Biology subjects

Massonnet, M.

Publications and source records attributed to Massonnet, M..

18 recordsLinked to original sources

bioRxiv2026

Haplotype-specific expression of a terpene synthase underlies linalool variation in the grapevine cultivar Riesling

Grapevine cultivars vary widely in monoterpenoid content, yet the genetic and regulatory mechanisms underlying this variation remain poorly characterized beyond highly aromatic Muscat types. We profiled free volatiles and monoterpenoid glycosides in a Riesling x Cabernet Sauvignon F1 mapping population, revealing extensive variation and transgressive segregation consistent with multigenic control. QTL mapping identified 59 significant loci associated with 47 volatile compounds and monoterpene glycosides, including two major QTLs explaining 33.8% and 32.4% of phenotypic variance in (3S)-linalool accumulation. Integration of haplotype-resolved transcriptomics with metabolite data, enabled by a chromosome-scale diploid Riesling genome assembly, resolved a (3S)-linalool/nerolidol synthase cluster on chromosome 10 and identified VviTPS54 as the strongest candidate underlying linalool variation. VviTPS54 exhibited haplotype-specific expression strongly correlated with (3S)-linalool accumulation across genotypes, while no QTL was detected at the VviDXS1 locus and VviDXS1 expression was not correlated with terpene levels, indicating that regulatory variation within terpene synthase clusters, rather than methylerythritol phosphate (MEP) pathway flux, drives monoterpenoid composition in this population. These results establish regulatory variation of terpene synthases as a key mechanism underlying monoterpenoid diversity in grapevine and demonstrate that resolving such variation requires haplotype-phased genome assemblies coupled with haplotype-resolved transcriptomics to detect allele-specific expression differences at complex, heterozygous loci.

plant biology↗

bioRxiv2025

Haplotype graph analysis of PdR1 uncovers resistance diversity to Pierce's Disease in Vitis arizonica and its hybrids

Previous genetic mapping studies indicate that multiple haplotypes of the Pierces disease (PD) Resistance 1 (PdR1) locus occur in Vitis arizonica and its hybrids. To characterize sequence diversity at this locus, we assembled chromosome-scale diploid genomes for four PD-resistant (PD-R) accessions: b43-17 (PdR1a/PdR1b), the backcross 07744-094 (PdR1c/PdR1-), b46-43 (PdR1e/PdR1f), and b42-26 (PdR1-/PdR1-), which displays quantitative PD resistance not associated with PdR1. Haplotype resolution of PdR1a, PdR1b, PdR1c, and PdR1e revealed substantial variation in intergenic repeat content and gene composition between PdR1 and their alternative haplotype at the PdR1 locus not associated with PD resistance phenotype (PdR1-), as well as among PdR1 haplotypes, demonstrating extensive sequence diversity at the PdR1 locus. Sequence graph analysis uncovered substantial structural divergence concentrated in approximately one quarter of the locus, together with smaller-scale variation across haplotypes. This analysis identified PdR1-specific graph nodes, showing that PdR1a and PdR1b share most of their PdR1-specific features, whereas PdR1c contains the highest number of private nodes, followed by PdR1e. Integration of sequence graph features with gene expression data further refined a set of defense-related candidate genes within PdR1c. Together, these results identify candidate genes for functional validation and indicate that multiple resistance determinants co-localized within the PdR1 locus may contribute to PD resistance, highlighting opportunities for targeted genetic improvement strategies.

genomics↗

bioRxiv2025

Dual single-nucleus gene expression atlas of grapevine and Erysiphe necator during early powdery mildew infection

We applied dual-organism single-nucleus transcriptomics to study the interaction between grapevine leaves and Erysiphe necator, the causal agent of powdery mildew, at one and five days post-infection, including controls and three biological replicates. We generated a grapevine leaf atlas encompassing over 100,000 nuclei, and a pathogen atlas of more than 3,000 nuclei. We successfully annotated all major grapevine cell types, including mesophyll, epidermis, phloem and xylem parenchyma, companion cells, and guard cells. We identified key E. necator structures, including appressoria, haustoria, and hyphae, and provided a list of novel cell type markers for both species. We reveal structure-specific gene expression programs in E. necator laying a foundation for future studies of fungal development and virulence mechanisms. In the host, we identified spatially distinct expression patterns of defense-related genes. As the infection progressed, we observed the activation of a coordinated immune response involving multiple cell types, mainly epidermal and mesophyll cells. High-dimensional weighted gene co-expression network analysis identified key hubs and networks associated with cell type-specific signaling and defense response. We describe a spatial separation of pattern- and effector-triggered immunity, supporting a model in which pattern-triggered immunity is activated at the site of pathogen contact and effector-triggered immunity is induced in surrounding tissue.

