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  • 301.
    Lindblad, Cecilia
    Stockholm University, Faculty of Science, Department of Zoology.
    Perturbation of functions in shallow benthic ecosystems: exemplified by the Fucus vesiculosus community in the Baltic Sea1994Doctoral thesis, comprehensive summary (Other academic)
  • 302.
    Lindenfors, Patrik
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology. Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Neocortex evolution in primates: the 'social brain' is for females2005In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 1, p. 407-410Article in journal (Refereed)
    Abstract [en]

    According to the social intelligence hypothesis, relative neocortex size should be directly related to the degree of social complexity. This hypothesis has found support in a number of comparative studies of group size. The relationship between neocortex and sociality is thought to exist either because relative neocortex size limits group size or because a larger group size selects for a larger neocortex. However, research on primate social evolution has indicated that male and female group sizes evolve in relation to different demands. While females mostly group according to conditions set by the environment, males instead simply go where the females are. Thus, any hypothesis relating to primate social evolution has to analyse its relationship with male and female group sizes separately. Since sex-specific neocortex sizes in primates are unavailable in sufficient quantity, I here instead present results from phylogenetic comparative analyses of unsexed relative neocortex sizes and female and male group sizes. These analyses show that while relative neocortex size is positively correlated with female group size, it is negatively, or not at all correlated with male group size. This indicates that the social intelligence hypothesis only applies to female sociality.

  • 303.
    Lindenfors, Patrik
    Stockholm University.
    Phylogenetic analyses of sexual size dimorphism2002Doctoral thesis, comprehensive summary (Other academic)
  • 304.
    Lindenfors, Patrik
    Stockholm University, Faculty of Science, Department of Zoology.
    The green beards of language2013In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 3, no 4, p. 1104-1112Article in journal (Refereed)
    Abstract [en]

    Language transfers information on at least three levels; (1) what is said, (2) how it is said (what language is used), and, (3) that it is said (that speaker and listener both possess the ability to use language). The use of language is a form of honest cooperation on two of these levels; not necessarily on what is said, which can be deceitful, but always on how it is said and that it is said. This means that the language encoding and decoding systems had to evolve simultaneously, through mutual fitness benefits. Theoretical problems surrounding the evolution of cooperation disappear if a recognition system is present enabling cooperating individuals to identify each other if they are equipped with green beards. Here, I outline how both the biological and cultural aspects of language are bestowed with such recognition systems. The biological capacities required for language signal their presence through speech and understanding. This signaling cannot be invaded by false green beards because the traits and the signal of their presence are one and the same. However, the real usefulness of language comes from its potential to convey an infinite number of meanings through the dynamic handling of symbols through language itself. But any specific language also signals its presence to others through usage and understanding. Thus, languages themselves cannot be invaded by false green beards because, again, the trait and the signal of its presence are one and the same. These twin green beards, in both the biological and cultural realms, are unique to language.

  • 305.
    Lindenfors, Patrik
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Dalén, Love
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    A monophyletic origin of delayed implantation and its implications2003In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 57, p. 1952-1956Article in journal (Refereed)
  • 306.
    Lindenfors, Patrik
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Fröberg, Laila
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Nunn, Charles L
    Section of Evolution and Ecology, University of California, Davis, USA.
    Females drive primate social evolution2004In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 271, p. S101-S103Article in journal (Refereed)
    Abstract [en]

    Within and across species of primates, the number of males in primate groups is correlated with the number of females. This correlation may arise owing to ecological forces operating on females, with subsequent competition among males for access to groups of females. The temporal relationship between changes in male and female group membership remains unexplored in primates and other mammalian groups. We used a phylogenetic comparative method for detecting evolutionary lag to test whether evolutionary change in the number of males lags behind change in the number of females. We found that change in male membership in primate groups is positively correlated with divergence time in pairwise comparisons. This result is consistent with male numbers adjusting to female group size and highlights the importance of focusing on females when studying primate social evolution

  • 307.
    Linderoth, Maria
    et al.
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Norman, Anna
    Noaksson, Erik
    Zebühr, Yngve
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Norrgren, Leif
    Balk, Lennart
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Steroid biosynthetic enzyme activities in leachate-exposed female perch (Perca fluviatilis) as biomarkers for endocrine disruption2006In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 366, no 2-6, p. 638-648Article in journal (Refereed)
    Abstract [en]

    Studies have shown that adult female perch in a freshwater lake, Molnbyggen, Sweden, have a reproductive disorder caused by unidentified endocrine disrupting compounds (EDCs) leaching from a local refuse dump. The adverse effects include shallow open sores, low ratio of sexually mature individuals, low gonadosomatic index and low circulating levels of androgens. We hypothesised that the low androgen levels could be a result of impaired production and/or stimulated excretion of androgens by EDCs.

    From October 2000 to November 2001, at time-points important in the perch reproductive cycle, adult female perch were collected in Molnbyggen and in the reference lake, Djursjön. The activities of three key enzymes in androgen biosynthesis: 17α-hydroxylase (17OHlase), 17,20-lyase (lyase) and 17β-hydroxysteroid dehydrogenase (17βHSD) were determined in head kidney or ovary. The relationship between enzyme activities and plasma steroid concentrations was examined. Ovarian histopathology and the determination of brain aromatase activity were also included in the study.

    Similar 17OHlase, 17βHSD and aromatase activities were found in Molnbyggen females and reference fish throughout the year. Head kidney 17OHlase showed a positive correlation to cortisol levels (r = 0.754; p < 0.001) but not to androgen levels. Molnbyggen females exhibited lower ovarian lyase activity during vitellogenesis than reference fish. Atretic oocytes were on most occasions more frequent in sexually immature than in sexually mature females. The results suggest that neither 17OHlase, 17βHSD nor aromatase is the target for EDCs disrupting the androgen homeostasis of exposed female perch. Further investigation is needed to establish the role of decreased ovarian lyase activity in endocrine homeostasis, but the possibility of increased excretion of androgens should also be examined.

  • 308.
    Lindquist, Johanna M
    Stockholm University.
    Adrenergic Pathways to Map Kinase Activation2001Doctoral thesis, comprehensive summary (Other academic)
  • 309.
    Lindström, Åke
    et al.
    Lund University.
    Lind, Johan
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    Fuel deposition and speed of early autumn migration of juvenile bluethroats Luscinia s. svecica leaving their natal area in Swedish Lapland2002In: Ornis Svecica, Vol. 11, p. 253-264Article in journal (Refereed)
  • 310. Lisney, Thomas J.
    et al.
    Rubene, Diana
    Rozsa, Jani
    Løvlie, Hanne
    Stockholm University, Faculty of Science, Department of Zoology.
    Hastad, Olle
    Odeen, Anders
    Behavioural assessment of flicker fusion frequency in chicken Gallus gallus domesticus2011In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 51, no 12, p. 1324-1332Article in journal (Refereed)
    Abstract [en]

    To interact with its visual environment, an organism needs to perceive objects in both space and time. High temporal resolution is hence important to the fitness of diurnally active animals, not least highly active aerial species such as birds. However, temporal resolution, as assessed by flicker fusion frequency (FFF; the stimulus frequency at which a flickering light stimulus can no longer be resolved and appears continuous) or critical flicker fusion frequency (CFF; the highest flicker fusion frequency at any light intensity) has rarely been assessed in birds. In order to further our understanding of temporal resolution as a function of light intensity in birds we used behavioural experiments with domestic chickens (Gallus gallus domesticus) from an old game breed 'Gammalsvensk dvarghona' (which is morphologically and behaviourally similar to the wildtype ancestor, the red jungle fowl, G. gallus), to generate an 'Intensity/FFF curve' (I/FFF curve) across full spectrum light intensities ranging from 0.2 to 2812 cd m(-2). The I/FFF curve is double-branched, resembling that of other chordates with a duplex retina of both rods and cones. Assuming that the branches represent rod and cone mediated responses respectively, the break point between them places the transition between scotopic and photopic vision at between 0.8 and 1.9 cd m(-2). Average FFF ranged from 19.8 Hz at the lowest light intensity to a CFF 87.0 Hz at 1375 cd m(-2). FFF dropped slightly at the highest light intensity. There was some individual variation with certain birds displaying CFFs of 90-100 Hz. The FFF values demonstrated by this non-selected breed appear to be considerably higher than other behaviourally derived FFF values for similar stimuli reported for white and brown commercial laying hens, indicating that the domestication process might have influenced temporal resolution in chicken.

