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  • 101.
    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.

  • 102.
    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

  • 103. 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.

  • 104.
    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

  • 105. 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.

  • 106.
    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. 

  • 107. 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.

  • 108.
    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.

  • 109.
    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.

  • 110.
    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.

  • 111. 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.

  • 112. 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.

  • 113.
    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.

  • 114.
    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.

  • 115.
    Dannelid, Erland
    Stockholm University.
    Dental morphology in Eurasian shrews of the genus Sorex: aspects on taxonomy, evolution and ecology1991Doctoral thesis, comprehensive summary (Other academic)
  • 116. Dapporto, Leonardo
    et al.
    Bruschini, Claudia
    Dinca, Vlad
    Stockholm University, Faculty of Science, Department of Zoology.
    Vila, Roger
    Dennis, Roger L. H.
    Identifying zones of phenetic compression in West Mediterranean butterflies (Satyrinae): refugia, invasion and hybridization2012In: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 18, no 11, p. 1066-1076Article in journal (Refereed)
    Abstract [en]

    Aim Distinct insular populations are generally considered important units for conservation. In islandmainland situations, unidirectional introgressive gene flow from the most abundant, typically continental, populations into the smaller island populations can erase native insular genetic units. As an indication of threat, the concept of phenetic slope is developed, a measure proportional to differentiation and to geographical proximity. Location The Western Mediterranean, including the following islands: Sardinia, Sicily, Corsica, Balearics, circum-Italian, circum-Sicilian and circum-Sardo-Corsican archipelagos. Eastern Europe is included for comparison. Methods Geometric morphometrics was applied to 2392 male genitalia of seven butterfly species groups. Geographic Information System techniques were used to depict the pattern in the distribution of morphotypes. The slope of variation in genital shape was computed to highlight geographical areas showing abrupt morphological changes. Correlation analyses were performed between the mean slope values across sea straits separating islands and nearest sources and ecological traits of the species that underlie their colonization and migration capacity. Results Phenetic slope analysis has revealed that the strait of Messina and the northern Tyrrhenian Sea support particularly contrasting populations. In these areas, mean slopes for species also correlated with certain ecological traits of the species. Sardinia emerges as the most stable refugium for ancestral mediterranean populations. Main conclusions There is strong support for the hypothesis that Italy has experienced invasion by populations from Eastern Europe with postglacial expansion of these populations across Italy. However, propagules are impeded from invading islands by the expanse of sea straits. Even so, sea straits are not invariably barriers. Our results suggest that wind direction in combination with habitat occupancy may have maintained ancestral insular populations in key locations distinguished by phenetic compression. We conclude that native insular populations acting as barriers to introgression in the areas showing particularly steep phenetic slopes deserve attention in conservation programmes.

  • 117. Dapporto, Leonardo
    et al.
    Fattorini, Simone
    Voda, Raluca
    Dinca, Vlad
    Stockholm University, Faculty of Science, Department of Zoology. University of Guelph, Canada.
    Vila, Roger
    Biogeography of western Mediterranean butterflies: combining turnover and nestedness components of faunal dissimilarity2014In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 41, no 9, p. 1639-1650Article in journal (Refereed)
    Abstract [en]

    Aim Unpartitioned dissimilarity indices such as the Sorensen index (beta(sor)) tend to categorize areas according to species number. The use of turnover indices, such as the Simpson index (beta(simp)), may lead to the loss of important information represented by the nestedness component (beta(nest)). Recent studies have suggested the importance of integrating nestedness and turnover information. We evaluated this proposition by comparing biogeographical patterns obtained by unpartitioned (beta(sor)) and partitioned indices (beta(simp) and beta(nest)) on presence data of western Mediterranean butterflies. Location Western Mediterranean. Methods We assessed the regionalization of 81 mainland and island faunas according to partitioned and unpartitioned dissimilarity by using cluster analyses with the unweighted pair-group method using arithmetic averages (UPGMA) combined with non-metric multidimensional scaling (NMDS). We also carried out dissimilarity interpolation for beta(sor), beta(simp), beta(nest) and the beta(nest)/beta(sor) ratio, to identify geographical patterns of variation in faunal dissimilarity. Results When the unpartitioned bsor index was used, the clustering of sites allowed a clear distinction between insular and mainland species assemblages. Most islands were grouped together, irrespective of their mainland source, because of the dominant effect of their shared low richness. bsimp was the most effective index for clustering islands with their respective mainland source. bsimp clustered mainland sites into broader regions than clusters obtained using bsor. A comparison of regionalization and interpolation provided complementary information and revealed that, in different regions, the patterns highlighted by bsor could largely be determined either by nestedness or turnover. Main conclusions Partitioned and unpartitioned indices convey complementary information, and are able to reveal the influence of historical and ecological processes in structuring species assemblages. When the effect of nestedness is strong, the exclusive use of turnover indices can generate geographically coherent groupings, but can also result in the loss of important information. Indeed, various factors, such as colonization-extinction events, climatic parameters and the peninsular effect, may determine dissimilarity patterns expressed by the nestedness component.

