall Ne-estimate of ~75. The actual number of adult fish (NC) was assessed as ~600, corresponding to an Ne/NC ratio of 0.13. In spite of the relatively small effective population size monitoring did not reveal loss of genetic variation.

  • 86.
    Charlier, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Laikre, Linda
    Stockholm University, Faculty of Science, Department of Zoology.
    Ryman, Nils
    Stockholm University, Faculty of Science, Department of Zoology.
    Genetic monitoring reveals temporal stability over 30 years in a small, lake-resident brown trout population2012In: Heredity, ISSN 0018-067X, E-ISSN 1365-2540, Vol. 109, no 4, p. 246-253Article in journal (Refereed)
    Abstract [en]

    Knowledge of the degree of temporal stability of population genetic structure and composition is important for understanding microevolutionary processes and addressing issues of human impact of natural populations. We know little about how representative single samples in time are to reflect population genetic constitution, and we explore the temporal genetic variability patterns over a 30-year period of annual sampling of a lake-resident brown trout (Salmo trutta) population, covering 37 consecutive cohorts and five generations. Levels of variation remain largely stable over this period, with no indication of substructuring within the lake. We detect genetic drift, however, and the genetically effective population size (Ne) was assessed from allele-frequency shifts between consecutive cohorts using an unbiased estimator that accounts for the effect of overlapping generation. The overall mean Ne is estimated as 74. We find indications that Ne varies over time, but there is no obvious temporal trend. We also estimated Ne using a one-sample approach based on linkage disequilibrium (LD) that does not account for the effect of overlapping generations. Combining one-sample estimates for all years gives an Ne estimate of 76. This similarity between estimates may be coincidental or reflecting a general robustness of the LD approach to violations of the discrete generations assumption. In contrast to the observed genetic stability, body size and catch per effort have increased over the study period. Estimates of annual effective number of breeders (Nb) correlated with catch per effort, suggesting that genetic monitoring can be used for detecting fluctuations in abundance.

  • 87.
    Charlier, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Laikre, Linda
    Stockholm University, Faculty of Science, Department of Zoology.
    Ryman, Nils
    Stockholm University, Faculty of Science, Department of Zoology.
    Genetic structure and evidence of a local bottleneck in moose in Sweden2008In: Journal of Wildlife Management, ISSN 0022-541X, E-ISSN 1937-2817, Vol. 72, no 2, p. 411-415Article in journal (Refereed)
    Abstract [en]

    The moose (Alces alces) is the most intensely managed game species in Sweden. Despite the biological and socioeconomical importance of moose, little is known of its population genetic structure. We analyzed 132 individuals from 4 geographically separate regions in Sweden for genetic variability at 6 microsatellite loci. We found evidence of strong substructuring and restricted levels of gene flow in this potentially mobile mammal. FST values were around 10%, and assignment tests indicated 3 genetically distinct populations over the study area. Spatial autocorrelation analysis provided a genetic patch size of approximately 420 km, implying that moose less than this distance apart are genetically more similar than 2 random individuals. Allele and genotype frequency distributions suggested a recent bottleneck in southern Sweden. Results indicate that moose may be more genetically divergent than currently anticipated, and therefore, the strong hunting pressure that is maintained over all of Sweden may have considerable local effects on genetic diversity. Sustainable moose hunting requires identification of spatial genetic structure to ensure that separate, genetically distinct subpopulations are not overharvested.

  • 88.
    Charlier, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Palmé, Anna
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Laikre, Linda
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Andersson, Jens
    Ryman, Nils
    Stockholm University, Faculty of Science, Department of Zoology, Population Genetics.
    Census (NC) and genetically effective (Ne) population size in a lake-resident population of brown trout Salmo trutta2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 79, no 7, p. 2074-2082Article in journal (Refereed)
    Abstract [en]

    Census (NC) and effective population size (Ne) were estimated for a lake-resident population of brown trout Salmo trutta as 576 and 63, respectively. The point estimate of the ratio of effective to census population size (Ne:NC) for this population is 0·11 with a range of 0·06–0·26, suggesting that Ne:NC ratio for lake-resident populations agree more with estimates for fishes with anadromous life histories than the small ratios observed in many marine fishes

