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  • 1.
    Betzholtz, Per-Eric
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Berger, Tobias
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Petersson, J.
    County Administrative Board of Kalmar.
    Stedt, Johan
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    What do population viability analyses tell about the future for Baltic Dunlin Calidris alpina schinzii and Montagu’s Harrier Circus pygargus on Öland?2010In: Ornis Svecica, ISSN 1102-6812, Vol. 20, p. 93-102Article in journal (Refereed)
    Abstract [en]

    Population viability analysis (PVA) has become an important tool in conservation biology. Even though detailed outcomes of PVA:s are constrained by data quality, it is a useful approach when the objective is exploratory, aiming to identify important parameters for viability or to guide future field work on endangered species. In this study we perform PVA:s based on scarce data to explore viability of two endangered bird species, Baltic Dunlin and Montagu’s Harrier, on Öland. Our simulation results underline that both species are under severe threats, with a median time to extinction of 24 years in Baltic Dunlin and 63 years in Montagu’s Harrier. Sensitivity analyses show that population growth rate is the most important factor for the model outcome in both species. Since there are no apparent threats for adult birds on Öland, this suggests that conservation measures should focus on improving conditions for successful breeding on the island. In additional simulations we explore some threats in more detail. In the case of Baltic Dunlin nest predation of eggs and chicks increase the extinction risk. In Montagu’s Harrier viability increases if breeding attempts within agricultural areas are detected and safeguarded. In order to enhance the PVA model, and build a stage-structured model, we suggest that detailed data on fecundity and survival should be collected.

  • 2.
    Betzholtz, Per-Eric
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Pettersson, Lars B
    Lund University.
    Ryrholm, Nils
    University of Gävle.
    Franzén, Markus
    Helmholtz Centre for Environmental Research, Germany.
    With that diet, you will go far: trait-based analysis reveals a link between rapid range expansion and a nitrogen-favoured diet.2013In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 280, no 1750, article id 20122305Article in journal (Refereed)
    Abstract [en]

    Recent global change has had a substantial influence on the distribution of organisms, and many species are currently expanding their ranges. To evaluate the underlying processes, long-term data with good geographic resolution are essential. One important but generally overlooked data source is offered by the taxon-specific national catalogues of first provincial records that are kept in many countries. Here, we use such data to quantify trait-based influences on range expansion in Swedish butterflies and moths between 1973 and 2010. Of 282 species meeting pre-defined quality criteria, 170 expanded their northern range margin, with a mean expansion rate of 2.7 km per year. The analyses demonstrate that habitat and diet generalists, forest species and species active during warm conditions have expanded their ranges more rapidly than other species. Notably, range expansion in diet specialists was positively related to a nitrogen-favoured larval diet, an effect not found among oligo- or polyphagous species. In contrast to the general view, this shows that specialist species can undergo rapid range expansion. We suggest that increased areas of nitrogen-rich habitat, and increased availability of a nitrogen-favoured diet, are among the most important drivers of range expansions, potentially having far-reaching consequences for a wide variety of organisms.

  • 3.
    Dragan, Smiljic
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Studies of small bicoid knock-down and overexpression at early and late stage of development in Drosophila melanogaster.2016Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
  • 4.
    Forsman, Anders
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Ahnesjö, Jonas
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Caesar, Sofia
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Fitness benefits of diverse offspring in pygmy grasshoppers2007In: Evolutionary Ecology Research, Vol. 9, no 8, p. 1305-1318Article in journal (Refereed)
    Abstract [en]

