Project Details
Projekt
Beyond averages: the evolution of transcriptional variability and its role in adaptation and evolutionary innovation
Applicants
Professor Dr. Dirk Metzler; Dr. Luisa Pallares
Subject Area
Evolution, Anthropology
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 570451068
Research on gene expression is usually focused on differences in mean expression values between the groups of interest, as for example populations living in different environments to understand the functional requirements for adaptation. There is growing evidence, however, that not only mean expression values but also transcriptional variability, which refers to differences between genetically identical multicellular organisms, plays an important role in the first stages of adaptation to new environments. Further, it has been shown that genes of high transcriptional variability tend to have higher nucleotide diversity and more adaptive substitutions, are more tolerant to loss-of-function mutations, and are less connected in gene co-expression networks. For Drosophila species it was found that alleles that reduce transcriptional variability tend to be derived rather than ancestral. In this project we investigate the evolution of transcriptional variability as well as its role in evolutionary adaptation and innovation with gene transcription data from six Drosophila species. For each of the six species we use 5 inbred lines and from each of these inbred lines we sample 20 female flies, which are genetically (almost) identical. The gene expression levels for all genes in each individual fly are measured separately for head and body by RNA sequencing. Thus, we can calculate for each genotype (that is for females of the same inbred line) the transcriptional variation of each gene. Using available information on gene regulation networks and based on stochastic models for the evolution of gene transcription regulation along the phylogeny of the Drosophila species, we analyze how transcriptional variability of genes that interact in the same pathway changed during Drosophila speciation and whether transcriptional variability was under directional or balancing selection. Further, we investigate the role of transcriptional variability in the regulation of de-novo genes and genes that were under selection in the adaptation of Drosophila species or populations to new environments. We use inbred-line specific genomes to scan genomic neighborhoods of candidate genes for genomic signatures that increase or decrease variability. These results will shed new light into the genomic neighborhoods of expression robustness and variability.
DFG Programme
Priority Programmes