  • 89. Chung, J. Sook
    et al.
    Katayama, Hidekazu
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    New Functions of Arthropod Bursicon: Inducing Deposition and Thickening of New Cuticle and Hemocyte Granulation in the Blue Crab, Callinectes sapidus2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 9, p. e46299-Article in journal (Refereed)
    Abstract [en]

    Arthropod growth requires molt-associated changes in softness and stiffness of the cuticle that protects from desiccation, infection and injury. Cuticle hardening in insects depends on the blood-borne hormone, bursicon (Burs), although it has never been determined in hemolymph. Whilst also having Burs, decapod crustaceans reiterate molting many more times during their longer life span and are encased in a calcified exoskeleton, which after molting undergoes similar initial cuticle hardening processes as in insects. We investigated the role of homologous crustacean Burs in cuticular changes and growth in the blue crab, Callinectes sapidus. We found dramatic increases in size and number of Burs cells during development in paired thoracic ganglion complex (TGC) neurons with pericardial organs (POs) as neurohemal release sites. A skewed expression of Burs β/Burs α mRNA in TGC corresponds to protein contents of identified Burs β homodimer and Burs heterodimer in POs. In hemolymph, Burs is consistently present at ~21 pM throughout the molt cycle, showing a peak of ~89 pM at ecdysis. Since initial cuticle hardness determines the degree of molt-associated somatic increment (MSI), we applied recombinant Burs in vitro to cuticle explants of late premolt or early ecdysis. Burs stimulates cuticle thickening and granulation of hemocytes. These findings demonstrate novel cuticle-associated functions of Burs during molting, while the unambiguous and constant presence of Burs in cells and hemolymph throughout the molt cycle and life stages may implicate further functions of its homo- and heterodimer hormone isoforms in immunoprotective defense systems of arthropods.

  • 90.
    Corral-López, Alberto
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Eckerström-Liedholm, Simon
    Stockholm University, Faculty of Science, Department of Zoology.
    Van der Bijl, Wouter
    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.
    No association between brain size and male sexual behavior in the guppy2015In: Current Zoology, ISSN 1674-5507, Vol. 61, no 2, p. 265-273Article in journal (Refereed)
    Abstract [en]

    Animal behavior is remarkably variable at all taxonomic levels. Over the last decades, research on animal behavior has focused on understanding ultimate processes. Yet, it has progressively become more evident that to fully understand behavioral variation, ultimate explanations need to be complemented with proximate ones. In particular, the mechanisms generating variation in sexual behavior remain an open question. Variation in aspects of brain morphology has been suggested as a plausible mechanism underlying this variation. However, our knowledge of this potential association is based almost exclusively on comparative analyses. Experimental studies are needed to establish causality and bridge the gap between micro-and macroevolutionary mechanisms concerning the link between brain and sexual behavior. We used male guppies that had been artificially selected for large or small relative brain size to study this association. We paired males with females and scored the full known set of male and female sexual behaviors described in guppies. We found several previously demonstrated associations between male traits, male behavior and female behavior. Females responded more strongly towards males that courted more and males with more orange coloration. Also, larger males and males with less conspicuous coloration attempted more coerced copulations. However, courting, frequency of coerced copulation attempts, total intensity of sexual behavior, and female response did not differ between large-and small-brained males. Our data suggest that relative brain size is an unlikely mechanism underlying variation in sexual behavior of the male guppy. We discuss these findings in the context of the conditions under which relative brain size might affect male sexual behavior

  • 91. Cresswell, Will
    et al.
    Lind, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Kaby, Ulrika
    Stockholm University, Faculty of Science, Department of Zoology.
    Quinn, John
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology.
    Does an opportunistic predator preferentially attack nonvigilant prey?2003In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 66, no 4, p. 643-648Article in journal (Refereed)
    Abstract [en]

