scholarly journals Recent hybrid speciation at the origin of the narrow endemic Pulmonaria helvetica

2020 ◽  
Vol 127 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Sandra Grünig ◽  
Markus Fischer ◽  
Christian Parisod
Keyword(s):  
Niche Differentiation ◽  
Ecological Modelling ◽  
Hybrid Origin ◽  
Hybrid Speciation ◽  
Niche Modelling ◽  
Hybrid Species ◽  
Intrinsic Factors ◽  
Narrow Endemic ◽  
Genetic Clusters ◽  
Original Number

Abstract Background and Aims Hybridization is known to drive plant speciation through the establishment of homoploid or allopolyploid hybrid species. Here we investigate the origin of Pulmonaria helvetica, a narrow endemic species described across a restricted area of Switzerland that was entirely covered by ice during the last glacial maximum. This species presents an original number of chromosomes (2n = 24) and morphological traits suggestive of a hybrid origin. Methods We sequenced a plastid locus and 1077 double-digest restriction-site-associated DNA (ddRAD) loci in 67 individuals from across the distribution range of P. helvetica and candidate progenitor species growing in the same area. Assignment of genotypes to main genetic clusters within and among taxa using STRUCTURE tested whether P. helvetica represents a genetically differentiated lineage and addressed the hypothesis of its hybrid origin. Comparative ecological modelling further addressed possible niche differentiation among taxa. Key Results Pulmonaria helvetica was highlighted as a genetically homogeneous species distinct from co-occurring taxa. Consistent with a scenario of hybrid speciation, it presented clear evidence of balanced admixture between Pulmonaria officinalis (2n = 16) and Pulmonaria mollis s.l. (2n = 18, 22), which was also highlighted as a maternal progenitor based on plastid sequences. Limited genetic structure within the maternal progenitor is consistent with an origin of P. helvetica through either homoploid hybridization with considerable karyotype changes or via complex scenarios of allopolyploidy involving a dysploid taxon of P. mollis s.l. Comparative niche modelling indicated non-significant ecological differences between P. helvetica and its progenitors, supporting intrinsic factors resulting from hybridization as main drivers of speciation. Conclusions Hybridization appears as a major process having promoted the postglacial origin of the narrow endemic P. helvetica, suggesting hybrid speciation as an effective process that rapidly produces new species under climate changes.

scholarly journals Reciprocal hybridization between diploid Ficaria calthifolia and tetraploid Ficaria verna subsp. verna: evidence from experimental crossing, genome size and molecular markers

2019 ◽  
Vol 189 (3) ◽  
pp. 293-310 ◽  
Author(s):  
Ondřej Popelka ◽  
Michal Sochor ◽  
Martin Duchoslav
Keyword(s):  
Genome Size ◽  
Morphological Variability ◽  
Plastid Dna ◽  
Genotypic Diversity ◽  
Hybrid Origin ◽  
Aflp Analysis ◽  
Sympatric Populations ◽  
Aflp Data ◽  
Evolutionary Forces ◽  
Genetic Clusters

Abstract Ficaria is a taxonomically intriguing polyploid complex with high morphological variability. Both hybridization and polyploidization have been suggested as the main evolutionary forces behind the high morphological variability in this genus; however, detailed studies are lacking. In Central Europe, two Ficaria taxa (diploid F. calthifolia and tetraploid F. verna subsp. verna) occasionally co-occur in local sympatry, which might result in hybridization. We investigated sympatric populations of the two Ficaria taxa using flow cytometry, chromosome counts, AFLP analysis and plastid DNA sequencing; we also performed experimental homoploid and heteroploid crosses to determine the frequency and direction of hybrid triploid formation, an alternative route of triploid origin (autopolyploidy) and the possibility of a one-step neoallotetraploid origin. Sympatric populations were composed of three genetic clusters corresponding to diploid F. calthifolia (2n = 16), tetraploid F. verna subsp. verna (2n = 32) and triploid plants (2n = 24). The holoploid genome size and AFLP data suggest a hybrid origin of the triploids, thereby making their formation via autopolyploidization in F. calthifolia unlikely. The triploid populations are monoclonal and of independent origin. In contrast, the parental populations exhibit high genotypic diversity and frequent sexual reproduction, including those of predominantly asexual F. verna subsp. verna. Experimental crossing confirmed that both parental taxa produce fertile seeds via a sexual pathway, but not by apomixis, and that both serve as pollen acceptors in heteroploid crosses, which is consistent with the plastid sequencing. However, hybridization is asymmetric, with maternal-excess crosses being significantly more successful. No signs of neoautotetraploidization or neoallotetraploidization were detected. In summary, recent gene flow between the studied Ficaria taxa is either limited or absent.

