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  • 1.
    Flenner, Ida
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Olne, Karin
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Suhling, Frank
    Technische Universität Braunschweig.
    Sahlén, Göran
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Predator-induced spine length and exocuticle thickness in Leucorrhinia dubia (Insecta: Odonata): a simple physiological trade-off?2009In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 34, p. 735-740Article in journal (Refereed)
    Abstract [en]

    1. Morphological defence structures evolve against predators but are costly to the individual, and are induced only when required. A well-studied example is the development of longer abdominal spines in dragonfly larvae in the presence of fish. Numerous attempts to discover trade-offs between spine size and behaviour, development time or body size have, however, produced little evidence.

    2. We considered a physiological trade-off. Spines consist of cuticle and using material to build longer structures may result in less material remaining elsewhere. We therefore measured exocuticle thickness at nine locations on Leucorrhinia dubia larvae from habitats with and without fish.

    3. Our results show a significant effect of the interaction between fish presence and spine length on head and fore leg exocuticle thickness. Relative thickness increased with relative length of lateral spine 9 in the absence of fish, whereas no such relationship existed with fish. Hence, synthesis and secretion of cuticle material occur as a trade-off when larvae react to fish presence.

    4. We assume the mechanism to be a selective synthesis of material with different responses in different parts of the larval body. These findings offer a new angle to the fish/spine trade off debate.

     

     

  • 2.
    Flenner, Ida
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Richter, Otto
    Technische Universität Braunschweig.
    Suhling, Frank
    Technische Universität Braunschweig.
    Rising temperature and development in dragonfly populations at different latitudes2010In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 55, no 2, p. 397-410Article in journal (Refereed)
    Abstract [en]

    1. For modelling the future ecological responses to climate change, data on individual species and on variation within and between populations from different latitudes are required. 2. We examined life cycle regulation and growth responses to temperature in Mediter- ranean and temperate populations of a widespread European odonate, Orthetrum cancellatum. In an experiment, offspring from individual females from different parts of the range were kept separately to elucidate differences between families.

    3. The experiment was run outdoors at 52°N at a natural photoperiod for almost a year. We used four temperature regimes, ambient (i.e. following local air temperature) and ambient temperature increased by 2, 4 and 6 °C, to mimic future temperature rise. A mathematical model was used to categorise the type of seasonal regulation and estimate parameters of the temperature response curve.

    4. Growth rate varied significantly with temperature sum, survival and geographic origin, as well as with family. Offspring of all females from the temperate part of the range had a life cycle with a 12 h day-length threshold necessary to induce diapause (i.e. diapause was induced once day length fell below 12 h). By contrast, Mediterranean families had a 10 h threshold or had an unregulated life cycle allowing winter growth. The temperature response did not significantly differ between populations, but varied between families with a greater variation in the optimum temperature for growth in the Mediterranean population.

    5. The variation in seasonal regulation leads to a diversity in voltinism patterns within species, ranging from bivoltine to semivoltine along a latitudinal gradient. Given that the type of seasonal regulation is genetically fixed, rising temperatures will not allow faster than univoltine development in temperate populations. We discuss the consequences of our results in the light of rising temperature in central Europe.

     

  • 3.
    Flenner, Ida
    et al.
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Sahlén, Göran
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Dragonfly community re-organisation in boreal forest lakes: rapid species turnover driven by climate change?2008In: Insect Conservation and Diversity, ISSN 1752-458X, Vol. 1, no 3, p. 169-179Article in journal (Refereed)
    Abstract [en]
    1. Climate change affects many ecosystems on earth. If not dying out or migrating, the species affected have to survive the altered conditions, including changes in community structure. It is, however, usually difficult to distinguish changes caused by a changing climate from other factors.
    2. Forestry is considered to be the major disturbance factor in Swedish forests. Here, we use forest lake data sets from 1996 and 2006 which include species abundance data for dragonfly larvae, water plant structure, forest age and forestry measures during a period of 25 years: from 1980 to 2005. Hence, we were able to discriminate between forestry effects and changes in species composition driven by recent climate change.
    3. We explored effects on regional species composition, species abundance and ecosystem functions, such as changes in niche use, utilising dragonflies (Odonata) as model organisms.
    4. Our results show that dragonflies react rapidly to climate change, showing strong responses over such a short time span as 10 years. We observed changes in both species composition and abundance; former rare species have become more frequent and now occur in lakes of a wider quality range, while former widespread species have become more selective in their choice of waters. The new communities harbour about the same number of species as before, but seen from a regional perspective, diversity is reduced.
    5. We predict that the altered species composition and abundance might raise new demands in conservation planning as well as altering the ecological functions of the aquatic systems.
  • 4.
    Mühle, Lesley
    et al.
    Technische Universität Braunschweig, Germany.
    Rohe, Lena
    Technische Universität Braunschweig, Germany.
    Flenner, Ida
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Suhling, Frank
    Technische Universität Braunschweig, Germany.
    Atmungsverhalten von Orthetrum cancellatum–Larven: Einfluss der aktuellen Temperatur und der Aufzuchtsbedingungen (Odonata: Libellulidae)2009In: Libellula, ISSN 0723-6514, Vol. 28, no 1-2, p. 59-68Article in journal (Refereed)
    Abstract [en]