    The dilution effect as an antipredation behaviour is the main theoretical reason for grouping in animals and states that all individuals in a group have an equal risk of being predated if equally spaced from each other and the predator. Stalking predators, however, increase their chance of attack success by preferentially targeting nonvigilant individuals, potentially making relative vigilance rates in a group relatively important in determining predation compared with the dilution effect. Many predators, however, attack opportunistically without stalking, when targeting of nonvigilant individuals may be less likely, so that the dilution effect will then be a relatively more important antipredation reason for grouping. We tested whether an opportunistically hunting predator, the sparrowhawk, Accipiter nisus, preferentially attacked vigilant or feeding prey models presented in pairs. We found that sparrowhawks attacked vigilant and feeding mounts at similar frequencies. Our results suggest that individuals should prioritize maximizing group size or individual vigilance dependent on the type of predator from which they are at risk. When the most likely predator is a stalker, individuals should aim to have the highest vigilance levels in a group, and there may be relatively little selective advantage to being in the largest group. In contrast, if the most likely predator is an opportunist, then individuals should simply aim to be in the largest group and can also spend more time foraging without compromising predation risk. For most natural systems this will mean a trade-off between the two strategies dependent on the frequency of attack of each predator type.

  • 92.
    Curini-Galletti, Marco
    et al.
    Universita` di Sassari, Italy.
    Artois, Tom
    Hasselt University, Belgium.
    Delogu, Valentina
    Universita` di Sassari, Italy.
    De Smet, Willem H.
    University of Antwerp, Belgium.
    Fontaneto, Diego
    Swedish Museum of Natural History, Sweden; Imperial College London, United Kingdom.
    Jondelius, Ulf
    Swedish Museum of Natural History, Sweden.
    Leasi, Francesca
    Imperial College London, United Kingdom; Universtità di Modena e Reggio Emilia, Italy.
    Martínez, Alejandro
    University of Copenhagen, Denmark.
    Meyer-Wachsmuth, Inga
    Swedish Museum of Natural History, Sweden.
    Nilsson, Karin Sara
    Swedish Museum of Natural History, Sweden.
    Tongiorgi, Paolo
    Universtità di Modena e Reggio Emilia, Italy.
    Worsaae, Katrine
    University of Copenhagen, Denmark.
    Todaro, M. Antonio
    Universtità di Modena e Reggio Emilia, Italy.
    Patterns of Diversity in Soft-Bodied Meiofauna: Dispersal Ability and Body Size Matter2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 3, article id e33801Article in journal (Refereed)
    Abstract [en]

    Background: Biogeographical and macroecological principles are derived from patterns of distribution in large organisms, whereas microscopic ones have often been considered uninteresting, because of their supposed wide distribution. Here, after reporting the results of an intensive faunistic survey of marine microscopic animals (meiofauna) in Northern Sardinia, we test for the effect of body size, dispersal ability, and habitat features on the patterns of distribution of several groups.

    Methodology/Principal Findings: As a dataset we use the results of a workshop held at La Maddalena (Sardinia, Italy) in September 2010, aimed at studying selected taxa of soft-bodied meiofauna (Acoela, Annelida, Gastrotricha, Nemertodermatida, Platyhelminthes and Rotifera), in conjunction with data on the same taxa obtained during a previous workshop hosted at Tja ̈rno ̈ (Western Sweden) in September 2007. Using linear mixed effects models and model averaging while accounting for sampling bias and potential pseudoreplication, we found evidence that: (1) meiofaunal groups with more restricted distribution are the ones with low dispersal potential; (2) meiofaunal groups with higher probability of finding new species for science are the ones with low dispersal potential; (3) the proportion of the global species pool of each meiofaunal group present in each area at the regional scale is negatively related to body size, and positively related to their occurrence in the endobenthic habitat.

    Conclusion/Significance: Our macroecological analysis of meiofauna, in the framework of the ubiquity hypothesis for microscopic organisms, indicates that not only body size but mostly dispersal ability and also occurrence in the endobenthic habitat are important correlates of diversity for these understudied animals, with different importance at different spatial scales. Furthermore, since the Western Mediterranean is one of the best-studied areas in the world, the large number of undescribed species (37%) highlights that the census of marine meiofauna is still very far from being complete. 

