homoploid hybrid
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Plants ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 182
Author(s):  
Jaume Pellicer ◽  
Manica Balant ◽  
Pol Fernández ◽  
Roi Rodríguez González ◽  
Oriane Hidalgo

The genus Urospermum is distributed in the Mediterranean region and Macaronesia, and has been introduced to other extra-Mediterranean regions. Although the two species constituting the genus, U. dalechampii and U. picroides, are frequently found together, hybrids have so far only been reported once, from Morocco. However, we found certain individuals in Catalonia, whose intermediate morphology suggested a potential hybrid origin. In this study, we applied morphological and molecular methods to investigate the origin of those individuals. Intermediate features at phenotype, karyological, cytogenetic, and genomic levels were identified in morphologically intermediate individuals, supporting their homoploid hybrid origin. Chloroplast sequence data suggest that U. dalechampii is the maternal progenitor of the hybrid. Together with the intermediate traits displayed, the lack of fertile seeds suggests that hybrids are probably F1. Future monitoring studies will be, nonetheless, needed to evaluate the extent of hybridisation and its potential impact on the biology of the genus.


Plants ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 125
Author(s):  
Francesco Blasio ◽  
Pilar Prieto ◽  
Mónica Pradillo ◽  
Tomás Naranjo

Hybridization and polyploidy have been considered as significant evolutionary forces in adaptation and speciation, especially among plants. Interspecific gene flow generates novel genetic variants adaptable to different environments, but it is also a gene introgression mechanism in crops to increase their agronomical yield. An estimate of 9% of interspecific hybridization has been reported although the frequency varies among taxa. Homoploid hybrid speciation is rare compared to allopolyploidy. Chromosome doubling after hybridization is the result of cellular defects produced mainly during meiosis. Unreduced gametes, which are formed at an average frequency of 2.52% across species, are the result of altered spindle organization or orientation, disturbed kinetochore functioning, abnormal cytokinesis, or loss of any meiotic division. Meiotic changes and their genetic basis, leading to the cytological diploidization of allopolyploids, are just beginning to be understood especially in wheat. However, the nature and mode of action of homoeologous recombination suppressor genes are poorly understood in other allopolyploids. The merger of two independent genomes causes a deep modification of their architecture, gene expression, and molecular interactions leading to the phenotype. We provide an overview of genomic changes and transcriptomic modifications that particularly occur at the early stages of allopolyploid formation.


Author(s):  
Juan F. Masello ◽  
Peter G. Ryan ◽  
Lara D. Shepherd ◽  
Petra Quillfeldt ◽  
Yves Cherel ◽  
...  

AbstractInterspecific introgression can occur between species that evolve rapidly within an adaptive radiation. Pachyptila petrels differ in bill size and are characterised by incomplete reproductive isolation, leading to interspecific gene flow. Salvin’s prion (Pachyptila salvini), whose bill width is intermediate between broad-billed (P. vittata) and Antarctic (P. desolata) prions, evolved through homoploid hybrid speciation. MacGillivray’s prion (P. macgillivrayi), known from a single population on St Paul (Indian Ocean), has a bill width intermediate between salvini and vittata and could also be the product of interspecies introgression or hybrid speciation. Recently, another prion population phenotypically similar to macgillivrayi was discovered on Gough (Atlantic Ocean), where it breeds 3 months later than vittata. The similarity in bill width between the medium-billed birds on Gough and macgillivrayi suggest that they could be closely related. In this study, we used genetic and morphological data to infer the phylogenetic position and evolutionary history of P. macgillivrayi and the Gough medium-billed prion relative other Pachyptila taxa, to determine whether species with medium bill widths evolved through common ancestry or convergence. We found that Gough medium-billed prions belong to the same evolutionary lineage as macgillivrayi, representing a new population of MacGillivray’s prion that originated through a colonisation event from St Paul. We show that macgillivrayi’s medium bill width evolved through divergence (genetic drift) and independently from that of salvini, which evolved through hybridisation (gene flow). This represents the independent convergence towards a similarly medium-billed phenotype. The newly discovered MacGillivray’s prion population on Gough is of utmost conservation relevance, as the relict macgillivrayi population in the Indian Ocean is very small.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guohong Albert Wu ◽  
Chikatoshi Sugimoto ◽  
Hideyasu Kinjo ◽  
Chika Azama ◽  
Fumimasa Mitsube ◽  
...  

