Biology subjects

Grover, C. E.

Publications and source records attributed to Grover, C. E..

At least 19 recordsLinked to original sources

bioRxiv2026

Four genome assemblies of new wild Gossypium hirsutum accessions from the Yucatan Peninsula, the center of domestication

Gossypium hirsutum is a leading source of natural cotton fiber, accounting for most of the market share. While domestication and improvement have led to significant gains in fiber quantity and quality, the narrow germplasm base of modern cultivars creates vulnerabilities, including to emerging pests. Wild populations provide a reservoir for genetic diversity that may be valuable in identifying and transferring resistance or stress-adaptation alleles to modern breeding lines. Here we report four new genome assemblies of G. hirsutum representing distinct populations from its center of diversity in Yucatan, Mexico. These chromosome-level assemblies are highly contiguous and structurally similar to existing G. hirsutum genomes; however, comparative analyses highlight their distinctiveness, suggesting they form a valuable reservoir of untapped diversity. Preliminary analyses of nucleotide-binding leucine-rich repeat (NLR) immune receptor genes underscore this variation, suggesting presence-absence variation may exist among populations. These findings demonstrate the potential of these new genomic resources for discovery of novel disease resistance alleles and, generally, for expanding the narrow germplasm base of the modern cotton cultivars.

genomics↗

bioRxiv2025

Population Genomics Informs Conservation Strategies for Critically Endangered Kokia Species in Hawaii

Island endemic species are particularly vulnerable to extinction due to their limited geographic ranges and small population sizes. Kokia is a genus found exclusively in the Hawaiian Islands, whose species were once major components of local forests but have experienced significant population reductions due to habitat destruction and the consequences of invasive species. Although conservation of Kokia species has been an ongoing topic for over a century, records regarding historical efforts are sparse. Recently generated genomes for each of the three extant species provide the foundation for understanding genetic diversity and population structure for future conservation work. Whole genome resequencing of K. cookei (n = 23 samples), K. drynarioides (n = 92), and K. kauaiensis (n = 45) suggests that K. drynarioides has the lowest overall diversity, reflecting propagation from a limited part of the remaining gene pool, whereas K. kauaiensis exhibits the most diversity. Diversity in the primarily graft-propagated K. cookei is higher than expected, and slightly higher than in the free-living K. drynarioides. Notably, our analyses identified a source of novel variation in K. cookei in a cultivated plant historically labeled K. drynarioides. Population structure analyses reveal a single population for K. cookei, but three groups for each of the other two species. Importantly, our analyses identify clusters of related individuals, reflected in genetic distance and clustering metrics, which provide valuable information for increasing diversity in managed populations and in ex situ conservation collections. These results provide a genomic framework for ongoing efforts in restoring and maintaining diversity in these critically endangered Hawaiian species.

genomics↗

bioRxiv2025

Sewing the future of cotton: a multi-omics study combining nanomechanics, transcriptomics, and phenotypic traits

Cellulose microfibrils that are essential for mechanical strength and overall quality of cotton fibers. This study quantifies and compares the nanoscale structural and mechanical properties of cellulose microfibrils such as microfibril dimensions, crossover count and angles, roughness, and Youngs modulus for two popular cotton species: Gossypium hirsutum (Gh) and Gossypium barbadense (Gb) fibers across four growth stages (8, 12, 18, and 22 days post-anthesis) using atomic force microscopy (AFM). Our results revealed for the first time that Gb fibers exhibit a better alignment, finer dimensions, and higher stiffness compared to Gh fibers at nanoscale, resulting in smoother fiber surfaces, and improved quality at macroscale. We are also the first to develop machine-learning models to predict macroscale phenotypic traits specifically boll length and cellulose content using nanoscale features alone and in combination with multi-omics modalities, substantially enhancing the predictive accuracy and highlighting opportunities for robust cross-species modeling of cotton fiber traits.

biophysics↗

bioRxiv2025

Comparative multi-omics profiling of Gossypium hirsutum and Gossypium barbadense fibers at high temporal resolution reveals key differences in polysaccharide composition and associated glycosyltransferases