  • 311.
    Lissåker, Maria
    Stockholm University, Faculty of Science, Department of Zoology.
    Does time of the season influence filial cannibalism in the sand goby, Pomatoschistus minutus?2007In: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 80, no 1, p. 69-75Article in journal (Refereed)
    Abstract [en]

    According to life-history theory, filial cannibalism by fish that breed over one season only should be more beneficial early than late in the season if they eat eggs to invest energy into later clutches. Also, filial cannibalism may be more costly late in the season if finding ripe females for replacing eaten eggs is harder then. On the other hand, offspring hatching early may have a competitive advantage over fry hatching late and hence provide higher fitness to the parent. Using data collected over three successive years, I tested if sand goby males are more prone to eat of their eggs early than late in the reproductive season. I found no difference in the amount of eggs eaten or in the frequency of males eating the whole clutch between early and late in the season. Furthermore, there was no difference in the frequency of males who ate parts of their clutches, early compared to late. This might reflect a tradeoff between quality (early hatching offspring) and quantity (producing as many offspring as possible over a long reproductive season). If so, the lack of seasonal pattern of filial cannibalism found in sand gobies might be the result of opposing selection pressures.

  • 312.
    Liu, Ling
    Stockholm University.
    Cell and molecular biology of muscular dystrophy2000Doctoral thesis, comprehensive summary (Other academic)
  • 313.
    Lomas Vega, Marta
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. University of Copenhagen, Denmark.
    Thorup, Kasper
    Local weather, food resources and breeding stage influence Thrush Nightingale movement2018In: Ornis Fennica, ISSN 0030-5685, Vol. 95, no 4, p. 151-159Article in journal (Refereed)
    Abstract [en]

    Insectivorous migrants breeding at northern latitudes often time the breeding period with the seasonal peak of food resources. Whether this general pattern transfers to movement behaviour during the breeding season requires detailed study from a local perspective. We investigated fine-scale environmental correlates of movements by six actively-breeding adult Thrush Nightingales (Luscinia luscinia) at a breeding site in Denmark, using radio tracking and multiple regression models. Overall, the chick-rearing period coincided with the peak of vegetation greenness at the site. Adults flew further from nesting areas during stable weather and as vegetation greenness decreased. Adults were more active at higher environmental temperatures and when fledglings were older but still dependent on adults. These changes in local movements likely reflect adjustments to chick developmental needs and to specific local environmental conditions, including resource availability.

  • 314. Luksenburg, Jolanda A.
    et al.
    Henriquez, Angiolina
    Sangster, George
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology. Swedish Museum of Natural History, Sweden.
    Molecular and morphological evidence for the subspecific identity of Bryde’s whales in the southern Caribbean2015In: Marine mammal science, ISSN 0824-0469, E-ISSN 1748-7692, Vol. 31, no 4, p. 1568-1579Article in journal (Refereed)
  • 315.
    Luksenburg, Jolanda
    et al.
    George Mason University.
    Sangster, George
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology.
    New seabird records from Aruba, southern Caribbean, including three pelagic species new for the island2013In: Marine Ornithology, ISSN 1018-3337, E-ISSN 2074-1235, Vol. 42, no 2, p. 183-186Article in journal (Refereed)
  • 316.
    Luo, Jiangnan
    Stockholm University, Faculty of Science, Department of Zoology.
    Regulation of insulin signaling and its developmental and functional roles on peptidergic neurons in the Drosophila central nervous system2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In Drosophila, eight insulin-like peptides (DILP1-8) are produced and secreted in different locations. They regulate many aspects of development and physiology, such as organism growth, metabolic homeostasis, reproduction, stress resistance and life span. DILP2, 3 and 5 are mainly produced by a cluster of median neurosecretory cells in the brain known as insulin producing cells (IPCs). Here we showed that IPCs are under tight regulation of two G-protein coupled receptors (GPCRs), serotonin receptor 5-HT1A and octopamine receptor OAMB. Genetic manipulations of these two receptors in IPCs affected transcription levels of DILPs, hence altered feeding, carbohydrate levels, and resistance to stress (Paper I and II). Moreover, we showed that the insulin receptor (dInR) is strongly expressed in leucokininergic neurons (LK neurons), and selectively regulates growth of around 300 neuropeptidergic neurons expressing the bHLH transcription factor DIMMED. Overexpression of dInR in DIMM-positive neurons led to substantial neuronal growth, including cell body size, golgi apparatus and nuclear size, while knockdown of dInR had the opposite effect (Paper III). Manipulations of components in the insulin signaling pathway in LK neurons resulted in the similar cell size phenotypes. Furthermore, dInR regulated size scaling of DIMM-postive neurons is nutrient-dependent and partially requires the presence of DIMM (Paper III). Finally, we investigated the roles of DILPs (2, 3, 5 and 7) and LK neurons in regulation of feeding and diuresis at the adult stage (Paper IV).  In summary, we have identified two more regulators for IPC activity and demonstrated developmental roles of  DILPs and dInR in regulating neuronal size. Moreover, DILPs regulate water homeostasis together with a diuretic hormone leucokinin and as a consequence affects feeding behavior.

  • 317.
    Luo, Jiangnan
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Lushchak, Oleh V.
    Stockholm University, Faculty of Science, Department of Zoology.
    Goergen, Philip
    Williams, Michael J.
    Nässel, Dick R.
    Stockholm University, Faculty of Science, Department of Zoology.
    Drosophila Insulin-Producing Cells Are Differentially Modulated by Serotonin and Octopamine Receptors and Affect Social Behavior2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 6, p. e99732-Article in journal (Refereed)
    Abstract [en]

    A set of 14 insulin-producing cells (IPCs) in the Drosophila brain produces three insulin-like peptides (DILP2, 3 and 5). Activity in IPCs and release of DILPs is nutrient dependent and controlled by multiple factors such as fat body-derived proteins, neurotransmitters, and neuropeptides. Two monoamine receptors, the octopamine receptor OAMB and the serotonin receptor 5-HT1A, are expressed by the IPCs. These receptors may act antagonistically on adenylate cyclase. Here we investigate the action of the two receptors on activity in and output from the IPCs. Knockdown of OAMB by targeted RNAi led to elevated Dilp3 transcript levels in the brain, whereas 5-HT1A knockdown resulted in increases of Dilp2 and 5. OAMB-RNAi in IPCs leads to extended survival of starved flies and increased food intake, whereas 5-HT1A-RNAi produces the opposite phenotypes. However, knockdown of either OAMB or 5-HT1A in IPCs both lead to increased resistance to oxidative stress. In assays of carbohydrate levels we found that 5-HT1A knockdown in IPCs resulted in elevated hemolymph glucose, body glycogen and body trehalose levels, while no effects were seen after OAMB knockdown. We also found that manipulations of the two receptors in IPCs affected male aggressive behavior in different ways and 5-HT1A-RNAi reduced courtship latency. Our observations suggest that activation of 5-HT1A and OAMB signaling in IPCs generates differential effects on Dilp transcription, fly physiology, metabolism and social interactions. However the findings do not support an antagonistic action of the two monoamines and their receptors in this particular system.

  • 318. Luo, Yi
    et al.
    Zhong, Mao Jun
    Huang, Yan
    Li, Feng
    Liao, Wen Bo
    Kotrschal, Alexander
    Stockholm University, Faculty of Science, Department of Zoology.
    Seasonality and brain size are negatively associated in frogs: evidence for the expensive brain framework2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 16629Article in journal (Refereed)
    Abstract [en]

    The challenges of seasonal environments are thought to contribute to brain evolution, but in which way is debated. According to the Cognitive Buffer Hypothesis (CBH) brain size should increase with seasonality, as the cognitive benefits of a larger brain should help overcoming periods of food scarcity via, for instance, increased behavioral flexibility. However, in line with the Expensive Brain Framework (EBF) brain size should decrease with seasonality because a smaller brain confers energetic benefits in periods of food scarcity. Empirical evidence is inconclusive and mostly limited to homoeothermic animals. Here we used phylogenetic comparative analyses to test the impact of seasonality on brain evolution across 30 species of anurans (frogs) experiencing a wide range of temperature and precipitation. Our results support the EBF because relative brain size and the size of the optic tectum were negatively correlated with variability in temperature. In contrast, we found no association between the variability in precipitation and the length of the dry season with either brain size or the sizes of other major brain regions. We suggest that seasonality-induced food scarcity resulting from higher variability in temperature constrains brain size evolution in anurans. Less seasonal environments may therefore facilitate the evolution of larger brains in poikilothermic animals.

