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Type of publication: Journal Article
Type of document: Full Paper

Year: 2019

Authors: Barghi, N; Tobler, R; Nolte, V; Jakšić, AM; Mallard, F; Otte, KA; Dolezal, M; Taus, T; Kofler, R; Schlötterer, C

Title: Genetic redundancy fuels polygenic adaptation in Drosophila.

Source: PLoS Biol. 2019; 17(2):e3000128

Authors Vetmeduni Vienna:

Barghi Neda
Dolezal Marlies
Jaksic Ana Marija
Kofler Robert
Mallard Francois Jean Robert
Nolte Viola
Otte Kathrin
Schlötterer Christian
Taus Thomas
Tobler Raymond

Vetmed Research Units
Institute of Population Genetics
Platform Bioinformatics and Biostatistics

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Project(s): ERC ADG: The architecture of adaptation

Population Genetics

The genetic architecture of adaptive traits is of key importance to predict evolutionary responses. Most adaptive traits are polygenic-i.e., result from selection on a large number of genetic loci-but most molecularly characterized traits have a simple genetic basis. This discrepancy is best explained by the difficulty in detecting small allele frequency changes (AFCs) across many contributing loci. To resolve this, we use laboratory natural selection to detect signatures for selective sweeps and polygenic adaptation. We exposed 10 replicates of a Drosophila simulans population to a new temperature regime and uncovered a polygenic architecture of an adaptive trait with high genetic redundancy among beneficial alleles. We observed convergent responses for several phenotypes-e.g., fitness, metabolic rate, and fat content-and a strong polygenic response (99 selected alleles; mean s = 0.059). However, each of these selected alleles increased in frequency only in a subset of the evolving replicates. We discerned different evolutionary paradigms based on the heterogeneous genomic patterns among replicates. Redundancy and quantitative trait (QT) paradigms fitted the experimental data better than simulations assuming independent selective sweeps. Our results show that natural D. simulans populations harbor a vast reservoir of adaptive variation facilitating rapid evolutionary responses using multiple alternative genetic pathways converging at a new phenotypic optimum. This key property of beneficial alleles requires the modification of testing strategies in natural populations beyond the search for convergence on the molecular level.

Keywords Pubmed: Adaptation, Physiologicalgenetics
Biological Evolution
Drosophila simulansgeneticsphysiology
Genetic Fitness
Genetic Heterogeneity
Genome, Insect
Multifactorial Inheritancegenetics
Polymorphism, Single Nucleotidegenetics
Quantitative Trait Locigenetics

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