  • 93. Dacke, Marie
    et al.
    Bell, Adrian T. A.
    Foster, James J.
    Baird, Emily J.
    Stockholm University, Faculty of Science, Department of Zoology.
    Strube-Bloss, Martin F.
    Byrne, Marcus J.
    el Jundi, Basil
    Multimodal cue integration in the dung beetle compass2019In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 116, no 28, p. 14248-14253Article in journal (Refereed)
    Abstract [en]

    South African ball-rolling dung beetles exhibit a unique orientation behavior to avoid competition for food: after forming a piece of dung into a ball, they efficiently escape with it from the dung pile along a straight-line path. To keep track of their heading, these animals use celestial cues, such as the sun, as an orientation reference. Here we show that wind can also be used as a guiding cue for the ball-rolling beetles. We demonstrate that this mechanosensory compass cue is only used when skylight cues are difficult to read, i.e., when the sun is close to the zenith. This raises the question of how the beetles combine multimodal orientation input to obtain a robust heading estimate. To study this, we performed behavioral experiments in a tightly controlled indoor arena. This revealed that the beetles register directional information provided by the sun and the wind and can use them in a weighted manner. Moreover, the directional information can be transferred between these 2 sensory modalities, suggesting that they are combined in the spatial memory network in the beetle's brain. This flexible use of compass cue preferences relative to the prevailing visual and mechanosensory scenery provides a simple, yet effective, mechanism for enabling precise compass orientation at any time of the day.

  • 94.
    Dalerum, F.
    Stockholm University, Faculty of Science, Department of Zoology.
    Phylogenetic reconstruction of carnivore social organizations2007In: Journal of Zoology, ISSN 0952-8369, E-ISSN 1469-7998, Vol. 273, no 1, p. 90-97Article in journal (Refereed)
    Abstract [en]

    It is generally assumed that carnivore social organizations evolved directionally from a solitary ancestor into progressively more advanced forms of group living. Although alternative explanations exist, this evolutionary hypothesis has never been tested. Here, I used literature data and maximum likelihood reconstruction on a complete carnivore phylogeny to test this hypothesis against two others: one assuming directional evolution from a non-solitary ancestor, and one assuming parallel evolutions from a socially flexible ancestor, that is, an ancestor with abilities to live in a variety of social organizations. The phylogenetic reconstructions did not support any of the three hypotheses of social evolution at the root of Carnivora. At the family level, however, there was support for a non-solitary and socially flexible ancestor to Canidae, a socially flexible or solitary ancestor to Mustelidae, a solitary or socially flexible ancestor to Mephitidae, a solitary or group living ancestor to Phocidae, a group living ancestor to Otariidae and a solitary ancestor to Ursidae, Felidae, Herpestidae and Viverridae. There was equivocal support for the ancestral state of Procyonidae and Hyaenidae. It is unclear whether the common occurrence of a solitary ancestry at the family level was caused by a solitary ancestor at the root of Carnivora or by multiple transitions into a solitary state. The failure to support a solitary ancestor to Carnivora calls for caution when using this hypothesis in an evolutionary framework, and I suggest continued investigations of the pathways of the evolution of carnivore social organizations.

  • 95.
    Dalerum, Fredrik
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Kunkel, K.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Shults, B. S.
    Diet of wolverines (Gulo gulo) in the western Brooks Range, Alaska2009In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 28, no 2, p. 246-253Article in journal (Refereed)
    Abstract [en]

    Migratory caribou herds are an important component of the North American tundra. We investigated the wolverine (Gulo gulo) diet in the migratory range of the Western Arctic Caribou Herd in north-western Alaska. Within this area, caribou are absent or occur at low densities for large parts of the year, and thus show a strong seasonality in abundance. Analyses of stomach and colon contents suggested that wolverines primarily consumed caribou during the winter, and that the dietary dependence was related more to caribou mortality than to caribou abundance in the area. We also found indications that wolverines may switch between moose and caribou during periods of low caribou abundance, but that such a switch did not affect wolverine body condition. Our results thus support previous observations that wolverines primarily consume ungulates. However, a better knowledge of how alternative food sources are utilized will be necessary to predict the dietary and demographic responses of wolverines to variations in caribou abundance. We also suggest that further efforts should be made to investigate the effects of other ungulate-dependent predators on wolverine feeding ecology, because such predators may function both as competitors and as suppliers of carrion for scavenging.