  • 319.
    Lyrholm, Thomas
    Stockholm University, Faculty of Science, Department of Zoology.
    Sperm Whales: Social Organization and Global Genetic Structure1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The social organization of most mammals is characterised by female philopatry and male dispersal. This thesis examines the social organization of sperm whales, Physeter macrocephalus, using a combination of field observations and molecular genetic techniques. A major conclusion is that widely dispersing males sometimes may move between oceans, whereas this is probably less common in females.

    Analyses of re-sightings of recognisable female and immature sperm whales in the Galápagos islands indicated that they live in stable social groups of about 13 whales, which may represent family units, and that these units associated with each other for periods of days. There was a high turnover by movements of groups in and out of the study area, and the groups seemed to be part of a larger population which may be geographically localised.

    These observations, together with previous knowledge that males disperse from their natal groups to higher latitudes, while females and juveniles are limited to low latitudes, led to the hypothesis that breeding dispersal between oceans may be more common among males than among females. If so, one might expect less differentiation in the bi-parental nuclear genome than in the maternally inherited mitochondrial DNA (mtDNA) on a global scale. This hypothesis was examined by genetic analyses of samples from the North Atlantic, North Pacific and Southern Hemisphere, representing a substantial part of the global range of the species.

    Global variation in mtDNA control region sequences revealed an unusually low diversity, and an evolutionarily recent common ancestry of less than 100,000 years, perhaps even less than 25,000 years. This implies a young global population structure of sperm whales. There was highly significant heterogeneity in mtDNA haplotype frequencies between oceans, indicating that female dispersal between oceans has been limited during the period since mtDNA ancestry, allowing some global differentiation to develop. In contrast, analysis of variation in allele frequencies at nine nuclear microsatellite loci did not indicate significant genetic heterogeneity between oceans. Taken together, these patterns suggest that movements between oceans have been more prevalent among males than among females. This is also consistent with observations of females being the philopatric sex and having a more limited latitudinal distribution than males. Consequently, the typical mammalian dispersal pattern may have operated on a global scale in sperm whales.

    Analysis of genetic differentiation between potential social groups of females within oceanic areas indicated significant heterogeneity in both mtDNA and microsatellites, and the amount of differentiation in mtDNA was estimated to be an order of magnitude higher than that between oceans. These results thus seem to support the notion of groups of females at least partly being composed of matrilineally related individuals, which may be of importance for an understanding of the evolution of sociality in this species.

  • 320.
    Löwenborg, Kristin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Gotthard, Karl
    Stockholm University, Faculty of Science, Department of Zoology.
    Hagman, Mattias
    Stockholm University, Faculty of Science, Department of Zoology.
    How a thermal dichotomy in nesting environments influences offspring of the world's most northerly oviparous snake, Natrix natrix (Colubridae)2012In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 107, no 4, p. 833-844Article in journal (Refereed)
    Abstract [en]

    Temperature has a major influence on the rate of embryonic development in ectothermic organisms. While incubation experiments unambiguously show that constant high temperature accelerates development and shortens embryonic life, studies on the effect of fluctuating temperatures have generated contradictory results. Grass snakes (Natrix natrix) occur at latitudes and altitudes that are unusually cool for an oviparous reptile. In these cool climates females typically lay their eggs in heat-generating anthropogenic microhabitats that provide either a highly fluctuating (compost piles) or a relatively constant (manure heaps) thermal nesting environment. A laboratory experiment with fluctuating and constant incubation temperatures mimicking those recorded in such nests in the field showed that this nest-site dichotomy influences the development of the embryos, and the morphology and locomotor performance of the hatchlings. The incubation period increased at fluctuating temperatures and the fact that the rate of embryonic development showed a decelerating pattern with temperature suggests that periods of low temperature had a relatively larger influence on average development than periods of high temperature. Our study demonstrates how a dichotomy in the nesting environments available to female grass snakes in cool climates can affect variation in the duration of the incubation period and offspring phenotypes in ways that may have consequences for fitness.

  • 321.
    Løvlie, Hanne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Pizzari, Tommaso
    Sex in the morning or in the evening?: Females adjust daily mating patterns to the intensity of sexual harassment2007In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 170, no 1, p. E1-E13Article in journal (Refereed)
    Abstract [en]

    Selection on males to mate at a higher rate than females often results in male harassment of females and counteracting female responses. When the reproductive value of copulation changes over time, these mating strategies are expected to be time dependent. Here, we demonstrate that variation in the intensity of male harassment leads to drastic changes in female daily mating patterns. In feral populations of fowl Gallus gallus domesticus, male harassment is intense, particularly in the evening when inseminations are most likely to result in fertilization. We experimentally manipulated the intensity of male harassment through similar‐sized groups of different sex ratios. Male mating propensity was always higher than females’, particularly in male‐biased groups and in the evening, when males were closer to and more likely to approach females. Females counteracted male harassment by escalating resistance to mating and—crucially—by shifting their daily mating pattern: in strongly female‐biased groups with relaxed sexual harassment, females solicited sex in the evening, while in male‐biased groups, they solicited sex in the morning, thus avoiding harassment in the evening. Together, these results indicate that intersexual conflict may occur not only over mating rates but also over when in the day to copulate.

  • 322. Mangerich, Sigrid
    et al.
    Keller, Rainer
    Dircksen, Heinrich
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Rao, K. Ranga
    Riehm, John P.
    Immunocytochemical localization of pigment-dispersing hormone (PDH) and its coexistence with FMRFamide-immunoreactive material in the eyestalks of the decapod crustaceans Carcinus maenas and Orconectes limosus1987In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 250, p. 365-375Article in journal (Refereed)
    Abstract [en]

    By use of a new antiserum, raised against synthetic pigment-dispersing hormone (PDH) from Uca pugilator, immunoreactive structures were studied at the light-microscopic level in the eyestalk ganglia of Carcinus maenas and Orconectes limosus. PDH-reactivity was mainly found in two types of neurons that were located between the medulla interna (MI) and the medulla terminalis (MT) in both species. Several additional perikarya were located in the distal part of the MI in O. limosus. In C. maenas, two to three PDH-positive perikarya were found in the region of the X-organ (XO) in the MT. Processes from single and clustered cells could be traced into all medullae of the eyestalk. Axons from the immunoreactive perikarya running between MI and MT form a larger tract that traverses the MT. Fibers from this tract give rise to extensive arborizations and plexuses throughout the proximal MT. A plexus containing very fine fibers is located at the surface of the MT in a position distal to the XO-area of C. maenas only. The proximal plexus also receives PDH-positive fibers through the optic nerve. PDH-perikarya in the cerebral ganglion may also project into the more distal regions of the eyestalk. Distal projections of the perikarya between the MI and MT consist of several branches. Most of these are directed toward the MI and ME (medulla externa) wherein they form highly organized, layered plexuses. One branch was traced into the principal neurohemal organ, the sinus gland (SG). In the SG, the tract gives off arborizations and neurosecretory terminals. It then proceeds in a proximal direction out of the SG, adjacent to the MT. Its further course could not be elucidated. The lamina ganglionaris (LG) receives PDH-fibers from the ME and fine processes from small perikarya located in close association with the LG in the distal part of the first optic chiasma. The architecture of PDH-positive elements was similar in both C. maenas and O. limosus. The distribution of these structures suggests that PDH is not only a neurohormone but may, in addition, have a role as a neurotransmitter or modulator. Immunostaining of successive sections with an FMRF-amide antiserum revealed co-localization of FMRFamideand PDH-immunoreactivities in most, but not all PDH-containing perikarya and fibers. The axonal branch leading to the SG and the SG proper were devoid of FMRFamide immunoreactivity.

