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  • 1.
    Bonnot, N. C.
    et al.
    Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, Riddarhyttan, 730 91, Sweden.
    Bergvall, U. A.
    Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, Riddarhyttan, 730 91, Sweden.
    Jarnemo, Anders
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Kjellander, P.
    Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, Riddarhyttan, 730 91, Sweden.
    Who’s afraid of the big bad wolf?: Variation in the stress response among personalities and populations in a large wild herbivore2018In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 188, no 1, p. 85-95Article in journal (Refereed)
    Abstract [en]

    Faced with rapid environmental changes, individuals may express different magnitude and plasticity in their response to a given stressor. However, little is known about the causes of variation in phenotypic plasticity of the stress response in wild populations. In the present study, we repeatedly captured individual roe deer (Capreolus capreolus) from two wild populations in Sweden exposed to differing levels of predation pressure and measured plasma concentrations of stress-induced cortisol and behavioral docility. While controlling for the marked effects of habituation, we found clear between-population differences in the stress-induced cortisol response. Roe deer living in the area that was recently recolonized by lynx (Lynx lynx) and wolves (Canis lupus) expressed cortisol levels that were around 30% higher than roe deer in the human-dominated landscape free of large carnivores. In addition, for the first time to our knowledge, we investigated the stress-induced cortisol response in free-ranging newborn fawns and found no evidence for hypo-responsiveness during early life in this species. Indeed, stress-induced cortisol levels were of similar magnitude and differed between populations to a similar extent in both neonates and adults. Finally, at an individual level, we found that both cortisol and docility levels were strongly repeatable, and weakly negatively inter-correlated, suggesting that individuals differed consistently in how they respond to a stressor, and supporting the existence of a stress-management syndrome in roe deer. © 2018, The Author(s).

  • 2.
    Koch, Kamilla
    et al.
    University of Mainz.
    Quast, Malte
    Waldweg 8, 38176, Wendeburg, Germany.
    Sahlén, Göran
    Halmstad University, School of Business, Engineering and Science, The Rydberg Laboratory for Applied Sciences (RLAS).
    Morphological differences in the ovary of Libellulidae (Odonata)2009In: International Journal of Odonatology, ISSN 1388-7890, Vol. 12, no 1, p. 147-156Article in journal (Refereed)
    Abstract [en]

    All female Odonata have been assumed to produce oocytes continuously during their mature life span. However, a recent study of ovariole orientation and development led to the suggestion that Libellulidae are divided into two groups of species, one with continuous, the other with stepwise oocyte production. To find more evidence of this division, we compared the size variation and growth within the vitellarium of the ovary, studying oocytes, and follicle cells. We found that morphological characters discriminate between the two ovary types in eight of the 10 investigated species. In both types we found an increase in all measurements from the anterior to the posterior end of the vitellarium. The increase in oocyte width and follicle cell length was significantly higher in species with a continuous oocyte production. We also noted that follicle cells may have more than one nucleus and that their number can vary during vitellogenesis. Our study confirmed the hypotheses that two different ovary types exist in Libellulidae. The two species not fitting into this grouping could be an artefact of small samp le size due to intraspecific phenotypic plasticity, or else there might be more than two ovary groups, or even a continuum. We could not offer an explanation as to how the process of stepwise oocyte production differs from continuous based production on morphological characters.

  • 3.
    Troast, Daniel
    et al.
    Department of Biology, Rutgers University, Newark, New Jersey, United States of America.
    Suhling, Frank
    Institut für Geoökologie, Technische Universität Braunschweig, Braunschweig, Germany.
    Jinguji, Hiroshi
    School of Food, Agricultural and Environmental Sciences, Miyagi University, Miyagi, Japan.
    Sahlén, Göran
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Ware, Jessica
    Department of Biology, Rutgers University, Newark, New Jersey, United States of America.
    A Global Population Genetic Study of Pantala flavescens2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 3, article id e0148949Article in journal (Refereed)
    Abstract [en]

    Among terrestrial arthropods, the dragonfly species Pantala flavescens is remarkable due to their nearly global distribution and extensive migratory ranges; the largest of any known insect. Capable of migrating across oceans, the potential for high rates of gene flow among geographically distant populations is significant. It has been hypothesized that P. flavescens may be a global panmictic population but no sufficient genetic evidence has been collected thus far. Through a population genetic analysis of P. flavescens samples from North America, South America, and Asia, the current study aimed to examine the extent at which gene flow is occurring on a global scale and discusses the implications of the genetic patterns we uncovered on population structure and genetic diversity of the species. This was accomplished using PCR-amplified cytochrome oxidase one (CO1) mitochondrial DNA data to reconstruct phylogenetic trees, a haplotype network, and perform molecular variance analyses. Our results suggested high rates of gene flow are occurring among all included geographic regions; providing the first significant evidence that Pantala flavescens should be considered a global panmictic population. © 2016 Troast et al.

  • 4.
    Ware, Jessica L.
    et al.
    Rutgers University, Newark, NJ, USA.
    Karlsson, Maria
    Lund University, Lund, Sweden.
    Sahlén, Göran
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS).
    Koch, Kamilla
    Johannes Gutenberg Universität Mainz, Mainz, Germany.
    Evolution of reproductive strategies in libellulid dragonflies (Odonata: Anisoptera)2012In: Organisms Diversity & Evolution, ISSN 1439-6092, E-ISSN 1618-1077, Vol. 12, no 3, p. 313-323Article in journal (Refereed)
    Abstract [en]

    In Libellulidae, oocyte production has been assumed to be continuous, with periods of egg-laying interspersed with periods of resting/eating; however, recent work suggests that two types of oocyte production are common: either (a) continuous or (b) step-wise. These are mirrored in the arrangement of the ovarioles in the ovaries. Likewise, two types of mate-guarding behavior have been observed in Libellulidae: (1) non–contact guarding and (2) tandem guarding in which the male either hovers above the female or is physically attached to her during oviposition. Using molecular (mitochondrial and nuclear) data we explored the evolution of female reproductive traits, focusing on ovariole morphology, as well as guarding behavior, in Libellulidae. Continuous egg production appears to have evolved more than once, as have tandem and non-contact guarding. We discuss how the evolution of different ovariole types and guarding behavior may have been influenced by habitat instability, dispersal and crowded oviposition sites; thus, migratory behavior or habitat availability may have been the driving force of ovariole evolution.

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