Among the two allopolyploid cultivated species of cotton, Gossypium barbadense is known for its superior quality fiber compared to G. hirsutum. Length and strength are key determinants of the fiber quality. Although the mature fibers are dried cell walls consisting mainly cellulose, the dynamic remodeling of pectin, xyloglucan, and xylan polysaccharides during fiber growth significantly impact the final fiber quality. Comprehensive knowledge about polysaccharides and their biosynthesis during fiber development of the cultivated species is important for improving fiber quality. In this study, comparative large-scale glycome, transcriptome and proteome profiling were conducted daily on fibers of both cotton species covering critical stages of fiber development spanning primary cell wall synthesis and the transition to secondary wall synthesis. Interspecific comparisons revealed that a delayed accumulation of cellulose content, as well as the occurrence of lower levels and differential compositions of non-fucosylated/fucosylated xyloglucans, homogalacturonans, and highly branched Rhamnogalacturonan-I polysaccharides might be contributing to longer fiber phenotypes of G. barbadense relative to G. hirsutum. Our study also suggests, differential temporal compositions of heteroxylans might contribute to variation in cellulose microfibril arrangement and strength of fiber exists between the two species of cotton. Comparative transcriptomic analysis identified differentially expressed polysaccharide-synthesizing glycosyltransferases that might underlie fiber quality differences between the two species. Transcripts encoding many cell wall localized expansins were more abundant in G. barbadense than in G. hirsutum. Overall, these findings extend our knowledge regarding the molecular factors that contribute to fiber quality and provide insights for targeted cotton fiber improvement. SIGNIFICANCE STATEMENTComparative multi-omics profiling of two major commercial cotton species, Gossypium hirsutum and Gossypium barbadense revealed substantial differences in polysaccharide structures and expressed polysaccharide-synthesizing glycosyltransferases, that potentially contribute to differences in fiber length and strength. The molecular details elucidated in the present study contribute to the goal of improving fiber quality and its commercial value.

plant biology↗

bioRxiv2025

Proteomics-based models of gene expression and cellular control of cotton fiber development

The shapes and material properties of cotton seed coat trichoblasts are the basis of a multibillion-dollar natural fiber industry. As such, these highly specialized cells are low-hanging fruit for intentional trait engineering. However, broad successes will require more mechanistic knowledge about their systems-level cellular controls. This time-series study integrates daily measurements of purified fiber transcriptomes and proteomes with multiscale fiber phenotyping datasets that span the same developmental interval. Abundance profiles of the subcellular proteomes are the foundation of the analyses. This resource article provides direct information concerning which homoeologs operate and informative depictions of how compartmentalized cellular systems change during developmental transitions. Prediction accuracy was partially validated by analysis of the protein expression group 11, which contained multiple known secondary cell wall cellulose synthases and dozens of unknown proteins and an averaged profile that was strongly correlated with a sharp state transition in cellulose microfibril alignment and increased cellulose content. The dataset as a whole can serve as a hypothesis-generating machine to guide future experiments that relate to cell shape and growth rate control, reversible tissue formation, and cell wall remodeling. Integration of mRNA and protein abundance revealed widespread evidence for post-transcriptional control. In addition, there were hundreds of transcriptionally controlled genes with differing timepoints of transition. This latter gene set can be used to more reliably analyze transcriptional control networks and to generate collections of gene expression drivers for cotton fiber research. The protein and transcript data are organized into user-friendly tables and a web interface that can be searched using any plant ortholog of interest based on developmental time, abundance, annotations, or phenotypic association.

plant biology↗

bioRxiv2024

Assessment of the Genetic Diversity of Atlantic Bottlenose Dolphin (Tursiops truncatus) Strandings in the Mississippi Sound (USA)

The common bottlenose dolphin (Tursiops truncatus) is a key marine mammal species in the northern Gulf of Mexico, playing an essential role as a top predator. This study focuses on the genetic diversity and population structure of bottlenose dolphins stranded in the Mississippi Sound from 2010 to 2021. A total of 511 tissue samples (muscle, liver, lung, kidney, and brain) were collected from stranded dolphins, and mitochondrial DNA (mtDNA) was extracted for analysis. Using high-throughput sequencing methods, 417 samples were successfully amplified and sequenced, producing 386 complete mitogenomes. Genetic diversity metrics, such as nucleotide and haplotype diversity, were calculated, and population structure was inferred for both mitochondrial control region (mtCR) and whole mitogenome sequences. Using the whole mitogenome, the study identified four genetically distinct populations within the Mississippi Sound, demonstrating regional variation in dolphin populations. Notably, some individuals likely originated from populations outside the sampled area. The use of whole mitogenomes allowed for improved resolution of genetic diversity and population differentiation compared to previous studies using partial mtDNA sequences. These findings provide critical insights into the genetic structure of bottlenose dolphins in the region and highlight the value of using stranded animals for population genetic studies.