    Question: Do females obtain fitness benefits from an increase in offspring diversity?Hypotheses: Polyandry increases offspring diversity within a clutch. Increased offspring diversity will reduce competition among siblings (manifested as increased mean survival in more diverse families) and the probability that all offspring might be ill-suited to future conditions (manifested as lower variance in survival in diverse families).Organisms: Pygmy grasshoppers, Tetrix subulata and Tetrix: undulata, that are polymorphic for colour pattern.Field site: South-central Sweden.Methods: We varied the number of mates provided to colour polymorphic pygmy grasshoppers. We reared families in either warm or cold conditions using a split-brood design.Conclusions: The colour morph diversity of broods increased with the number of experimentally provided mates. Colour morphs represent alternative strategies that differ in body size, physiology, behaviour, and life history. Survival increased with increasing sibling diversity, supporting the hypothesis that different morphs avoid competition by using different subsets of available resources. Homogeneous families (in which all siblings belong to the same or only a few colour morphs) varied more in survival than did families with diverse siblings, supporting the hypothesis that morphs vary in their ability to cope with and utilize different resources.

  • 5.
    Forsman, Anders
    et al.
    Dept of Zoology, Univ. of Uppsala.
    Ås, S
    Dept of Zoology, Univ. of Uppsala.
    Maintenance of colour polymorphism in adder populations, Vipera berus L.: a test of a popular hypothesis1987In: Oikos, Vol. 50, p. 13-16Article in journal (Refereed)
    Abstract [en]

    Accordingt o a currenth ypothesis,t he colourp olymorphismin populationso f the adder,Vipera berus L., is maintained by a thermal superiority of melanistic snakes,which enables them to grow more quickly than normally coloured ones. Since largermales are superior in sexual combats, and larger females get more offspring, thisclearly should favour the melanistic trait. On the other hand, melanistic individualsare believed to suffer a higher predation pressure due to their more conspicuous appearance.T he predictionf rom this hypothesisi s that melanistici ndividualso n averageshould be largert han normali ndividualsi n mixed populations.T his predictionwas tested on adders captured on several small islands in the Stockholm archipelago(N 59°20';E 19°20').N o significantd ifferencew as found in weight, lengtho r weight/length ratio between melanistic and normally coloured male adders. Neither slopenor elevation of the regression lines of length on weight differed. Thus, the hypothesiswas not supported by our data. 

  • 6.
    Hargeby, Anders
    et al.
    Lund University, Sweden.
    Johansson, Jonas
    Lund University, Sweden.
    Ahnesjö, Jonas
    Växjö University, Faculty of Mathematics/Science/Technology, Institutionen för biovetenskaper och processteknik.
    Habitat-specific pigmentation in a freshwater isopod: Adaptive evolution over a small spatiotemporal scale2004In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 58, no 1, p. 81-94Article in journal (Refereed)
    Abstract [en]

    Pigmentation in the freshwater isopod Asellus aquaticus (Crustacea) differed between habitats in two Swedish lakes. In both lakes, isopods had lighter pigmentation in stands of submerged vegetation, consisting of stoneworts (Chara spp.), than in nearby stands of reed (Phragmites australis). Experimental crossings of light and dark isopods in a common environment showed that pigmentation had a genetic basis and that genetic variance was additive. Environmental effects of diet or chromatophore adjustment to the background had minor influence on pigmentation, as shown by laboratory rearing of isopods on stonewort or reed substrates, as well as analyses of stable isotope ratios for isopods collected in the field. In both study lakes, the average phenotype became lighter with time (across generations) in recently established stonewort stands. Taken together, these results indicate that altered phenotype pigmentation result from evolutionary responses to local differences in natural selection. Based on the assumption of two generations per year, the evolutionary rate of change in pigmentationwas 0.08 standard deviations per generation (haldanes) over 20 generations in one lake and 0.22 haldanes over two generations in the other lake. This genetic change occurred during an episode of population growth in a novel habitat, a situation known to promote adaptive evolution. In addition, stonewort stands constitute large and persistent patches, characteristics that tend to preserve local adaptations produced by natural selection. Results from studies on selective forces behind the adaptivedivergence suggest that selective predation from visually oriented predators is a possible selective agent. We found no indications of phenotype-specificmovements between habitats. Mating within stonewort stands was random with respect to pigmentation, but on a whole-lake scale it is likely that mating is assortative, as a result of local differences in phenotype distribution.