plant biology↗

bioRxiv2025

Stress-dependent responses of grapevine wood and fungal pathogen activity under esca and drought

O_LIBiotic and abiotic stresses alter the physiology of perennial plants, with consequences for fungal endophytes and disease expression. In grapevine, one of the worlds most valuable crops, drought inhibits esca disease expression, but the underlying molecular interactions between plant and fungi are unknown. C_LIO_LIWe combined wood metatranscriptomics, metabolomics, and metabarcoding to investigate these interactions in 30-year-old grapevines and eight wood-pathogenic fungi under conditions of drought or esca leaf symptom expression. C_LIO_LIBoth esca and drought decreased grapevine transpiration, but with different transcriptomic and metabolic signatures. Similar pathways were also activated, including the phenylpropanoid and stilbenoid synthesis pathways. These stress responses could potentially confer cross-tolerance, and elicit different fungal molecular responses. The levels of putative fungal virulence factors increased significantly under both stresses. Under drought, only the relative abundance of Phaeomoniella chlamydospora and gene expression involved in anti-oxidative mechanisms, growth, and reproduction increased. Under esca expression conditions, only the relative abundance of Fomitiporia mediterranea and gene expression involved in wood degradation, competition, detoxification, and growth increased. C_LIO_LIThe grapevine defense mechanisms induced by drought coupled with a low transpiration rate and a low abundance and virulence of F. mediterranea may account for esca leaf symptom inhibition upon water deficit. C_LI

plant biology↗

bioRxiv2025

Integration of diploid T2T parental genomes with progeny genomes and transcriptomes identifies resistance genes in the grape powdery mildew resistance loci Ren6 and Ren7 of Vitis piazeskii

The Chinese grape accession Vitis piasezkii DVIT2027 carries two loci associated with powdery mildew (PM) resistance loci, Ren6 and Ren7, which differ in timing and strength of response to Erysiphe necator. Both loci are consistent with recognition by intracellular immune receptors. To identify the underlying nucleotide-binding leucine-rich repeat (NLR) genes, we assembled chromosome-scale diploid genomes of DVIT2027 and the susceptible V. vinifera F2-35, parents of a segregating F1 population. We integrated these assemblies with deep resequencing data from eight F1 sib-lines carrying different Ren6/Ren7 combinations and generated trio-binned, parent-phased genomes for six progeny. This resolved both PM-resistant (PMR) and PM-susceptible (PMS) haplotypes at Ren6 and Ren7. Comparative analyses revealed extensive structural variation and complete haplotype specificity among NLRs, with several candidate genes lacking allelic counterparts in PMS haplotypes. Expression profiling across PMR sib-lines identified four and two CC-NBS-LRR genes potentially associated with Ren6 and Ren7, respectively. Sequence graph reconstruction of these loci across multiple V. piasezkii accessions revealed broad intraspecific diversity and DVIT2027-specific nodes, including within candidate NLR genes. These results provide a high-resolution view of Ren6 and Ren7 and support the identification of resistance gene candidates for functional validation and grapevine breeding.

plant biology↗

bioRxiv2025

The Genetic Basis of Microbiome Recruitment in Grapevine and its Association with Fermentative and Pathogenic Taxa

O_LIWhile grapevine is an exceptional perennial model for studying host-microbiome interactions, the host genomes role in microbiome assembly is often masked by environmental factors. This research provides a first insight into the genetic mechanisms shaping berry-associated microbial communities. C_LIO_LIUsing QTL mapping in a newly established population of 140 F1-progeny grapevine genotypes in a complete random block design, we were able to control abiotic effects and investigate how the host genome influences grape berry-associated bacterial and fungal communities. C_LIO_LIWe identify significant associations between various microorganisms and the grape genome, including pathogenic fungi such as Botrytis spp. and fermentative yeasts such as Saccharomyces cerevisiae. Many of these taxa map to the same genetic loci associated with plant immune responses, suggesting that specific genetic loci broadly influence microbial community assembly in fruits. C_LIO_LIOur findings demonstrate that grapevine genetics significantly shape the microbiome, even under varying environmental conditions; moreover, that broad, rather than known symbiont-specific mechanisms control microbial colonization of fruit, revealing an emergent "domino" effect with implications for plant-fungal-bacterial interactions. We provide a framework for understanding genotype-microbiome interactions in perennial plants, enabling future targeted experiments to establish causal relationships in microbiome recruitment and offer a potential avenue for breeding programs advancing sustainable viticulture. C_LI