  • 118. Dapporto, Leonardo
    et al.
    Voda, Raluca
    Dinca, Vlad
    Stockholm University, Faculty of Science, Department of Zoology. Pompeu Fabra University, Spain; Autonomous University of Barcelona, Spain.
    Vila, Roger
    Comparing population patterns for genetic and morphological markers with uneven sample sizes. An example for the butterfly Maniola jurtina2014In: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 5, no 8, p. 834-843Article in journal (Refereed)
    Abstract [en]

    1. Integrating genetic and/or phenotypic traits at population level is considered a fundamental approach in the study of evolutionary processes, systematics, biogeography and conservation. But combining the two types of data remain a complex task, mostly due to the high, and sometimes different, sample sizes required for reliable assessments of community traits. Data availability has been increasing in recent years, thanks to online resources, but it is uncommon that different types of markers are available for any given specimen. 2. We provide new R functions aimed at directly correlating traits at population level, even if data sets only overlap partially. The new functions are based on a modified Procrustes algorithm that minimizes differences between bidimensional ordinations of two different markers, based on a subsample of specimens for which both characters are known. To test the new functions, we used a molecular and morphological data set comprising Mediterranean specimens of the butterfly Maniola jurtina. 3. By using this method, we have been able to maximize similarities between genotypic and phenotypic configurations obtained after principal coordinate analysis for the model species and evaluated their degree of correlation at both individual and population level. The new recluster. procrustes function retained the information of the relative importance of different morphological variables in determining the observed ordinations and preserved it in the transformed configurations. This allowed calculating the best combination of morphological variables mirroring genetic relationships among specimens and populations. Finally, it was possible to analyse the modality and variance of the phenotypic characters correlated with the genetic structure among populations. 4. The genetic and phenotypic markers displayed high overall correlation in the study area except in the contact zone, where discrepancies for particular populations were detected. Interestingly, such discrepancies were spatially structured, with southern populations displaying typical western morphotype and eastern haplotypes, while the opposite occurred in the northern populations. The methodology here described can be applied to any number and type of traits for which bidimensional configurations can be obtained, and opens new possibilities for datamining and formeta-analyses combining existing data sets in biogeography, systematics and ecology.

  • 119. Delling, Bo
    Species diversity and phylogeny of Salmo with emphasis on southern trouts (Teleostei, Salmonidae)2003Doctoral thesis, comprehensive summary (Other academic)
  • 120. Derst, Christian
    et al.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Meusemann, Karen
    Zhou, Xin
    Liu, Shanlin
    Predel, Reinhard
    Evolution of neuropeptides in non-pterygote hexapods2016In: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 16, article id 51Article in journal (Refereed)
    Abstract [en]

    Background

    Neuropeptides are key players in information transfer and act as important regulators of development, growth, metabolism, and reproduction within multi-cellular animal organisms (Metazoa). These short protein-like substances show a high degree of structural variability and are recognized as the most diverse group of messenger molecules. We used transcriptome sequences from the 1KITE (1K Insect Transcriptome Evolution) project to search for neuropeptide coding sequences in 24 species from the non-pterygote hexapod lineages Protura (coneheads), Collembola (springtails), Diplura (two-pronged bristletails), Archaeognatha (jumping bristletails), and Zygentoma (silverfish and firebrats), which are often referred to as “basal” hexapods. Phylogenetically, Protura, Collembola, Diplura, and Archaeognatha are currently placed between Remipedia and Pterygota (winged insects); Zygentoma is the sistergroup of Pterygota. The Remipedia are assumed to be among the closest relatives of all hexapods and belong to the crustaceans.

