Université de Fribourg

Reduced lifespan and increased ageing driven by genetic drift in small populations

Lohr, Jennifer N. ; David, Patrice ; Haag, Christoph R.

In: Evolution, 2014, vol. 68, no. 9, p. 2494–2508

Explaining the strong variation in lifespan among organisms remains a major challenge in evolutionary biology. Whereas previous work has concentrated mainly on differences in selection regimes and selection pressures, we hypothesize that differences in genetic drift may explain some of this variation. We develop a model to formalize this idea and show that the strong positive relationship between...

Université de Fribourg

Prior residency does not always pay off – co-infections in Daphnia

Lohr, Jennifer N. ; Yin, Mingbo ; Wolinska, Justyna

In: Parasitology, 2010, p. -

The epidemiological and ecological processes which govern the success of multiple-species co-infections are as yet unresolved. Here we investigated prior versus late residency within hosts, meaning which parasite contacts the host first, to determine if the outcomes of intra-host competition are altered. We infected a single genotype of the waterflea Daphnia galeata with both the...

Université de Fribourg

Quantitative PCR to detect, discriminate and quantify intracellular parasites in their host: an example from three microsporidians in Daphnia

Refardt, Dominik ; Ebert, Dieter

In: Parasitology, 2006, vol. 133, p. 11–18

Reliable detection, discrimination and quantification of parasites are important for host-parasite studies and diagnostics. Microsporidial infections are problematic in this respect. Their discrimination and quantification using light microscopy is difficult because spores are the only light microscopically visible form of the parasite and they offer few distinct characters. We developed a...

Université de Fribourg

Variation in phenoloxidase activity and its relation to parasite resistance within and between populations of Daphnia magna

Mucklow, Patrick T. ; Vizoso, Dita B. ; Jensen, Knut Helge ; Refardt, Dominik ; Ebert, Dieter

In: Proceedings of the Royal Society of London: Biological Sciences, 2004, vol. 271, p. 1175-1183

Estimates of phenoloxidase (PO) activity have been suggested as a useful indicator of immunocompetence in arthropods, with the idea that high PO activity would indicate high immunocompetence against parasites and pathogens. Here, we test for variation in PO activity among clones of the planktonic crustacean Daphnia magna and its covariation with susceptibility to infections from four different...