scholarly journals Patterns of hybridization and cryptic introgression among one- and four-needled pinyon pines

2020 ◽  
Vol 126 (3) ◽  
pp. 401-411
Author(s):  
Ryan Buck ◽  
Sandra Hyasat ◽  
Alice Hossfeld ◽  
Lluvia Flores-Rentería
Keyword(s):  
Distinct Species ◽  
Hybrid Origin ◽  
Interspecific Mating ◽  
Nucleotide Polymorphisms ◽  
Intermediate Morphology ◽  
The Status ◽  
Number Variation ◽  
Genetic Clusters ◽  
Variable Morphology ◽  
Genetic Contributions

Abstract Background and Aims Pinyon pine hybridization is widely acknowledged, but the frequency of and contributors to such interspecific mating remain largely unstudied. Pinus quadrifolia has three to four needles per fascicle, suggesting that it is a result of hybridization between the five-needled P. juarezensis and the single-needled P. monophylla. In this study we address the taxonomic validity of P. juarezensis, the hybrid origin of P. quadrifolia and the presence of hybridization and intermediate morphology as a result of interspecific hybridization in this complex. Methods We address these questions by combining a genomic and morphological approach. We generated 1868 single nucleotide polymorphisms (SNPs) to detect genetic clusters using principal co-ordinates analyis, discriminant analysis of principal components, fastSTRUCTURE and ADMIXTURE analyses, and performed a morphological analysis of the leaves. Key Results We found that the five-needled pinyons did not differ genetically from the four-needled P. quadrifolia, reducing the status of P. juarezensis to P. quadrifolia. We also found no evidence that P. quadrifolia is of hybrid origin from P. juarezensis × P. monophylla but is instead a genetically distinct species with natural needle number variation that has yet to be explained. Hybridization does occur in this complex, but mostly between P. quadrifolia and P. californiarum, and less commonly between P. quadrifolia and P. monophylla. Interestingly, some hybrid derivatives were detected between both single-needled taxa, P. monophylla and P. californiarum, a hybrid combination that has not yet been proposed. Hybrids have intermediate morphology when they have similar genetic contributions from both parental species; however, when one parent contributes more, hybrid derivatives resemble the parent with higher genetic contribution, resulting in cryptic introgression. Conclusions Our detailed sampling across the distribution of this complex allows us to describe the patterns of hybridization among these taxa, resolves an ancient taxonomic conflict and provides insights into the challenges of exclusively using morphological traits when identifying these taxa with cryptic hybridization and variable morphology.