    Results

    We identified neuropeptide precursor sequences within whole-body transcriptome data from these five hexapod groups and complemented this dataset with homologous sequences from three crustaceans (including Daphnia pulex), three myriapods, and the fruit fly Drosophila melanogaster. Our results indicate that the reported loss of several neuropeptide genes in a number of winged insects, particularly holometabolous insects, is a trend that has occurred within Pterygota. The neuropeptide precursor sequences of the non-pterygote hexapods show numerous amino acid substitutions, gene duplications, variants following alternative splicing, and numbers of paracopies. Nevertheless, most of these features fall within the range of variation known from pterygote insects. However, the capa/pyrokinin genes of non-pterygote hexapods provide an interesting example of rapid evolution, including duplication of a neuropeptide gene encoding different ligands.

    Conclusions

    Our findings delineate a basic pattern of neuropeptide sequences that existed before lineage-specific developments occurred during the evolution of pterygote insects.

  • 121.
    Dimitrova, Marina
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Merilaita, Sami
    Prey pattern regularity and background complexity affect detectability of background-matching prey2012In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 23, no 2, p. 384-390Article in journal (Refereed)
    Abstract [en]

    We investigated how regularity of prey color pattern affects crypsis and how visual complexity of the background affects prey detection. We performed 2 predation experiments with artificial prey and backgrounds, using blue tits (Cyanistes caeruleus) as predators. In experiment 1, we found that contrary to a previous hypothesis, a pattern with repeated background-matching pattern element shapes was not easier to detect than a pattern with variable background-matching shapes. Increased background complexity with respect to shape diversity and complexity made prey detection more difficult. In experiment 2, we tested how spatial regularity of background-matching pattern elements affects crypsis. We found that spatially irregular prey with randomly placed pattern elements were harder to detect on both simple and complex backgrounds compared with spatially regular prey that had the elements aligned. Increased background element shape complexity made both prey categories harder to detect. In conclusion, our study shows that spatial regularity of prey pattern but not regularity due to invariable pattern element shapes deteriorates crypsis. Visually complex backgrounds and specifically those consisting of elements with complex shapes make detection of cryptic prey difficult.

  • 122.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Conserved crustacean cardioactive peptide neural networks and functions in arthropod evolution1998In: Recent Advances in Arthropod Endocrinology / [ed] Geoffrey M. Coast, Simon G. Webster, Cambridge: Cambridge University Press, 1998, 65, p. 302-333Chapter in book (Refereed)
  • 123.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Crustacean bioactive peptides2013In: Handbook of Biologically Active Peptides / [ed] Abba J. Kastin, New York: Academic Press Elsevier , 2013, 2, p. 209-221Chapter in book (Refereed)
    Abstract [en]

    Research on crustacean peptides has concentrated mainly on decapods and isopods, and a growing number of >200 peptides have been sequenced from these two groups, the majority from decapods, but recently, the annotation of the Daphnia pulexgenome has contributed many more novel peptides many of which were also sequenced de novo. Identified and bioactive crustacean peptides — the only ones reported here — regulate a large range of physiological functions, including color change, activities of heart, exoskeletal and visceral muscles, metabolic function, development, metamorphosis, and reproduction.

  • 124.
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Neurosecretory endings in the pericardial organs of the shore crab Carcinus maenas L., and their identification by neuropeptide immunocytochemistry1991In: Comparative aspects of neuropeptide function. / [ed] Ernst Florey, George B. Stefano, Manchester, New York: Manchester University Press, 1991, p. 198-200Chapter in book (Other academic)
  • 125.
    Dircksen, Heinrich
    et al.
    University of Bonn, Germany.
    Heyn, Uwe
    Crustacean hyperglycemic hormone-like peptides in crab and locust peripheral intrinsic neurosecretory cells1998In: Annals of the New York Academy of Sciences, ISSN 0077-8923, E-ISSN 1749-6632, Vol. 839, p. 392-394Article in journal (Refereed)
  • 126.
    Dircksen, Heinrich
    et al.
    Rheinische Friedrich-Wilhelms-Universität, Germany.
    Homberg, Uwe
    Crustacean Cardioactive Peptide-immunoreactive neurons innervating brain neuropils, retrocerebral complex and stomatogastric nervous-system of the locust, Locusta migratoria1995In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 279, p. 495-515Article in journal (Refereed)
    Abstract [en]

