Natural Hybridization between Two Butterfly Bushes in Tibet: Dominance of F1 Hybrids Promotes Strong Reproductive Isolation

Abstract Background: F1 hybrids acting as a bridgehead for producing later generation hybrids can have evolutionary significance through strengthening reproductive isolation or facilitating gene flow between parental species, depending on whether backcrossing can occur. It had been suggested that the Tibetan plant Buddleja wardii was a hybrid species between B. alternifolia and B. crispa based on their sympatric distributions and the morphological characters in last century. Till now however, we still have limited evidence to prove key issues to B. wardii, like if it is of hybrid origin indeed and whether it is currently a true hybrid species already.Results: In the present study, two sympatric populations of these three taxa were examined and compared using four nuclear genes and three chloroplast intergenic spacers, as well as with 10 morphological characters. Our results suggest that at both sites B. × wardii was likely to be a hybrids between B. alternifolia and B. crispa, and moreover, most of the hybrids present were confirmed to be F1s. This was further supported by morphology as no transgressive characters were detected. B. crispa was found to be the maternal parent in one population (BH), while in the second population (TJ), it was difficult to distinguish the hybridization direction due to shared haplotypes of cpDNA between B. alternifolia and B. crispa. Conclusions: These results provide evidence that the natural hybrids between B. alternifolia and B. crispa mainly comprise F1 hybrids, which have subsequently been given the name B. wardii. The F1 hybrids have also contributed to strong reproductive isolation between parental species.

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Natural hybridization between two butterfly bushes in Tibet: dominance of F1 hybrids promotes strong reproductive isolation

10.21203/rs.3.rs-42245/v2 ◽

2020 ◽

Author(s):

Rongli Liao ◽

Weibang Sun ◽

Yongpeng Ma

Keyword(s):

Reproductive Isolation ◽

Parental Species ◽

Morphological Characters ◽

Natural Hybridization ◽

Hybrid Origin ◽

F1 Hybrids ◽

Evolutionary Significance ◽

Sympatric Populations ◽

Hybrid Species ◽

Intergenic Spacers

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Natural hybridization between two butterfly bushes in Tibet: dominance of F1 hybrids promotes strong reproductive isolation

10.21203/rs.3.rs-42245/v3 ◽

2021 ◽

Author(s):

Rongli Liao ◽

Weibang Sun ◽

Yongpeng Ma

Keyword(s):

Morphological Characters ◽

Natural Hybridization ◽

Hybrid Origin ◽

F1 Hybrids ◽

Sympatric Populations ◽

Intergenic Spacers ◽

Typical Distribution ◽

Hybridization Origin ◽

Butterfly Bush ◽

Disturbed Habitats

Abstract Background: It has been recognized that certain amount of habitat disturbance is a prerequisite for occurrence of natural hybridization, yet we are currently still not aware of any studies exploring hybridization and reproductive barriers to those plants preferably occupying disturbed habitats. Buddleja plants (also called butterfly bush) generally grow in disturbed habitat, and several species with hybrid origin only on basis of morphology evidence have been proposed. Results: In the present study, we test the natural hybridization origin hypothesis of B. × wardii in two sympatric populations of three taxa including B. × wardii and its parents (B. alternifolia and B. crispa) plus 4 referenced parental populations, using four nuclear genes and three chloroplast intergenic spacers, as well as with 10 morphological characters. Our results suggest that at both sites B. × wardii was likely to be hybrids between B. alternifolia and B. crispa, and moreover, most of the hybrids examined were confirmed to be F1s. This was further supported by morphology as no transgressive characters were detected. B. crispa was found to be the maternal parent in Bahe (BH) population from the cpDNA. While in the Taji (TJ) population was difficult to distinguish the hybridization direction due to the shared haplotypes of cpDNA between B. alternifolia and B. crispa, we still predicted the similar unidirectional hybridization pattern due to results from cross-specific pollination treatments which supported the “SI x SC rule”. Conclusions: Hybrids mainly consisting of F1s can successfully impede gene flow and thus maintain species boundaries of parental species in its typical distribution of Buddleja, i.e. disturbed habitats.

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Natural hybridization between two butterfly bushes in Tibet: dominance of F1 hybrids promotes strong reproductive isolation

BMC Plant Biology ◽

10.1186/s12870-021-02909-7 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Rongli Liao ◽

Weibang Sun ◽

Yongpeng Ma

Keyword(s):