Allopolyploid Speciation Accompanied by Gene Flow in a Tree Fern

2020 ◽  
Vol 37 (9) ◽  
pp. 2487-2502 ◽  
Author(s):  
Jing Wang ◽  
Shiyong Dong ◽  
Lihua Yang ◽  
Aj Harris ◽  
Harald Schneider ◽  
...  
Keyword(s):  
Gene Flow ◽  
East Asian Monsoon ◽  
Southern China ◽  
Evolutionary Process ◽  
Data Sets ◽  
Hybrid Speciation ◽  
Tree Fern ◽  
Hybrid Species ◽  
Allopolyploid Speciation ◽  
New Perspective

Abstract Hybridization in plants may result in hybrid speciation or introgression and, thus, is now widely understood to be an important mechanism of species diversity on an evolutionary timescale. Hybridization is particularly common in ferns, as is polyploidy, which often results from hybrid crosses. Nevertheless, hybrid speciation as an evolutionary process in fern lineages remains poorly understood. Here, we employ flow cytometry, phylogeny, genomewide single nucleotide polymorphism data sets, and admixture and coalescent modeling to show that the scaly tree fern, Gymnosphaera metteniana is a naturally occurring allotetraploid species derived from hybridization between the diploids, G. denticulata and G. gigantea. Moreover, we detected ongoing gene flow between the hybrid species and its progenitors, and we found that G. gigantea and G. metteniana inhabit distinct niches, whereas climatic niches of G. denticulata and G. metteniana largely overlap. Taken together, these results suggest that either some degree of intrinsic genetic isolation between the hybrid species and its parental progenitors or ecological isolation over short distances may be playing an important role in the evolution of reproductive barriers. Historical climate change may have facilitated the origin of G. metteniana, with the timing of hybridization coinciding with a period of intensification of the East Asian monsoon during the Pliocene and Pleistocene periods in southern China. Our study of allotetraploid G. metteniana represents the first genomic-level documentation of hybrid speciation in scaly tree ferns and, thus, provides a new perspective on evolution in the lineage.

Speciation by hybridization in phasmids and other insects

1990 ◽  
Vol 68 (8) ◽  
pp. 1747-1760 ◽  
Author(s):  
Luciano Bullini ◽  
Giuseppe Nascetti
Keyword(s):  
Hybrid Origin ◽  
Clonal Variation ◽  
Female Reproduction ◽  
Bisexual Species ◽  
Hybrid Species ◽  
Carausius Morosus ◽  
Origin And Evolution ◽  
Parthenogenetic Development ◽  
Hybrid Genome ◽  
Disturbed Habitats

Speciation by hybridization in insects has been recently recognized on the basis of isozyme and chromosome studies showing that several species, either diploid or polyploid, have genomes that combine the genes and chromosome sets of two (or more) bisexual species. Until this evidence became available, thelytokous invertebrates were all considered uniparental derivatives of bisexual species. In this paper, we review examples including the stick insects Bacillus whitei, B. atticus, B. lynceorum, Leptynia hispanica D, Clonopsis gallica, Carausius morosus; the grasshopper Warramaba virgo; some Otiorrhynchus weevils; the planthopper Muellerianella 2-fairmairei–brevipennis; and black flies of the genera Gymnopais and Prosimulium. For several species (e.g., Warramaba virgo and Bacillus whitei), both parental taxa have been recognized, and their hybrid origin has been genetically assessed. In others (e.g., B. atticus), only one of the bisexual parental species has been detected; but their hybrid origin is supported by strong evidence, at both the isozyme and chromosome levels. For other supposed hybrid species (e.g., Clonopsis gallica, Carausius morosus), no bisexual ancestors have been detected, possibly because competition with their hybrid derivatives has made them rare or extinct. Insect hybrid species may differ in their mode of reproduction (apomictic or automictic thelytokous parthenogenesis, gynogenesis), degree of ploidy, and genetic structure (level of heterozygosity, clonal variation). The parallels between insect and vertebrate hybrid species, in which this phenomenon has been recognized and widely studied in the past 50 years, are drawn. The main problems involved in the origin and evolution of hybrid species are discussed, with particular regard to (i) changes in the maturation divisions allowing the transmission of the hybrid genome to the next generation, and (ii) their successful adaptation. The "spontaneous" and "hybrid" theories for the origin of unisexual forms are compared, with regard to hybrid species. An origin of hybrid species from occasional parthenogenetic development of hybrid eggs produced in areas of extensive interspecific hybridization (e.g., disturbed habitats) is suggested. Hybridization would not itself cause changes in the maturation divisions (which are controlled by genes of tychoparthenogenetic eggs) but only favour their selection through heterosis. The role of the so-called "heterotic" advantage (resulting from high levels of heterozygosity) and "demographic" advantage (resulting from all-female reproduction) in the evolutionary success of hybrid species is discussed. It is concluded that habitat disturbance by man is favouring both the onset of hybrid species and their successful spread.

