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  • 501.
    Shao, Yi Ta
    Stockholm University, Faculty of Science, Department of Zoology.
    The brain-pituitary-gonadal axis of the three-spined stickleback, Gasterosteus aculeatus2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The seasonal reproduction of the three-spined stickleback is stimulated by long day photoperiod. As in other vertebrates, the reproductive system of stickleback is regulated by the brain-pituitary-gonadal (BPG) axis which is largely controlled by feedback effects. Both negative and positive feedback effects on the BPG axis have been found in fish. So far, the roles feedback effects on the BPG axis play in the photoperiodic regulation of seasonal reproduction are still unclear. This thesis focused on the photoperiodic regulation and gonadal feedback effects on the gene expressions of gonadotropin (GtH) and gonadotropin-releasing hormones (GnRH) in the brain and pituitary, and how gonadal feedback regulated the steroid homeostasis in stickleback.Both GnRH2 and GnRH3 mRNA was found in the hypothalamus. Higher expression levels of both GnRH2 and 3 in breeding than in post-breeding males suggested that they are both involved in seasonal reproduction. There was no evidence for a role of GnRH3, which may be the dominating form, in the photoperiodic control of reproduction. However, the polarity of the feedback effect on gnrh3 gene expression may turn from positive to be negative when the males went into post-breeding state. Tapeworm, Schistocephalus solidus, infection inhibited the reproduction of sticklebacks. However, the infection caused higher expression levels of both GnRHs and GtHs genes, which may be due to feedback effect on the BPG axis.Under short day, both lh-β and fsh-β were suppressed by low androgen levels. This negative feedback may inhibit maturation completely, unless a rise of androgens triggers positive feedback under long day. The change in feedback polarity may result in all or nothing maturation. Furthermore, the androgen inhibitory effect on lh-β and fsh-β under short day could be abolished by aromatase inhibitor, which means the estrogen may cause negative feedback in males under short day.There was no compensation effect on plasma androgen level in fully mature hemi-castrated fish. However, both testosterone and 11-ketoandrostenedione treatments increased plasma levels much less in sham-operated fish than in castrated ones, indicating that homeostatic mechanisms are nevertheless present.

  • 502.
    Shao, Yi Ta
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Arvidsson, Mia
    Stockholm University, Faculty of Science, Department of Zoology.
    Trombley, Susanne
    Schulz, Rudiger W.
    Schmitz, Monika
    Borg, Bertil
    Stockholm University, Faculty of Science, Department of Zoology.
    Androgen feedback effects on LH and FSH, and photoperiodic control of reproduction in male three-spined sticklebacks, Gasterosteus aculeatus2013In: General and Comparative Endocrinology, ISSN 0016-6480, E-ISSN 1095-6840, Vol. 182, p. 16-23Article in journal (Refereed)
    Abstract [en]

    Sexual maturation in the stickleback is controlled by photoperiod. The aim of this study was to find out whether changes in feedback effects exerted by sex steroids could mediate the photoperiodic effect, which is regarded to be of an all-or-nothing character. To that end, males were castrated and treated with different doses of testosterone (T) and in one experiment also with the aromatase inhibitor fadrozole (AI) and kept under different photoperiods. In control fish, long day (LD 16:8) stimulated maturation, associated with more hypertrophied kidneys (a secondary sexual character) and higher levels of pituitary lhb and fshb mRNA than under short day conditions (LD 8:16). Under LD 8:16, low doses of T suppressed both lhb and fshb mRNA levels. However, with the use of high doses of T and/or longer photoperiods the inhibitory effects on lhb and fshb mRNA levels became less clear or instead positive effects were observed. Under intermediate photoperiod conditions, the negative feedback effect of a low dose of T on fshb was more prominent with shorter photoperiods, whereas no such shift was observed for lhb mRNA. The inhibitory effect of the low dose of T on lhb mRNA levels under LD 8:16 was abolished by AI, whereas the stimulatory effect of the high dose of T was not. The negative feedback effects were more marked under short days than under long days, whereas positive feedback effects were more marked under long days. The suppression of both fshb and lhb mRNA levels by low androgen levels, especially under short days, may inhibit maturation completely unless a rise of androgens above threshold levels would allow complete maturation.

  • 503. Shao, Yi Ta
    et al.
    Roufidou, Chrysoula
    Stockholm University, Faculty of Science, Department of Zoology.
    Chung, Pei Chi
    Borg, Bertil
    Stockholm University, Faculty of Science, Department of Zoology.
    Changes in kisspeptin, GnRH, and gonadotropin mRNA levels in male threespine stickleback (Gasterosteus aculeatus) during photoperiod-induced sexual maturation2019In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 20, no 3, p. 317-329Article in journal (Refereed)
    Abstract [en]

    Background: Both gonadotropin-releasing hormone (GnRH) and kisspeptin have a critical role in the photoperiodic control of sexual maturation in mammals. Question: What are the roles of GnRH and kisspeptin in the photoperiodic control of sexual maturation in the threespine stickleback, Gasterosteus aculeatus? Method: If kisspeptin and GnRH trigger the photoperiodic induction of maturation in fishes, they would be expected to be activated prior to, or at least no later than, the gonadotropins. The mRNA levels of brain gnrh2, gnrh3, kiss2 and its receptor, gpr54, as well as of pituitary lh-beta and fsh-beta, were measured in males under standard laboratory conditions [16 hours light/8 hours dark (L16/D8) or 8 hours light/16 hours dark (L8/D16)] after 3, 10, 19, and 29 days at 20 degrees C. Results: From day 19, males in the long-day photoperiod (L16/D8) condition were visibly mature with bright breeding coloration. Compared with short-day photoperiod (L8/D16) fish, L16/D8 fish had higher lh-beta mRNA levels at days 10, 19, and 29, and higher fsh-beta mRNA levels at day 10 only. Furthermore, L16/D8 fish had higher gnrh3 mRNA levels at days 10 and 29, and higher gnrh2 mRNA levels at day 29, than L8/D16 fish. Finally, kiss2 and gpr54 mRNA levels of L16/D8 fish were significantly higher than those of L8/D16 fish at days 19 and 29, respectively. Conclusions: At the onset of sexual maturation, the levels of lh-beta, fsh-beta, and gnrh3 rose earlier than those of kiss2 and gpr54. These results are consistent with GnRH3 having a role in the early phases of maturation, but do not support a role for kisspeptin in photoperiodic initiation of maturation in male stickleback.