  • 96.
    Dalerum, Fredrik
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Loxterman, Janet
    Shults, Brad
    Kunkel, Kyran
    Cook, Joseph A.
    Sex-specific dispersal patterns of wolverines: Insights from microsatellite markers2007In: Journal of Mammalogy, ISSN 0022-2372, E-ISSN 1545-1542, Vol. 88, no 3, p. 793-800Article in journal (Refereed)
    Abstract [en]

    Dispersal of individuals can be defined as movement and settling outside the natal home range. Such dispersal is often sex-biased among vertebrates, and is generally expected to be male-biased in polygynous mammals. We used microsatellite markers scored on harvested wolverines (Gulo gulo) to test the prediction of male-biased dispersal in a population in the western Brooks Range, Alaska. Our analyses suggested a high rate of dispersal within the population, but provided no support for sex differences in dispersal tendencies across the sampled spatial scale. Previous studies have implied male-biased dispersal among wolverine populations on an interpopulation scale. We suggest 3, not exclusive, explanations to reconcile these differences: low power to detect sex biases in dispersal tendencies in this panmictic population; a scale-dependent component in dispersal tendencies, where males are overrepresented among interpopulation migrants; and lower reproductive success for dispersing females compared to more philopatric ones.

  • 97. Dalerum, Fredrik
    et al.
    Perbro, Anna
    Stockholm University, Faculty of Science, Department of Zoology.
    Magnusdottir, Rannveig
    Hersteinsson, Pall
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    The influence of coastal access on isotope variation in Icelandic arctic foxes2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 3, p. e32071-Article in journal (Refereed)
    Abstract [en]

    To quantify the ecological effects of predator populations, it is important to evaluate how population-level specializations are dictated by intra-versus inter-individual dietary variation. Coastal habitats contain prey from the terrestrial biome, the marine biome and prey confined to the coastal region. Such habitats have therefore been suggested to better support predator populations compared to habitats without coastal access. We used stable isotope data on a small generalist predator, the arctic fox, to infer dietary strategies between adult and juvenile individuals with and without coastal access on Iceland. Our results suggest that foxes in coastal habitats exhibited a broader isotope niche breadth compared to foxes in inland habitats. This broader niche was related to a greater diversity of individual strategies rather than to a uniform increase in individual niche breadth or by individuals retaining their specialization but increasing their niche differentiation. Juveniles in coastal habitats exhibited a narrower isotope niche breadth compared to both adults and juveniles in inland habitats, and juveniles in inland habitats inhabited a lower proportion of their total isotope niche compared to adults and juveniles from coastal habitats. Juveniles in both habitats exhibited lower intra-individual variation compared to adults. Based on these results, we suggest that foxes in both habitats were highly selective with respect to the resources they used to feed offspring, but that foxes in coastal habitats preferentially utilized marine resources for this purpose. We stress that coastal habitats should be regarded as high priority areas for conservation of generalist predators as they appear to offer a wide variety of dietary options that allow for greater flexibility in dietary strategies.

