1 Ecoinformatics & Biodiversity, Faculty of Science, Aarhus University, Aarhus University2 Department of Bioscience - Ecoinformatics and Biodiversity, Department of Bioscience, Science and Technology, Aarhus University3 Department of Bioscience - Ecoinformatics and Biodiversity, Department of Bioscience, Science and Technology, Aarhus University
All scenarios for future climate change predict an increase in global temperature between 1.8 and 6.4 ° C in the 21 century. In a fluctuating climatic environment the phenotypic plasticity plays a key role in many organisms, but it is virtually impossible for their adaptive skills to adjust and keep pace with the rate of climate change. As an effect of such warming species are expected to change their distribution rather than adapt to warmer temperatures in situ. Several European species of dragonflies are spreading to the north and some species emerge between few days to a few weeks earlier due to the warmer climate, but the nymph responses in populations across latitudes is still mostly unresolved. Stress levels and physical fitness are affected by a change in phenology and accelerated growth rate. By a specific shift in temperature nymphs at low latitudes (e.g. southern France) may experience increased mortality, whereas individuals from northern latitudes (e.g. Denmark) under the same relative temperature increase may not experience definite effects on mortality, but rather respond with a higher growth rate. To clarify such issues eggs from Ischnura pumilio are going to be collected at three different populations along a latitude gradient in Europe. Eggs are supposed to be collected in southern France, Belgium and Denmark where sampling hopefully takes place in the same days in each country. Females should be caught in the field immediately after mating and before oviposition and then placed separately in a disposable cup with a piece of wet filter paper in the bottom for egg laying substrate. After collecting the eggs the filter paper is sent express from France and Belgium to Denmark, where the eggs are hatched and the nymphs transferred to climate units. We use four water tanks that each simulate modelled climate scenarios, i.e. one tank follow standard temperature whereas the other three follows a 2, 4 and 6 ° C temperature elevation. The water temperature is dictated by a computer and based on empirical data measured in situ in a shallow Danish lake, thus through thermostats it is possible to simulate both annual and diurnal variation in water temperature. Similarly, the computer sets the daylight strip lights according to outdoor day length standards. To record growth rate, head width is measured every 14 days from digital photos with ImageJ software (Version 1.43). Through the controlled laboratory experiments, the project will highlight adjustments in life cycle and growth response in relation to temperature, family genetics and geographical origin. Information on physiological responses such as temperature optimum together with growth response and voltinisme in the different geographical populations are going to be combined with data on present species distribution, and available data for different climate change scenarios, to model future changes in distribution, regulation in life cycle and climatic niche.