| 1. |
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| 2. |
- Suhling, Frank, et al.
(författare)
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Rising temperatures, altered life cycles and their consequences for dragonflies in Europe
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 3. |
- Suhling, Ida, et al.
(författare)
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Thermal adaptation affects interactions between a range-expanding and a native odonate species
- 2013
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Ingår i: Freshwater Biology. - Chichester : Wiley-Blackwell. - 0046-5070 .- 1365-2427. ; 58:4, s. 705-714
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 4. |
- Flenner, Ida, 1976-, et al.
(författare)
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Predator-induced spine length and exocuticle thickness in Leucorrhinia dubia (Insecta : Odonata): a simple physiological trade-off?
- 2009
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Ingår i: Ecological Entomology. - Oxford : Wiley. - 0307-6946 .- 1365-2311. ; 34:6, s. 735-740
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Flenner, Ida, 1976-, et al.
(författare)
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Rising temperature and development in dragonfly populations at different latitudes
- 2010
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Ingår i: Freshwater Biology. - Oxford : Wiley. - 0046-5070 .- 1365-2427. ; 55:2, s. 397-410
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Tidskriftsartikel (refereegranskat)abstract
- 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 Mediterranean 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 degrees 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 degrees 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.
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| 6. |
- Maasri, Alain, et al.
(författare)
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A global agenda for advancing freshwater biodiversity research
- 2022
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 25:2, s. 255-263
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Tidskriftsartikel (refereegranskat)abstract
- Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation.
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| 7. |
- Mühle, Lesley, et al.
(författare)
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Atmungsverhalten von Orthetrum cancellatum–Larven: Einfluss der aktuellen Temperatur und der Aufzuchtsbedingungen (Odonata: Libellulidae)
- 2009
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Ingår i: Libellula. - Börnsen : Gesellschaft deutschsprachiger Odonatologen. - 0723-6514. ; 28:1-2, s. 59-68
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 8. |
- Sahlén, Göran, 1964-, et al.
(författare)
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Critical species of Odonata in Europe
- 2004
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Ingår i: International Journal of Odonatology. - Abingdon : Taylor & Francis. - 1388-7890 .- 2159-6719. ; 7:2, s. 385-398
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Tidskriftsartikel (refereegranskat)abstract
- The status of the odonate fauna of Europe is fairly well known, but the current IUCN Red List presents only six species out of ca 130, two of which are actually out of danger today. In this paper we propose a tentative list of 22 possibly declining or threatened species in the region. For the majority, reliable data of population size and possible decline is still lacking. Also 17 endemic species are listed, most occurring in the two centres of endemism in the area: the south-eastern (mountains and islands) and the western Mediterranean. These species should receive extra attention in future updates of the world Red List due to their limited distribution. The extreme variation in biomes and the human exploitation of habitats make conservation planning complicated in Europe. Within the EU, the FFH directive is a working tool aiding conservation. However, the species included do not fully correspond to those on the current Red List, nor to those discussed in this paper. We believe that future conservation efforts should focus on the most valuable and threatened habitats in each sub-region. Active conservation measures could be implemented on a European scale, provided that research will establish a solid ground for such measures. © 2004 Taylor & Francis Group, LLC.
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| 9. |
- Sahlén, Göran, 1964-, et al.
(författare)
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For consistency’s sake? A reply to Bybee et al.
- 2016
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Ingår i: Systematic Entomology. - Chichester : Wiley-Blackwell. - 0307-6970 .- 1365-3113. ; 41:2, s. 307-308
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Sahlén, Göran, et al.
(författare)
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Morphology of dragonfly larvae along a habitat gradient : interactions with feeding behaviour and growth (Odonata: Libellulidae)
- 2008
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Ingår i: International Journal of Odonatology. - Abingdon, Oxfordshire : Taylor & Francis. - 1388-7890. ; 11:2, s. 225-240
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Tidskriftsartikel (refereegranskat)abstract
- It has been shown that life history, behavioural as well as morphological traits vary with the habitats occupied by odonate larvae. Here we ask the following questions: (1) Are the morphological traits, which are associated with perception and foraging, related to the larval habitat? (2) Do these traits influence foraging success and growth rate? We analysed the morphology of species pairs belonging to the genera Crocothemis, Orthetrum and Trithemis; one species in each pair occurring in perennial spring-fed streams, the other able to develop in temporary waters. A PCA reveals four principal components of morphological characters which may be expressed as PC1: prey handling, PC2: visual perception, and PC3 and PC4: density of long and short setae on the feet. The variances of PC1, PC2 and PC3 were affected by phylogeny. PC1, PC2 and PC4 differed between habitats. Species of perennial springs had larger values for visual perception. These waters are clear and larger eyes should be beneficial. But, a high PC2 value was associated with low growth rate and did not affect foraging success. We therefore conclude that investment in better sight made by perennial water species may reflect the need of avoiding predators. Development in temporary waters mainly requires rapid growth and species may not be capable to invest also in visual perception. PC1 was negatively correlated with foraging behaviour and PC3 was positively so. This indicates the importance of prey capture mode to foraging success, which may, however, not translate into a higher growth rate.
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