AbstractThe origin and dispersal of cultivated and wild mandarin and related citrus are poorly understood. Here, comparative genome analysis of 69 new east Asian genomes and other mainland Asian citrus reveals a previously unrecognized wild sexual species native to the Ryukyu Islands: C. ryukyuensis sp. nov. The taxonomic complexity of east Asian mandarins then collapses to a satisfying simplicity, accounting for tachibana, shiikuwasha, and other traditional Ryukyuan mandarin types as homoploid hybrid species formed by combining C. ryukyuensis with various mainland mandarins. These hybrid species reproduce clonally by apomictic seed, a trait shared with oranges, grapefruits, lemons and many cultivated mandarins. We trace the origin of apomixis alleles in citrus to mangshanyeju wild mandarins, which played a central role in citrus domestication via adaptive wild introgression. Our results provide a coherent biogeographic framework for understanding the diversity and domestication of mandarin-type citrus through speciation, admixture, and rapid diffusion of apomictic reproduction.


Evolution ◽  
2021 ◽  
Author(s):  
Benjamin E. Goulet‐Scott ◽  
Austin G. Garner ◽  
Robin Hopkins

2021 ◽  
Author(s):  
Homa Papoli Yazdi ◽  
Melissah Rowe ◽  
Mark Ravinet ◽  
Glenn-Peter Sætre ◽  
Caroline Øien Guldvog ◽  
...  

Hybridization is increasingly recognized as an important evolutionary force contributing novel variation for selection to act on. While mis-expression in F1 hybrids is well documented, how gene expression evolves in stabilized hybrid taxa and contributes novel variation remains an open question, especially for hybrid species without an increase in ploidy. As gene expression evolves in a stabilizing manner, break-up of co-evolved cis- and trans-regulatory elements could lead to transgressive patterns of gene expression in hybrids. Here, we address to what extent gonad gene expression has evolved in an old homoploid hybrid, Italian sparrow, Passer italiae. Through comparing the gene expression of parental species and F1 hybrids to that of the Italian sparrow, we find evidence for strongly transgressive expression in the Italian sparrow, with 22% of the testis genes exhibiting expression patterns outside the range of both parent species, compared to only 0.37% in the F1s. In contrast, Italian sparrow ovary expression was similar to that of one parent species, the house sparrow (P. domesticus). Moreover, the Italian sparrow testis transcriptome is 26.2 -26.6 times as diverged from those of the parent species compared to how divergent their transcriptomes are in spite of it being genetically intermediate. This highlights the potential for regulation of gene expression to produce novel variation following hybridization. Genes involved in energy production and protein synthesis are enriched in the subset that is over-dominantly expressed in Italian sparrow testis, suggesting that selection on key functions have molded the hybrid transcriptome.


2021 ◽  
Vol 307 (2) ◽  
Author(s):  
Božo Frajman ◽  
Dmitry Geltman

AbstractThe Caucasus is one of the richest areas in the world in terms of animal and plant diversity, harbouring 6400 plant species. As a part of the Northern Caucasus, the Stavropol Heights are renowned for their local endemism, highlighted by six species of flowering plants endemic to this area. One of them is the annual species Euphorbia normannii, described in 1891, but with uncertain taxonomic position. We here used nuclear ribosomal internal transcribed spacer and plastid trnT–trnF sequences to infer the phylogenetic position of E. normannii. The nuclear data inferred its position within E. sect. Myrsiniteae, whereas the plastid data placed it within E. sect. Pithyusa, thus indicating a hybrid origin. Relative genome size (RGS) data indicate that E. normannii has the highest RGS compared to three other annual species belonging to both sections (E. aleppica, E. gaillardotii and E. falcata). Our data are inconclusive whether E. normannii is of allopolyploid or homoploid hybrid origin, or whether later hybridisation and plastid capture from E. sect. Pithyusa was responsible for the incongruent phylogenetic signal. Morphologically, E. normannii is distinct, as are all three before-mentioned annuals, which fall in predominately perennial sections. However, the species most similar to E. normannii is E. falcata from E. sect. Pithyusa and therefore we propose inclusion of E. normannii in this section.


2021 ◽  
Vol 11 ◽  
Author(s):  
Karolina Heyduk ◽  
Edward V. McAssey ◽  
Jane Grimwood ◽  
Shengqiang Shu ◽  
Jeremy Schmutz ◽  
...  

