Natural hybridization between an outcrossing and a selfingPhlox (Polemoniaceae): The maternal species of F1 hybrids

Natural hybridization between wild/weedy and crop species often results in rare hybrids, which can be more weedy and difficult to control. Moreover, the advent of transgenic crop plants raises questions of biosafety risk assessment on the consequences of rare hybrids with possible fitness enhancing genes on the environment. This study aimed at measuring the fitness components of wild–crop sorghum hybrids for various juvenile survival and adult morphological and fertility characters as part of the risk assessment of transgenic sorghum in Africa where the crop was believed to have first domesticated and serves as the major staple. Out of a pool of hybrids made in 2010 from 23 wild sorghum accessions and two released cultivated sorghum varieties using hand emasculation techniques, seven were selected for the field study of their fitness components in 2011. The study confirmed that crop–wild hybrids of sorghum are fertile. Two approaches were followed (relative fitness and mid-parent heterosis) which showed that most of the hybrids were as fit as their wild parents, and in some cases they showed mid-parent heterosis for the measured traits. The results of this study highlighted a potential risk that hybrids carrying crop genes (including herbicide resistance transgenes) could pose because they could be more weedy than their wild/weedy parents if transgenic sorghum is deployed in regions where the wild and cultivated sorghum populations coexist, such as in Ethiopia and in other parts of Africa.

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Contrasting Success of Natural Hybridization in Two Eucalyptus Species Pairs

Australian Journal of Botany ◽

10.1071/bt9800167 ◽

1980 ◽

Vol 28 (2) ◽

pp. 167 ◽

Cited By ~ 4

Author(s):

DW Drake

Keyword(s):

Principal Component ◽

Flowering Phenology ◽

Natural Hybridization ◽

F1 Hybrids ◽

Hybrid Population ◽

Eucalyptus Species ◽

Major Barrier ◽

Species Pairs ◽

Plant Hybridization ◽

Hybrid Number

A morphological study with univariate and principal component analyses of mature tree and open-pollinated seedling populations shows that natural hybridization is occurring between Eucalyptus melanophloia and E. crebra, and E. populnea and E. crebra (subgenus Symphyomyrtus, section Adnataria). The level of successful hybridization in these two systems, where fundamental genetic (reproductive) and ecological (habitat and spatial) barriers are absent, is examined. Within the ecotone, hybrids between E. melanophloia and E. crebra are about one-fifth as frequent as those between E. populnea and E. crebra. Analyses of the phenotype/genotype compositions of the hybrid populations, the patterns of segregation, and outcrossing frequencies between the species pairs indicate the level of development of the hybrid populations. All E. melanophloia × E. crebra hybrids appear to be F1 hybrids. In contrast, the E.populnea x E. crebra hybrid population attains a much higher level of development in terms of both hybrid number and genotypic complexity. Flowering phenology is a major barrier to E. melanophloia × E. crebra hybrid formation compared with the other hybrids, although it is considered an incomplete barrier and alone may not explain the diversity of hybrid success which occurs.A theory of plant hybridization which incorporates the concept of hybridization success is presented and discussed in relation to the two hybridizing systems, as a basis for further investigating the mechanisms involved.

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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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Comparative growth response in Carduus nutans, C. acanthoides, and their F1 hybrids

Canadian Journal of Botany ◽

10.1139/b90-215 ◽

1990 ◽

Vol 68 (8) ◽

pp. 1675-1679 ◽

Cited By ~ 5

Author(s):

S. I. Warwick ◽

B. K. Thompson ◽

L. D. Black

Keyword(s):