  • 98. Dalin, Peter
    et al.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Host-plant quality adaptively affects the diapause threshold: evidence from leaf beetles in willow plantations2012In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 37, no 6, p. 490-499Article in journal (Refereed)
    Abstract [en]

    1. Voltinism of herbivorous insects can vary depending on environmental conditions. The leaf beetle Phratora vulgatissima L. is univoltine in Sweden but will sometimes initiate a second generation in short-rotation coppice (SRC) willow plantations. 2. The study investigated whether increased voltinism by P. vulgatissima in plantations can be explained by (i) rapid life-cycle development allowing two generations, or (ii) postponed diapause induction on coppiced willows. 3. In the field, no difference was found in the phenology or development of first-generation broods between plantations (S. viminalis) and natural willow habitats (S. cinerea). However, the induction of diapause occurred 12 weeks later in SRC willow plantations. 4. Laboratory experiments indicated no genetic difference in the critical day-length for diapause induction between beetles originating from plantations and natural habitats. Development time was unaffected by host-plant quality but critical day-length was prolonged by almost an hour when the beetles were reared on a non-preferred willow species (S. phylicifolia). When reared on new leaves from re-sprouting shoots of recently coppiced willow plants, diapause incidence was significantly less than when the beetles were reared on mature leaves from uncoppiced plants. 5. The study suggests that P. vulgatissima has a plastic diapause threshold influenced by host-plant quality. The use of host-plant quality as a diapause-inducing stimulus is likely to be adaptive in cases where food resources are unpredictable, such as when new host-plant tissue is produced after a disturbance. SRC willows may allow two beetle generations due to longer growing seasons of coppiced plants that grow vigorously.

  • 99.
    Dalén, Love
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Fuglei, Eva
    Hersteinsson, Pall
    Kapel, Christion M.O.
    Roth, James D.
    Samelius, Gustaf
    Tannerfeldt, Magnus
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Population history and genetic structure of a circumpolar species: the arctic fox2005In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 84, no 1, p. 79-89Article in journal (Refereed)
    Abstract [en]

    The circumpolar arctic fox Alopex lagopus thrives in cold climates and has a high migration rate involving long-distance movements. Thus, it differs from many temperate taxa that were subjected to cyclical restriction in glacial refugia during the Ice Ages. We investigated population history and genetic structure through mitochondrial control region variation in 191 arctic foxes from throughout the arctic. Several haplotypes had a Holarctic distribution and no phylogeographical structure was found. Furthermore, there was no difference in haplotype diversity between populations inhabiting previously glaciated and unglaciated regions. This suggests current gene flow among the studied populations, with the exception of those in Iceland, which is surrounded by year-round open water. Arctic foxes have often been separated into two ecotypes: ‘lemming’ and ‘coastal’. An analysis of molecular variance suggested particularly high gene flow among populations of the ‘lemming’ ecotype. This could be explained by their higher migration rate and reduced fitness in migrants between ecotypes. A mismatch analysis indicated a sudden expansion in population size around 118 000 BP, which coincides with the last interglacial. We propose that glacial cycles affected the arctic fox in a way opposite to their effect on temperate species, with interglacials leading to short-term isolation in northern refugia.

  • 100.
    Dalén, Love
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Götherström, Anders
    Stockholm University, Faculty of Humanities, Department of Archaeology and Classical Studies, Archaeological Research Laboratory.
    Tannerfeldt, Magnus
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Is the endangered Fennoscandian arctic fox (Alopex lagopus) population genetically isolated?2002In: Biological Conservation, Vol. 105, no 2, p. 171-178Article in journal (Refereed)
    Abstract [en]

    The arctic fox population in Fennoscandia is on the verge of going extinct after not being able to recover from a severe bottleneck at the end of the 19th century. The Siberian arctic fox population, on the other hand, is large and unthreatened. In order to resolve questions regarding gene flow between, and genetic variation within the populations, a 294 bp long part of the mitochondrial hypervariable region 1 was sequenced. This was done for 17 Swedish, 15 Siberian and two farmed foxes. Twelve variable nucleotide sites were observed, which resulted in 10 different haplotypes. Three haplotypes were found in Sweden and seven haplotypes were found in Siberia. An analysis of molecular variance showed a weak, but significant, differentiation between the populations. No difference in haplotype diversity was found between the populations. A phylogenetic analysis revealed that the three Swedish haplotypes were not monophyletic compared to the Siberian haplotypes. These results indicate a certain amount of gene flow between the two populations. both before and after the bottleneck. Restocking the Fennoscandian population with arctic foxes from Siberia might therefore be a viable option.

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