Hybrid Origin and Genomic Mosaicism of Dubautia scabra (Hawaiian Silversword Alliance; Asteraceae, Madiinae)

2008 ◽  
Vol 33 (3) ◽  
pp. 589-597 ◽  
Author(s):  
Elizabeth A. Friar ◽  
Linda M. Prince ◽  
Jennifer M. Cruse-Sanders ◽  
Mitchell E. McGlaughlin ◽  
Charles A. Butterworth ◽  
...  
Keyword(s):  
Single Copy ◽  
Nuclear Genes ◽  
Hybrid Origin ◽  
Internal Transcribed Spacer Region ◽  
Hybrid Species ◽  
Cytogenetic Data ◽  
Molecular Phylogenetic ◽  
Distinct Lineage ◽  
Phylogenetic Hypotheses ◽  
Genomic Regions

Incongruence among different estimates of species relationships in plants, from different molecules, cytogenetic data, biogeographic data, morphological/anatomical data or other sources, has been used frequently as an indication of introgression, hybrid species origin, or chloroplast (cp) capture. In plants, these incongruences are most often seen between data derived from the nuclear vs. the cp genomes and the nuclear markers used for comparison usually have been from the nuclear ribosomal (nr) internal transcribed spacer region (ITS). The amount of genomic material shared between introgressing species can be highly variable. In some of these cases, other nuclear genomic regions have moved between species without leaving a signature on the nrITS. An example of well-supported phylogenetic incongruence is the placement of Dubautia scabra (DC.) D. D. Keck in the Hawaiian silversword alliance (HSA); evolutionary hypotheses for D. scabra based on molecular as opposed to cytogenetic data are strongly discordant. In this paper, we test these two conflicting phylogenetic hypotheses regarding the evolutionary relationships of Dubautia scabra using evidence from six low-copy nuclear genes, as well as multiple chloroplast noncoding regions and nrITS. The nrITS region is also examined for the presence of multiple copy types. Incongruence between inferred relationships based on nuclear chromosomal arrangements and molecular phylogenetic data from chloroplast DNA and nrITS is resolved in favor of a hypothesis of ancient hybridization rather than cytogenetic homoplasy involving dysploidy. Most single-copy nuclear genes track histories of D. scabra compatible with cytogenetic data whereas chloroplast and nrITS data track a common, different history that appears to reflect hybridization with a chromosomally distinct lineage that also occurs on Maui Nui and Hawai'i (the Big Island).

scholarly journals Evidence for continual hybridization rather than hybrid speciation betweenLigularia duciformisandL. paradoxa(Asteraceae)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3884 ◽  
Author(s):  
Rong Zhang ◽  
Xun Gong ◽  
Ryan Folk
Keyword(s):  
Parental Species ◽  
Reproductive Traits ◽  
Issr Markers ◽  
Natural Hybridization ◽  
Hybrid Origin ◽  
Phenotypic Traits ◽  
Hybrid Species ◽  
Network Analyses ◽  
Hybrid Swarms ◽  
Ssr Loci