Growth Response ◽

Parental Species ◽

Diploid Species ◽

Dry Weight ◽

Natural Hybridization ◽

F1 Hybrids ◽

Soil Conditions ◽

Hybrid Superiority ◽

Test Models ◽

Better Than

The growth response of F1 hybrids relative to parental genotypes was compared in a natural hybridization system involving the diploid species Carduus acanthoides L. (2n = 22) and C. nutans L. (2n = 16). The data were used to test models of hybrid intermediacy, superiority, or greater similarity to a single parent in response to variable soil conditions and intra- and inter-genotypic competition. Progeny from paired reciprocal crosses between the two species were used in the experiments. In each of the half-sib families produced, the rapid and early identification of F1 hybrid genotypes and parental genotypes (resulting from selfing) was confirmed using allozyme markers (Pgi-2, Tpi-1, and Tpi-2). Growth of the F1 hybrids was better than C. nutans in poor soil, and both F1 hybrid and C. nutans genotypes produced significantly more dry weight than C. acanthoides in all soil treatments. F1 hybrids grew at least as well as the maternal parental species C. nutans and significantly better than C. acanthoides in the presence of intra- and inter-genotypic competitors. The F1 hybrid genotypes formed a more aggressive competitive environment than C. nutans, as evidenced by the growth of all three genotypes. These data primarily supported the model of greater hybrid similarity to one parental species rather than hybrid intermediacy, with evidence of hybrid superiority under certain extreme conditions.

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Genetic evidence of natural hybridization between Podarcis sicula and Podarcis tiliguerta (Reptilia: Lacertidae)

Amphibia-Reptilia ◽

10.1163/15685380260449199 ◽

2002 ◽

Vol 23 (3) ◽

pp. 313-321 ◽

Cited By ~ 13

Author(s):

Massimo Capula

Keyword(s):

Habitat Disturbance ◽

Genetic Evidence ◽

Natural Hybridization ◽

F1 Hybrids ◽

Parent Species ◽

Podarcis Sicula

AbstractAn allozyme survey revealed instances of natural hybridization between Podarcis sicula and P. tiliguerta from a locality of southern Sardinia. Pure specimens of both species together with some F1 hybrids were found, but no evidence of backcrossing was detected. The hybrid specimens appeared morphologically intermediate between the parent species. The absence of backcrossed individuals indicate that free interbreeding between the two species is unlikely. Hybrids were found in areas of habitat disturbance only.

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Cytology, fertility, and origin of Elymus abolinii (Drob.) Tzvelev and its F1 hybrids with Pseudoroegneria spicata, E. lanceolatus, E. dentatus ssp. ugamicus, and E. drobovii (Poaceae: Triticeae)

Genome ◽

10.1139/g89-470 ◽

1989 ◽

Vol 32 (3) ◽

pp. 468-474 ◽

Cited By ~ 13

Author(s):

Kevin B. Jensen

Keyword(s):

Chromosome Pairing ◽

Phylogenetic Relationships ◽

Morphological Characters ◽

Intergeneric Hybrids ◽

Natural Hybridization ◽

F1 Hybrids ◽

Direct Measure ◽

Species Hybrid ◽

Pseudoroegneria Spicata ◽

Hybrid Complex

Chromosome pairing and hybrid fertility provide a direct measure of phylogenetic relationships between different taxa. Five accessions of Elymus abolinii (Drob.) Tzvelev were studied to (i) determine their reproductive characteristics; (ii) describe phylogenetic relationships and genomic affinities through chromosome pairing and fertility in the species and species hybrid complex with closely related taxa; (iii) evaluate the morphological variation between related taxa; and (iv) propose a possible origin for E. abolinii. Interspecific and intergeneric hybrids with E. abolinii were obtained from the following "analyzer" parents: Pseudoroegneria spicata (Pursh) A. Love, E. lanceolatus (Scribn. &Smith) Gould, E. dentatus (Hook, f.) Tzvelev ssp. ugamicus (Drob.) Tzvelev, and E. drobovii (Nevski) Tzvelev. The results showed that E. abolinii is an allotetraploid forming 14 bivalents in 95% of the cells, and it is self-fertilizing. Chromosome pairing within the species hybrid complex demonstrated that E. abolinii comprises the S and Y genomes, with close affinities to other eastern Chinese taxa that comprise the S and Y genomes. Multivariate analysis of morphological characters supports the hypothesis that E. abolinii originated from a natural hybridization between E. dentatus ssp. ugamicus and E. gmelinii Ledeb.) Tzvelev, followed by a possible backcross with E. dentatus ssp. ugamicus.Key words: genome, meiosis, chromosome pairing, morphology, hybrid, Triticeae.