  • 323. Martínez-Abadias, Neus
    et al.
    Esparza, Mireia
    Sjøvold, Torstein
    Stockholm University, Faculty of Humanities, Osteology Unit.
    Gonzalez-Jose, Rolando
    Santos, Mauro
    Hernandez, Miquel
    Heritability of human cranial dimensions: comparing the evolvability of different cranial regions2009In: Journal of Anatomy, ISSN 0021-8782, E-ISSN 1469-7580, Vol. 214, no 1, p. 19-35Article, review/survey (Refereed)
    Abstract [en]

    Quantitative craniometrical traits have been successfully incorporated into population genetic methods to provide insight into human population structure. However, little is known about the degree of genetic and non-genetic influences on the phenotypic expression of functionally based traits. Many studies have assessed the heritability of craniofacial traits, but complex patterns of correlation among traits have been disregarded. This is a pitfall as the human skull is strongly integrated. Here we reconsider the evolutionary potential of craniometric traits by assessing their heritability values as well as their patterns of genetic and phenotypic correlation using a large pedigree-structured skull series from Hallstatt (Austria). The sample includes 355 complete adult skulls that have been analysed using 3D geometric morphometric techniques. Heritability estimates for 58 cranial linear distances were computed using maximum likelihood methods. These distances were assigned to the main functional and developmental regions of the skull. Results showed that the human skull has substantial amounts of genetic variation, and a t-test showed that there are no statistically significant differences among the heritabilities of facial, neurocranial and basal dimensions. However, skull evolvability is limited by complex patterns of genetic correlation. Phenotypic and genetic patterns of correlation are consistent but do not support traditional hypotheses of integration of the human shape, showing that the classification between brachy- and dolicephalic skulls is not grounded on the genetic level. Here we support previous findings in the mouse cranium and provide empirical evidence that covariation between the maximum widths of the main developmental regions of the skull is the dominant factor of integration in the human skull.

  • 324. McClanahan, Tim R.
    et al.
    Muthiga, Nyawira A.
    Maina, Joseph
    Kamukuru, Alboghast T.
    Yahya, Saleh A.S.
    Stockholm University, Faculty of Science, Department of Zoology.
    Changes in northern Tanzania coral reefs during a period of increased fisheries management and climatic disturbance2009In: Aquatic conservation, ISSN 1052-7613, E-ISSN 1099-0755, Vol. 19, no 7, p. 758-771Article in journal (Refereed)
    Abstract [en]

    1. Surveys of coral reefs in northern Tanzania were conducted in 2004/5 with the aim of comparing them over an∼8-year period during a time of increased efforts at fisheries management and the 1998 El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) coral mortality event that caused 45% mortality in northern Tanzania and much of the Indian Ocean.

    2. Changes associated with both management, its absence, and the ENSO were found but changes were generally small and ecological measures indicated stability or improvements over this period, particularly when compared with reports from much of the northern Indian Ocean.

    3. Fisheries management in two areas increased the biomass of fish and benthic communities. A small fisheries closure (0.3 km2) displayed little change in the coral community but ecological conditions declined as measured by sea urchins and fish abundances. This change may be associated with its small size because similar changes were not measured in the large closure (28 km2).

    4. The few sites without any increased management were still degraded and one site had experienced a population explosion of a pest sea urchin, Echinometra mathaei.

    5. The lack of significant changes across this disturbance indicates that these reefs are moderately resilient to climate change and, therefore, a high priority for future conservation actions.

  • 325. Meager, J. J.
    et al.
    Rodewald, P.
    Domenici, P.
    Ferno, A.
    Järvi, Torbjörn
    Stockholm University, Faculty of Science, Department of Zoology.
    Skjaeraasen, J. E.
    Sverdrup, G. K.
    Behavioural responses of hatchery-reared and wild cod Gadus morhua to mechano-acoustic predator signals2011In: Journal of Fish Biology, ISSN 0022-1112, E-ISSN 1095-8649, Vol. 78, no 5, p. 1437-1450Article in journal (Refereed)
    Abstract [en]

    The behavioural responses of wild (predator-experienced) and hatchery-reared (predator-naive) cod Gadus morhua to standardized mechano-acoustic (MA) stimuli were compared in the laboratory. Wild fish responded mainly with freezing and fast-start escapes away from the stimulus, whereas hatchery-reared fish often ignored or approached the stimulus. Wild fish also had stronger responses, turning faster during escapes and reducing activity immediately after the stimulus. Both fish types were less active on a 'risky' bare substratum after the stimulus. The antipredator responses of wild fish were consistent to repeated stimuli, whereas hatchery-reared fish that had generally only encountered harmless stimuli showed more variable responses with lower repeatability. This suggests that experience plays a role in shaping the behavioural response of fishes to MA stimuli.

  • 326.
    Mehnert, Kerstin I.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Cantera, Rafael
    Stockholm University, Faculty of Science, Department of Zoology.
    Circadian rhythms in the morphology of neurons in Drosophila2011In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 344, no 3, p. 381-389Article, review/survey (Refereed)
    Abstract [en]

    Neurons have an enormous capacity to adapt to changing conditions through the regulation of gene expression, morphology, and physiology. In the fruit fly Drosophila melanogaster, this plasticity includes recurrent changes taking place within intervals of a few hours during the day. The rhythmic alterations in the morphology of neurons described so far include changes in axonal diameter, branching complexity, synapse numbers, and the number of synaptic vesicles. The cycles of these changes have larger amplitude when the fly is exposed to light, but they persist in constant darkness and require the expression of the clock genes period and timeless, leading to the concept of circadian plasticity. The molecular mechanisms driving these cycles appear to require the expression of these genes either inside the neurons themselves or in other peripheral pacemaker cells. Loss-of-function mutations in period and timeless not only abolish the morphological rhythms, but also often cause abnormal axonal branching suggesting that circadian plasticity is relevant for the maintenance of normal morphology. Research into whether (1) circadian plasticity is a common feature of neurons in all animals and (2) our own neurons change shape between day and night will be of interest.

  • 327.
    Meijer, Tomas
    Stockholm University, Faculty of Science, Department of Zoology.
    To survive and reproduce in a cyclic environment – demography and conservation of the Arctic fox in Scandinavia2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns the conservation and life history of the Arctic fox (Vulpes lagopus) in Scandinavia. The Arctic fox was historically a widely distributed species in the Scandinavian mountain tundra with a population size of approximately 10 000 individuals during years with high resource availability, i.e. rodent peaks. However, due to over-harvest in the end of the 19th century, the population numbers declined to a few hundred individuals. Although legally protected for more than 80 years, the population has remained small. The main causes of the non-recovery have been attributed to irregularities in the lemming cycle and increased competitions with the larger red fox. 

    Through conservation actions including red fox culling and supplementary feeding, the population has started to recover in parts of its former distribution range. The Arctic fox is highly adapted to the lemming cycle and determine whether to reproduce or not and adjust the litter size relation to small rodent phase in combination with food abundance. In the small rodent increase phase, females produce litters equal to the peak phase, despite higher food abundance in the later. This overproduction of cubs can be selected for through a higher juvenile survival and reproductive value of cubs born in the increase phase compared to the other phases. The most important component affecting the reproductive value seem to be the survival during the first year after birth. In the small rodent increase phase 32% of the cubs survives their first year compared to 9% in the decrease phase. The Arctic fox in Scandinavia constitute an example of how a species can adapt their reproductive strategy to a fluctuating environment by adjustment of the reproduction.

  • 328.
    Meijer, Tomas
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Mattsson, Roland
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Osterman-Lind, Eva
    Fernandez-Aguilar, Xavier
    Gavier-Widen, Dolores
    Endoparasites in the endangered Fennoscandian population of arctic foxes (Vulpes lagopus)2011In: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 57, no 4, p. 923-927Article in journal (Refereed)
    Abstract [en]

    The Fennoscandian arctic fox (Vulpes lagopus) population is endangered due to overharvest and competition with the larger red fox (Vulpes vulpes). In this study, we have screened the population in Sweden for endoparasites by analysis of non-invasively faecal samples collected at reproductive dens during two summers, one with low food abundance (2008) and the other with high food abundance (2010). Eggs, larvae and oocysts of a total of 14 different endoparasites were identified with a species richness per inhabited den of 3.2 (CI95% +/- 0.48) in 2008 and 2.7 (CI95% +/- 0.72) in 2010. Capillariidae-like eggs was identified at 59% of the dens in 2008 and 57% in 2010 and Toxocara canis with 7% (2008) and 30% (2010); Toxascaris leonina with 93% (2008) and 65% (2010); Uncinaria stenocephala 65% (2008) and 39% (2010); Crenosoma vulpis 3% (2008) and 4% (2010); Trichuris sp. 7% (2008) and 4% (2010); Cystoisospora canis-like oocysts 28% (2008) and 26% (2010); Cystoisospora ohiensis-like oocysts 38% (2008) and 4% (2010); Eimeria sp. 7% (2008) and 9% (2010); Sarcocystis sp. 3% (2008) and 9% (2010); Taenia sp. 10% (2008) and 4% (2010); Mesocestoides sp. 3% (2008) and 0% (2010); Balantidium sp. 0% (2008) and 9% (2010) and Spiruroidea-like eggs 0% (2008) and 4% (2010). To our knowledge, Balantidium sp., Sarcocystis sp. and Trichuris sp. has never been described before in wild arctic foxes.

