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03.06.2022: In a recently published study in the journal Genome Biology, a research team from Vetmeduni presents a new model for the measurement of pleiotropy. In their study, the researchers show that many genetic loci, each with a weak effect, contribute to genome-wide pleiotropy. The new measurement method that was developed as part of the research work also contributes to a better understanding of the phenomenon of pleiotropy, which has only been investigated to a limited extent to date.

The phenotype of an organism refers to the set of its observable characteristics. Most phenotypic traits involve several genes interacting in complex relationships. The opposite may also be the case, however, where one gene affects multiple traits. This is called pleiotropy. The extent of pleiotropy is still disputed, mainly due to issues arising from inadequate analysis and testing.

New method to measure pleiotropy

To overcome these limitations, a team of researchers led by Christian Schlötterer from the Institute of Population Genetics at Vetmeduni has developed a new method for measuring pleiotropy. “The new method integrates across many phenotypes and multiple generations to improve the power and validity of the measurement,” says Christian Schlötterer, the study’s senior author.

The method was applied to Drosophila fruit flies, which are considered an ideal laboratory model for genetic and evolutionary research because they are easy to culture, have a short generation time and produce a high number of offspring per generation.

Fitness cost as experimental marker for pleiotropy

In their study, the authors use experimental evolution to measure pleiotropy. When a pleiotropic gene becomes more common through selection, this also has disadvantages, as this is not beneficial for other traits. “We measured the cost of pleiotropy by mixing two populations that adapted independently to the same new environment – in our case a higher temperature regime. The observed changes after mixing are an indication of pleiotropy,” explains the study’s first author Eirini Christodoulaki from the Institute of Population Genetics at Vetmeduni. “Interestingly, many loci with small effect contribute to the cost of pleiotropy,” Christian Schlötterer adds.

The finding that many loci, each with a weak effect, contribute to genome-wide pleiotropy contrasts with previous studies characterising the molecular basis of pleiotropy. To explain the observed phenomenon, the researchers propose that the costs of pleiotropy are reduced by the modular architecture of gene expression, which facilitates adaptive gene expression changes with low impact on other functions.


The article “Natural variation in Drosophila shows weak pleiotropic effects” by Eirini Christodoulaki, Viola Nolte, WeiYun Lai und Christian Schlötterer was published in Genome Biology.

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