  • 504.
    Shao, Yi Ta
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Schulz, Rüdiger
    Borg, Bertil
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Homeostasis of circulating androgens levels in the male three-spined stickleback (Gasterosteus aculeatus)2012In: Zoological Studies, ISSN 1021-5506, E-ISSN 1810-522X, Vol. 51, no 8, p. 1282-1289Article in journal (Refereed)
    Abstract [en]

    In mammals, plasma androgen levels are regulated by homeostatic feedbackmechanisms operating in the brain-pituitary-gonadal axis. However, some earlierstudies suggest that this may not be the case in all teleosts. This study aims atinvestigating to what extent androgens levels are homeostatically regulated in malethree-spined stickleback (Gasterosteus aculeatus), and whether aromatisation ofandrogens plays a role in this. To that end, breeding male sticklebacks were eithercompletely castrated or hemi-castrated or sham-operated, and implanted with differentdoses of 11- ketoandrostenedione (11KA) and testosterone (T) or with the aromataseinhibitor (AI) fadrozole. Hemi-castration alone diminished androgen levels andcomplete castration almost removed them. Low doses of 11KA and T increasedplasma androgen levels in castrated but not in sham-operated fish. Both low and highdoses of 11KA increased plasma 11-ketotestosterone (11KT) in hemi-castrated fish,whereas only the high dose of 11KA did so in sham-operated fish. If aromatizationplays a role in homeostatic mechanisms, androgen levels would be expected to rise insham-operated fish treated with AI. However, this was not the case. The reduction ofplasma androgen levels in fully mature hemi-castrated fish may suggest that theremaining testis is not able to increase its steroidogenesis further. However, both311KA and T treatments increased plasma levels much less in sham-operated fish thanin castrated ones, indicating that homeostatic mechanisms are nevertheless present.

  • 505.
    Shao, Yi Ta
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Acad Sinica, Marine Research Station, Taiwan.
    Wang, Feng-Yu
    Fu, Wen-Chun
    Yan, Hong Young
    Anraku, Kazuhiko
    Chen, I-Shiung
    Borg, Bertil
    Stockholm University, Faculty of Science, Department of Zoology.
    Androgens Increase Iws Opsin Expression and Red Sensitivity in Male Three-Spined Sticklebacks2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6, p. e100330-Article in journal (Refereed)
    Abstract [en]

    Optomotor studies have shown that three-spined sticklebacks (Gasterosteus aculeatus) are more sensitive to red during summer than winter, which may be related to the need to detect the red breeding colour of males. This study aimed to determine whether this change of red light sensitivity is specifically related to reproductive physiology. The mRNA levels of opsin genes were examined in the retinae of sexually mature and immature fish, as well as in sham-operated males, castrated control males, or castrated males implanted with androgen 11-ketoandrostenedione (11 KA), maintained under stimulatory (L16:D8) or inhibitory (L8:D16) photoperiods. In both sexes, red-sensitive opsin gene (Iws) mRNA levels were higher in sexually mature than in immature fish. Under L16:D8, lws mRNA levels were higher in intact than in castrated males, and were up-regulated by 11 KA treatment in castrated males. Moreover, electroretinogram data confirmed that sexual maturation resulted in higher relative red spectral sensitivity. Mature males under L16:D8 were more sensitive to red light than males under L8:D16. Red light sensitivity under L16:D8 was diminished by castration, but increased by 11 KA treatment. Thus, in sexually mature male sticklebacks, androgen is a key factor in enhancing sensitivity to red light via regulation of opsin gene expression. This is the first study to demonstrate that sex hormones can regulate spectral vision sensitivity.

  • 506.
    Sigray, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Andersson, Mathias H.
    Stockholm University, Faculty of Science, Department of Zoology.
    Particle motion measured at an operational wind turbine in relation to hearing sensitivity in fish2011In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 130, no 1, p. 200-207Article in journal (Refereed)
    Abstract [en]

    The effect of sound pressure on the hearing of fish has been extensively investigated in laboratory studies as well as in field trials in contrast to particle motion where few studies have been carried out. To improve this dearth of knowledge, an instrument for measuring particle motion was developed and used in a field trial. The particle motion is measured using a neutrally buoyant sphere, which co-oscillates with the fluid motion. The unit was deployed in close vicinity to a wind turbine foundation at Utgrunden wind farm in the Baltic Sea. Measurements of particle motion were undertaken at different distances from the turbine as well as at varying wind speeds. Levels of particle motion were compared to audiograms for cod (Gadus morhua L.) and plaice (Pleuronectes platessa L.). 

  • 507.
    Sigvaldadóttir, Elín
    Stockholm University, Faculty of Science, Department of Zoology.
    Systematics of Spionidae and Prionospio (Polychaeta)1996Doctoral thesis, comprehensive summary (Other academic)
  • 508.
    Silfvergrip, Anders M. C.
    Stockholm University.
    A systematic revision of the Neotropical catfish genus Rhamdia (Teleostei, Pimelodidae)1996Doctoral thesis, monograph (Other academic)
  • 509.
    Sillén-Tullberg, Birgitta
    Stockholm University.
    Behavioural ecology and population dynamics of an aposematic seed bug, Lygaeus equestris L. (Heteroptera, Lygaeidae)1982Doctoral thesis, comprehensive summary (Other academic)
  • 510.
    Sjöberg Lindfors, Virpi
    Stockholm University, Faculty of Science, Department of Zoology.
    Butterfly life history and mating systems1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The general hypothesis tested in this thesis is whether butterfly mating strategies are affected by their life history. Several components of mating behaviour, morphological and physiological traits were studied and related to various life histories. Male and female interests are often in conflict. Males maximise their reproductive output by mating repeatedly, whereas females maximise their reproductive output by soliciting matings to obtain viable sperm and male donated nutrients, but avoiding harassment by males while searching for host plants.

    Male butterflies increase their reproductive output either by delaying, or preventing, their mates from remating, because in most species the latest male to mate with a female has sperm precedence. One way in which males can delay or prevent female remating is by delivering a large spermatophore at mating. There are two ways in which males can increase ejaculate mass: 1) by growing larger - since large males produce larger ejaculates, or 2) by feeding as adults and mate at an older adult age. These two strategies are in conflict, since a larger size results from growing for a longer time as a larva. We show that large males rather than older males deliver the heaviest ejaculates. Therefore the strategy males should adopt is dependent on the mating system. In monandrous species early male emergence is especially important, since receptive females will be available during a short period. In polyandrous species it may be more beneficial to deliver large ejaculates that delay female remating; hence polyandrous males should grow for a longer time as larvae.

    Males in polyandrous species deliver heavier ejaculates, and polyandrous females incorporate male donated nutrients in their eggs, and increase their reproductive output by remating. However, a comparative study of seven butterfly species failed to provide evidence that polyandrous butterfly females in general are more efficient in sequestering nitrogen from spermatophores than are monandrous females.