  • 329.
    Meijer, Tomas
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    The impact of maternal experience on post-weaning survival in an endangered arctic fox population2011In: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 57, no 3, p. 549-553Article in journal (Refereed)
    Abstract [en]

    Behavioural differences in parental care can influence offspring survival through variation in e.g. antipredator behaviour and ability to provide food. In a broad range of species, offspring survival has been found to be higher for experienced females compared to inexperienced first-time breeders. The increase in offspring survival for experienced females has mainly been explained by improved experience in providing food. In this paper, we have studied post-weaning juvenile survival in relation to maternal experience in an endangered population of arctic foxes (Vulpes lagopus) in Fennoscandia. For cubs raised by inexperienced and experienced females, the survival rate was 0.42 (CI 95% +/- 0.31) and 0.87 (CI 95% +/- 0.08), respectively. There was no difference in body condition between the cubs and no observations of starvation. We suggest that the difference in survival was due to lack of experience to one of the most common predators, the golden eagle (Aquila chrysaetos). Golden eagles were mainly observed on dens with litters where the females were inexperienced first-time breeders. From a conservation perspective, it is therefore important to increase adult survival through actions to enlarge the proportion of experienced breeders.

  • 330.
    Meijer, Tomas
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Hellström, Peter
    Stockholm University, Faculty of Science, Department of Zoology.
    Dalén, Love
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Estimating population parameters in a threatened arctic fox population using molecular tracking and traditional field methods2008In: Animal Conservation, ISSN 1469-1795, Vol. 11, no 4, p. 330-338Article in journal (Refereed)
    Abstract [en]

    Comprehensive population parameter data are useful for assessing effective conservation actions. The Fennoscandian arctic fox Alopex lagopus is critically endangered and the population size is estimated at 120 individuals that are fragmented into four isolated populations. Here, we use molecular tracking and visual observations to estimate population size and survival in one of the populations on the Swedish mountain tundra during a year of low food availability. We collected 98 arctic fox faecal samples during the winter of 2006 and recorded visual observations of ear-tagged individuals during the summer of 2005 and 2006. The faecal samples were analysed for variation in nine microsatellite loci and matched to the genetic profiles of previously ear-tagged individuals from 2001 to 2005. During winter 2006, the minimum number alive was 12 individuals using visual observations, 30 using molecular tracking and 36 by combining the datasets. Population size was estimated through mark–recapture for the molecular tracking and visual observation datasets and through rarefaction analyses for molecular tracking data. The mark–recapture estimate for visual observations was uninformative due to the large confidence interval (CI) (i.e. 6–212 individuals). Based on the molecular tracking dataset combined with the minimum number alive for visual observations and molecular tracking, we concluded a consensus population size of 36–55 individuals. We also estimated the age-specific finite survival rate during 1 year (July 2005 to July 2006) by combining molecular tracking with visual observations. Juvenile survival on a yearly basis was 0.08 (95% CI 0.02–0.18) while adults had a survival of 0.59 (95% CI 0.39–0.82). Juveniles displayed a lower survival than the adults during autumn (P<0.01) whereas no age-specific survival difference during spring was found. The risk of negative effects due to the small population size and low juvenile survival is accordingly considerable.

  • 331.
    Merilaita, Sami
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Lind, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Background-matching, disruptive coloration and the evolution of cryptic coloration2005In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 272, p. 665-670Article in journal (Refereed)
    Abstract [en]

    Cryptic prey coloration typically bears a resemblance to the habitat the prey uses. It has been suggested that coloration which visually matches a random sample of the background maximizes background matching. We studied this previously untested hypothesis, as well as another, little studied principle of concealment, disruptive coloration, and whether it could, acting in addition to background matching, provide another plausible means of achieving camouflage. We presented great tits (Parus major) with artificial background-matching and disruptive prey (DP), and measured detection times. First, we studied whether any random sample of a background produces equally good crypsis. This turned out to not be the case. Next, we compared the DP and the best background-matching prey and found that they were equally cryptic. We repeated the tests using prey with all the coloration elements being whole, instead of some of them being broken by the prey outline, but this did not change the result. We conclude that resemblance of the background is an important aspect of concealment, but that coloration matching a random visual sample of the background is neither sufficient nor necessary to minimize the probability of detection. Further, our study lends empirical support to the principle of disruptive coloration.

  • 332.
    Merilaita, Sami
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Ruxton, Graeme
    Optimal apostatic selection: how should predators adjust to variation in prey frequencies?2009In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 77, no 1, p. 239-245Article in journal (Refereed)
    Abstract [en]

    Although frequency-dependent predation or apostatic selection has been established as one of the phenomena that may promote prey diversity, little is known about its selection. We studied such selection with a model with two prey types, treating frequency-dependent predator behaviour as an evolving trait determined by two parameters. One parameter controlled change in both prey type detection probabilities as a consequence of detecting a prey individual of a given type, and the other controlled the maximal amount of bias in detection probabilities of the two prey types. We let frequency-dependent behaviour evolve under different conditions of prey frequency variation. We found that frequency-dependent predator behaviour was most beneficial when deviations from equal prey type frequencies were large. Furthermore, different patterns of prey type variation selected for different types of frequency-dependent predator behaviour. We conclude that optimal frequency-dependent predator behaviour is likely to vary with ecological conditions.

  • 333. Merilaita, Sami
    et al.
    Vallin, Adrian
    Kodandaramaiah, Ullasa
    Stockholm University, Faculty of Science, Department of Zoology.
    Dimitrova, Marina
    Stockholm University, Faculty of Science, Department of Zoology.
    Ruuskanen, Suvi
    Laaksonen, Toni
    Number of eyespots and their intimidating effect on naive predators in the peacock butterfly2011In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 22, no 6, p. 1326-1331Article in journal (Refereed)
    Abstract [en]

    Predation experiments have shown that the large eyespots (concentric rings of contrasting colors) found on the wings of several lepidopteran species intimidate passerine predators. According to the eye mimicry hypotheses, the intimidation is caused by predators associating the eyespots with the presence (of the eyes) of their own enemy. The conspicuousness hypothesis suggests, instead, that it is simply the conspicuousness of eyespot patterns that is intimidating, possibly due to a sensory bias. We studied how the number of eyespots, 2 or 4, influences intimidation. We predicted that if eye mimicry is important, the maximum response would be reached with a pair of eyespots. On the other hand, if conspicuousness is important, then more than 2 eyespots should result in an even stronger response. The peacock butterfly, Inachis io, has 4 large eyespots on its wings. We presented naive insectivorous birds (pied flycatcher, Ficedula hypoleuca) 2 different prey items made from wings of dead peacock butterflies and a mealworm between the wings. One group of birds received prey that had no or only 2 eyespots visible and the other group received prey that had no or all 4 eyespots visible. Eyespots clearly increased hesitation before attacks. Because the birds were naive, this difference in response to the eyespots was innate. Importantly, there was no difference in attack latency between 2 and 4 eyespots. We conclude that it is unlikely that conspicuousness as such has selected for eyespots in the peacock butterfly.

  • 334.
    Meyer-Wachsmuth, Inga
    Stockholm University, Faculty of Science, Department of Zoology. Naturhistoriska riksmuseet, Enheten för zoologi; Swedish Museum of Natural History, Department of Zoology.
    Through the magnifying glass - The big small world of marine meiofauna: Morphology, species and evolution in Nemertodermatida2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nemertodermatida is a group of microscopic marine worm-like animals that live as part of the marine meiofauna in sandy or muddy sediments; one species lives commensally in a holothurian. These benthic worms were thought to disperse passively with ocean currents, resulting in little speciation and thus wide or even cosmopolitan distributions. Individuals occur in low abundance and have few light microscopically available characters, which altogether may explain why only eight species had been described between the discovery of the taxon in 1930 and this thesis. We used molecular methods to address the diversity and phylogeny of this group for the first time. In a study of two nominal species with samples from all around the world, a high degree of cryptic speciation was discovered and several new species described. Diagnoses were based on molecular data complemented by morphological characters, where available. Given the patchy geographical record it can be assumed that the majority of the biodiversity of Nemertodermatida is yet to be described. A phylogenetic study including all but three known species revealed a deep divergence between the two families of Nemertodermatida but non-monophyly of the taxon was rejected by an Approximately Unbiased test.

