Bridging the gap between the evolutionary dynamics and the molecular mechanisms of meiosis : a model based exploration of thePRDM9intra-genomic Red Queen

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2023, Volume and Issue: unknown

Published: March 8, 2023

Abstract Molecular dissection of meiotic recombination in mammals, combined with population-genetic and comparative studies, have revealed a complex evolutionary dynamic characterized by short-lived hotspots. Hotspots are chromosome positions containing DNA sequences where the protein PRDM9 can bind cause crossing-over. To explain these fast dynamic, so-called intra-genomic Red Queen model has been proposed, based on interplay between two antagonistic forces: biased gene conversion, mediated double-strand breaks, resulting hotspot extinction (the conversion paradox), followed positive selection favoring mutant alleles recognizing new sequence motifs. Although this predicts many empirical observations, exact causes acting is still not well understood. In direction, experiment mouse hybrids suggested that, addition to targeting double strand another role during meiosis. Specifically, symmetric binding (simultaneous at same site both homologues) would facilitate homology search and, as result, pairing homologues. discovered hybrids, second function could also be involved observed within populations. address point, here, we present theoretical integrating current knowledge about molecular PRDM9. Our modeling work gives important insights into selective forces driving turnover reduced symmetrical caused loss high affinity sites induces net eliciting targets. The offers influence dosage PRDM9, which paradoxically result negative entering population, their eviction thus reducing standing variation locus. Author summary Meiosis an step eukaryotic life cycle, leading formation gametes implementing genetic mixing paternal maternal genomes. A key meiosis homologous chromosomes, required order distribute them evenly gametes. Chromosome will determine position chromosomes exchange material. Research basis gene, . encoded binds specific sequences, it determines location points. Symmetric (at chromosomes) facilitates pairing. This mechanism, however, paradoxical consequences, among local destruction recognized rapid level population over short time. better understand why maintained time despite process, developed simulation program taking account mechanisms. makes realistic predictions evolution confirms played

Language: Английский

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Rapid evolution of recombination landscapes during the divergence of cichlid ecotypes in Lake Masoko

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: March 23, 2024

Abstract Meiotic recombination is fundamental to evolution of sexually reproducing organisms and differences in rates are important during rapid adaptation organismal diversification. Many unknowns remain regarding how why landscapes evolve nature. Here, we reconstruct maps based on linkage disequilibrium use subsampling simulations show that fine-scale differ substantially between two cichlid fish ecotypes Astatotilapia calliptera diverged only ∼2,500 generations ago. The observed results not driven by PDRM9, whose binding sites do any relationship this species. We regions where histories have non-random distribution across chromosomes. They associated with, but partially explained, high divergence allele frequency ( F ST ) / or nucleotide diversity. also found 47 large haplotype blocks polymorphic Lake Masoko, cover 21% the genome, appear include inversions, contribute disproportionately recombination. Only a small number them elevated . While some old likely maintained balancing selection, for most, age ancestry close genome-wide average. Among blocks, there strong clear association degree ecotype clustering individual heterozygosity. Overall, our work provides holistic view changes early stages speciation with gene flow advances understanding combinatorial basis evolution.

Language: Английский

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Rapid evolution of recombination landscapes during the divergence of cichlid ecotypes in Lake Masoko

Evolution, Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 26, 2024

Abstract Variation of recombination rate along the genome is crucial importance to rapid adaptation and organismal diversification. Many unknowns remain regarding how why landscapes evolve in nature. Here, we reconstruct maps based on linkage disequilibrium use subsampling simulations derive a new measure landscape evolution: Population Recombination Divergence Index (PRDI). Using PRDI, show that fine-scale differ substantially between two cichlid fish ecotypes Astatotilapia calliptera diverged only ~2,500 generations ago. Perhaps surprisingly, differences are not driven by divergence terms allele frequency (FST) nucleotide diversity (Δ(π)): although there some association, observe positive PRDI regions where FST Δ(π) zero. We found stronger association evolution 47 large haplotype blocks polymorphic Lake Masoko, cover 21% genome, appear include multiple inversions. Among blocks, strong clear degree heterozygosity, consistent with suppression heterozygotes. Overall, our work provides holistic view changes population during early stages speciation gene flow.

Language: Английский

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