    The distribution and morphology of crustacean cardioactive peptide-immunoreactive neurons in the brain of the locust Locusta migratoria has been determined. Of more than 500 immunoreactive neurons in total, about 380 are interneurons in the optic lobes. These neurons invade several layers of the medulla and distal parts of the lobula. In addition, a small group of neurons projects into the accessory medulla, the lamina, and to several areas in the median protocerebrum. In the midbrain, 12 groups or individual neurons have been reconstructed. Four groups innervate areas of the superior lateral and ventral lateral protocerebrum and the lateral horn. Two cell groups have bilateral arborizations anterior and posterior to the central body or in the superior median protocerebrum. Ramifications in subunits of the central body and in the lateral and the median accessory lobes arise from four additional cell groups. Two local interneurons innervate the antennal lobe. A tritocerebral cell projects contralaterally into the frontal ganglion and appears to give rise to fibers in the recurrent nerve, and in the hypocerebral and ingluvial ganglia. Varicose fibers in the nervi corporis cardiaci III and the corpora cardiaca, and terminals on pharyngeal dilator muscles arise from two subesophageal neurons. Some of the locust neurons closely resemble immunopositive neurons in a beetle and a moth. Our results suggest that the peptide may be (1) a modulatory substance produced by many brain interneurons, and (2) a neurohormone released from subesophageal neurosecretory cells.

  • 127.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Müller, Arno
    Keller, Rainer
    Crustacean cardioactive peptide in the nervous system of the locust, Locusta migratoria: an immunocytochemical study on the ventral nerve cord and peripheral innervation1991In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 263, p. 439-457Article in journal (Refereed)
    Abstract [en]

    Crustacean cardioactive peptide-immunoreactive neurons occur in the entire central nervous system of Locusta migratoria. The present paper focuses on mapping studies in the ventral nerve cord and on peripheral projection sites. Two types of contralaterally projecting neurons occur in all neuromers from the subesophageal to the seventh abdominal ganglia. One type forms terminals at the surface of the thoracic nerves 6 and 1, the distal perisympathetic organs, the lateral heart nerves, and on ventral and dorsal diaphragm muscles. Two large neurons in the anterior part and several neurons of a different type in the posterior part of the terminal ganglion project into the last tergal nerves. In the abdominal neuromers 1–7, two types of ipsilaterally projecting neurons occur, one of which gives rise to neurosecretory terminals in the distal perisympathetic organs, in peripheral areas of the transverse, stigmata and lateral heart nerves. Four subesophageal neurons have putative terminals in the neurilemma of the nervus corporis allati II, and in the corpora allata and cardiaca. In addition, several immunoreactive putative interneurons and other neurons were mapped in the ventral nerve cord. A new in situ whole-mount technique was essential for elucidation of the peripheral pathways and targets of the identified neurons, which suggest a role of the peptide in the control of heartbeat, abdominal ventilatory and visceral muscle activity.

  • 128.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Neupert, Susanne
    Predel, Reinhard
    Verleyen, Peter
    Huybrechts, Jurgen
    Strauss, Johannes
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Hauser, Frank
    Stafflinger, Elisabeth
    Schneider, Martina
    Pauwels, Kevin
    Schoofs, Liliane
    Grimmelikhuijzen, Cornelis J. P.
    Genomics, transcriptomics and peptidomics of Daphnia pulex neuropeptides and protein hormones2011In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 10, no 10, p. 4478-4504Article in journal (Refereed)
    Abstract [en]

    We report 43 novel genes in the water flea Daphnia pulex encoding 73 predicted neuropeptide and protein hormones as partly confirmed by RT-PCR. MALDI-TOF mass spectrometry identified 40 neuropeptides by mass matches and 30 neuropeptides by fragmentation sequencing. Single genes encode adipokinetic hormone, allatostatin-A, allatostatin-B, a first crustacean allatotropin, Ala7-CCAP, one CCHamide, Arg7-corazonin, CRF-like (DH52) and calcitonin-like (DH31) diuretic hormones, two ecdysis-triggering hormones, two FIRFamides, one insulin- and one each of three IGF-related peptides, two alternative splice forms of short and long ion transport peptide (ITP), one each of two N-terminally elongated ITPs, myosuppressin, neuroparsin, two neuropeptide-F splice forms, three periviscerokinins (but no pyrokinins), pigment dispersing hormone, proctolin, Met4-proctolin, one novel short neuropeptide-F, three RYamides, SIFamide, two sulfakinins, three tachykinins. Two genes encode orcokinins, three genes different allatostatins-C. Paired gene clusters occur for two novel eclosion hormones; bursicons alpha, beta; glycoproteins GPA2, GPB5; and two of the allatostatin-C genes. Detailed comparisons of genes or their products with those from insects and decapod crustaceans revealed that the D. pulex peptides are often closer to their insect than to their decapod crustacean homologues, confirming that branchiopods, to which Daphnia belongs, are the ancestor group of insects.