microbiology↗

bioRxiv2024

Evolutionary history of the grape sex-determining region in angiosperms and emergence of dioecy in Vitaceae

Dioecy, defined by the presence of either female or male flowers on separate individual plants, is rare in angiosperms. However, it has independently evolved multiple times from hermaphroditic ancestors. In Vitis spp., flower sex is determined by a [~]200-kbp region with five genes involved in flower development and sexual identity. This study traces the evolutionary history of the Vitis sex-determining region (SDR) to assess whether it evolved in a conserved flowering-related locus. We analyzed the conservation of the Vitis SDR across 42 plant genomes and found collinearity in all 39 angiosperms, but not in non-flowering plants. The number of collinear genes and their rank-normalized gene conservation score were higher in the Vitis SDR compared to the rest of the genome, indicating its importance for flowering. We further explored SDR conservation within the Vitaceae family by long-read sequencing and haplotype phasing of eight species, including the outgroup Leea coccinea. Similarly, the Vitis SDR was highly conserved across the Vitaceae genomes, although variations in region size, primarily attributed to differences in repetitive elements, were observed. Interestingly, no recombination suppression was found in the dioecious Tetrastigma, suggesting a different sex determination mechanism. In Muscadinia rotundifolia, linkage disequilibrium analysis, haplotype comparison, and gene expression profiling showed that muscadine grapes have similar SDR boundaries and candidate sex-determining genes as Vitis. These results suggest that dioecy emerged in a common ancestor of the two grape genera at a locus associated with flower morphology and fertility, highly conserved in flowering plants.

evolutionary biology↗

bioRxiv2023

A reference-unbiased super-pangenome of the North American wild grape species (Vitis spp.) reveals genus-wide association with adaptive traits

Capturing the genetic diversity of wild relatives is crucial for improving crops because wild species are valuable sources of agronomic traits that are essential to enhance the sustainability and adaptability of domesticated cultivars. Genetic diversity across a genus can be captured in super-pangenomes, which provide a framework for interpreting genomic variations. Here we report the sequencing, assembly, and annotation of nine wild North American grape genomes, which were phased and scaffolded at chromosome scale. We generate a reference-unbiased super-pangenome using pairwise whole-genome alignment methods, revealing the extent of the genomic diversity among wild grape species from sequence to gene level. The pangenome graph captures genomic variation between haplotypes within a species and across the different species, and it accurately assesses the similarity of hybrids to their parents. The species selected to build the pangenome are a great representation of the genus, as illustrated by capturing known allelic variants in the sex-determining region and for Pierces disease resistance loci. Using pangenome-wide association analysis, we demonstrate the utility of the super-pangenome by effectively mapping short-reads from genus-wide samples and identifying loci associated with salt tolerance in natural populations of grapes. This study highlights how a reference-unbiased super-pangenome can reveal the genetic basis of adaptive traits from wild relatives and accelerate crop breeding research.

genomics↗

bioRxiv2022

The grape powdery mildew resistance loci Ren2, Ren3, Ren4D, Ren4U, Run1, Run1.2b, Run2.1, and Run2.2 activate different transcriptional responses to Erysiphe necator