  • 511.
    Sjöberg, Stig
    Stockholm University.
    Modelling, simulation, and analysis of pelagic ecosystems: with special reference to the Baltic Sea1980Doctoral thesis, comprehensive summary (Other academic)
  • 512.
    Sjölander, Sverre
    Stockholm University.
    Reproductive behaviour of the divers (Gaviidae): a comparative study1977Doctoral thesis, comprehensive summary (Other academic)
  • 513.
    Skoog, Gunnel
    Stockholm University.
    Aspects on the biology and ecology of Theodoxus fluviatilis (L.) and Lymnea peregra (O.F. Müller) (Gastropoda) in the northern Baltic1978Doctoral thesis, comprehensive summary (Other academic)
  • 514.
    Skoog, Perarvid
    Stockholm University.
    The food of the Swedish badger, Meles meles L.1970Doctoral thesis, monograph (Other academic)
  • 515.
    Slove, Jessica
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Eriksson, Torsten
    Department of Biodiversity informatics, Swedish Museum of Natural History.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology.
    Exploring a complex trait - the effect of larval feeding ability and unequal transition costs on the dynamics ofhost range evolution in two groups of related butterfliesManuscript (preprint) (Other academic)
    Abstract [en]

    Host plant use is a complex trait, better described as the combined outcome of many interrelated traits, such as female preference and larval ability to feed, grow and survive. The necessary co-adaptation of these traits would suggest that the host shifts should be difficult to accomplish. Still, even though a large-scale conservatism can be seen in most groups, frequent changes in host use are not uncommon, suggesting that under some circumstances adding new plants to the range might not be as difficult as one might expect. In a case study on two closelyr elated butterfly genera, we investigate the effect of unequal transition costs and of including available data on larval feeding ability as well as plants used in the field, and describe and compare the dynamics of host range evolution in these groups. We find that apparent independent colonisations are in many cases likely to be the result of non-independent processes such as multiple losses, recolonisation or parallel colonisations following some preadaptation. Host plants shifts and range expansions are likely important drivers of the exceptional diversity of herbivorousinsects. A better understanding of the dynamics of host range evolution will improve our understanding of the source of this diversity.

  • 516.
    Slove, Jessica
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Janz, Niklas
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    The Relationship between Diet Breadth and Geographic  Range Size in the Butterfly Subfamily Nymphalinae: A  Study of Global Scale2011In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, no 1, p. e16057-Article in journal (Refereed)
    Abstract [en]

    The ‘‘oscillation hypothesis’’ has been proposed as a general explanation for the exceptional diversification of herbivorous insect species. The hypothesis states that speciation rates are elevated through repeated correlated changes – oscillations – in degree of host plant specificity and geographic range. The aim of this study is to test one of the predictions from the oscillation hypothesis: a positive correlation between diet breadth (number of host plants used) and geographic range size, using the globally distributed butterfly subfamily Nymphalinae. Data on diet breadth and global geographic range were collected for 182 Nymphalinae butterflies species and the size of the geographic range was measured using a GIS. We tested both diet breadth and geographic range size for phylogenetic signal to see if species are independent of each other with respect to these characters. As this test gave inconclusive results, data was analysed both using cross-species comparisons and taking phylogeny into account using generalised estimating equations as applied in the APE package in R. Irrespective of which method was used, we found a significant positive correlation between diet breadth and geographic range size. These results are consistent for two different measures of diet breadth and removal of outliers. We conclude that the global range sizes of Nymphalinae butterflies are correlated to diet breadth. That is, butterflies that feed on a large number of host plants tend to have larger geographic ranges than do butterflies that feed on fewer plants. These results lend support for an important step in the oscillation hypothesis of plant-driven diversification, in that it can provide the necessary fuel for future population fragmentation and speciation.

  • 517. Smith, Steve
    et al.
    Sandoval-Castellanos, Edson
    Kempe Lagerholm, Vendela
    Stockholm University, Faculty of Science, Department of Zoology.
    Napierala, Hannes
    Sablin, Michael
    Nyström, Johanna
    Fladerer, Florian A.
    Germonpré, Mietje
    Wojtal, Piotr
    Stewart, John R.
    Dalén, Love
    Stockholm University, Faculty of Science, Department of Zoology.
    Non-receding hare lines: genetic continuity since the Late Pleistocene in European mountain hares (Lepus timidus)Manuscript (preprint) (Other academic)
  • 518.
    Sohlenius, Björn
    Stockholm University.
    Growth, reproduction and population dynamics in some bacterial feeding soil nematodes1973Doctoral thesis, comprehensive summary (Other academic)
  • 519.
    Solbreck, Christer
    Stockholm University.
    Flight habits and environment of a seed bug, Lygaeus equestris (L.) (Heteroptera, Lygaeidae)1975Doctoral thesis, comprehensive summary (Other academic)
  • 520.
    Stach, Robert
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Kullberg, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Jakobsson, Sven
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Ström, Kåre
    Fransson, Thord
    Migration routes and timing in a bird wintering in South Asia, the Common Rosefinch Carpodacus erythrinus2016In: Journal of Ornithology, ISSN 2193-7192, E-ISSN 2193-7206, Vol. 157, no 3, p. 671-679Article in journal (Refereed)
    Abstract [en]

    Only few bird species from Western Europe migrate eastward to wintering areas in South Asia, and little is known about this migratory flyway. The Common Rosefinch has in the past century expanded its breeding range westward to include Western Europe and migrate along this flyway to wintering sites in South Asia. This is the first study describing the migration routes of Common Rosefinches between Europe and Asia in detail, revealed by light level geolocators. The rosefinches showed loop-migration with more northerly routes in autumn than in spring, possibly in order to shorten the flight over the Central Asian deserts, which are very inhospitable at this time of the year. In spring the deserts are less dry and richer in vegetation, which may have supported the more southerly routes. During autumn migration the birds used several staging sites in Central Asia for prolonged periods. Although the birds passed over mountain regions at this time, which potentially act as barriers to them, the length of the stops seem unrealistically long for only fuel deposition. Instead, this suggests that the birds temporarily suspended migration to take advantage of abundant and predictable food sources in this region. During spring migration the birds made a few longer stops while still in north India or Central Asia, before migrating at fast speeds towards the breeding grounds. The birds covered 4–5000 km with only very short stopovers and thus most of the fuel used on spring migration must have been accumulated in Asia. Our results thus indicate that Central Asia, and north India, are important staging areas for this species in both autumn and spring. During winter, birds used two sites located several hundred kilometres apart, and relocation was probably a response to local food availability.