Morphological Characters ◽

Natural Hybridization ◽

Hybrid Origin ◽

F1 Hybrids ◽

Morphological Evidence ◽

Sympatric Populations ◽

Intergenic Spacers ◽

Hybridization Origin ◽

Butterfly Bush ◽

Disturbed Habitats

AbstractBackgroundIt has been recognized that a certain amount of habitat disturbance is a facilitating factor for the occurrence of natural hybridization, yet to date we are unaware of any studies exploring hybridization and reproductive barriers in those plants preferentially occupying disturbed habitats.Buddlejaplants (also called butterfly bush) generally do grow in disturbed habitats, and several species with hybrid origin have been proposed, based solely on morphological evidence.ResultsIn the present study, we test the hypothesis thatB. × wardiiis of natural hybridization origin in two sympatric populations of three taxa includingB. × wardiiand its parents (B. alternifoliaandB. crispa) plus 4 referenced parental populations, using four nuclear genes and three chloroplast intergenic spacers, as well as with 10 morphological characters. Our results suggest that at both sitesB. × wardiiis likely to be a hybrid betweenB. alternifoliaandB. crispa, and moreover, we confirm that most of the hybrids examined are F1s. That these plants are F1s is further supported by morphology, as no transgressive characters were detected.B. crispawas found to be the maternal parent in the Bahe (BH) population, from cpDNA evidence. However, in the Taji (TJ) population, the direction of hybridization was difficult to establish due to the shared cpDNA haplotypes betweenB. alternifoliaandB. crispa, however we still predicted a similar unidirectional hybridization pattern due to results from cross-specific pollination treatments which supported the “SI × SC rule”.ConclusionsThe presence of mainly F1hybrids can successfully impede gene flow and thus maintain species boundaries in parental species in a typical distribution ofBuddleja, i.e. in disturbed habitats.

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

PeerJ ◽

10.7717/peerj.3884 ◽

2017 ◽

Vol 5 ◽

pp. e3884 ◽

Cited By ~ 5

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.

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Molecular evidence for the hybrid origin of Rosa lichiangensis (Rosaceae)

Phytotaxa ◽

10.11646/phytotaxa.222.3.5 ◽

2015 ◽

Vol 222 (3) ◽

pp. 221 ◽

Cited By ~ 1

Author(s):

Zhangming Zhu ◽

Xinfen Gao

Keyword(s):

Significant Role ◽

Single Copy ◽

Morphological Characters ◽

Molecular Data ◽

Natural Hybridization ◽

Hybrid Origin ◽

Molecular Evidence ◽

Nuclear Marker

Natural hybridization was assumed to play a significant role in the diversification of Rosa. Rosa lichiangensis was suspected to be of hybrid origin based on its intermediate morphological characters between R. soulieana and R. multiflora var. cathayensis. In this study, four chloroplast regions (ndhC-trnV, ndhF-rpl32, ndhJ-trnF, and psbJ-petA) and a single copy nuclear marker (GAPDH) were used to test the hybrid origin of R. lichiangensis. The results from molecular data supported the hybrid origin of R. lichiangensis and further identified R. soulieana as its maternal progenitor and R. multiflora var. cathayensis as the paternal progenitor.

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The identity of Erica flavisepala

Bothalia ◽

10.4102/abc.v12i2.1395 ◽

1977 ◽

Vol 12 (2) ◽

pp. 195-197

Author(s):

E. G. H. Oliver

Keyword(s):

Morphological Characters ◽

Hybrid Origin ◽

Putative Hybrid ◽

Sympatric Populations

The recording of a few scattered plants of E. flavisepala Guth. Bol. among sympatric populations of two other species led to a comparison of their morphological characters. From this comparison a putative hybrid origin was indicated, thus E. x flavisepala Guth. Bol.=E. thunbergii Montin X E. sphaerocephala Wendl.

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Molecular genetic evidence for allotetraploid hybrid speciation in the genus Crocus L. (Iridaceae)

Phytotaxa ◽

10.11646/phytotaxa.258.2.2 ◽

2016 ◽

Vol 258 (2) ◽

pp. 121 ◽

Cited By ~ 5

Author(s):

ÁGNES MOSOLYGÓ-L ◽

GÁBOR SRAMKÓ ◽

SÁNDOR BARABÁS ◽

LEVENTE CZEGLÉDI ◽

ANDRÁS JÁVOR ◽

...

Keyword(s):