genomics↗

bioRxiv2024

Developmental variability in cotton fiber cell wall properties linked to important agronomic traits

The economic value of cotton is based on its long, thin, strong, and twisted trichoblasts that emerge from the ovule epidermis. The mature dried fiber cell reflects the outcome of a rapid tapering of the nascent trichoblast, weeks of polarized diffuse growth, followed by a transition to persistent secondary cell wall synthesis. Highly conserved and dynamic microtubule and cellulose microfibril-based anisotropic growth control modules are central to all of these phases. In this paper, we developed novel quantitative phenotyping and computational modeling pipelines to analyze fiber growth behaviors at a daily resolution. We uncovered unexpected variability in growth rate, cell wall properties, and cell geometry across a critical window of fiber development. Finite element computational modeling of fiber growth was used to analyze the instability of cell diameter control and predict how spatial gradients of fiber and matrix material properties can interact to dictate the patterns of shape change. As an initial step toward gaining insight into the molecular orchestration of cellulose biosynthesis, expression profiles of a broad set of relevant genes were quantified across the same developmental timeline and correlated with fiber phenotypes. This analysis identified specific candidate genes that may serve as targets for fiber quality improvement.

plant biology↗

bioRxiv2024

Dynamics of duplicated gene regulatory networks governing cotton fiber development following polyploidy

Cotton fiber development entails complex genome-wide gene regulatory networks (GRN) that remain mostly unexplored. Here we present integrative analyses of fiber GRNs using public RNA-seq datasets, integrated with multi-omics genomic, transcriptomic, and cistromic data. We detail the fiber co-expression dynamics and regulatory connections, validating findings with external datasets and transcription factor (TF) binding site data. We elucidate previously uncharacterized TFs that regulate genes involved in fiber-related functions and cellulose synthesis, and identify the regulatory role of two homoeologous G2-like transcription factors on fiber length. Analysis of duplicated gene expression and network relationships in allopolyploid cotton, which has two co-resident genomes (A, D), revealed novel aspects of asymmetric subgenomic developmental contributions. Whereas D-based homoeolog pairs drive higher overall gene expression from the D subgenome, TFs from the A subgenome play a preferential regulatory role in the fiber gene regulatory network. Following allopolyploid formation, it appears that the trans-regulatory roles of TFs diversified more rapidly between homoeologs than did the cis-regulatory elements of their target genes. Our approach underscores the utility of network analysis for detection of master regulators and provides fresh perspectives on fiber development and polyploid functional genomics, through the lens of co-expression and GRN dynamics.

bioinformatics↗

bioRxiv2024

A high-resolution model of gene expression during Gossypium hirsutum (cotton) fiber development

Cotton fiber development relies on complex and intricate biological processes to transform newly differentiated fiber initials into the mature, extravagantly elongated cellulosic cells that are the foundation of this economically important cash crop. Here we extend previous research into cotton fiber development by employing controlled conditions to minimize variability and utilizing time-series sampling and analyses to capture daily transcriptomic changes from early elongation through the early stages of secondary wall synthesis (6 to 24 days post anthesis; DPA). A majority of genes are expressed in fiber, largely partitioned into two major coexpression modules that represent genes whose expression generally increases or decreases during development. Differential gene expression reveals a massive transcriptomic shift between 16 and 17 DPA, corresponding to the onset of the transition phase that leads to secondary wall synthesis. Subtle gene expression changes are captured by the daily sampling, which are discussed in the context of fiber development. Coexpression and gene regulatory networks are constructed and associated with phenotypic aspects of fiber development, including turgor and cellulose production. Key genes are considered in the broader context of plant secondary wall synthesis, noting their known and putative roles in cotton fiber development. The analyses presented here highlight the importance of fine-scale temporal sampling on understanding developmental processes and offer insight into genes and regulatory networks that may be important in conferring the unique fiber phenotype.

cell biology↗

bioRxiv2024

Daily glycome and transcriptome profiling reveals polysaccharide structures and glycosyltransferases critical for cotton fiber growth