  • 521.
    Stark, Tuula
    Stockholm University.
    Hormonal regulation of glutathione transferases in the mammalian liver, adrenal and ovary2002Doctoral thesis, comprehensive summary (Other academic)
  • 522. Steinarsdottir, M. B.
    et al.
    Ingolfsson, A.
    Olafsson, E.
    Stockholm University, Faculty of Science, Department of Zoology.
    Trophic relationships on a fucoid shore in south-western Iceland as revealed by stable isotope analyses, laboratory experiments, field observations and gut analyses2009In: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 61, no 4, p. 206-215Article in journal (Refereed)
    Abstract [en]

    Rocky shores in the North Atlantic are known for their zonation patterns of both algae and animals, which can be expected to greatly affect food availability to consumers at different height levels on the shore. We tested the hypothesis that consumers would feed on the most abundant suitable food source in their surroundings. In total 36 species/taxa of common primary producers and consumers were sampled for stable isotope analyses from a sheltered fucoid shore at Hvassahraun in south-western Iceland. A selection of these species was also collected seasonally and from different height levels. Feeding experiments, field observations and gut analyses were also conducted. Our results were in good overall agreement with preexisting knowledge of trophic relationships in the rocky intertidal. Consumers often appeared to be assimilating carbon and nitrogen from the most common diet in their immediate surroundings. The predator Nucella lapillus was thus feeding on different prey at different height levels in accordance with different densities of prey species. When tested in the laboratory, individuals taken from low on the shore would ignore the gastropod Littorina obtusata, uncommon at that height level, even when starved, while individuals from mid-shore readily ate the gastropod. This indicated that some kind of learned behaviour was involved. There were, however, important exceptions, most noteworthy the relatively small contribution to herbivores, both slow moving (the gastropod L obtusata) and fast moving (the isopod Idotea granulosa and the amphipod Gammarus obtusatus) of the dominant alga at this site, Ascophyllum nodosum. The recent colonizer Fucus serratus seemed to be favoured. Selective feeding was indicated both by isotope signatures as well as by results of feeding experiments. Seasonal migrations of both slow and fast moving species could partly explain patterns observed. 

  • 523.
    Stenius, Susanne
    Stockholm University, Faculty of Science, Department of Zoology.
    Cooperation and conflict during reproduction in polyterritorial wood warblers (Phylloscopus sibilatrix)2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, the reproductive strategies of male and female wood warblers are studied. Males which arrived early to the breeding grounds had higher reproductive success than later males. This was due to early males more often mating polygynously than late males. Females preferred early males and by settling in attractive territories they had a relatively high reproductive success because of low rates of nest predation. Males in monogamous pairs were the principal providers in feeding the nestlings, especially during early nestling stage. Polygynous males assisted both females in feeding the young, each female receving less assistance than in monogamous pairs. Females of polygynous males then had to increase their feeding rates to compensate for reduced male assistance. In cases of nest predation for one of a polygynous males two females, males gave full assistance to the female that did not suffer from nest predation. On average, however, females of polygynous males had a cost in compensating for relatively little assistance by their males. It has been suggested that females could use behavioural cues to separate already mated males singing to attract additional females from unmated males. Mated males sang less frequently and spent significantly less time in their secondary territories than unmated males were in their territories, since mated males frequently visited their female in the primary territory. The variation was, however, large with some unmated males also leaving their territories. This variation makes territory presence an unreliable cue for females in assessing pairing status of males. When males returned to their females in their primary territories they often flew close to the nest and sang a short song. To test if this song function as an "all-clear" signal to the female, a stuffed marten (Martes martes) was shown close to the to the incubating female. All males stopped singing and uttered warning calls. There was a difference between monoterritorial and polyterritorial males in the trade-off between helping the primary female and trying to attract a second female.

  • 524.
    Stenmark, Arnold
    Stockholm University.
    Studies on the pea moth (Laspeyresia nigricana Steph.) in central Sweden.1974Doctoral thesis, comprehensive summary (Other academic)
  • 525.
    Stensland, Eva
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Berggren, Per
    Stockholm University, Faculty of Science, Department of Zoology.
    Mixed species groups in mammals2003In: Mammal Review, ISSN 0305-1838, E-ISSN 1365-2907, Vol. 33, no 3, p. 205-223Article in journal (Refereed)
    Abstract [en]

    1. Mixed species groups have long been noted in birds, but they also occur among different species of mammals ranging from closely related species to species from different orders. Mixed species groups of mammals occur in many different habitats, e.g. ungulates on the savannah, primates in various types of forests and cetaceans in the oceans. Mixed species groups are very different in their duration, frequency, predominant activity and structure depending on the species interacting and the habitat they occur in. 2. Functional explanations for mixed species groups usually fall within two categories: foraging advantages and predator avoidance. However, there could also be other social and reproductive advantages of mixed species groups that could contribute to their formation and stability. The advantages do not have to be equally distributed between the participating species and can also vary according to season and the presence of predators. 3. It is important that all investigators of mixed species groups take their studies one step further after the naturalistic description and test the function and benefits of mixed species groups in order to give more strength to their conclusions. In this paper we review and discuss the function of mixed species groups in mammals and suggest an approach on how to investigate the function of such groups.

  • 526.
    Stensland, Eva
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Berggren, Per
    Mixed species groups of Indo-Pacific bottlenose (Tursiops aduncus) and humpback (Sousa chinensis) dolphins off the south coast of Zanzibar, East AfricaManuscript (preprint) (Other academic)
  • 527. Stevens, Martin
    et al.
    Merilaita, Sami
    Stockholm University, Faculty of Science, Department of Zoology.
    Animal camouflage: current issues and new perspectives2009In: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 364, no 1516, p. 423-427Article in journal (Refereed)
  • 528. Stevens, Martin
    et al.
    Merilaita, Sami
    Stockholm University, Faculty of Science, Department of Zoology.
    Defining disruptive coloration and distinguishing its functions2009In: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 364, p. 481-488Article in journal (Refereed)
    Abstract [en]

    Disruptive coloration breaks up the shape and destroys the outline of an object, hindering detection. The principle was first suggested approximately a century ago, but, although research has significantly increased, the field remains conceptually unstructured and no unambiguous definition exists. This has resulted in variable use of the term, making it difficult to formulate testable hypotheses that are comparable between studies, slowing down advancement in this field. Related to this, a range of studies do not effectively distinguish between disruption and other forms of camouflage. Here, we give a formal definition of disruptive coloration, reorganize a range of sub-principles involved in camouflage and argue that five in particular are specifically related to disruption: differential blending; maximum disruptive contrast; disruption of surface through false edges; disruptive marginal patterns; and coincident disruptive coloration. We discuss how disruptive coloration can be optimized, how it can relate to other forms of camouflage markings and where future work is particularly needed.

  • 529.
    Stigenberg, Julia
    Stockholm University, Faculty of Science, Department of Zoology.
    Hidden Creatures – systematics of the Euphorinae (Hymenoptera)2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Parasitic wasps constitute one of the last remaining frontiers in the charting of animal diversity. The Braconidae is the second most species-rich family of parasitic wasps; the world fauna has been estimated at 40 000 species and the Swedish fauna is believed to include a little more than 2 000 species, 1 200 of which are currently documented. This thesis is a contribution to the rapidly increasing knowledge of braconid diversity. In paper I, a new gregarious parasitoid, Meteorus acerbiavorus sp. nov. (Braconidae: Eupohrinae), is described from specimens reared from the cocoons of the butterfly Acerbia alpina (Quensel) (Lepidoptera, Arctiidae) in northwestern Finnish Lapland. Based on a molecular phylogenetic analysis, the new species is shown to belong to the M. rubens species group. In the second paper, the Western Palearctic fauna of the tribe is revised, seven new species are described and a key to the Western Palearctic species is presented. Two molecular markers, 28S and COI, are used to study phylogenetic relationships in the tribe. The molecular results showed that the Meteorini fall into four well supported clades. The results also reveal a considerable cryptic species diversity. The third paper deals with distributional, phenological and in many cases rearing data from nearly 2 500 specimens (44 species) of the Meteorini in the collection of the National Museums of Scotland (NMS), Edinburgh. Patterns in the breadth of host ranges are discussed in relation to a reiterated speciation hypothesis. Paper IV examines the phylogenetic relationships of the entire subfamily Euphorinae based upon four gene regions (18S, CAD, 28S D2, and COI). A revised classification of the Euphorinae is proposed that recognizes 55 genera and 14 tribes. Our study shows that early members of the Euphorinae were parasitoids of coleopteran larvae, with a host shift to larval Lepidoptera, adult or immature hosts in the Hemiptera, Hymenoptera, Neuroptera, Orthoptera and Psocoptera.