Hybridization in plants results in phenotypic and genotypic perturbations that can have dramatic effects on hybrid physiology, ecology, and overall fitness. Hybridization can also perturb epigenetic control of transposable elements, resulting in their proliferation. Understanding the mechanisms that maintain genomic integrity after hybridization is often confounded by changes in ploidy that occur in hybrid plant species. Homoploid hybrid species, which have no change in chromosome number relative to their parents, offer an opportunity to study the genomic consequences of hybridization in the absence of change in ploidy. Yucca gloriosa (Asparagaceae) is a young homoploid hybrid species, resulting from a cross between Yucca aloifolia and Yucca filamentosa. Previous analyses of ∼11 kb of the chloroplast genome and nuclear-encoded microsatellites implicated a single Y. aloifolia genotype as the maternal parent of Y. gloriosa. Using whole genome resequencing, we assembled chloroplast genomes from 41 accessions of all three species to re-assess the hybrid origins of Y. gloriosa. We further used re-sequencing data to annotate transposon abundance in the three species and mRNA-seq to analyze transcription of transposons. The chloroplast phylogeny and haplotype analysis suggest multiple hybridization events contributing to the origin of Y. gloriosa, with both parental species acting as the maternal donor. Transposon abundance at the superfamily level was significantly different between the three species; the hybrid was frequently intermediate to the parental species in TE superfamily abundance or appeared more similar to one or the other parent. In only one case—Copia LTR transposons—did Y. gloriosa have a significantly higher abundance relative to either parent. Expression patterns across the three species showed little increased transcriptional activity of transposons, suggesting that either no transposon release occurred in Y. gloriosa upon hybridization, or that any transposons that were activated via hybridization were rapidly silenced. The identification and quantification of transposon families paired with expression evidence paves the way for additional work seeking to link epigenetics with the important trait variation seen in this homoploid hybrid system.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jong-Soo Park ◽  
Dong-Pil Jin ◽  
Byoung-Hee Choi

AbstractSpecies in the genus Suaeda have few diagnostic characters and substantial morphological plasticity. Hence, regional floras do not provide clear taxonomic information for Suaeda spp. in East Asia. In order to assess the taxonomy of four species in the genus Suaeda (S. australis, S. maritima, S. japonica, and S. heteroptera), cpDNA (rpl32-trnL and trnH-psbA), nDNA (ITS), and MIG-seq analyses were carried out. Genome-wide SNP results indicated three lineages: (1) S. australis in Korea and S. maritima in Japan, (2) S. maritima in Korea and S. heteroptera in China, and (3) S. japionica. In phylogenetic trees and genotype analyses, cpDNA and nDNA results showed discrepancies, while S. japonica and S. maritima in Korea, and S. heteroptera in China shared the same haplotype and ribotype. We suggest that the shared haplotype may be due to chloroplast capture. Based on our results, we assume that S. japonica was formed by homoploid hybrid speciation between the two lineages.


2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Birthe H. Barke ◽  
Kevin Karbstein ◽  
Mareike Daubert ◽  
Elvira Hörandl

Abstract Background Hybridization and polyploidization are powerful evolutionary factors that are associated with manifold developmental changes in plants such as irregular progression of meiosis and sporogenesis. The emergence of apomixis, which is asexual reproduction via seeds, is supposed to be connected to these factors and was often regarded as an escape from hybrid sterility. However, the functional trigger of apomixis is still unclear. Recently formed di- and polyploid Ranunculus hybrids, as well as their parental species were analysed for their modes of mega- and microsporogenesis by microscopy. Chromosomal configurations during male meiosis were screened for abnormalities. Meiotic and developmental abnormalities were documented qualitatively and collected quantitatively for statistical evaluations. Results Allopolyploids showed significantly higher frequencies of erroneous microsporogenesis than homoploid hybrid plants. Among diploids, F2 hybrids had significantly more disturbed meiosis than F1 hybrids and parental plants. Chromosomal aberrations included laggard chromosomes, chromatin bridges and disoriented spindle activities. Failure of megasporogenesis appeared to be much more frequent in than of microsporogenesis is correlated to apomixis onset. Conclusions Results suggest diverging selective pressures on female and male sporogenesis, with only minor effects of hybridity on microsporogenesis, but fatal effects on the course of megasporogenesis. Hence, pollen development continues without major alterations, while selection will favour apomixis as alternative to the female meiotic pathway. Relation of investigated errors of megasporogenesis with the observed occurrence of apospory in Ranunculus hybrids identifies disturbed female meiosis as potential elicitor of apomixis in order to rescue these plants from hybrid sterility. Male meiotic disturbance appears to be stronger in neopolyploids than in homoploid hybrids, while disturbances of megasporogenesis were not ploidy-dependent.


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