Cotton fiber length and strength are key determinants of its quality. Dynamic changes in the pectin, xyloglucan, xylan, and cellulose polysaccharide epitopes content during fiber growth contribute to complex remodeling of fiber cell wall (CW) and quality. Detailed knowledge about polysaccharide compositional and structural alteration in the fiber during fiber elongation and strengthening is vastly limited. Here, large-scale glycome profiling coupled with fiber phenotype and transcriptome profiling was conducted on fiber collected daily covering the most critical fiber developmental window. High temporal resolution profiling allowed us to identify specific polysaccharide epitopes associated with distinct fiber phenotypes that might contribute to fiber quality. This study revealed the critical role of highly branched RG-I pectin epitopes such as, {beta}-1,4-linked-galactans, {beta}-1,6-linked-galactans, and arabinogalactans, in addition to earlier reported homogalacturonans and xyloglucans in the formation of cotton-fiber-middle-lamella and contributing to fiber plasticity and elongation. We also propose the essential role of heteroxylans (Xyl-MeGlcA and Xyl-3Ar), as a guiding factor for secondary CW cellulose-microfibril arrangement, thus contributing to fiber strength. Correlation analysis of glycome and transcriptome data identified several key putative glycosyltransferases involved in synthesizing the critical polysaccharide epitopes. Novel details discovered here provide a foundation to identify molecular factors that dictate important fiber traits.

plant biology↗

bioRxiv2024

Genomic diversity and evolution in the Hawaiian Islands endemic Kokia (Malvaceae)

Island species are highly vulnerable due to habitat destruction and their often small population sizes with reduced genetic diversity. The Hawaiian Islands constitute the most isolated archipelago on the planet, harboring many endemic species. Kokia is an endangered flowering plant genus endemic to these islands, encompassing three extant and one extinct species. Recent studies provided evidence of unexpected genetic diversity within Kokia. Here, we provide high quality genome assemblies for all three extant Kokia species, including an improved genome for K. drynarioides. All three Kokia genomes contain 12 chromosomes exhibiting high synteny within and between Kokia and the sister taxon Gossypioides kirkii. Gene content analysis revealed a net loss of genes in K. cookei compared to other species, whereas the gene complement in K. drynarioides remains stable and that of K. kauaiensis displays a net gain. A dated phylogeny estimates the divergence time from the last common ancestor for the three Kokia species at [~]1.2 million years ago (mya), with the sister taxa [K. cookei + K. drynarioides] diverging [~]0.8 mya. Kokia appears to have followed a stepping-stone pattern of colonization and diversification of the Hawaiian Archipelago, likely starting on low or now submerged older islands. The genetic resources provided may benefit conservation efforts of this endangered endemic genus.

genomics↗

bioRxiv2023

Little Evidence for Homoeologous Gene Conversion and Homoeologous Exchange Events in Gossypium Allopolyploids

A complicating factor in analyzing allopolyploid genomes is the possibility of physical interactions between homoeologous chromosomes during meiosis, resulting in either crossover (homoeologous exchanges) or non-crossover products (homoeologous gene conversion). This latter process was first described in cotton by comparing SNP patterns in sequences from two diploid progenitors with those from the allopolyploid subgenomes. These analyses, however, did not explicitly account for autapomorphic SNPs that may lead to similar patterns as homoeologous gene conversion, creating uncertainties about the reality of the inferred gene conversion events. Here, we use an expanded phylogenetic sampling of high-quality genome assemblies from seven allopolyploid Gossypium species (all derived from the same polyploidy event), four diploid species (two closely related to each subgenome), and a diploid outgroup to derive a robust method for identifying potential genomic regions of gene conversion and homoeologous exchange. Using this new method, we find little evidence for homoeologous gene conversion in allopolyploid cottons and that only two of the forty best-supported events are shared by more than one species. We do, however, reveal a single, shared homoeologous exchange event at one end of chromosome 1, which occurred shortly after allopolyploidization but prior to divergence of the descendant species. Overall, our analyses demonstrate that homoeologous gene conversion and homoeologous exchanges are uncommon in Gossypium, affecting between zero and 24 genes per subgenome (0.0 - 0.065%) across the seven species. More generally, we highlight the potential problems of using simple four-taxon tests to investigate patterns of homoeologous gene conversion in established allopolyploids. SIGNIFICANCE STATEMENTAllopolyploidy is a prominent process in plant diversification, involving the union of two divergent genomes in a single nucleus via interspecific hybridization and genome doubling. The merger of genomes sets in motion a variety of inter-genomic and epigenomic interactions that are thought to lead to the origin of new phenotypes. Among these is recombinational exchange between duplicated chromosomes, which can involve sequence lengths ranging from several bases to entire chromosome arms, and which can be either reciprocal or unidirectional in their effects. Here we present a new analytical framework for detecting these inter-genomic recombinational processes in allopolyploids, and demonstrate that they have been rare in a group of allopolyploid species in the cotton genus.