Multiple grape powdery mildew (PM) genetic resistance (R) loci have been found in wild grape species. Little is known about the defense responses associated with each R locus. In this study, we compare the defense mechanisms associated with PM resistance in interspecific crosses segregating for a single R locus from Muscadinia rotundifolia (Run1, Run1.2b, Run2.1, Run2.2), Vitis cinerea (Ren2), V. romanetii (Ren4D and Ren4U), and the interspecific hybrid Villard blanc (Ren3). By combining optical microscopy, visual scoring, and biomass estimation, we show that the eight R loci confer resistance by limiting infection at different stages. We assessed the defense mechanisms triggered in response to PM at 1 and 5 days post inoculation (dpi) via RNA sequencing. To account for the genetic differences between species, we developed for each accession a diploid synthetic reference transcriptome by incorporating into the PN40024 reference homozygous and heterozygous sequence variants and de novo assembled transcripts. Most of the R loci exhibited a higher number of differentially expressed genes (DEGs) associated with PM resistance at 1 dpi compared to 5 dpi, suggesting that PM resistance is mostly associated with an early transcriptional reprogramming. Comparison of the PM resistance-associated DEGs showed a limited overlap between pairs of R loci, and nearly half of the DEGs were specific to a single R locus. The largest overlap of PM resistance-associated DEGs was found between Ren3+, Ren4D+, and Ren4U+ genotypes at 1 dpi, and between Ren4U+ and Run1+ accessions at 5 dpi. The Ren3+, Ren4D+, and Ren4U+ were also found to have the highest number of R locus-specific DEGs in response to PM. Both shared and R locus-specific DEGs included genes from different defense-related categories, indicating that the presence of E. necator triggered distinct transcriptional responses in the eight R loci.

genetics↗

bioRxiv2022

HiFi chromosome-scale diploid assemblies of the grape rootstocks 110R, Kober 5BB, and 101-14 Mgt

Cultivated grapevines are commonly grafted on closely related species to cope with specific biotic and abiotic stress conditions. The three North American Vitis species V. riparia, V. rupestris, and V. berlandieri, are the main species used for breeding grape rootstocks. Here, we report the diploid chromosome-scale assembly of three widely used rootstocks derived from these species: Richter 110 (110R), Kober 5BB, and 101-14 Millardet et de Grasset (Mgt). Draft genomes of the three hybrids were assembled using PacBio HiFi sequences at an average coverage of 53.1 X-fold. Using the tool suite HaploSync, we reconstructed the two sets of nineteen chromosome-scale pseudomolecules for each genome with an average haploid genome size of 494.5 Mbp. Residual haplotype switches were resolved using shared-haplotype information. These three reference genomes represent a valuable resource for studying the genetic basis of grape adaption to biotic and abiotic stresses, and designing trait-associated markers for rootstock breeding programs.

genomics↗

bioRxiv2021

Characterization of the grape powdery mildew genetic resistance loci in Muscadinia rotundifolia Trayshed

Muscadinia rotundifolia cv. Trayshed is a valuable source of resistance to grape powdery mildew. It carries two powdery mildew resistance-associated genetic loci, Run1.2 on chromosome 12 and Run2.2 on chromosome 18. In this study, we identified, phased, and reconstructed the two haplotypes of each resistance-associated locus. Haplotype phasing allowed the identification of several structural variation events between haplotypes of both loci. Combined with manual refinement of the gene models, we found that the heterozygous structural variants affected the gene content, with some resulting in duplicated or hemizygous nucleotide-binding leucine-rich repeat (NLR) genes. Structural variations also impacted the domain composition of some NLRs. These findings emphasize the need of generating haplotype-resolved sequences instead of using consensus sequences for identifying haplotype-specific candidate genes. Comparison of the NLRs in the Run1.2 and Run2.2 loci indicated that the two loci are composed of a different number and classes of NLR genes. We provide a list of candidate NLR genes from the Run1.2b and Run2.2 loci, whose expression suggests a role in powdery mildew resistance in Trayshed. These first complete and haplotype-resolved resistance-associated loci, and their candidate NLR genes, represent new resources to develop powdery mildew-resistant grape cultivars.

plant biology↗

bioRxiv2021

Assembly of complete diploid phased chromosomes from draft genome sequences

De novo genome assembly is essential for genomic research. High-quality genomes assembled into phased pseudomolecules are challenging to produce and often contain assembly errors because of repeats, heterozygosity, or the chosen assembly strategy. Although algorithms that produce partially phased assemblies exist, haploid draft assemblies that may lack biological information remain favored because they are easier to generate and use. We developed HaploSync, a suite of tools that produces fully phased, chromosome-scale diploid genome assemblies, and performs extensive quality control to limit assembly artifacts. HaploSync scaffolds sequences from a draft diploid assembly into phased pseudomolecules guided by a genetic map and/or the genome of a closely related species. HaploSync generates a report that visualizes the relationships between current and legacy sequences, for both haplotypes, and displays their gene and marker content. This quality control helps the user identify misassemblies and guides Haplosyncs correction of scaffolding errors. Finally, HaploSync fills assembly gaps with unplaced sequences and resolves collapsed homozygous regions. In a series of plant, fungal, and animal kingdom case studies, we demonstrate that HaploSync efficiently increases the assembly contiguity of phased chromosomes, improves completeness by filling gaps, corrects scaffolding, and correctly phases highly heterozygous, complex regions.