BackgroundHybrids possess phenotypic traits that are often intermediate between their parental taxa, which commonly serves as evidence of hybridization in morphological analyses. Natural hybridization has been shown to occur frequently inLigularia(Asteraceae). In a previous study,Ligularia×maoniushanensiswas demonstrated as a natural hybrid species betweenL. duciformisandL.paradoxabased on morphological and reproductive traits.MethodsWe used three chloroplast (cpDNA) fragments (psbA-trnH,trnL-rpl32 andtrnQ-5′rps16), the nuclear ribosomal internal transcribed spacer (nrITS), and co-dominant SSR and dominant ISSR markers to study natural hybridization betweenL. duciformisandL. paradoxagrowing sympatrically in two locations. Parental taxa were inferred using network analyses of cpDNA and nrITS haplotypes. Admixture among individuals was examined using the Bayesian clustering programs STRUCTURE and NewHybrids based on the SSR and ISSR data; and potential introgression in the SSR loci was assessed using the INTROGRESS package.ResultsThe putative parental species were clearly distinguished from other sympatricLigulariaspecies by nrITS data, andL.×maoniushanensisindividuals were confirmed to be the hybrid offspring ofL.duciformisandL.paradoxa. Moreover, introgression was detected among several individuals morphologically identified asL.duciformisorL. paradoxa. Analyses of the cpDNA data revealed primarily unidirectional hybridization betweenL. duciformisandL. paradoxa, withL.paradoxaas the maternal parent in Mt. Maoniu, whereas bidirectional but asymmetrical hybridization was inferred to occur in Heihai Lake. The STRUCTURE analyses based on the SSR data detected two distinct clusters among the three taxa. The NewHybrids analyses showed that individuals circumscribed asL.×maoniushanensiswere dominated by early- and later-generation and backcrossing hybrids. The NewHybrids results based on the ISSR data were congruent with SSR results. In addition, introgression was detected in some SSR loci, and heterogeneity among loci was found in terms of detected patterns of introgression.ConclusionsOur data provide strong evidence for hybridization and introgression betweenL.duciformisandL.paradoxa.Ligularia×maoniushanensiswas demonstrated to be of hybrid origin. Since no evident reproductive isolation was found between the two parental species, detected hybrids appear to be part of hybrid swarms resulting from frequent and ongoing gene flow, which might impede the formation of a new hybrid species.

scholarly journals Whole-genome sequencing uncovers cryptic and hybrid species among Atlantic and Pacific cod-fish

2015 ◽  
Author(s):  
Katrín Halldórsdóttir ◽  
Einar Árnason
Keyword(s):  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Atlantic Cod ◽  
Walleye Pollock ◽  
Evolutionary Status ◽  
Whole Genome ◽  
Hybrid Speciation ◽  
Hybrid Species ◽  
The Pacific ◽  
Starting Point

Speciation often involves the splitting of a lineage and the adaptation of daughter lineages to different environments. It may also involve the merging of divergent lineages, thus creating a stable homoploid hybrid species1that constructs a new ecological niche by transgressing2the ecology of the parental types. Hybrid speciation may also contribute to enigmatic and cryptic biodiversity in the sea.3,4The enigmatic walleye pollock, which is not a pollock at all but an Atlantic cod that invaded the Pacific 3.8 Mya,5differs considerably from its presumed closest relatives, the Pacific and Atlantic cod. Among the Atlantic cod, shallow-water coastal and deep-water migratory frontal ecotypes are associated with highly divergent genomic islands;6,7however, intermediates remain an enigma.8Here, we performed whole-genome sequencing of over 200 individuals using up to 33 million SNPs based on genotype likelihoods9and showed that the evolutionary status of walleye pollock is a hybrid species: it is a hybrid between Arctic cod and Atlantic cod that transgresses the ecology of its parents. For the first time, we provide decisive evidence that the Atlantic cod coastal and frontal ecotypes are separate species that hybridized, leading to a true-breeding hybrid species that differs ecologically from its parents. We refute monophyly and dichotomous branching of these taxa, and stress the importance of looking beyond branching trees at admixture and hybridity. Our study demonstrates the power of whole-genome sequencing and population genomics in providing deep insights into fundamental processes of speciation. Our study was a starting point for further work aimed at examining the criteria of hybrid speciation,10selection, sterility and structural chromosomal variation11among cod-fish, which are among the most important fish stocks in the world. The hybrid nature of both the walleye pollock and Atlantic cod raises the question concerning the extent to which very profitable fisheries12,13depend on hybrid vigour. Our results have implications for management of marine resources in times of rapid climate change.14,15

scholarly journals Genomic Screening Reveals That the Endangered Eucalyptus paludicola (Myrtaceae) Is a Hybrid