    Confocal laser scanning microscopic studies of several species show that the pattern of the body-wall musculature and the nervous system are specific for different genera. The muscular system of all species consists of a basic orthogonal grid with specific diagonal musculature and specialized muscles associated with body openings. The mouth appears to be transient feature in Nemertodermatida, developing only after hatching and being reduced again in mature worms. The nervous system is highly variable with very different ground patterns between the genera, such as an epidermal net, a centralized neuropile or a commissural brain.

  • 335.
    Meyer-Wachsmuth, Inga
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology. Swedish Museum of Natural History, Sweden.
    Curini Galletti, Marco
    Jondelius, Ulf
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology. Swedish Museum of Natural History, Sweden.
    Hyper-Cryptic Marine Meiofauna: Species Complexes in Nemertodermatida2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 9, article id e107688Article in journal (Refereed)
    Abstract [en]

    Nemertodermatida are microscopically small, benthic marine worms. Specimens of two nominal species, Sterreria psammicola and Nemertinoides elongatus from 33 locations worldwide were sequenced for three molecular markers. Species delimitation and validation was done using gene trees, haplotype networks and multilocus Bayesian analysis. We found 20 supported species of which nine: Nemertinoides glandulosum n.sp., N. wolfgangi n.sp., Sterreria boucheti n.sp., S. lundini n.sp., S. martindalei n.sp., S. monolithes n.sp., S. papuensis n.sp., S. variabilis n.sp. and S. ylvae n.sp., are described including nucleotide-based diagnoses. The distribution patterns indicate transoceanic dispersal in some of the species. Sympatric species were found in many cases. The high level of cryptic diversity in this meiofauna group implies that marine diversity may be higher than previously estimated. 

  • 336.
    Meyer-Wachsmuth, Inga
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology. Naturhistoriska riksmuseet, Enheten för zoologi; Swedish Museum of Natural History, Department of Zoology.
    Jondelius, Ulf
    Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology. Naturhistoriska riksmuseet, Enheten för zoologi; Swedish Museum of Natural History, Department of Zoology.
    A multigene molecular assessment reveals deep divergence in the phylogeny of NemertodermatidaManuscript (preprint) (Other academic)
    Abstract [en]

    Here we present a comprehensive phylogeny of Nemertodermatida, a taxon of microscopic marine worms, based for the first on molecular marker with consideration of morphological characters. Our dataset comprises three nuclear genes and most nominal and putative species including recently described cryptic species; only species of the genus Ascoparia could not be obtained. We show that the two families of Nemertodermatida, Ascopariidae and Nemertodermatidae, are retrieved as separate clusters, although not in all analyses as sister groups. We also validate sequences published before 2013 against our dataset; some sequences are shown to be chimeric and have falsified prior hypotheses about nemertodermatid phylogeny, other sequences should be assigned new names. We also show that the genus Nemertoderma needs revision. 

  • 337.
    Meyer-Wachsmuth, Inga
    et al.
    Department of Invertebrate Zoology, Swedish Museum of Natural History.
    Raikova, Olga I.
    Russian Academy of Sciences.
    Jondelius, Ulf
    Department of Invertebrate Zoology, Swedish Museum of Natural History.
    The muscular system of Nemertoderma westbladi and Meara stichopi (Nemertodermatida, Acoelomorpha)2013In: Zoomorphology, ISSN 0720-213X, E-ISSN 1432-234X, Vol. 132, no 3, p. 239-252Article in journal (Refereed)
    Abstract [en]

    Nemertodermatida is a small taxon of marine worm-like animals; its position in the tree of life is highly contested The musculature of Nemertoderma westbladi and Meara stichopi is studied here in detail using fluorescent phalloidin and confocal microscopy.

    In both species the musculature is composed of an outer layer of circular and an inner layer of longitudinal musculature, diagonal muscles form a distinct layer in N westbladi but in M. stichopi these fibres connect to both other layers. The supraterminally opening male pore and antrum are formed by invagination of the whole body-wall in both species and the seminal vesicle is lined by a thin net of musculature only in full male maturity. Modifications of the ventral body-wall adjacent to the mouth are small and transient in N. westbladi including no extra musculature whereas it consists of additional strong U-shaped musculature in M. stichopi. Myogenesis in N. westbladi is not finished in hatchlings and will be completed dorsally in juvenile specimens and ventrally in male mature ones, after the loss of the mouth.

    Musculature between the two species differs considerably and might give insights into the internal relationships of Nemertodermatida and might prove to be useful in studies investigating their phylogenetic position. More data of other species and developmental changes are needed.

  • 338.
    Miettinen, Minna
    Stockholm University, Faculty of Science, Department of Zoology.
    Egg carrying in the golden egg bug2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Females of the golden egg bug, Phyllomorpha laciniata Vill (Heteroptera, Coreidae), lay their eggs on the backs of male and female conspecifics. Eggs survive poorly in nature unless being carried by living conspecifics. The most likely evolutionary explanation to egg carrying is that individuals carry their own eggs. Thus, egg carrying has been considered to be paternal care. In this thesis I show that it is unlikely that the peculiar breeding system of these bugs has evolved or is maintained as a paternal care strategy. Firstly, females are prone to lay eggs on the backs of any individual available. Thus, males commonly receive eggs they have not fertilised. Secondly, males do not prefer to accept eggs from females they have mated with. Instead, oviposition attempts are sometimes resisted and high certainty of paternity do not influence males to carry their own eggs. Thirdly, paternity analyses with microsatellite DNA markers revealed that half of the males analysed did not carry any eggs of their own, and only 21% of the eggs carried by the remaining males were fertilised by them.

    When conspecifics receive eggs involuntarily or if egg carrying is costly, then female egg carrying may be regarded as intraspecific parasitism. I found no support for egg carrying being costly, either in terms of increased predation or decreased mobility. However, as eggs survive poorly unless being carried, females bring other individuals to carry their eggs. Especially, when a female utilises resisting individuals as oviposition sites, she is behaving like an intraspecific parasite.

  • 339.
    Min Yung, Kim
    Stockholm University, Faculty of Science, Department of Zoology.
    Neuropeptides Related to Tachykinins and Leucokinins in the Developing Nervous System of Insects1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In insects more than 300 neuropeptides have been identified and these have been implicated in a vast range of functional roles. These peptides have been grouped into families based on amino acid sequence similarities. This thesis focuses on insect neuropeptides of two families, the leucokinin-like peptides (LKs) and tachykinin-related peptides (TRPs). The distribution of LKs and TRPs has been studied in developing and adult blowflies, moths and dragonflies. In the blowfly Calliphora vomitoria two isoforms of TRPs have been identified (CavTK-I and -II). It was shown here by a combination of high performance liquid chromatography, radioimmunoassay and immunoenzyme assay that these two isoforms are present in a ratio of about 1:1 in different portions of the central nervous system and intestine. One or two additional isoforms of TRPs may be present in the larval nervous system, but not in adults. These are yet to be isolated and sequenced. Immunocytochemistry was used to localize TRPs in neurons of the developing nervous system of the blowfly. Several TRP-containing neurons could be identified throughout postembryonic development, suggesting that larval neurons are remodeled and utilized by the adult fly. The distribution of TRPs was also studied during postembryonic development of the moth Spodoptera litura and in the adult nervous system and intestine of the dragonfly Aeshna grandis. In the moth the distribution of TRPs in the brain is similar to that in the blowfly, but is different in the ventral nerve cord. Several neuron types could be identified throughout metamorphosis. A novel finding was that in the moth brain there are TRP-containing neurosecretory cells with release sites in the corpora cardiaca. In the dragonfly ventral nerve cord the distribution of TRPs was different from that of other insects: immunoreactive cell bodies were only detected in the terminal abdominal ganglion. It can be suggested that the TRPs in the studied insects are mainly used as neuromodulators by a variety of interneurons and as regulators of midgut function or as neurohormones released from the midgut endocrine cells. Leucokinin-like immunoreactivity was detected in 2 pairs of identified neurons in each of the abdominal ganglia of the blowfly from first instar larvae to adults. These neurons are lateral neurosecretory cells with axon terminals in peripherally located neurohemal areas. A similar distribution of leucokinin-like immunoreactivity was seen during postembryonic development of the moth Spodoptera litura. In three species of dragonflies similar neurosecretory cells were detected, but instead of 2 pairs per abdominal ganglion up to 10 pairs per ganglion were seen. In conclusion it appears as if the TRPs have variable distributions in interneurons of the different studied insects, especially in the ventral nerve cord. The LKs on the other hand appear distributed in a phylogenetically preserved fashion in neurosecretory cells of abdominal ganglia. Both peptides are likely to have multiple functions both as neuromodulators and as neurohormones.