  • 530.
    Stigenberg, Julia
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Boring, Charles Andrew
    University of Kentucky, Department of Entomology.
    Phylogeny of the parasitic wasp subfamily Euphorinae (Braconidae) and evolution of its host preferencesManuscript (preprint) (Other academic)
    Abstract [en]

    The braconid subfamily Euphorinae is a large, cosmopolitan group of endoparasitoid wasps. The majority of species attack adult hosts, a strategy that is rare among parasitic wasps, but there are also many species that attack nymphs and larval stages. Euphorine hosts may belong to a variety of insect orders (Coleoptera, Hemiptera, Hymenoptera, Neuroptera, Psocoptera, Orthoptera and Lepidoptera) although most euphorine tribes are confined to Coleoptera. Here we investigate the phylogenetic relationships of the Euphorinae based on molecular data (3 kb of nucleotide data from four markers: 18S, 28S, CAD and COI) and revise their higher-level classification. We also infer the evolution of host associations, and discuss the diversification of the Euphorinae. Results from both Bayesian inference and maximum-likelihood analysis show that the subfamily, as previously circumscribed, is paraphyletic. We propose that the subfamily be expanded to include the tribes Meteorini and Planitorini (Mannokeraia+Planitorius), so that it corresponds to a clade that is strongly supported as monophyletic in our analyses. Based on our results, a revised higher classification of the Euphorinae is proposed, in which 55 extant genera and 14 tribes are recognized. We reinstate the genus Microctonus belonging to the tribe Perilitini and propose the following tribal rearrangements: Spathicopis and Stenothremma are transferred to Perilitini; Tuberidelus, Sinuatophorus and Plynops to Cosmophorini; Ecclitura and Napo to Dinocampini; Chrysopophthorus and Wesmaelia to Helorimorphini; and Proclithoporus to Townesilitini. The monotypic tribes Cryptoxilonini and Myiocephalini are synonymized with Cosmophorini and Syntretini, respectively. The genus Pygostolus, previously placed among the Centistini, is established as its own tribe Pygostolini. Parsimony-based ancestral state reconstructions suggest that the ancestor of Euphorinae was a parasitoid of coleopteran larvae, and that a host shift to larval Lepidoptera occurred early in the evolution of the Meteorini. In the remainder of the subfamily, there was an initial shift from larval to adult coleopterans, followed by subsequent shifts to adults or larvae of Hemiptera, Hymenoptera, Neuroptera, Orthoptera and Psocoptera.

  • 531.
    Stigenberg, Julia
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Ronquist, Fredrik
    Revision of the Western Palearctic Meteorini (Hymenoptera, Braconidae), with a molecular characterization of hidden Fennoscandian species diversity2011In: Zootaxa, ISSN 1175-5326, E-ISSN 1175-5334, no 3084, p. 1-95Article in journal (Refereed)
    Abstract [en]

    The tribe Meteorini includes two genera, Meteorus and Zele, which are koinobiont endoparasitoids of larval Lepidoptera and Coleoptera. More than 300 species are known, about one fifth of which occur in the Western Palearctic. Here, we re- vise the Western Palearctic species, based partly on traditional approaches and partly on molecular analysis of recent Swedish and Finnish material. For the analyses of phylogenetic relationships and cryptic species diversity, we coded 17 morphological characters and sequenced two markers, 28S D2 (649 bp) and CO1 (665 bp). More than 1 970 specimens representing 54 species of Meteorus Haliday and 5 species of Zele Curtis were studied; of these, 177 specimens represent- ing 41 species were sequenced. Seven new species are described, all from the Fennoscandian material: Meteorus artocer- cus sp. nov., M. densipilosus sp. nov., M. eklundi sp. nov., M. longipilosus sp. nov., M. sibyllae sp. nov., M. stenomastax sp. nov., and M. subtilisulcus sp. nov. Four new synonyms are introduced: Z. chlorophthalmus (Spinola 1808), syn. nov. for M. pallidus (Nees 1812), M. punctifrons Thomson 1895, syn. nov. for M. varinervis (Tobias 1986), M. melanostictus Capron 1887, syn. nov for M. monachae (Tobias 1986), and M. tenellus Marshall 1887, syn. nov. for M. boreus (Tobias 1986). Meteorus tenellus is removed from synonymy with M. cinctellus. Sequence analysis indicated the presence of at least 12 additional cryptic species but these cannot be separated morphologically at this point and, therefore, we do not describe them here. The phylogenetic results suggest that Zele should be included within Meteorus but we refrain from formal changes of the generic classification until more comprehensive phylogenetic analyses of the tribe can be complet- ed. A key to the known Western Palearctic species is presented.

  • 532.
    Stigenberg, Julia
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Shaw, Mark
    National Museums of Scotland.
    Western Palaearctic Meteorinae (Hymenoptera: Braconidae) in the National Museums of Scotland, with rearing, phenological and distributional data, including six species new to Britain, and a discussion of a potential route to speciationIn: Entomologist's Gazette, ISSN 0013-8894Article in journal (Refereed)
    Abstract [en]

    Distributional, phenological and in many cases rearing data are given for 44 species of western Palaearctic Meteorinae in the genera Meteorus and Zele, from the nearly 2,500 specimens of the group present in the collection of the National Museums of Scotland, Edinburgh. Six species are newly recorded from Britain. Patterns in the breadth of host ranges are discussed in relation to a reiterated speciation hypothesis and a recently published molecular phylogeny.