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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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Progeny Trials in an Introgressive Hybrid Population of Anigozanthos Labill. (Haemodoraceae)

Australian Journal of Botany ◽

10.1071/bt9780309 ◽

1978 ◽

Vol 26 (3) ◽

pp. 309 ◽

Cited By ~ 3

Author(s):

SD Hopper

Keyword(s):

Floral Morphology ◽

Natural Hybridization ◽

F1 Hybrids ◽

Hybrid Population ◽

Evolutionary Significance ◽

Gene Exchange ◽

Present Evidence ◽

Close Proximity ◽

Two Generations ◽

Open Question

The floral morphology and pollen fertility of progeny from open-pollinated plants in a hybrid population of A. manglesii and A. humilis were measured to investigate patterns of gene exchange occurring between hybrid and parental individuals. Introgression occurs where the two species and F1 hybrids grow in close proximity in the population but the possibility of more backcrossing to A. manglesii than to A. humilis remains an open question on present evidence. The morphological effects of hybridization became cryptic in some cases within one and in most cases within two generations of backcrossing. The possible evolutionary significance of natural hybridization between A. manglesii and A. humilis is discussed in the light of these results.

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PHENETIC ANALYSIS OF POPULUS NIGRA, P. LAURIFOLIA AND P. × JRTYSCHENSIS IN NATURAL HYBRIDIZATION ZONE

Vavilov Journal of Genetics and Breeding ◽

10.18699/vj18.384 ◽

2018 ◽

Vol 22 (4) ◽

pp. 468-475 ◽

Cited By ~ 5

Author(s):

A. V. Klimov ◽

B. V. Proshkin

Keyword(s):

River Basin ◽

Population Differentiation ◽

Leaf Blade ◽

Sharp Decrease ◽

Population Diversity ◽

Population Variability ◽

Natural Hybridization ◽

Disjunct Distribution ◽

F1 Hybrids ◽

Poplar Trees

The wide spread of hybridization in the genus Populus, including spontaneous hybridization, caused by cultivars, requires studying the variability and inheritance of morphological traits by hybrids for initial tracking of these processes. The analysis of endogenous, intra- and inter-population variability was performed on 533 individual poplar trees in seven populations of P. nigra, seven populations of P. laurifolia and four populations of P. × jrtyschensis in the Tom river basin. On each specimen, 15 leaves from short mid-crown branches were collected to determine the shape of the leaf blade, the shape of its tip and base, as well as the branch morphotype. Some biometric indicators were proposed for geometric assessment of the leaf blade shapes of poplar species. The analysis showed that of all the traits examined only the leaf blade shape did not meet the criterion for “phene”, since it is usually represented by several forms in the crown of one and the same tree. In all the species studied, the level of their intra-population diversity was found to be much higher than the inter-population one. According to the increase of intra-population variability of qualitative traits, the taxa could be ranked as P. nigra < P. laurifolia < P. × jrtyschensis. The share of inter-population diversity differed among the species studied, accounting for 21.5% in P. laurifolia, 13.8% in P. nigra and 8.0% in P. × jrtyschensis. The P. laurifolia populations showed the greatest inter-population differentiation, most likely because of a disjunct distribution due to narrow specialization to the montane river environment. The lower differentiation in P. nigra is probably due to the facts that this species dominates the poplar stands of the Tom River basin; its populations are not fragmented and are linked by vast gene flow. In P. nigra, an increase in the diversity of qualitative characteristics and phenotypes was observed in populations confined to hybridization centers. Natural selection is most likely the factor governing the inter-population differentiation in P. × jrtyschensis, leading to the predominance of F1 hybrids in populations and hence to a sharp decrease in inter-population variability.

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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

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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