  • 340.
    Modig, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Social behaviour and reproductive success in southern elephant seal (Mirounga leonina)1995Doctoral thesis, comprehensive summary (Other academic)
  • 341.
    Modig, Helene
    Stockholm University, Faculty of Science, Department of Zoology.
    Responses of Baltic soft-bottom invertebrates to settled organic material2000Doctoral thesis, comprehensive summary (Other academic)
  • 342.
    Mohammed, Salim
    Stockholm University.
    Nutrient Dynamics and Exchanges Between a Mangrove Forest and a Coastal Embayment: Chwaka Bay, Zanzibar1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nutrient dynamics and exchanges were studied in the Mapopwe Creek, a tidally dominated mangrove lined waterway, and a shallow lagoon in Chwaka Bay, Zanzibar, in order to assess whether there was any ecological coupling between the mangrove forest and adjacent ecosystems. In this study it was found that seasonal terrestrial input sources and benthic microalgal uptake strongly influenced the concentrations and distribution of dissolved nutrients in the system. The waterway had low inorganic nutrient levels and concentrations showed considerable spatial variability with values decreasing towards the mouth. The low water column concentrations were attributed principally to low input from the sediment. The sediment showed strong porewater gradients of ammonia and soluble reactive phosphorus (SRP) while nitrate plus nitrite (NOx) was limited to the top 1 cm of sediment in low concentrations. Generally, both water column and porewater nutrients showed strong seasonal fluctuations in concentrations. Mapopwe sediment showed complex and inconsistent sediment-water exchange patterns. Generally though, ammonia dominated benthic fluxes and fluxes of ammonia were mainly directed towards the water column. By contrast SRP showed low levels of exchange and the creek sediment acted as a sink for the nutrient. No fluxes of NOx were detected. Unlike the mangrove waterway, there was no significant sediment-water exchange of nutrients in the bay.

    The sediment in the creek showed low denitrification rates. This was attributed to low water column nitrate concentrations, low rates of in situ nitrification and competition for nitrate between nitrifiers and other benthic microbial populations. Strong spatial differences in the denitrification rates in the creek were attributed to unequal supply of organic matter between sites, and spatial differences in the distribution of bioturbating organisms and microautotrophs in the sediment.

    The study showed that there was a strong coupling between the forest and adjacent seagrasses and algal communities. Although measurements of tidal exchanges of dissolved nutrients between the mangrove forest and the bay did not show any exchanges between these biotopes, however the study showed that the forest exported a significant amount of particulate organic matter to the bay. This material was however trapped and utilised in production by seagrass beds just outside the mangrove forest; the communities growing farther from the forest were only indirectly affected. Apparently, mangroves may support productions in other systems but not directly. However, the seagrass and algal communities growing adjacent to the forest were vital in utilising and conserving mangrove outputs. Cosnsequently, nutrients are efficiently conserved within the bay and the associated mangrove forest implying that if the forest were to receive an increased nutrient load, they will not be removed and may result in eutrophication of the system.

  • 343.
    Mueller-Blenkle, Christina
    et al.
    CEFAS, UK.
    McGregor, Peter K.
    Cornwall College, UK.
    Gill, Andrew B.
    Cranfield University.
    Andersson, Mathias H.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Metcalfe, Julien
    CEFAS, UK.
    Bendall, Victoria
    CEFAS, UK.
    Sigray, Peter
    Stockholm University, Faculty of Science, Department of Meteorology .
    Wood, Daniel
    CEFAS, UK.
    Thomsen, Frank
    CEFAS, UK.
    Effects of pile-driving noise on the behaviour of marine fish2010Report (Other academic)
    Abstract [en]

    Studies on the effects of offshore wind farm construction on marine life have so far focussed on behavioural reactions in porpoises and seals. The effects on fish have only very recently come into the focus of scientists, regulators and stakeholders. Pile-driving noise during construction is of particular concern as the very high sound pressure levels could potentially prevent fish from reaching breeding or spawning sites, finding food, and acoustically locating mates. This could result in longterm effects on reproduction and population parameters. Further, avoidance reactions might result in displacement away from potential fishing grounds and lead to reduced catches. However, reaction thresholds and therefore the impacts of pile-driving on the behaviour of fish are completely unknown. We played back pile-driving noise to cod and sole held in two large (40 m) net pens located in a quiet Bay in West Scotland. Movements of the fish were analysed using a novel acoustic tracking system. Received sound pressure level and particle motion were measured during the experiments. There was a significant movement response to the pile-driving stimulus in both species at relatively low received sound pressure levels (sole: 144 – 156 dB re 1μPa Peak; cod: 140 – 161 dB re 1 μPa Peak, particle motion between 6.51x10-3 and 8.62x10-4 m/s2 peak). Sole showed a significant increase in swimming speed during the playback period compared to before and after playback. Cod exhibited a similar reaction, yet results were not significant. Cod showed a significant freezing response at onset and cessation of playback. There were indications of directional movements away from the sound source in both species. The results further showed a high variability in behavioural reactions across individuals and a decrease of response with multiple exposures.

    This study is the first to document behavioural response of marine fish due to playbacks of pile-driving sounds. The results indicate that a range of received sound pressure and particle motion levels will trigger behavioural responses in sole and cod. The results further imply a relatively large zone of behavioural response to pile-driving sounds in marine fish. Yet, the exact nature and extent of the behavioural response needs to be investigated further. Some of our results point toward habituation to the sound.

    The results of the study have important implications for regulatory advice and the implementation of mitigation measures in the construction of offshore wind farms in the UK and elsewhere. First, the concerns raised about the potential effects of pile-driving noise on fish were well founded. This suggests to both regulators and developers that the costs imposed by some mitigation measures that have so far been applied following the precautionary principle go some of the way to addressing a real problem. We also suggest that our behavioural thresholds are considered in assessments of impacts of offshore wind farms in the UK and elsewhere. Mitigation measures should be further discussed developed and, if meaningful, applied especially if these could lead to a reduction of acoustic energy that is emitted into the water column. Further studies should investigate the response at critical times (e.g. mating and spawning) and the effects of pile-driving on communication behaviour. It will also be necessary to further investigate habituation to the sound to effectively manage effects of pile-driving sound on marine fish.

  • 344. Muheim, Rachel
    et al.
    Henshaw, Ian
    Stockholm University, Faculty of Science, Department of Zoology.
    Sjöberg, Sissel
    Deutschlander, Mark E.
    BirdOriTrack: a new video-tracking program for orientation research with migratory birds2014In: Journal of field ornithology, ISSN 0273-8570, E-ISSN 1557-9263, Vol. 85, no 1, p. 91-105Article in journal (Refereed)
    Abstract [en]

    Experimental research on the orientation of migratory songbirds is traditionally conducted using orientation funnels or automatic registration cages that record the directional activity of individual birds on paper or a computer. Most traditionally used funnel and cage designs do not permit investigators to observe detailed behavior of the birds and, therefore, we have gained little insight into the actual behavior of birds while they are exhibiting migratory restlessness and making directional choices. Such behavior can only be studied by direct observation or by video filming. Here, we present BirdOriTrack, a video-tracking program for extracting time-resolved, positional data of birds ( and potentially other animal species) to determine their orientation relative to the center of a circular cage/funnel. With relatively inexpensive cameras, recording equipment, and cages, orientation experiments can easily be conducted and analyzed using BirdOriTrack. The program is designed to be flexible, allowing analysis of orientation behavior of birds of any size in different cage designs and in both controlled laboratory settings and field-based studies. To demonstrate the program's utility, we show the results of preliminary field experiments on several species of migratory birds captured at a migration monitoring station. BirdOriTrack is freely available at http://canmove.lu.se/birdoritrack.

