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Université de Fribourg

Parasite‐driven replacement of a sexual by a closely related asexual taxon in nature

Lohr, Jennifer N. ; Haag, Christoph R.

In: Ecology, 2020, vol. 101, no. 10, p. -

Asexual species are thought to suffer more from coevolving parasites than related sexuals. Yet a variety of studies do not find the patterns predicted by theory. Here, to shine light on this conundrum, we investigate one such case of an asexual advantage in the presence of parasites. We follow the frequency dynamics of sexual and asexual Daphnia pulex in a natural pond that was initially...

Université de Fribourg

How clonal are clones? A quest for loss of heterozygosity during asexual reproduction in Daphnia magna

Dukić, Marinela ; Berner, Daniel ; Haag, Christoph R. ; Ebert, Dieter

In: Journal of Evolutionary Biology, 2019, vol. 32, no. 6, p. 619–628

Due to the lack of recombination, asexual organisms are predicted to accumulate mutations and show high levels of within‐individual allelic divergence (heterozygosity); however, empirical evidence for this prediction is largely missing. Instead, evidence of genome homogenization during asexual reproduction is accumulating. Ameiotic crossover recombination is a mechanism that could lead to...

Université de Fribourg

Evolution of gene expression during a transition from environmental to genetic sex determination

Molinier, Cécile ; Reisser, Céline M O ; Fields, Peter D ; Ségard, Adeline ; Galimov, Yan ; Haag, Christoph R

In: Molecular Biology and Evolution, 2019, vol. 36, no. 7, p. 1551–1564

Genetic sex determination (GSD) can evolve from environmental sex determination (ESD) via an intermediate state in which both coexist in the same population. Such mixed populations are found in the crustacean Daphnia magna, where non-male producers (NMP, genetically determined females) coexist with male producers (MP), in which male production is environmentally inducible and can also...

Université de Fribourg

Identification of general patterns of sex-biased expression in Daphnia, a genus with environmental sex determination

Molinier, Cécile ; Reisser, Céline M.O. ; Fields, Peter ; Ségard, Adeline ; Galimov, Yan ; Haag, Christoph R.

In: G3& Genes|Genomes|Genetics, 2018, vol. 8, no. 5, p. 1523–1533

Daphnia reproduce by cyclic-parthenogenesis, where phases of asexual reproduction are intermitted by sexual production of diapause stages. This life cycle, together with environmental sex determination, allow the comparison of gene expression between genetically identical males and females. We investigated gene expression differences between males and females in four genotypes of Daphnia...

Université de Fribourg

A high-density genetic map reveals variation in recombination rate across the genome of Daphnia magna

Dukić, Marinela ; Berner, Daniel ; Roesti, Marius ; Haag, Christoph R. ; Ebert, Dieter

In: BMC Genetics, 2016, vol. 17, p. 137

Recombination rate is an essential parameter for many genetic analyses. Recombination rates are highly variable across species, populations, individuals and different genomic regions. Due to the profound influence that recombination can have on intraspecific diversity and interspecific divergence, characterization of recombination rate variation emerges as a key resource for population...

Université de Fribourg

Uncovering cryptic asexuality in Daphnia magna by RAD sequencing

Svendsen, Nils ; Reisser, Celine M. O. ; Dukić, Marinela ; Thuillier, Virginie ; Ségard, Adeline ; Liautard-Haag, Cathy ; Fasel, Dominique ; Hürlimann, Evelin ; Lenormand, Thomas ; Galimov, Yan ; Haag, Christoph R.

In: Genetics, 2015, vol. 201, no. 3, p. 1143–1155

The breeding systems of many organisms are cryptic and difficult to investigate with observational data, yet they have profound effects on a species’ ecology, evolution, and genome organization. Genomic approaches offer a novel, indirect way to investigate breeding systems, specifically by studying the transmission of genetic information from parents to offspring. Here we exemplify this method...

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

Local adaptation of sex induction in a facultative sexual crustacean: insights from QTL mapping and natural populations of Daphnia magna

Roulin, Anne C. ; Routtu, Jarkko ; Hall, Matthew D. ; Janicke, Tim ; Colson, Isabelle ; Haag, Christoph R. ; Ebert, Dieter

In: Molecular Ecology, 2013, vol. 22, no. 13, p. 3567–3579

Dormancy is a common adaptation in invertebrates to survive harsh conditions. Triggered by environmental cues, populations produce resting eggs that allow them to survive temporally unsuitable conditions. Daphnia magna is a crustacean that reproduces by cyclical parthenogenesis, alternating between the production of asexual offspring and the sexual reproduction of diapausing eggs (ephippia)....

Université de Fribourg

Genetic estimates of population age in the water flea, Daphnia magna

Robinson, John D. ; Haag, Christoph R. ; Hall, David W. ; Pajunen, V. Ilmari ; Wares, John P.

In: Journal of Heredity, 2012, vol. 103, no. 6, p. 887-897

Genetic datasets can be used to date evolutionary events, even on recent time scales if sufficient data are available. We used statistics calculated from multilocus microsatellite datasets to estimate population ages in data generated through coalescent simulations and in samples from populations of known age in a metapopulation of Daphnia magna in Finland. Our simulation results show that age...

See also: similar author names
1 Haag, C.
2 Haag, Christoph
1 Haag, Christoph R