bioinformatics↗

bioRxiv2021

Rootstocks influence the response of ripening grape berries to leafroll associated viruses

Grapevine leafroll-associated virus (GLRaV) infections are accompanied by symptoms with varying severity. Using a dedicated experimental vineyard, we studied the responses to GLRaVs in ripening berries from Cabernet franc grapevines grafted to different rootstocks and with zero, one, or pairs of leafroll infection(s). RNA sequencing data were mapped to a high-quality Cabernet franc genome reference assembled to carry out this study and integrated with hormone and metabolite abundance data. This study identified several molecular levers that participate in responses to GLRaVs, including those that are condition-dependent. This included describing common responses to GLRaVs that were reproduced in two consecutive years, in plants grafted to different rootstocks, and in more than one infection condition. Though different infections were inconsistently distinguishable from one another overall, the effects of infections in plants grafted to different rootstocks were distinct at each developmental stage. Conserved responses included the modulation of pathogen detecting genes, increases in abscisic acid signaling and cytoskeleton remodeling gene expression. The abundance of abscisic acid (ABA), related metabolites, ABA and hormone signaling-related gene expression, and the expression of several transcription factor families differentiated rootstocks overall. These data show that rootstock influences the effect of GLRaVs in ripening berries.

plant biology↗

bioRxiv2019

The genetic basis of sex determination in grapevines (Vitis spp.)

Sex determination in grapevine evolved through a complex succession of switches in sexual systems. Phased genomes built with single molecule real-time sequencing reads were assembled for eleven accessions of cultivated hermaphrodite grapevines and dioecious males and females, including the ancestor of domesticated grapevine and other related wild species. By comparing the phased sex haplotypes, we defined the sex locus of the Vitis genus and identified polymorphisms spanning regulatory and coding sequences that are in perfect association with each sex-type throughout the genus. These findings identified a novel male-fertility candidate gene, INP1, and significantly refined the model of sex determination in Vitis and its evolution.

evolutionary biology↗

bioRxiv2018

Structural variants, clonal propagation, and genome evolution in grapevine (Vitis vinifera)

Little is known about the type and numbers of structural variants (SVs) in plant genomes, the evolutionary processes that shape SV variation, or their effects on phenotypes. Here we assembled the 605Mb genome of the Chardonnay grape (Vitis vinifera ssp. sativa), which we use to catalog SVs within and between genomes and also across 69 cultivars and wild accessions. SVs underlie widespread hemizygosity of protein coding genes within Chardonnay and genic presence-absence variation between cultivars. Negative selection acts against all SV types, but they also accrue as heterozygous, recessive mutations in clonally propagated grapevines. SV hotspots in the sex determination region and the berry color locus illustrate their impact on phenotype and the role of SVs as drivers of convergent phenotypic evolution.

evolutionary biology↗

bioRxiv2018

Isoform-scale annotation and expression profiling of the Cabernet Sauvignon transcriptome using single-molecule sequencing of full-length cDNA

Transcriptomics has been widely applied to study grape berry development. With few exceptions, transcriptomic studies in grape are performed using the available genome sequence, PN40024, as reference. However, differences in gene content among grape accessions, which contribute to phenotypic differences among cultivars, suggest that a single reference genome does not represent the species entire gene space. Though whole genome assembly and annotation can reveal the relatively unique or \"private\" gene space of any particular cultivar, transcriptome reconstruction is a more rapid, less costly, and less computationally intensive strategy to accomplish the same goal. In this study, we used single molecule-real time sequencing (Iso-Seq) to sequence full-length cDNA and reconstruct the transcriptome of Cabernet Sauvignon berries during berry ripening. In addition, Illumina short reads from ripening berries were used to error-correct low-expression isoforms and to profile isoform expression. By comparing the annotated gene space of Cabernet Sauvignon to other grape cultivars, we demonstrate that the transcriptome reference built with Iso-Seq data represents most of the expressed genes in the grape berries and includes 1,501 cultivar-specific genes. Iso-Seq produced transcriptome profiles similar to those obtained after mapping on a complete genome reference. Together, these results justify the application of Iso-Seq to identify cultivar-specific genes and build a comprehensive reference for transcriptional profiling that circumvents the necessity of a genome reference with its associated costs and computational weight.