  • 533.
    Stigenberg, Julia
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Vikberg, Veli
    Belokobylskij, Sergey
    Meteorus acerbiavorus sp. nov. (Hymnoptera, Braconidae), a gregarious parasitoid of Acerbia alpina (Quensel) (Lepidoptera, Arctiidae) in North Finland2011In: Journal of Natural History, ISSN 0022-2933, E-ISSN 1464-5262, Vol. 45, no 21-24, p. 1275-1294Article in journal (Refereed)
    Abstract [en]

    The new gregarious parasitoid Meteorus acerbiavorus sp. nov. (Hymenoptera, Braconidae) was reared from the cocoons of Acerbia alpina (Quensel) (Lepidoptera, Arctiidae) in north-western Finnish Lapland. This species belongs to Meteorus rubens (Nees) species group and differs from the most related M. rubens in the following features: the eyes densely setose; the median lobe of the mesos- cutum, scutellum, mesopleuron, and the hind coxa entirely or at least partly rugulose-granulate or rugose-areolate and sometimes with granulation; the ovipos- itor subapically with distinct dorsal node; the ventral borders of the first metasomal tergum weakly separated by narrow space in its basal half; the colour of the body and legs mostly or entirely dark; the fore wing more or less darkened. Phylogenetic relationships among several Meteorus species close to M. rubens including new M. acerbiavorus were investigated based on DNA sequence fragments of the mito- chondrial COI and the nuclear 28S rDNA genes. The discussions on the species groups of Meteorus, on distribution of Acerbia alpina in the Holarctic and on its known parasitoids are presented.

  • 534.
    Strandberg, Jonas
    Stockholm University, Faculty of Science, Department of Zoology.
    Taking a Bite out of Diversity - Taxonomy and systematics of biting midges2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The biting midges (family Ceratopogonidae) is one of the most species rich amongst the biting flies (Diptera) and has been recorded from most parts of the world. The species are mostly known for their capability to act as vectors for several important diseases, which have helped in shaping the focus to one of its genera, Culicoides Latreille, 1809.

     

    This thesis gives an overview of the knowledge of the Swedish diversity, in the first paper (paper I) with a closer look at the species of Dasyhelea Kieffer, 1911 where all twenty species found in Sweden are presented with their associated localities, and two new species are described.  In the second paper (paper II) the biting midge diversity of Sweden is presented based on specimens collected from several localities. All these individuals were barcoded using the mitochondrial cytochrome oxidase I gene (COI). The analysis included 773 specimens that were assigned into 214 barcoding clusters (BINs) and sorted into 164 groups based on their morphology. The third paper (paper III) broadens the scale were the evolutionary relationships within the family are investigated by applying five protein coding genes (COI, CAD, TPI, AATS and PGD) and specimens from different parts of the World. The analysis recovers Ceratopogonini, Forcipomyia Meigen, 1818 and Bezzia Kieffer, 1899 as paraphyletic and Palpomyia Meigen, 1818 polyphyletic. In the last and fourth paper (paper IV) the family is used as a model organism together with Hymenoptera for an alternative analysis method for reducing the impact of saturation and long-branch attraction using non-synonymous coding (e.g. Degen1) on only parts of a dataset. The effectiveness of the method is compared to the removal of the faster evolving third codon position. The result yields a higher number of supported nodes as well as a higher median of support for the method as well as an ability to reduce long-branch attraction artifacts.

  • 535.
    Strauss, Johannes
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Zhang, Qian
    Verleyen, Peter
    Huybrechts, Jurgen
    Neupert, Susanne
    Predel, Reinhard
    Pauwels, Kevin
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Pigment-dispersing hormone in Daphnia interneurons, one type homologous to insect clock neurons displaying circadian rhythmicity2011In: Cellular and Molecular Life Sciences (CMLS), ISSN 1420-682X, E-ISSN 1420-9071, Vol. 68, no 20, p. 3403-3423Article in journal (Refereed)
    Abstract [en]

    We report identification of a beta-type pig-ment-dispersing hormone (PDH) identical in two water fleaspecies, Daphnia magna and Daphnia pulex. It has been identified by cloning of precursors, chromatographic iso-lation from tissue extracts followed by immunoassays and de novo-mass spectrometric sequencing. The peptide is restricted to a complex system of distinct interneurons in the brain and visual ganglia, but does not occur in neurosecretory cells projecting to neurohemal organs as in decapod crustaceans. Thirteen neuron types individually identified and reconstructed by immunohistochemistry were almost identical in terms of positions and projection patterns in both species. Several neurons invade and form plexuses in visual ganglia and major brain neuropils including the central body. Five neuron types show con-tralateral pathways and form plexuses in the lateral, dorsal,or postlateral brain neuropils. Others are local interneurons,and a tritocerebral neuron connects the protocerebrum with the neuropil of the locomotory second antenna. Two visual ganglia neuron types lateral to the medulla closely resemble insect medulla lateral circadian clock neurons containing pigment-dispersing factor based upon positional and projectional criteria. Experiments under 12:12 h light/dark cycles and constant light or darkness conditions showed significant circadian changes in numbers and activities of one type of medulla lateral PDH neuron with an acrophase in the evening. This simple PDH system shows striking homologies to PDH systems in decapod crustaceans and well-known clock neurons in several insects, which suggests evolutionary conservation of an ancient peptidergic interneuronal system that is part of biological clocks.

  • 536.
    Strauss, Johannes
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Stockholm University, Faculty of Science, Department of Zoology.
    Zhang, Qian
    Verleyen, Peter
    Huybrechts, Jurgen
    Pauels, Kevin
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Stockholm University, Faculty of Science, Department of Zoology.
    Multiple identified peptidergic interneurons express a novel pigment-dispersing hormone in the Daphnia brain and visual ganglia, some showing evidence for clock-neuron functions2009In: Comparative Biochemistry and Physiology A, ISSN 1095-6433, E-ISSN 1531-4332, Vol. 153A, no 2, suppl. 1, p. S156-S157Article in journal (Refereed)
    Abstract [en]

    Postgenomic, precursor, expressed sequence tag, and mass spectrometric peptidomic analyses allowed us to identify a single gene leading to a novel 18mer-isoform of a bety-type pigment-dispersing hormone (PDH) that is identical in two waterflea species, Daphnia magna and Daphnia pulex. PDH is restricted to interneurons, ten types in the brain and two types in the visual ganglia, and does not occur in neurosecretory cells connected to neurohaemal areas. The neurons individually identified by immunohistochemistry (IHC) were virtually identical in terms of their positions and projection patterns in both species. Whereas the brain neurons are found associated with almost all major neuropils incl. the central body, the visual ganglia neurons adjacent to and innervating the medulla closely resemble the insect so-called pigment-dispersing factor medulla lateral neurons based upon positional and projection criteria. Since the latter neurons are established members of insect circadian clock systems, we analysed these neurons for IHC-detectable circadian changes. Preliminary results under 12:12 h light dark cycles showed significant circadian changes in numbers and staining intensities of the Daphnia medulla PDH neurons. These PDH neurons comprise a simple system currently studied in more depth in behavioural contexts. The discovered homologies to PDH-systems in decapod crustaceans and the well known clock system in several insects suggest evolutionary conservation of an ancient peptidergic interneuronal system in arthropods.