Dna Sequences ◽

Phylogenetic Trees ◽

Parental Species ◽

Molecular Genetic ◽

Parallel Evolution ◽

Carpathian Basin ◽

Hybrid Origin ◽

F1 Hybrids ◽

Aflp Data ◽

F1 Hybrid

Although dysploidy and polyploidisation events are known to be important drivers in the evolutionary history of the genus Crocus, only a few examples of natural hybrid origins have so far been documented. Here, we describe the phylogenetic affinities of five taxa in the Crocus vernus species complex from the Carpathian Basin in Central Europe. Genetic variability was evaluated using chloroplast DNA sequences of the accD-psaI intergenic spacer and amplified fragment length polymorphism (AFLP) in combination with karyological observations. Genetic diversity and differentiation of the seven investigated Crocus species were also evaluated using AFLP data. We created a phylogenetic hypothesis using both sequences and AFLP fingerprinting data under maximum parsimony (MP). AFLPs were also analysed by means of multivariate statistics using principal coordinate (PCoA) analysis and Bayesian clustering (BC) to test for hybridity. Both the AFLP and plastid phylogenetic trees separated the taxa into two groups: (1) a ‘Balkan’ clade, and; (2) an ‘Adriatic’ clade. The Balkan clade contained Crocus heuffelianus samples and one Crocus vittatus from Croatia as well as Crocus tommasinianus samples from Hungary; the Adriatic clade included Crocus vittatus and Crocus vernus samples from Hungary and Croatia as well as Crocus neapolitanus from Italy. A hard incongruence was found in the placement of the Slovakian Crocus scepusiensis which clustered inside the Balkan clade on our plastid tree, while it fell in the Adriatic clade on the AFLP tree. The same populations occupied intermediate position on the PCoA plot. The BC analysis assigned all Crocus scepusiensis specimens as F1 hybrids, while Crocus vernus and Crocus heuffelianus were assigned as parental species. Together with our cytological investigation that determined a 2n=18 chromosome number of Crocus scepusiensis, we conclude an allopolyploid hybrid origin for this Northern Carpathian taxon as the result of a cross between members of the 2n=10 Balkan clade (e.g., Crocus heuffelianus from Transylvania) and the 2n=8 Adriatic clade (Crocus vernus). A similar origin is postulated for the North Balkan Crocus vittatus (2n=18), which was clustered as an F1 hybrid in the BC analysis; thus, parallel evolution may have taken place in the northern and southern part of the Carpathian Basin beginning from the same parental species but leading to different allopolyploid derivatives.

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Natural Hybridization and Morphometric Relationships Between Three Mallee Eucalypts in the Fitzgerald River National Park, W.A

Australian Journal of Botany ◽

10.1071/bt9780319 ◽

1978 ◽

Vol 26 (3) ◽

pp. 319 ◽

Cited By ~ 9

Author(s):

SD Hopper ◽

DJ Coates ◽

AH Burbidge

Keyword(s):

Multivariate Analysis ◽

National Park ◽

Parental Species ◽

Natural Hybridization ◽

Reproductive Parameters ◽

Sympatric Population ◽

Sympatric Populations

The suspected occurrence of natural hybridization between Eucalyptus preissiana Schau, and E. Buprestium F. Muell, near West Mount Barren was investigated through a study of morphometric and reproductive parameters in allopatric and sympatric populations of these species. While E. Preissiana and E. buprestium were morphometrically distinct in allopatry, a small number of intermediate individuals occurred in one of the two sympatric populations examined. These intermediates set less fruit per plant than the parental species on average, a fact consistent with the hypothesis that they were hybrids showing partial F2 breakdown. The demonstration that New Holland honeyeaters (Phylidonyris novae-hollandiae) carried pollen of both parental species in a sympatric population was interpreted as further evidence in support of the occurrence of hybridization. The possible hybrid status of E. chrysantha Blakely & Steedman was investigated through determining its morphometric relationships in a multivariate analysis of E. sepulcralis F. Muell., E. Preissiana and E. buprestium. E. chrysantha was intermediate between E. sepulcralis and E. preissiana, and distinguishable from E. preissiana-E. buprestium hybrids in this analysis. The taxonomic and evolutionary implications of the study are discussed.

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Reproductive isolation of hybrid populations driven by genetic incompatibilities

10.1101/007518 ◽

2014 ◽

Author(s):

Molly Schumer ◽

Rongfeng Cui ◽

Gil G Rosenthal ◽

Peter Andolfatto

Keyword(s):

Reproductive Isolation ◽

Alternative Model ◽

Parental Species ◽

Small Population ◽

Hybrid Population ◽

Ecological Niches ◽

Simple Consequence ◽

Hybrid Species ◽

Population Sizes ◽

Adaptive Radiations

Despite its role in homogenizing populations, hybridization has also been proposed as a means to generate new species. The conceptual basis for this idea is that hybridization can result in novel phenotypes through recombination between the parental genomes, allowing a hybrid population to occupy ecological niches unavailable to parental species. A key feature of these models is that these novel phenotypes ecologically isolate hybrid populations from parental populations, precipitating speciation. Here we present an alternative model of the evolution of reproductive isolation in hybrid populations that occurs as a simple consequence of selection against incompatibilities. Unlike previous models, our model does not require small population sizes, the availability of new niches for hybrids or ecological or sexual selection on hybrid traits. We show that reproductive isolation between hybrids and parents evolves frequently and rapidly under this model, even in the presence of ongoing migration with parental species and strong selection against hybrids. Our model predicts that multiple distinct hybrid species can emerge from replicate hybrid populations formed from the same parental species, potentially generating patterns of species diversity and relatedness that mimic adaptive radiations.

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

Diversity ◽

10.3390/d12120468 ◽

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.

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