As a consequence of my successful application to the German Research Foundation (DFG), I am pleased to announce that I have been awarded a two-year research fellowship (2017-2019) for the project “Transgenerational phenotypic plasticity in the cyprinid Pimephales promelas“, which I will tackle during a stay abroad in Canada.

While phenotypic plasticity – the adaptation of the appearance (phenotype) to the environment within a single generation has already been well researched – examples are the melanin production of the skin induced by solar radiation (UV radiation) or muscle growth induced by exercise – not much is known about transgenerational phenotypic plasticity. This term refers to the effects of an organism’s current environment on the phenotypes of future generations. This mechanism allows offspring to adapt to the environmental conditions of previous generations, to which they are likely exposed as well.

A well-known example of transgenerational plasticity in humans is a study published in the European Journal of Human Genetics by Kaati and colleagues in 2007. They found that men whose paternal grandfathers suffered from hunger as children during World War II have a shorter life expectancy. Transgenerational responses have also been observed in other animals and plants. In the presence of predators, the water flea Daphnia cucullata forms a large helmet and tail spine that prevents it from fitting into the mouth of predators easily. These effects are also observable in subsequent generations, as shown by a study from Nature by Agrawal and colleagues in 1999. The authors also found a similar effect in the field radish Raphanus raphanistrum: In the presence of herbivores, this plant produces more secondary plant substances that make it less palatable. This effect continued over generations even when no herbivore was present anymore.

In my previous research, I have studied the effects of predation risk on the behaviour and morphology of the cichlid Pelvicachromis taeniatus. Now I will be able to investigate in the fathead minnow Pimephales promelas to what extent the adaptations to predation risk affect future generations. To this end, I plan a large-scale breeding program in which clutches are split between two treatments in each generation over multiple generations. The offspring will be reared either under simulated high predation risk or under control conditions. First, in my experiments, I will separate the predator-induced transgenerational effects mediated by sperm and oocytes from the effects of an altered brood care caused by simulated high predation risk. Secondly, I will investigate the consequences of transgenerational plasticity over several generations. Here I will test the hypothesis that phenotypic plasticity favors the development of (genetic) adaptations. Third, I will compare the effects of paternal and maternal exposure to simulated predation to determine sex-specific inheritance during the transgenerational response. I will also compare the effects of directly perceived predation risk on offspring with the inherited transgenerational response.

I will carry out this project at the University of Saskatchewan in the workgroup of Prof. Douglas P. Chivers. More information can be found in the project description on GEPRIS (the “Funded Projects Information System” of the DFG) and the publications resulting from this project can be found in my profile on ResearchGate.

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Prior to marriage, men often have to make an effort to convince their beloved. This is also the case with some animals – before they are willing to mate, some female animals demand a gift in the form of a dead prey animal from their admirers. The nursery web spider presents this nuptial gift inside a package of spider silk. Current research revealed that some clever spider males take advantage of this circumstance and wrap inedible objects in silk so as to obtain access to females with little effort. The Danish biologist Maria J. Albo and her colleagues investigated this interesting behaviour and reported on their findings in the scientific journal “BMC Evolutionary Biology”. In their experiments, they caught several young nursery web spiders (Pisaura mirabilis) and raised them in the laboratory. Subsequently, male spiders were given either a fresh fly or inedible objects of the same size such as a cotton ball, an apple blossom or the empty shell of an already eaten fly. The males wrapped each of these objects in silk and presented these gifts to females that were added shortly afterwards. When the females noticed that the male was carrying a gift, they approached it and allowed it to mate. However, the swindlers didn’t profit the same as honest spiders – females that found a worthless object after unwrapping the gift immediately stopped mating. Only the males that packaged fresh, juicy flies were allowed to mate with the females for a long time. Obviously, females attempt to punish cheating males. However, finding and catching an attractive piece of prey requires a lot of diligence and effort – which weak spider males rarely manage to do. If those instead wrap a worthless object, they may be able to exchange at least a little sperm with a female. Similarly, in humans, men often try to entrance women by offering fake objects as for example worthless jewellery – but until the women find out the truth, they may already be pregnant with the cheaters having escaped long ago.

Photo: © Lukas Jonaitis/flickr.com