  • 345.
    Muren, Eric
    Stockholm University, Faculty of Science, Department of Zoology.
    Tachykinin-related neuropeptides in the Madeira cockroach: structures, distributions and actions1996Doctoral thesis, comprehensive summary (Other academic)
  • 346. Nachman, Ronald J.
    et al.
    Mahdian, Kamran
    Nässel, Dick R.
    Stockholm University, Faculty of Science, Department of Zoology, Functional Morphology.
    Isaac, R. Elwyn
    Pryor, Nan
    Smagghe, Guy
    Biostable multi-Aib analogs of tachykinin-related peptides demonstrate potent oral aphicidal activity in the pea aphid Acyrthosiphon pisum (Hemiptera : Aphidae)2011In: Peptides, ISSN 0196-9781, E-ISSN 1873-5169, Vol. 32, no 3, p. 587-594Article in journal (Refereed)
    Abstract [en]

    The tachykinin-related peptides (TRPs) are multifunctional neuropeptides found in a variety of arthropod species, including the pea aphid Acyrthosiphon pisum (Hemiptera: Aphidae). Two new biostable TRP analogs containing multiple, sterically hindered Aib residues were synthesized and found to exhibit significantly enhanced resistance to hydrolysis by angiotensin converting enzyme and neprilysin, membrane-bound enzymes that degrade and inactivate natural TRPs. The two biostable analogs were also found to retain significant myostimulatory activity in an isolated cockroach hindgut preparation, the bioassay used to isolate and identify the first members of the TRP family. Indeed one of the analogs (Leuma-TRP-Aib-1) matched the potency and efficacy of the natural, parent TRP peptide in this myotropic bioassay. The two biostable TRP analogs were further fed in solutions of artificial diet to the pea aphid over a period of 3 days and evaluated for antifeedant and aphicidal activity and compared with the effect of treatment with three natural, unmodified TRPs. The two biostable multi-Aib TRP analogs were observed to elicit aphicidal effects within the first 24h. In contrast natural, unmodified TRPs, including two that are native to the pea aphid, demonstrated little or no activity. The most active analog, double-Aib analog Leuma-TRP-Aib-1 (pEA[Aib]SGFL[Aib]VR-NH(2)), featured aphicidal activity calculated at an LC(50) of 0.0083nmol/μl (0.0087μg/μl) and an LT(50) of 1.4 days, matching or exceeding the potency of commercially available aphicides. The mechanism of this activity has yet to be established. The aphicidal activity of the biostable TRP analogs may result from disruption of digestive processes by interfering with gut motility patterns and/or with fluid cycling in the gut; processes shown to be regulated by the TRPs in other insects. These active TRP analogs and/or second generation analogs offer potential as environmentally friendly pest aphid control agents.

  • 347.
    Neethiraj, Ramprasad
    Stockholm University, Faculty of Science, Department of Zoology.
    Advances in studying the role of genetic divergence and recombination in adaptation in non-model species2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Understanding the role of genetic divergence and recombination in adaptation is crucial to understanding the evolutionary potential of species since they can directly affect the levels of genetic variation present within populations or species. Genetic variation in the functional parts of the genome such as exons or regulatory regions is the raw material for evolution, because natural selection can only operate on phenotypic variation already present in the population. When natural selection acts on a phenotype, it usually results in reduction in the levels of genetic variation at the causal loci, and the surrounding linked loci, due to recombination dynamics (i.e. linkage); the degree to which natural selection influences the genetic differentiation in the linked regions depends on the local recombination rates.

    Studies investigating the role of genetic divergence and recombination are common in model species such as Drosophila melanogaster. Only recently have genomic tools allowed us to start investigating their role in shaping genetic variation in non-model species. This thesis adds to the growing research in that domain. In this thesis, I have asked a diverse set of questions to understand the role of genetic divergence and recombination in adaptation in non-model species, with a focus on Lepidoptera.

    First, how do we identify causal genetic variation causing adaptive phenotypes? This question is fundamental to evolutionary biology and addressing it requires a well-assembled genome, the generation of which is a cost, labor, and time intensive task. In paper I, I present a tool, MESPA, that stitches together exonic sequences in fragmented assemblies to produce high-quality gene models. These high-quality gene models can be used by researchers in the downstream analyses, providing genomic insights for a fraction of cost of a high quality genome. 

    Second, what does the pattern of recombination rate look like in chromosomes that lack centromeres (i.e.holocentric chromosomes)? In paper II, I compare the recombination landscape and the patterns of nucleotide diversity in three Lepidotera with holocentric chromosomes, Pieris napi, Bombyx mandarina, and Bombyx mori, with a monocentric species. Our results show that on average these three Lepidoptera have high rates of recombination across the vast majority of their genome. Our results also suggest that given similar effective population sizes, these species are likely to harbor more genetic diversity compared to monocentric species, which has important evolutionary consequences for these species.

    Third, what is the potential for parallelism at the genetic level in convergent melanic phenotypes? In paper III, I investigated the genetic basis of the female-limited melanic phenotype in the green-veined white (Pieris napi) butterfly, and found a 20kb region, approximately 50kb from the gene cortex, associated with this trait. This gene has been implicated in melanic phenotypes in other Lepidoptera that diverged from Pieris approximately 100my, indicating very high predictability for this trait.

    Finally, what is the role of cis-regulatory variation in local adaptation? In paper IV, I analyzed the relationship between allele specific expression (ASE) and genetic divergence (FST) in the F1 hybrids of Pieris napi napi and Pieris napi adalwinda. I show that intersecting results from ASE with FST is a powerful approach to identify genes involved in local adaptation.

  • 348.
    Neethiraj, Ramprasad
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Wheat, Christopher
    Stockholm University, Faculty of Science, Department of Zoology.
    Holocentric chromosomes facilitate recombination and genetic variation in LepidopteraManuscript (preprint) (Other academic)
  • 349.
    Nekoro, Marmar
    et al.
    Stockholm University, Stockholm Resilience Centre.
    Sundström, Helena
    Stormusslor i Kilaån 2004 och 2005: Utbredning av tjockskalig målarmussla och flat dammussla - hotstatus samt åtgärdsförslag till bevarande i Kilaådalen, Södermanlands län2005Report (Other academic)
    Abstract [en]

    Aim of the study

    The aim of this study was to investigate the status regarding distribution and species composition of major mussels in the Kilaå River in the Province of Södermanland, Eastern Sweden, with special emphasis on rare and red listed species.

    Earlier studies have revealed that all seven naturally occurring species have been found in the Kilaå River System. The findings of the pearl mussel (Margaritifera margaritifera) are only of shells, and the species is probably extinct in the river system. The Kilaå River System thus has an exceptionally rich diversity of major mussels, giving the River System a very high national and international conservation value.

    Results

    The Kilaå River System was found to have rich mussel species diversity, with findings of six of the seven species naturally occurring in Swedish waters.

    These were thick-shelled river mussel (Unio crassus), depressed river mussel (Pseudanodonta complanata), common painter mussel (Unio pictorum), bulbous river mussel (Unio tumidus), larger pond mussel/swan mussel (Anodonta cygnea) and common pond mussel/duck mussel (Anodonta anatina).

  • 350.
    Nekoro, Marmar
    et al.
    Stockholm University, Stockholm Resilience Centre.
    Sundström, Helena
    Stormusslor i Södermanlands län 2005: Inventering av potentiella lokaler för tjockskalig målarmussla och flat dammussla i Södermanlands län2005Report (Other academic)
    Abstract [sv]

    Samanfattning mål & syfte

    Studien har haft som syfte att kartlägga förekomst och utbredning av stormusselfaunan i Södermanlands län med tonvikt på tjockskalig målarmussla och flat dammussla.

    Lokaler har valts ut utifrån bedömd lämplighet som potentiella mussellokaler. Under tidigare inventeringar i länet 2004 och 2005 (Nekoro och Sundström 2005) har Kilaån och delar av Ålbergaån, Vretaån samt Hannsjöbäcken inventerats, varför dessa åar uteslöts i denna undersökning. Val av lokaler har gjorts i samrådan mellan Länsstyrelsen och de Naturhistoriska museerna.

    Målsättningen har varit att öka det generella kunskapsunderlaget om musslornas förekomst och utbredning i länet, samt bidra med kunskaper inför kompletteringen av Natura 2000-nätverket i landet.

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