title: Reconstruction of Haplotype-Blocks Selected during Experimental Evolution.
abstract: The genetic analysis of experimentally evolving populations typically relies on short reads from pooled individuals (Pool-Seq). While this method provides reliable allele frequency estimates, the underlying haplotype structure remains poorly characterized. With small population sizes and adaptive variants that start from low frequencies, the interpretation of selection signatures in most Evolve and Resequencing studies remains challenging. To facilitate the characterization of selection targets, we propose a new approach that reconstructs selected haplotypes from replicated time series, using Pool-Seq data. We identify selected haplotypes through the correlated frequencies of alleles carried by them. Computer simulations indicate that selected haplotype-blocks of several Mb can be reconstructed with high confidence and low error rates, even when allele frequencies change only by 20% across three replicates. Applying this method to real data from D. melanogaster populations adapting to a hot environment, we identify a selected haplotype-block of 6.93 Mb. We confirm the presence of this haplotype-block in evolved populations by experimental haplotyping, demonstrating the power and accuracy of our haplotype reconstruction from Pool-Seq data. We propose that the combination of allele frequency estimates with haplotype information will provide the key to understanding the dynamics of adaptive alleles.
authors.affiliation: Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria.
authors.forename: Susanne U
authors.initials: SU
authors.lastname: Franssen
authors.affiliation: Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria.
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Barton
authors.affiliation: Institut für Populationsgenetik, Vetmeduni Vienna, Vienna, Austria christian.schloetterer@vetmeduni.ac.at.
authors.forename: Christian
authors.initials: C
authors.lastname: Schlötterer
mesh_terms: D000483:Alleles; D000818:Animals; D005075:Biological Evolution; D003198:Computer Simulation; D019020:Directed Molecular Evolution / Q000379:methods*; D004331:Drosophila melanogaster / Q000235:genetics*; D005260:Female; D018703:Founder Effect; D005787:Gene Frequency; D056726:Genetic Association Studies / Q000379:methods; D008040:Genetic Linkage; D005828:Genetics, Population; D006239:Haplotypes; D017422:Sequence Analysis, DNA / Q000379:methods
keywords: Evolve and Resequence (E&R); experimental evolution; haplotype reconstruction; replicated time series data; selection; sequencing of pooled individuals (Pool-Seq)