  • 129.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology. Rheinische Friedrich-Wilhelms Universität, Germany.
    Webster, Simon G.
    School of Biological Sciences University of Wales, Bangor, UK.
    Keller, Rainer
    Immunocytochemical demonstration of the neurosecretory systems containing putative moult-inhibiting hormone and hyperglycemic hormone in the eyestalk of brachyuran crustaceans1988In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 251, p. 3-12Article in journal (Refereed)
    Abstract [en]

    By use of antisera raised against purified moultinhibiting (MIH) and crustacean hyperglycemic hormone (CHH) from Carcinus maenas, complete and distinct neurosecretory pathways for both hormones were demonstrated with the PAP and immunofluorescence technique. By double staining, employing a combination of silver-enhanced immunogold labelling and PAP, both antigens could be visualized in the same section. Immunoreactive structures were studied in Carcinus maenas, Liocarcinus puber, Cancer pagurus, Uca pugilator and Maja squinado. They were only observed in the X-organ sinus gland (SG) system of the eyestalks and consisted of MIH-positive perikarya, which were dispersed among the more numerous CHH-positive perikarya of the medulla terminalis X-organ (XO). The MIH-positive neurons form branching collateral plexuses adjacent to the XO and axons that are arranged around the CHH-positive central axon bundle of the principal XO-SG tract. In the SG, MIH-positive axon profiles and terminals, clustered around hemolymph lacunae, are distributed between the more abundant CHH-positive axon profiles and terminals. Colocalisation of MIH and CHH was never observed. The gross morphology of both neurosecretory systems was similar in all species examined, however, in U. pugilator and M. squinado immunostaining for MIH was relatively faint unless higher concentrations of antiserum were used. Possible reasons for this phenomenon as well as observed moult cycle-related differences in immunostaining are discussed.

  • 130.
    Dircksen, Heinrich
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Wilcockson, Dave C
    Webster, Simon G
    Neuropeptides in a forgotten crustacean neurohaemal organ classic, the postcomissural organs of the shrimp Palaemon serratus2005In: Comparative Biochemistry and Physiology A, ISSN 1095-6433, E-ISSN 1531-4332, Vol. 141, no 3, p. S156-S157Article in journal (Refereed)
  • 131.
    Duplisea, Daniel E.
    Stockholm University, Faculty of Science.
    Structuring of benthic communities, with a focus on size-spectra1998Doctoral thesis, comprehensive summary (Other academic)
  • 132.
    Döving, Kjell B.
    Stockholm University.
    Electrophysiological studies on olfactory discrimination in the frog1966Doctoral thesis, comprehensive summary (Other academic)
  • 133.
    Edsman, Lennart
    Stockholm University, Faculty of Science, Department of Zoology.
    Territoriality and competition in wall lizards1990Doctoral thesis, comprehensive summary (Other academic)
  • 134.
    Eidmann, Hubertus H.
    Stockholm University.
    Ökologische und physiologische Studien über die Lärchenminiermotte, Coleophora laricella HBN1965Doctoral thesis, monograph (Other academic)
  • 135.
    Eiríksson, Thorleifur
    Stockholm University, Faculty of Science, Department of Zoology.
    Female response and male singing strategies in two orthopteran species1992Doctoral thesis, comprehensive summary (Other academic)
  • 136.
    Ejdung, Gunilla
    Stockholm University, Faculty of Science, Department of Zoology.
    Predatory processes in Baltic benthos1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Baltic soft-bottom community is uniquely simple, with only a few benthic macro-faunal species, and is therefore well suited for mechanistic studies of inter-specific interactions. Two of the dominating organisms in this benthic community are the amphipod Monoporeia affinis and the bivalve Macoma balthica. Field surveys have shown that M. balthica is generally absent or scarce when the density of M. affinis is high. The hypothesis that adult M. affinis kill the newly settled bivalves was confirmed experimentally in the laboratory, and it was also shown that adult Pontoporeia femorata amphipods have a negative impact on bivalve survival. Further experiments, showed that juvenile M. affinis, contrary to earlier beliefs, can kill and presumably eat the newly settled M. balthica. The response of M. affinis to increased bivalve densities was a type III like functional response, indicating that bivalves at low densities find a partial refuge from amphipod predation.