  • 7.
    Johansson, Jenny
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Drivers of polymorphism dynamics in pygmy grasshoppers2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, I used colour polymorphism in pygmy grasshoppers as a model system to study the influence of selection, developmental plasticity, mating behaviour and gene flow on patterns of phenotypic and genetic diversity within and among populations in changing environments.

    Data for more than 5,000 individuals collected from natural populations showed that the incidence of black (melanic) pygmy grasshoppers was higher in burnt than in non-burnt areas, and rapidly declined over time within populations in post-fire environments. A common garden experiment confirmed that differences among populations were genetically determined. A split brood experiment further uncovered no developmental plasticity in response to rearing substrate, but a high resemblance between mothers and their offspring thus indicating that colour morphs are under strong genetic control.

    To investigate the role of polyandry, I experimentally mated virgin females to multiple males; genotyped families using microsatellite markers developed for this purpose, and demonstrated that polyandrous females can produce offspring sired by different males. Analysis of families produced by females collected from a natural population confirmed that multiple paternities can increase colour morph diversity among half-siblings in the wild. Analysis of 130 AFLP (Amplified Fragment Length Polymorphism) markers in individuals from 5 localities uncovered two distinct gene clusters, as well as high genetic diversity within and significant divergence among populations within each cluster.

    My studies of colour polymorphism dynamics demonstrate an important role of population differentiation and rapid adaptive evolution in response to selection in heterogeneous environments, indicate limited effects of plasticity and gene flow, and implicate multiple mating as promoting diversity within populations in this pygmy grasshopper system.

  • 8.
    Tinnert, Jon
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Forsman, Anders
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    The role of dispersal for genetic and phenotypic variation: insights from comparisons of sympatric pygmy grasshoppers2017In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 122, no 1, p. 84-97Article in journal (Refereed)
    Abstract [en]

    Patterns of genetic and phenotypic variation within and among populations are influenced by a complex interplay of ecological and evolutionary processes. Theory posits that gene flow should increase diversity within and reduce differentiation between populations. Evaluating these predictions is potentially complicated by selection, population dynamics and plasticity that may also affect genetic and phenotypic variation. Here, we compare genetic and morphological variation between sympatric populations of two pygmy grasshopper species, Tetrix subulata and T. undulata, that differ in dispersal capacity. We found that genetic differentiation between populations is lower on average in the generally dispersive T. subulata compared with the mostly sedentary T. undulata, suggesting that genetic structure in the latter species has been less influenced by the homogenizing effects of migration. Our results also provided weak support for the hypothesis that neutral genetic diversity within populations should be higher in T. subulata than in T. undulata. We further found that body size varied among populations in both species, but the differences seen in T. subulata did not parallel those seen in T. undulata, indicating that the two species have unique plasticity responses or that they have responded differently to shared selective regimes. Our findings illustrate the utility of the pairwise comparative approach and further highlight that results and conclusions may not be transferrable even between closely related species.

  • 9.
    Wennersten, Lena
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Johansson, Jenny
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Karpestam, Einat
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Forsman, Anders
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Higher establishment success in more diverse groups of pygmy grasshoppers under seminatural conditions2012In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 93, no 12, p. 2519-2525Article in journal (Refereed)
    Abstract [en]

    Large founder groups and habitat match have been shown to increase the establishment success of reintroduced populations. Theory posits that the diversity of founder groups should also be important, but this has rarely been investigated. Here, experimental introductions of color-polymorphic Tetrix subulata pygmy grasshoppers into outdoor enclosures were used to test whether higher phenotypic diversity promotes establishment success. We show that the number of individuals present one year after introduction increases with color morph diversity in founder groups. Variance in establishment success did not decrease with increasing founder diversity, arguing against an important contribution of sampling effects or evolutionary rescue. Color morphs in T. subulata covary with a suite of other functionally important traits and utilize different resources. The higher establishment success in more diverse founder groups may therefore result, in part, from niche complementarity. Variation in establishment among groups was not associated with differences among source populations in reproductive capacities.

1 - 9 of 9
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