  • 537.
    Stålhandske, Sandra
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Spring warmth and winter chilling have contrasting effects on spring phenology of pupal-overwintering butterfliesManuscript (preprint) (Other academic)
  • 538.
    Stålhandske, Sandra
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Posledovich, Diana
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Variation in two phases of post-winter development of a butterfly2014In: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 27, no 12, p. 2644-2653Article in journal (Refereed)
    Abstract [en]

    The temporal aspects of life cycle characteristics, such as diapause development, are under strong selection in seasonal environments. Fine-tuning of the life cycle may be particularly important to match the phenology of potential mates and resources as well as for optimizing abiotic conditions at eclosion. Here, we experimentally study the spring phenology of the orange tip butterfly, Anthocharis cardamines, by analysing post-winter pupal development in three populations along a latitudinal cline in each of Sweden and the United Kingdom. These countries differ substantially in their seasonal temperature profile. By repeatedly recording pupal weights, we established that post-winter development has two separate phases, with a more rapid weight loss in the second phase than in the first, likely corresponding to a ramping up of the rate of development. Variation in the duration of the first phase contributed more strongly than the second phase to the differences in phenology between the localities and sexes. We found that insects from Sweden had a faster overall rate of development than those from the United Kingdom, which is consistent with countergradient variation, as Sweden is colder during the spring than the United Kingdom. Similar trends were not observed at the within-country scale, however. A cogradient pattern was found within Sweden, with populations from the north developing more slowly, and there was no clear latitudinal trend within the United Kingdom. In all localities, males developed faster than females. Our results point to the importance of variation in the progression of post-winter development for spring phenology.

  • 539.
    Stålhandske, Sandra
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Lehmann, Philipp
    Stockholm University, Faculty of Science, Department of Zoology.
    Pruisscher, Peter
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Effect of winter cold duration on spring phenology of the orange tip butterfly, Anthocharis cardamines 2015In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 5, no 23, p. 5509-5520Article in journal (Refereed)
    Abstract [en]

    The effect of spring temperature on spring phenology is well understood in a wide range of taxa. However, studies on how winter conditions may affect spring phenology are underrepresented. Previous work on Anthocharis cardamines (orange tip butterfly) has shown population-specific reaction norms of spring development in relation to spring temperature and a speeding up of post-winter development with longer winter durations. In this experiment, we examined the effects of a greater and ecologically relevant range of winter durations on post-winter pupal development of A. cardamines of two populations from the United Kingdom and two from Sweden. By analyzing pupal weight loss and metabolic rate, we were able to separate the overall post-winter pupal development into diapause duration and post-diapause development. We found differences in the duration of cold needed to break diapause among populations, with the southern UK population requiring a shorter duration than the other populations. We also found that the overall post-winter pupal development time, following removal from winter cold, was negatively related to cold duration, through a combined effect of cold duration on diapause duration and on post-diapause development time. Longer cold durations also lead to higher population synchrony in hatching. For current winter durations in the field, the A. cardamines population of southern UK could have a reduced development rate and lower synchrony in emergence because of short winters. With future climate change, this might become an issue also for other populations. Differences in winter conditions in the field among these four populations are large enough to have driven local adaptation of characteristics controlling spring phenology in response to winter duration. The observed phenology of these populations depends on a combination of winter and spring temperatures; thus, both must be taken into account for accurate predictions of phenology.

  • 540.
    Stålhandske, Sandra
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Olofsson, Martin
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Wiklund, Christer
    Stockholm University, Faculty of Science, Department of Zoology.
    Leimar, Olof
    Stockholm University, Faculty of Science, Department of Zoology.
    Phenological matching rather than genetic variation in host preference underlies geographical variation in host plants used by the orange tip butterflies2016In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 119, no 4, p. 1060-1067Article in journal (Refereed)
    Abstract [en]

    An insect species that shows variation in host species association across its geographical range may do so either because of local adaptation in host plant preference of the insect, or through environmentally or genetically induced differences in the plants, causing variation in host plant suitability between regions. Here we experimentally investigate host plant preference of Anthocharis cardamines (orange tip butterfly) of two populations from UK and two from Sweden. Previous reports indicate that A. cardamines larvae are found on different host plant species in different regions of the United Kingdom, and some variation has been reported in Sweden. Host plant choice trials showed that females prefer to oviposit on plants in an earlier phenological stage, as well as on larger plants. When controlling for plant phenological stage and size, the host species had no statistically significant effect on the choice of the females. Moreover, there were no differences in host plant species preference among the four butterfly populations. Based on our experiment, the oviposition choice by A. cardamines mainly depends on the phenological stage and the size of the host plant. This finding supports the idea that the geographical patterns of host-plant association of A. cardamines in the UK and Sweden are consequences of the phenology and availability of local hosts, rather than regional genetic differences in host species preference of the butterfly.

  • 541.
    Stålstedt, Jeanette
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology. Swedish Museum of Natural History, Sweden.
    Bergsten, Johannes
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology.
    Mąkol, Joanna
    Matching adults and larvae of Erythraeus spp. velvet mites (Actinotrichida: Erythraeidae) with the help of DNAManuscript (preprint) (Other academic)
  • 542. Sumpter, David J. T.
    et al.
    Szorkovszky, Alex
    Kotrschal, Alexander
    Stockholm University, Faculty of Science, Department of Zoology.
    Kolm, Niclas
    Stockholm University, Faculty of Science, Department of Zoology.
    Herbert-Read, James E.
    Stockholm University, Faculty of Science, Department of Zoology.
    Using activity and sociability to characterize collective motion2018In: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 373, no 1746, article id 20170015Article, review/survey (Refereed)
    Abstract [en]

    A wide range of measurements can be made on the collective motion of groups, and the movement of individuals within them. These include, but are not limited to: group size, polarization, speed, turning speed, speed or directional correlations, and distances to near neighbours. From an ecological and evolutionary perspective, we would like to know which of these measurements capture biologically meaningful aspects of an animal's behaviour and contribute to its survival chances. Previous simulation studies have emphasized two main factors shaping individuals' behaviour in groups; attraction and alignment. Alignment responses appear to be important in transferring information between group members and providing synergistic benefits to group members. Likewise, attraction to conspecifics is thought to provide benefits through, for example, selfish herding. Here, we use a factor analysis on a wide range of simple measurements to identify two main axes of collective motion in guppies (Poecilia reticulata): (i) sociability, which corresponds to attraction (and to a lesser degree alignment) to neighbours, and (ii) activity, which combines alignment with directed movement. We show that for guppies, predation in a natural environment produces higher degrees of sociability and (in females) lower degrees of activity, while female guppies sorted for higher degrees of collective alignment have higher degrees of both sociability and activity. We suggest that the activity and sociability axes provide a useful framework for measuring the behaviour of animals in groups, allowing the comparison of individual and collective behaviours within and between species.