evolutionary biology↗

bioRxiv2022

A high-quality chromosome-level genome assembly of rohu carp, Labeo rohita, and its utilization in SNP-based exploration of gene flow and sex determination

Labeo rohita (rohu) is a carp important to aquaculture in South Asia, with a production volume close to Atlantic salmon. While genetic improvements to rohu are ongoing, the genomic methods commonly used in other aquaculture improvement programs have historically been precluded in rohu, partially due to the lack of a high quality reference genome. Here we present a high-quality de novo genome produced using a combination of next-generation sequencing technologies, resulting in a 946 Mb genome consisting of 25 chromosomes and 2,844 unplaced scaffolds. Notably, while approximately half the size of the existing genome sequence, our genome represents 97.9% of the genome size newly estimated here using flow cytometry. Sequencing from 120 individuals was used in conjunction with this genome to predict the population structure, diversity, and divergence in three major rivers (Jamuna, Padma, and Halda), in addition to infer a likely sex determination mechanism in rohu. These results demonstrate the utility of the new rohu genome in modernizing some aspects of rohu genetic improvement programs.

genomics↗

bioRxiv2022

Innovations in double digest restriction-site associated DNA sequencing (ddRAD-Seq) method for more efficient SNP identification

We present an improved ddRAD-Seq protocol for identifying single nucleotide polymorphisms (SNPs). It utilizes optimally sized restriction enzyme digestion fragments, quick acting ligases that are neutral with the restriction enzyme buffer eliminating buffer exchange steps, and adapters designed to be compatible with Illumina index primers. Library amplification and barcoding are completed in one PCR step, and magnetic beads are used to purify the genomic fragments from the ligation and library generation steps. Our protocol increases the efficiency and decreases the time to complete a ddRAD-Seq experiment. To demonstrate its utility, we compared SNPs from our protocol with those from whole genome resequencing data from Gossypium herbaceum and Gossypium arboreum. Principal component analysis demonstrated that the variability of the combined data was explained by the genotype (PC1) and methodology applied (PC2). Phylogenetic analysis showed that the SNPs from our method clustered with SNPs from the resequencing data of the corresponding genotype. Sequence alignments illustrated that for homozygous loci, more than 90% of the SNPs from the resequencing data were discovered by our method. Our analyses suggest that our ddRAD-Seq method is reliable in identifying SNPs suitable for phylogenetic and association genetic studies while reducing cost and time over known methods.

genomics↗

bioRxiv2022

The Gossypium herbaceum L. Wagad genome as a resource for understanding cotton domestication

Gossypium herbaceum is a species of cotton native to Africa and Asia that is one of the two domesticated diploids. Together with its sister-species G. arboreum, these A-genome taxa represent models of the extinct A-genome donor of modern polyploid cotton, which provide about 95% of cotton grown worldwide. As part of a larger effort to characterize variation and improve resources among diverse diploid and polyploid cotton genomes, we sequenced and assembled the genome of G. herbaceum cultivar (cv) Wagad, representing the first domesticated accession for this species. This chromosome-level genome was generated using a combination of PacBio long-read technology, HiC, and Bionano optical mapping and compared to existing genome sequences in cotton. We compare the genome of this cultivar to the existing genome of wild G. herbaceum subspecies africanum to elucidate changes in the G. herbaceum genome concomitant with domestication, and extend these analyses to gene expression using available RNA-seq. Our results demonstrate the utility of the G. herbaceum cv Wagad genome in understanding domestication in the diploid species, which could inform modern breeding programs.

genomics↗

bioRxiv2022

Organellar transcripts dominate the cellular mRNA pool across plants of varying ploidy levels

