We found pronounced differences between naturally coexisting Daphnia longispina genotypes in their specific patterns of susceptibility to limitations by the availability of essential dietary polyunsaturated fatty acids. On average, D. longispina population was more strongly susceptible to availability of the omega6-PUFA arachidonic acid (20:4 n-6) than to the availability of omega3-PUFAs alpha-linolenic acid (18:3 n-3) and eicosapentaenoic acid (20:5 n-3). Our findings suggest that such intrapopulation variation in susceptibility to absence of dietary PUFAs might be one of the driving forces of natural selection and local adaptation among freshwater zooplankton.
Our results show that there is a specialisation of the stage one nymphs in which they differ from later stages, which may be understood in the framework of ant mimicry. However, we did not find support for a more specific mimicry beyond generally resembling ants. In order to get a clearer picture, a similar investigation of other mantodean species is necessary.
Using dose-response growth experiments and bootstrapping to determine the growth and reproduction saturation thresholds, we show that ω6-PUFA arachidonic acid (ARA, 20:4 n-6) limits the growth and reproduction of two Daphnia species to an equal extent as ω3-PUFA eicosapentaenoic acid (EPA, 20:5 n-3).
Here we report significant variation in heat tolerance, measured as knock-out time (time until immobilization, Timm) in a single D. magna population. Furthermore, we show that Timm negatively correlates with the body PUFA-content of D. magna clonal lineages.
We found strong temporal and spatial variation in population density of larval salamanders along three headwater streams in the Eifel mountains, Western Germany. Random drift of salamander larvae was particularly rare, and drift did not result in a size structuring of larval populations in the field. Yet, catastrophic events of high summer precipitation were the best predictor for pulse-wise restructuring of the salamander larvae’s density distribution. Strong discharge coincided with a severe decrease in population density, and thus appears to be the most relevant cause of mortality for salamander larvae.
We show that increased NO3− concentrations foster cyanobacterial blooms directly by providing more nutrients and indirectly by increasing the negative interference of cyanobacteria with their consumers due to an increased content of Protease Inhibitors.