Fate of a supergene in the shift from diploidy to polyploidy

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 22, 2025

ABSTRACT Despite the evolutionary importance of supergenes, their properties in polyploids remain unexplored. Polyploid genomes are expected to undergo chromosomal rearrangements and gene losses over time, potentially affecting supergene architecture. The iconic distyly ( S -locus), controlling a floral heteromorphism with two self-incompatible morphs, has been well-documented diploids, but remains unknown polyploids. Primula , classic model for since Darwin, is ancestrally diploid distylous, yet polyploid, homostylous species single, self-compatible morph evolved repeatedly. intraspecific loss associated small loss-of-function mutations -locus CYP T style length female self-incompatibility. Over longer timescales, relaxed selection on should generate greater accumulation larger mutations, including exon loss. By analyzing first assembled genome an allotetraploid, grandis ) comparative framework, we discovered two, nearly identical alleles same subgenome, suggesting it originated via inter-specific hybridization between distylous progenitor. Conformant predictions from theory, macroevolutionary coincided considerable degeneration while other genes remained largely unaffected, shift homostyly preceded facilitated polyploid establishment. At whole-genome level, found minimal subgenome dominance — as expected, given inferred recent origin P. highly reduced genetic diversity, congruently its narrow distribution self-compatibility. This study provides comparison across ploidy levels reproductive systems, contributing new knowledge previously fate supergenes SIGNIFICANCE advances evolution by elucidating how (clusters tightly linked genes) evolve different sets chromosomes systems. newly broad provide outcrossers self-fertilizers. We one pair rather than per revealing cross self-incompatibility was considerably degenerated, because rest unaffected.

Language: Английский

Genomic studies inLinumshed light on the evolution of the distyly supergene and the molecular basis of convergent floral evolution

Published: April 17, 2025

Summary Distyly, an example of convergent evolution, is governed by a supergene called the S- locus. Recent studies highlight similar genetic architectures independently evolved S -loci, but whether regulatory pathways underlie evolution distyly remains unclear. We examined supergenes and mechanisms underlying in Linum species that diverged ∼33 Mya. Using haplotype-resolved genomes population genomics, we identified characterized loci perenne (distylous) grandiflorum (style length dimorphic), compared them to tenue (distylous). then tested for conserved hormonal mechanism regulating style polymorphism . Hemizygosity short-styled individuals shared feature -locus supergene, though its size, gene content, repeat elements, extent recombination suppression vary greatly among species. Two candidate genes, TSS1 length) WDR-44 (anther height/pollen self-incompatibility) are at Consistent with brassinosteroid-dependent role , epibrassinolide treatment revealed conserved, morph-specific effect on length. locus architecture, key genes remain >30 Mya In combination findings from other systems, our results suggest brassinosteroid pathway frequently contributes polymorphism.

Language: Английский

Unveiling the genome-wide consequences of range expansion and mating-system transitions in Primula vulgaris

Genome Biology and Evolution, Journal Year: 2024, Volume and Issue: 16(10)

Published: Sept. 28, 2024

Abstract Genetic diversity is heterogeneously distributed among populations of the same species, due to joint effects multiple demographic processes, including range contractions and expansions, mating systems shifts. Here, we ask how both processes shape genomic in space time classical Primula vulgaris model. This perennial herb originated Caucasus region was hypothesized have expanded westward following glacial retreat Quaternary. Moreover, this species a long-standing model for system transitions, exemplified by shifts from heterostyly homostyly. Leveraging high-quality reference genome closely related veris whole-genome resequencing data heterostylous homostylous individuals encompassing wide distribution P. vulgaris, reconstructed history vulgaris. Results are compatible with previously proposed hypothesis expansion approximately 79,000 years ago suggest later homostyly rather than preceding postglacial colonization England. Furthermore, accordance population genetic theoretical predictions, associated reduced diversity, increased linkage disequilibrium, efficacy purifying selection. A novel result concerns contrasting versus shift on transposable elements, former, process changes element content, while latter not. Jointly, our results elucidate interactions expansion, transitions selfing, Quaternary climatic oscillations plant evolution.

Language: Английский