    The effect of the predatory isopod Saduria entomon on the Macoma balthica population was assessed both in the laboratory and the field. In the laboratory, the presence of the isopod did not affect the small just settled bivalves (0.3 mm), whereas slightly larger and larger bivalves (>0.8 mm) suffered from increased mortality, as did bivalves in the three month long field study. The isopods are physically capable of opening quite large bivalves, a 34 mm long isopod can break open a 17 mm long bivalve, but given a choice, smaller bivalves are selected. When S. entomon is offered the two prey species, Monoporeia affinis and M. balthica, the amphipod is preferred, leaving the bivalve relatively safe from predation.

    In the aquatic environment, chemical substances released by predators or their activities can convey information, to which prey can respond, for example, by a change in behaviour. In a three-trophic-level food chain, species-specific chemical substances from a predatory fish, the short-horned sculpin (Myoxocephalus scorpius), directly affected the behaviour of the isopod Saduria entomon. The isopod remained buried in the sediment longer, and fewer prey amphipods, Monoporeia affinis, were eaten. Further, exposure to chemical substances from isopods feeding on amphipods, lead the amphipod to lower their swimming activity, whereas water from non-feeding isopods did not have this effect.

  • 137.
    Ekengren, Sophia
    Stockholm University.
    Stress- and immune defence in Drosophila melanogaster2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Many cellular responses are regulated at the transcriptional level. Newly synthesized proteins and peptides rapidly exert their function at the time of expression, as a response to different environmental cues. In an attempt to analyze transcriptional activation in response to bacteria, we have identified a novel family of eight stress-induced humoral factors, the Turandot proteins. All Turandot (Tot) genes are induced under stressful conditions such as bacterial infection, heat shock, UV-irradiation and oxidizing agents. One of the members, TotA, is shown to promote increased resistance to the lethal effects of high temperature, indicating that this protein family plays an important role for a systemic stress adaptation.

    This thesis also describes some novel aspects of the Drosophila immune response. Flies mutant for the transcriptional activator, and NF-kB homolog, Relish will not survive a bacterial or fungal infection. Transcriptional characterization shows that the synthesis of antibacterial effector molecules is almost eliminated in these flies. This establishes Relish as the main transcriptional activator for defence against Gram-negative bacteria and fungi.

    I also present novel findings about the antifungal properties of the immune peptide Cecropin A.

  • 138.
    Ekvall, Kenneth
    Stockholm University, Faculty of Science, Department of Zoology.
    Alloparental care and social dynamics in the fallow deer (Dama dama)1999Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In mammals, a sex difference exists in natal dispersal with females remaining in the natal area and males generally leaving the area of birth. Female groups are regarded as the basic social unit of many mammalian species, and in species with overlapping generations groups may develop a matrilineal structure. Under those conditions where daughters remain in their natal area, altruistic and/or co-operative behaviour may be favoured among both close and more distantly related kin.

    This thesis examines the social organisation and occurrence of co-operative behaviours in fallow deer populations in southern Sweden. Social groups were often stable in their constitution during and between years and consisted mostly of close relatives, mainly mothers and their daughters. When daughters gave birth they increased their association with their mothers. Alloparental care such as allosuckling and allogrooming, was common, preferably exhibited by older females toward fawns in the social group. All fawns in the group were given milk from alloparenting females but young females behaved more restrictively and approaching fawns were often met with aggression. Allosuckling attempts from fawns from other groups were not tolerated and met with aggression even from old females.

    Allogrooming, which reduced the number of attached ectoparasites on fawns, was distributed according to relatedness in the stable social unit and not performed towards fawns from other groups. Fawns started to reciprocate both the mother's, other females' and occasionally other fawns' grooming from the age of 8 weeks.

    Allogrooming between adult females was also performed unidirectionally between close kin members of the same group, or reciprocally between members of different groups in a tit for tat manner with a duration evenly matched between the performers. The results seem to support the notion of kin-based groups in fallow deer, with both kin-selected and reciprocal behaviours.

