Institut für Populationsgenetik, Vetmeduni Vienna, Austria.
Vienna Graduate School of Population Genetics, Vetmeduni Vienna, Austria.
Genome Biol Evol. 2021 Nov 5;13(11). doi: 10.1093/gbe/evab239.
Many adaptive traits are polygenic and frequently more loci contributing to the phenotype are segregating than needed to express the phenotypic optimum. Experimental evolution with replicated populations adapting to a new controlled environment provides a powerful approach to study polygenic adaptation. Because genetic redundancy often results in nonparallel selection responses among replicates, we propose a modified evolve and resequence (E&R) design that maximizes the similarity among replicates. Rather than starting from many founders, we only use two inbred Drosophila melanogaster strains and expose them to a very extreme, hot temperature environment (29 °C). After 20 generations, we detect many genomic regions with a strong, highly parallel selection response in 10 evolved replicates. The X chromosome has a more pronounced selection response than the autosomes, which may be attributed to dominance effects. Furthermore, we find that the median selection coefficient for all chromosomes is higher in our two-genotype experiment than in classic E&R studies. Because two random genomes harbor sufficient variation for adaptive responses, we propose that this approach is particularly well-suited for the analysis of polygenic adaptation.
许多适应性特征是多基因的，并且经常有比表达表型最优所需的更多的基因座在分离。通过对适应新控制环境的重复种群进行实验进化，提供了研究多基因适应的强大方法。因为遗传冗余通常会导致重复之间的非平行选择反应，所以我们提出了一种改进的进化和重测序 (E&R) 设计，以最大限度地提高重复之间的相似性。我们不是从许多起始者开始，而是只使用两个近交黑腹果蝇品系，并将它们暴露在非常极端的高温环境（29°C）下。经过 20 代，我们在 10 个进化的重复中检测到许多具有强烈、高度平行选择反应的基因组区域。X 染色体的选择反应比常染色体更明显，这可能归因于显性效应。此外，我们发现所有染色体的中位选择系数在我们的两基因型实验中都高于经典 E&R 研究。由于两个随机基因组具有足够的适应反应变异，我们提出这种方法特别适合于多基因适应的分析。