Diversity ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 468
Author(s):  
Kor-jent van Dijk ◽  
Michelle Waycott ◽  
Joe Quarmby ◽  
Doug Bickerton ◽  
Andrew H. Thornhill ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
South Australia ◽  
Hybrid Origin ◽  
F1 Hybrids ◽  
Management Options ◽  
Hybrid Species ◽  
Conservation Implications ◽  
Hybrid Class ◽  
Low Incidence ◽  
Stable Hybrid

A hybrid origin for a conservation listed taxon will influence its status and management options. Here, we investigate the genetic origins of a nationally endangered listed taxon—Eucalyptus paludicola—a tree that is restricted to the Fleurieu Peninsula and Kangaroo Island of South Australia. Since its description in 1995, there have been suggestions that this taxon may potentially be a stable hybrid species. Using a high throughput sequencing approach, we developed a panel of polymorphic loci that were screened across E. paludicola and its putative parental species E. cosmophylla and E. ovata. Bayesian clustering of the genotype data identified separate groups comprising E. ovata and E. cosmophylla while E. paludicola individuals were admixed between these two, consistent with a hybrid origin. Hybrid class assignment tests indicate that the majority of E. paludicola individuals (~70%) are F1 hybrids with a low incidence of backcrossing. Most of the post-F1 hybrids were associated with revegetation sites suggesting they may be maladapted and rarely reach maturity under natural conditions. These data support the hypothesis that E. paludicola is a transient hybrid entity rather than a distinct hybrid species. We briefly discuss the conservation implications of our findings.

scholarly journals Investigating the Current and Future Co-Occurrence of Ambrosia artemisiifolia and Ophraella communa in Europe through Ecological Modelling and Remote Sensing Data Analysis

2019 ◽  
Vol 16 (18) ◽  
pp. 3416 ◽  
Author(s):  
Mattia Iannella ◽  
Walter De Simone ◽  
Paola D’Alessandro ◽  
Giulia Console ◽  
Maurizio Biondi
Keyword(s):  
Remote Sensing ◽  
Invasive Plant ◽  
Remote Sensing Data ◽  
Leaf Beetle ◽  
Ambrosia Artemisiifolia ◽  
Ecological Modelling ◽  
Niche Modelling ◽  
Sensing Data ◽  
Starting Point ◽  
Ophraella Communa

The common ragweed Ambrosia artemisiifolia has spread throughout Europe since the 1800s, infesting croplands and causing severe allergic reactions. Recently, the ragweed leaf beetle Ophraella communa was found in Italy and Switzerland; considering that it feeds primarily on A. artemisiifolia in its invaded ranges, some projects started biological control of this invasive plant through the adventive beetle. In this context of a ‘double’ invasion, we assessed the influence of climate change on the spread of these alien species through ecological niche modelling. Considering that A. artemisiifolia mainly lives in agricultural and urbanized areas, we refined the models using satellite remote-sensing data; we also assessed the co-occurrence of the two species in these patches. A. artemisiifolia is predicted to expand more than O. communa in the future, with the medium and high classes of suitability of the former increasing more than the latter, resulting in lower efficacy for O. communa to potentially control A. artemisiifolia in agricultural and urbanized patches. Although a future assessment was performed through the 2018 land-cover data, the predictions we propose are intended to be a starting point for future assessments, considering that the possibility of a shrinkage of target patches is unlikely to occur.

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