  • 543.
    Sun, Yunfei
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Ocean University of China, China.
    Wang, Fang
    Hu, Nan
    Su, Xianpeng
    Liu, Zhi
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Prey selection of the swimming crab Portunus trituberculatus (Miers, 1876) (Brachyura: Portunidae) foraging on bivalves2017In: Journal of Crustacean Biology, ISSN 0278-0372, E-ISSN 1937-240X, Vol. 37, no 5, p. 521-528Article in journal (Refereed)
    Abstract [en]

    Predators may be exposed to different prey types simultaneously, and so may select certainprey types over others. We examined prey selection, predation rate, and foraging behaviourof the swimming crab Portunus trituberculatus (Miers, 1876) provided with three types of clams, the Manila Ruditapes philippinarum (Adams & Reeve, 1850), bloody Scapharca subcrenata (Lischke,1896), and hard Meretrix meretrix (Linnaeus, 1758) clams in laboratory experiments. When provided will all three possible prey simultaneously, crabs exhibited higher preference for R. philippinarum over S. subcrenata and M. meretrix (Chesson’s selectivity index; P = 0.003). In the single-prey experiments, predation rates were signifcantly higher on R. philippinarum and S. subcrenata than on M. meretrix (P = 0.002). Video analysis revealed that prey type signifcantly affected both the proportion of time crabs spent on searching, and the probability of consumption upon capture. The proportion of time crabs spent on handling (P = 0.171), the encounter rate (P = 0.918), and the probability of capture upon encounter (P = 0.456), however, were not signifcantly affected by prey types. Handling time per prey was not signifcantly different among clam species. For the crab, prey proftability (energy intake perunit handling time) of R. philippinarum was similar to that of S. subcrenata, in both cases being signifcantly higher than that of M. meretrix (P ﹤ 0.001). The relative frequencies of changing from searching to handling were significantly higher for M. meretrix than for R. philippinarum and S. subcrenata (P = 0.007). These results suggest that the probability of consumption upon capture explained the observed selection by crabs. Furthermore, prey proftability, shell strength, and shell width, are important elements to affect prey selection of the crab.

  • 544.
    Sundberg, Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Ishaq, Rasha
    Tjärnlund, Ulla
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Åkerman, Gun
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Grunder, Kerstin
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Bandh, Cecilia
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Broman, Dag
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Balk, Lennart
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Contribution of commonly analyzed polycyclic aromatic hydrocarbons (PAHs) in sediment to potential toxicity in early life-stages of rainbow trout (Oncorhynchus mykiss)2006In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 63, no 6, p. 1320-1333Article in journal (Refereed)
    Abstract [en]

    In a series of bio-effect-directed fractionation experiments, we investigated the potential toxicity of sediment extracts from a contaminated bay. A previous study investigated abnormalities and hepatic ethoxyresorufin O-deethylase (EROD) activities in rainbow trout (Oncorhynchus mykiss) larvae by exposing newly fertilized eggs to the total extract and to fractions separated by degree of aromaticity. A major part of the potential toxicity was isolated in a fraction containing polycyclic aromatic compounds (PACs). In this study, we prepared a synthetic PAC mixture with 17 commonly analyzed polycyclic aromatic hydrocarbons (PAHs) in amounts equimolar to those found in the sediment PAC fraction. The 17 PAHs, which included 11 of the 16 United States Environmental Protection Agency (US EPA) priority PAHs, were unable to account for the toxicopathic effects observed and could explain less than 4% of the total EROD induction. The lack of a clear relationship between toxicopathic effects and EROD induction underlines the need for a battery of biomarkers for estimating environmental risk. These results reveal the limits of our knowledge regarding compounds responsible for potential toxicity in field situations.

  • 545.
    Sundberg, P
    et al.
    Göteborgs universitet.
    Chernyshev, AV
    Russian Academy of Sciences.
    Kajihara, H
    Kånneby, Tobias
    Stockholm University, Faculty of Science, Department of Zoology.
    Strand, M
    Göteborgs universitet.
    Character-matrix based descriptions of two new nemertean (Nemertea) species2009In: Zoological Journal of the Linnean Society, ISSN 0024-4082, E-ISSN 1096-3642, Vol. 157, no 2, p. 264-294Article in journal (Refereed)
    Abstract [en]

    Ribbon worms (phylum Nemertea) have traditionally been described and classified based on a combination of internal and external morphological characters. The extent, and wealth of details, of these descriptions vary both over time and amongst authors. In addition, definitions of characters and character states are in many cases vague, causing problems both for identification and in phylogenetic analyses. Here, we suggest a system of describing nemerteans based on a list of characters and their states with the actual description in the form of a vector of character state symbols. We argue that this system makes it easier for other systematists to extract the necessary characters/character states for comparative and phylogenetic analyses. The proposed list of characters can also act as a checklist for nemertean description, whereby hopefully ambiguities (such as does the nonmentioning of a character actually mean 'missing' or just not looked for) can be avoided in the future. We describe two new species and one new genus Carinina ochracea sp. nov. and Raygibsonia bergi gen. et sp. nov. using this concept in combination with molecular analyses based on 18S and cytochrome oxidase I (COI) DNA sequences.

  • 546.
    Sundelin, Brita
    Stockholm University, Faculty of Science, Department of Zoology.
    Ecological effect assessment of pollutants using Baltic benthic organisms1989Doctoral thesis, comprehensive summary (Other academic)
  • 547. Sundin, Ulf
    Brown adipose tissue: control of heat production : development during ontogeny and cold adaptation1981Doctoral thesis, comprehensive summary (Other academic)
  • 548.
    Svartberg, Kenth
    Stockholm University, Faculty of Science.
    Personality in dogs2003Doctoral thesis, comprehensive summary (Other academic)
  • 549.
    Svensson, Ola
    et al.
    University of Gothenburg Department of Zoology .
    Lissåker, Maria
    Stockholm University, Faculty of Science, Department of Zoology.
    Mobley, Kenyon B.
    3.Umeå University Department of Ecology and Environmental Science .
    Offspring recognition and the influence of clutch size on nest fostering among male sand gobies, Pomatoschistus minutus2010In: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 64, no 8, p. 1325-1331Article in journal (Refereed)
    Abstract [en]

    When parental care is costly, parents should avoid caring for unrelated young. Therefore, it is an advantage to discriminate between related and unrelated offspring so that parents can make informed decisions about parental care. In the present study, we test the hypothesis that male sand gobies (Pomatoschistus minutus) recognize and differentially care for their own offspring when given a choice between a nest with sired eggs and a second nest with eggs sired by an unrelated male. The sand goby is a species with exclusive and costly paternal care. Male parasitic spawnings (e.g., sneaking) as well as nest takeovers by other males are common. Our results show that nests containing sired eggs were preferred and received significantly more care, as measured by nest building and nest occupancy, than nests with foreign eggs even when males cared for both nests. These findings suggest that males respond to paternity cues and recognize their own clutches. Relative clutch size also had a significant effect on male parental care. When sired clutches were larger than foreign clutches, males preferred to care for their own nest. In the few cases where males chose to take care of foreign nests, the foreign clutch was larger than their own clutch. Taken together, our results provide evidence that both paternity cues and clutch size influence parenting decisions among male sand gobies.

  • 550.
    Svärd, Lena
    Stockholm University, Faculty of Science, Department of Zoology.
    Mating strategies of male butterflies in relation to female fecundity and polyandry1988Doctoral thesis, comprehensive summary (Other academic)
8910111213 501 - 550 of 636
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