    Ventilation behaviour of Orthetrum cancellatum larvae: influence of the current temperature and rearing conditions (Odonata: Libellulidae) — The intensity of respiration of larval Anisoptera can be determined by observing the frequency of abdominal movements. We used this to study the influence of the current temperature on the larval respiration of O. cancellatum. We assumed that (1) the breathing rate of the larvae increases with rising temperature and that (2) the response to the current temperature depends on the rearing conditions. The larvae were kept for nine months under four different rearing conditions. The egg clutches originated from two countries in different climate zones, from southern France in the Mediterranean area and from northern Germany in the temperate zone. Our experiment revealed that the ventilation rate increased with increasing temperature. This was more pronounced with higher rearing temperatures that the larvae experienced. We interpreted this as a habituation effect. The size of the larvae influenced the ventilation rate as well. On the other hand, the genetic and geographic origin of the larvae had no significant effect.

     

  • 5.
    Suhling, Frank
    et al.
    Technische Universität Braunschweig.
    Suhling, Ida
    Halmstad University, School of Business and Engineering (SET), Biological and Environmental Systems (BLESS).
    Richter, Otto
    Environmental System Analysis, Institute of Geoecology, Braunschweig University of Technology.
    Rising temperatures, altered life cycles and their consequences for dragonflies in Europe2010Conference paper (Other academic)
    Abstract [en]

    Besides range expansion, altered life cycle patterns are the most visible signal of dragonfly responses to recent climate change. Since dragonflies are poikilotherm organisms their metabolism is directly responding to the ambient temperature. Thus, rising temperatures, which have already been recorded and are predicted to be even more severe in the future, should lead to alterations in all aspects of dragonfly life cycles. This may lead to temporal mismatches with other environmental variables relevant for the survival of dragonfly populations. The aim of our contribution is reviewing the known facts about temperature on growth rates and voltinism. We investigated temperature response of growth by laboratory experiments mainly in Libellulidae. Physiological structured mathematical models were used to simulate life cycle duration with various types of seasonal regulation. We will try predictions of consequences of rising temperatures for voltinism and phenology of some European dragonflies in future considering the regionally different climatic conditions. With the aid of such models we will also stress the question how temperature as environmental factor may influence present and future distribution of species in Europe.

  • 6.
    Suhling, Ida
    et al.
    Halmstad University, School of Business, Engineering and Science, Biological and Environmental Systems (BLESS). Technische Universität Braunschweig, Braunschweig, Germany.
    Suhling, Frank
    Technische Universität Braunschweig, Braunschweig, Germany.
    Thermal adaptation affects interactions between a range-expanding and a native odonate species2013In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 58, no 4, p. 705-714Article in journal (Refereed)
    Abstract [en]

    1.Increasing temperature and invading species may interact in their effects on communities. In this study, we investigated how rising temperatures alter larval interactions between a naturally range-expanding dragonfly, Crocothemis erythraea, and a native northern European species, Leucorrhinia dubia. Initial studies revealed that C.erythraea grow up to 3.5 times faster than L.dubia at temperatures above 16 degrees C. As a result, we hypothesised that divergent temperature responses would lead to rapid size differences between coexisting larvae and, consequently, to asymmetric intraguild predation at higher ambient temperatures. 2. Mortality and growth rates were measured in interaction treatments (with both species present) and non-interaction controls (one species present) at four different temperature regimes: at an ambient temperature representative of central Germany, where both species overlap in distribution, and at temperatures increased by 2, 4 and 6 degrees C. 3.The mortality of C.erythraea did not differ between treatment and control. In contrast, mortality of L.dubia remained similar over all temperatures in the controls, but increased with temperature in the presence of the other species and was significantly higher there than in the controls. We concluded that L.dubia suffered asymmetric intraguild predation, particularly at increased temperature. Reduced growth rate of L.dubia in the interaction treatment at higher temperatures also suggested asymmetric competition for prey in the first phase of the experiment. 4.The results imply that the range expansion of C.erythraea may cause reduction in population size of syntopic L.dubia when temperature rises by more than 2 degrees C. The consequences for future range patterns, as well as other factors that may influence the interaction in nature, are discussed. © 2013 Blackwell Publishing Ltd.

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