Mitochondrial and plastid functions depend on coordinated expression of proteins encoded by genomic compartments that have radical differences in copy number of organellar and nuclear genomes. In polyploids, doubling of the nuclear genome may add challenges to maintaining balanced expression of proteins involved in cytonuclear interactions. Here, we use ribo-depleted RNA-seq to analyze transcript abundance for nuclear and organellar genomes in leaf tissue from four different polyploid angiosperms and their close diploid relatives. We find that, even though plastid genomes contain <1% of the number of genes in the nuclear genome, they generate the majority (69.9-82.3%) of mRNA transcripts in the cell. Mitochondrial genes are responsible for a much smaller percentage (1.3-3.7%) of the leaf mRNA pool but still produce much higher transcript abundances per gene compared to nuclear genome. Nuclear genes encoding proteins that functionally interact with mitochondrial or plastid gene products exhibit mRNA expression levels that are consistently more than ten-fold lower than their organellar counterparts, indicating an extreme cytonuclear imbalance at the RNA level despite the predominance of equimolar interactions at the protein level. Nevertheless, interacting nuclear and organellar genes show strongly correlated transcript abundances across functional categories, suggesting that the observed mRNA stoichiometric imbalance does not preclude coordination of cytonuclear expression. Finally, we show that nuclear genome doubling does not alter the cytonuclear expression ratios observed in diploid relatives in consistent or systematic ways, indicating that successful polyploid plants are able to compensate for cytonuclear perturbations associated with nuclear genome doubling.

plant biology↗

bioRxiv2022

Variation in cytonuclear expression accommodation among allopolyploid plants

Cytonuclear coevolution is a common feature among plants, which coordinates gene expression and protein products between the nucleus and organelles. Consequently, lineage-specific differences may result in incompatibilities between the nucleus and cytoplasm in hybrid taxa. Allopolyploidy is also a common phenomenon in plant evolution. The hybrid nature of allopolyploids may result in cytonuclear incompatibilities, but the massive nuclear redundancy created during polyploidy affords additional avenues for resolving cytonuclear conflict (i.e., cytonuclear accommodation). Here we evaluate expression changes in organelle-targeted nuclear genes for six allopolyploid lineages that represent four genera (i.e., Arabidopsis, Arachis, Chenopodium, and Gossypium) and encompass a range in polyploid ages. Because incompatibilities between the nucleus and cytoplasm could potentially result in biases toward the maternal homoeolog and/or maternal expression level, we evaluate patterns of homoeolog usage, expression bias, and expression level dominance in cytonuclear genes relative to the background of non-cytonuclear expression changes and to the diploid parents. Although we find subsets of cytonuclear genes in most lineages that match our expectations of maternal preference, these observations are not consistent among either allopolyploids or categories of organelle-targeted genes. Our results indicate that cytonuclear expression accommodation may be a subtle and/or variable phenomenon that does not capture the full range of mechanisms by which allopolyploid plants resolve nuclear-cytoplasmic incompatibilities.

evolutionary biology↗

bioRxiv2021

Dual domestication, diversity, and differential introgression in Old World cotton diploids

Domestication in the cotton genus is remarkable in that it has occurred independently four different times at two different ploidy levels. Relatively little is known about genome evolution and domestication in the cultivated diploid species Gossypium herbaceum and G. arboreum, because of the absence of wild representatives for the latter species, their ancient domestication, and their joint history of human-mediated dispersal and interspecific gene flow. Using in-depth resequencing of a broad sampling from both species, we confirm their independent domestication, as opposed to a progenitor-derivative relationship, showing that diversity (mean {pi} = 2.3x10-3) within species is similar, and that divergence between species is modest (weighted FST=0.4430). Individual accessions were homozygous for ancestral SNPs at over half of variable sites, while fixed, derived sites were at modest frequencies. Notably, two chromosomes with a paucity of fixed, derived sites (i.e., chromosomes 7 and 10) were also strongly implicated in introgression analyses. Collectively, these data demonstrate variable permeability to introgression among chromosomes, which we propose is due to divergent selection under domestication and/or the phenomenon of F2 breakdown in interspecific crosses. Our analyses provide insight into the evolutionary forces influencing diversity and divergence in the diploid cultivated species, and establish a foundation for understanding the contribution of introgression and/or strong parallel selection to the extensive morphological similarities shared between species. Significance statementThe cotton genus (Gossypium) contains four different species that were independently domesticated at least 4,000 years ago. Relatively little is understood about diversity and evolution in the two diploid African-Asian sister-species G. herbaceum and G. arboreum, despite their historical importance in the region and contemporary cultivation, largely in the Indian subcontinent. Here we address questions regarding the relationship between the two species, their contemporary levels of diversity, and their patterns of interspecific gene flow accompanying their several millennia history of human-mediated dispersal and contact. We validate independent domestication of the two species and document the genomic distribution of interspecific genetic exchange.

evolutionary biology↗