  • 139. Elliott, Kyle H.
    et al.
    Le Vaillant, Maryline
    Stockholm University, Faculty of Science, Department of Zoology. University of Strasbourg .
    Kato, Akiko
    Gaston, Anthony J.
    Ropert-Coudert, Yan
    Hare, James F.
    Speakman, John R.
    Croll, Donald
    Age-related variation in energy expenditure in a long-lived bird within the envelope of an energy ceiling2014In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 83, no 1, p. 136-146Article in journal (Refereed)
    Abstract [en]

    Energy expenditure in wild animals can be limited (i) intrinsically by physiological processes that constrain an animal's capacity to use energy, (ii) extrinsically by energy availability in the environment and/or (iii) strategically based on trade-offs between elevated metabolism and survival. Although these factors apply to all individuals within a population, some individuals expend more or less energy than other individuals. To examine the role of an energy ceiling in a species with a high and individually repeatable metabolic rate, we compared energy expenditure of thick-billed murres (Uria lomvia) with and without handicaps during a period of peak energy demand (chick-rearing, N=16). We also compared energy expenditure of unencumbered birds (N=260) across 8years exhibiting contrasting environmental conditions and correlated energy expenditure with fitness (reproductive success and survival). Murres experienced an energy ceiling mediated through behavioural adjustments. Handicapped birds decreased time spent flying/diving and chick-provisioning rates such that overall daily energy expenditure remained unchanged across the two treatments. The energy ceiling did not reflect energy availability or trade-offs with fitness, as energy expenditure was similar across contrasting foraging conditions and was not associated with reduced survival or increased reproductive success. We found partial support for the trade-off hypothesis as older murres, where prospects for future reproduction would be relatively limited, did overcome an energy ceiling to invest more in offspring following handicapping by reducing their own energy reserves. The ceiling therefore appeared to operate at the level of intake (i.e. digestion) rather than expenditure (i.e. thermal constraint, oxidative stress). A meta-analysis comparing responses of breeding animals to handicapping suggests that our results are typical: animals either reduced investment in themselves or in their offspring to remain below an energy ceiling. Across species, whether a handicapped individual invested in its own energy stores or its offspring's growth was not explained by life history (future vs. current reproductive potential). Many breeding animals apparently experience an intrinsic energy ceiling, and increased energy costs lead to a decline in self-maintenance and/or offspring provisioning.

  • 140.
    Elmgren, Ragnar
    Stockholm University.
    Baltic benthos communities and the role of the meiofauna1976Doctoral thesis, comprehensive summary (Other academic)
  • 141.
    Elmhagen, Bodil
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Åtgärdsprogram för fjällräv 2008-2012 : (Vulpes lagopus) : hotkategori: akut hotad2009Report (Other academic)
  • 142.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Eide, Nina E.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Killengreen, Siw T.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Wallén, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Åtgärdsprogram för fjällräv, 2017–2021 (Vulpes lagopus): Hotkategori: Starkt hotad EN2017Report (Other academic)
  • 143.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Hellström, Peter
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Kindberg, Jonas
    Changes in vole and lemming fluctuations in northern Sweden 1960-2008 revealed by fox dynamics2011In: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 48, no 3, p. 167-179Article in journal (Refereed)
    Abstract [en]

    Cyclic dynamics with extensive spatial synchrony has long been regarded as characteristic of key herbivores at high latitudes. This contrasts to recent reports of fading cycles in arvicoline rodents in boreal and alpine Fennoscandia. We investigate the spatio-temporal dynamics of boreal red fox and alpine arctic fox in Sweden as a proxy for the dynamics of their main prey, voles and Norwegian lemming, respectively. We analyse data from five decades, 1960-2008, with wavelets and autocorrelation approaches. Cyclic dynamics were identified with at least one method in all populations (arctic fox n = 3, red fox n = 6). The dynamics were synchronous between populations, or coupled with a 1-yr lag, in 8 of 13 pairwise comparisons. Importantly though, the dynamics were heterogeneous in space and time. All analytical approaches identified fading cycles in the three arctic fox populations and two northern red fox populations. At least one method identified similar patterns in three southern red fox populations. Red fox dynamics were cyclic in the 1970s primarily, while arctic fox dynamics was cyclic until the late 1980s or early 1990s. When cyclic, 4-yr cycles dominated in arctic fox and northern red fox, whilst 3-4-yr cycles was found in southern red foxes. Significant cyclic regimes reappeared in the 1990s or 2000s in two red fox populations and one arctic fox population. Cycles and regionally coupled dynamics appeared associated in northern arctic and red foxes. This study supports accumulating evidence which suggests that cyclic and synchronous patterns in the dynamics of lemmings and voles are nonstationary in space and time. Furthermore, the similar patterns of change in both fox species indicate that persistence of cycles is governed by similar mechanisms in lemmings and voles.

