Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2021
Erindi/veggspjald / Talk/poster E58
Höfundar / Authors: Arnar Pálsson (1), Baldur Kristjánsson (1), Lea Jerman Plesec (1), Dagný Ásta Rúnarsdóttir (1)
Starfsvettvangur / Affiliations: 1. Háskóli Íslands
Kynnir / Presenter: Arnar Pálsson
Evolutionary theory predicts that positive selection promotes alleles influencing phenotypic trait if the positive fitness effects outweigh the negative fitness effects of linked variants (or pleiotropic side effects of that exact variant on other traits). With tightly linked genes, gene dense regions in some species or relatively low rate of recombination, episodes of strong positive selection can drag one or more deleterious alleles to high frequency and even fixation. Our theory on transcriptional cooption and decay predicts that following fixation of such an allele two mechanisms can work to reduce these deleterious fitness effects. Firstly, alleles with negative fitness, that rose to high frequency (but not fixation) due to hitchhiking, will be selected against and eventually weeded out of the population. Secondly, the deleterious effects of alleles that were fixed along with the focal mutation can only be suppressed by modifier loci, thus episodes of compensatory selection are expected. Assessing these fitness effects is complicated, but we study this indirectly by analysing gene expression in the wings of Drosophila melanogaster that have experienced artificial selection for wing phenotypes, using our RNA sequencing and published Microarray data. This enabled us to study transcriptional “disruption” in linked variations, and how selection can reduce these side effects. The results support this theoretical model and have implications for our understanding on selective sweeps, adaptive introgression, genome landscapes and the origins of functional diversity segregating in eukaryotic populations.