genomics↗

bioRxiv2018

Whole-genome resequencing and pan-transcriptome reconstruction highlight the impact of genomic structural variation on secondary metabolism gene clusters in the grapevine Esca pathogen Phaeoacremonium minimum

The Ascomycete fungus Phaeoacremonium minimum is one of the primary causal agents of Esca, a widespread and damaging grapevine trunk disease. Variation in virulence among Pm. minimum isolates has been reported, but the underlying genetic basis of the phenotypic variability remains unknown. The goal of this study was to characterize intraspecific genetic diversity and explore its potential impact on virulence functions associated with secondary metabolism, cellular transport, and cell wall decomposition. We generated a chromosome-scale genome assembly, using single molecule real-time sequencing, and resequenced the genomes and transcriptomes of multiple isolates to identify sequence and structural polymorphisms. Numerous insertion and deletion events were found for a total of about 1 Mbp in each isolate. Structural variation in this extremely gene dense genome frequently caused presence/absence polymorphisms of multiple adjacent genes, mostly belonging to biosynthetic clusters associated with secondary metabolism. Because of the observed intraspecific diversity in gene content due to structural variation we concluded that a transcriptome reference developed from a single isolate is insufficient to represent the virulence factor repertoire of the species. We therefore compiled a pan-transcriptome reference of Pm. minimum comprising a non-redundant set of 15,245 protein-coding sequences. Using naturally infected field samples expressing Esca symptoms, we demonstrated that mapping of meta-transcriptomics data on a multi-species reference that included the Pm. minimum pan-transcriptome allows the profiling of an expanded set of virulence factors, including variable genes associated with secondary metabolism and cellular transport.

genomics↗

bioRxiv2017

The Evolutionary Genomics of Grape (Vitis vinifera ssp. vinifera) Domestication

We gathered genomic data from grapes (Vitis vinifera ssp. vinifera), a clonally propagated perennial crop, to address three ongoing mysteries about plant domestication. The first is the duration of domestication; archaeological evidence suggests that domestication occurs over millennia, but genetic evidence indicates it can occur rapidly. We estimated that our wild and cultivated grape samples diverged ~22,000 years ago and that the cultivated lineage experienced a steady decline in population size (Ne) thereafter. The long decline may reflect low intensity management by humans prior to domestication. The second mystery is the identification of genes that contribute to domestication phenotypes. In cultivated grapes, we identified candidate-selected genes that function in sugar metabolism, flower development and stress responses. In contrast, candidate selected genes in the wild sample were limited to abiotic and biotic stress responses. A genomic region of high divergence corresponded to the sex determination region and included a candidate male sterility factor and additional genes with sex-specific expression. The third mystery concerns the cost of domestication. Annual crops accumulate putatively deleterious variants, in part due to strong domestication bottlenecks. The domestication of perennial crops differs from annuals in several ways, including the intensity of bottlenecks, and it is not yet clear if they accumulate deleterious variants. We found that grape accessions contained 5.2% more deleterious variants than wild individuals, and these were more often in a heterozygous state. Using forward simulations, we confirm that clonal propagation leads to the accumulation of recessive deleterious mutations but without decreasing fitness.\n\nSignificance StatementWe generated genomic data to estimate the population history of grapes, the most economically important horticultural crop in the world. Domesticated grapes experienced a protracted, 22,000 year population decline prior to domestication; we hypothesize that this decline reflects low intensity cultivation by humans prior to domestication. Domestication altered the mating system of grapes. The sex determination region is detectable as a region of heightened genetic divergence between wild and cultivated accessions. Based on gene expression analyses, we propose new candidate genes that alter sex determination. Finally, grapes contain more deleterious mutations in heterozygous states than their wild ancestors. The accumulation of deleterious mutations is due in part to clonal propagation, which shelters deleterious, recessive mutations.

evolutionary biology↗