  • 144.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Pasanen-Mortensen, Marianne
    Stockholm University, Faculty of Science, Department of Zoology.
    Världens lodjursarter2014In: Lodjuret / [ed] Roger Bergström, Kjell Danell & Ingvar Svanberg, Stockholm: Atlantis , 2014, p. 9-29Chapter in book (Other (popular science, discussion, etc.))
  • 145.
    Enell, Lina E.
    Stockholm University, Faculty of Science, Department of Zoology.
    Chemical signalling in the Drosophila brain: GABA, short neuropeptide F and their receptors2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Gamma-aminobutyric acid (GABA) and short neuropeptide F (sNPF) are widespread signalling molecules in the brain of insects. In order to understand more about the signalling and to some extent start to unravel the functional roles of these two substances, this study has examined the locations of the transmitters and their receptors in the brain of the fruit fly Drosophila melanogaster using immunocytochemistry in combination with Gal4/UAS technique. The main focus is GABA and sNPF in feeding circuits and in the olfactory system. We found both GABA receptor types in neurons in many important areas of the Drosophila brain including the antennal lobe, mushroom body and the central body complex. The metabotropic GABAB receptor (GABABR) is expressed in a pattern similar to the ionotropic GABAAR, but some distribution differences can be distinguished (paper I). The insulin producing cells contain only GABABR, whereas the GABAAR is localized on neighbouring neurons. We found that GABA regulates the production and release of insulin-like peptides via GABABRs (paper II). The roles of sNPFs in feeding and growth have previously been established, but the mechanisms behind this are unclear. We mapped the distribution of sNPF with antisera to the sNPF precursor and found the peptide in a large variety of interneurons, including the Kenyon cells of the mushroom bodies, as well as in olfactory sensory neurons that send axons to the antennal lobe (paper III). We also mapped the distribution of the sNPF receptor in larval tissues and found localization in six median neurosecretory cells that are not insulin-producing cells, in neuronal branches in the larval antennal lobe and in processes innervating the mushroom bodies (paper IV).

    In summary, we have studied two different signal substances in the Drosophila brain (GABA and sNPF) in some detail. We found that these substances and their receptors are widespread, that both sNPF and GABA act in very diverse systems and that they presumably play roles in feeding, metabolism and olfaction.

  • 146.
    Englund, Jan
    Stockholm University.
    Population dynamics of the Swedish red fox, Vulpes vulpes (L.)1970Doctoral thesis, comprehensive summary (Other academic)
  • 147.
    Engström, Kjell
    Stockholm University.
    Studies on teleostean visual cells1963Doctoral thesis, comprehensive summary (Other academic)
  • 148.
    Enquist, Magnus
    Stockholm University.
    Game theory studies on aggressive behaviour1984Doctoral thesis, comprehensive summary (Other academic)
  • 149.
    Enquist, Magnus
    et al.
    Stockholm University, Faculty of Humanities, Centre for Cultural Evolution. Stockholm University, Faculty of Science, Department of Zoology.
    Hurd, Peter L.
    Ghirlanda, Stefano
    Stockholm University, Faculty of Humanities, Centre for Cultural Evolution.
    Signaling2010In: Evolutionary Behavioral Ecology / [ed] David F. Westneat, Charles W. Fox, Oxford: Oxford University Press, 2010, p. 266-284Chapter in book (Other academic)
  • 150.
    Envall, Ida
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Erséus, Christer
    Zoologiska institutionen, Göteborgs universitet.
    Gustavsson, Lena
    Avdelningen för evertebratzoologi, Naturhistoriska riksmuseet.
    Ultrastructural investigation of coelomocytes in representatives of Naidinae and Rhyacodrilinae (Annelida, Clitellata, Tubificidae)2008In: Journal of Morphology, Vol. 269, no 9, p. 1157-1167Article in journal (Refereed)
    Abstract [en]

    Various types of free-floating cells are found in the coelomic fluid of representatives of several annelid groups. The ultrastructure of these "coelomocytes," however, has been studied to a limited degree. In this study, we used a transmission electron microscope to investigate the coelomocytes in specimens of five species of Naidinae and three species of Rhyacodrilinae (all oligochaetous clitellates within the family Tubificidae). These were compared with each other and with previously described coelomocytes of representatives of other oligochaete taxa. Only one distinguishable coelomocyte type was found in the studied specimens: a round to oblong cell without pseudopodia or other appendages, primarily containing membrane-bound granules of varying electron density, a prominent network of rough endoplasmic reticulum, and free ribosomes. This type differs to a great extent from most of the previously described coelomocytes, but shows similarities to certain types found in members of Enchytraeidae and Megascolecidae. Although we noticed some variation, we did not find any ultrastructural characters in these cells obviously useful for phylogenetic studies within Tubificidae.

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