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 ◽  
1989 ◽  
Vol 32 (3) ◽  
pp. 468-474 ◽  
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.

Cytogenetics of Elymus caucasicus and Elymus longearistatus (Poaceae: Triticeae)

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 860-867 ◽  
Author(s):  
Kevin B. Jensen ◽  
Richard R.-C. Wang
Keyword(s):  
Chromosome Pairing ◽  
Interspecific Hybrid ◽  
Intergeneric Hybrids ◽  
Cytological Analysis ◽  
Meiotic Behavior ◽  
Pseudoroegneria Spicata ◽  
Central Asian ◽  
Elymus Lanceolatus

Two accessions of Elymus caucasicus (Koch) Tzvelev and three accessions of Elymus longearistatus (Boiss.) Tzvelev were studied to determine the meiotic behavior and chromosome pairing in the two taxa, their interspecific hybrid, and their hybrids with various "analyzer" parents. Interspecific and intergeneric hybrids of the target taxa were obtained with the following analyzer species: Pseudoroegneria spicata (Pursh) A. Löve (2n = 14, SS), Pseudoroegneria libanotica (Hackel) D. R. Dewey (2n = 14, SS), Hordeum violaceum Boiss. &Hohenacker (2n = 14, HH) (= Critesion violaceum (Boiss. &Hohenacker) A. Löve), Elymus lanceolatus (Scribn. &Smith) Gould (2n = 28, SSHH), Elymus abolinii (Drob.) Tzvelev (2n = 28, SSYY), Elymus pendulinus (Nevski) Tzvelev (2n = 28, SSYY), Elymus fedtschenkoi Tzvelev (2n = 28, SSYY), Elymus panormitanus (Parl.) Tzvelev (2n = 28, SSYY), and Elymus drobovii (Nevski) Tzvelev (2n = 42, SSHHYY). Cytological analysis of their F1 hybrids showed that E. caucasicus and E. longearistatus were allotetraploids comprising the same basic genomes. Chromosome pairing in the E. caucasicus × P. libanotica hybrid demonstrated that the target taxa contained the S genome, based on 6.1 bivalents per cell. The lack of chromosome pairing, less than one bivalent per cell, in the E. longearistatus × H. violaceum hybrid showed that the H genome was absent. Increased pairing in the tetraploid and pentaploid hybrids when the Y genome was introduced indicated that the second genome in the two taxa was a segmental homolog of the Y genome. The S and Y genomes in E. caucasicus and E. longearistatus have diverged from each other and from those in many of the eastern and central Asian SY tetraploids.Key words: genome, meiosis, chromosome pairing, morphology, hybrid, Triticeae.

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

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.

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

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.

Cytology of Elymus panormitanus and its F1 hybrids with Pseudoroegneria spicata, Elymus caninus, and Elymus dentatus ssp. ugamicus

Genome ◽  
1988 ◽  
Vol 30 (6) ◽  
pp. 879-884 ◽  
Author(s):  
Kevin B. Jensen ◽  
Stephan L. Hatch
Keyword(s):  
Seed Set ◽  
Karyotype Analysis ◽  
The United States ◽  
Intergeneric Hybrids ◽  
F1 Hybrids ◽  
Genomic Constitution ◽  
Pseudoroegneria Spicata ◽  
Elymus Caninus ◽  
Modified Forms ◽  
Sterile Hybrids

Three accessions of Elymus panormitanus (Parl.) Tzvelev were introduced into the United States in 1967 from Iraq and Turkey. A study was undertaken to describe the cytological behavior, mode of reproduction, cytology and fertility of E. panormitanus and its F1 hybrids with "analyzer" species, and genomic formula. Chromosome pairing was studied at meta-phase I in a series of interspecific and intergeneric hybrids to characterize the genomic constitution of E. panormitanus. All plants of E. panormitanus studied were 2n = 28, and averaged 13.96 bivalents per cell, suggesting that E. panormitanus is an allotetraploid with two different genomes. Seed set under controlled pollination indicated that E. panormitanus is highly self-compatible. Hybrids between E. panormitanus and the following analyzer species (with known genomic constitution) were obtained: Pseudoroegneria spicata (Pursh.) A. Love, 2n = 14, SS; Elymus caninus (L.) L., 2n = 28, SSHH; Elymus dentatus (Hook, f.) Tzvelev ssp. ugamicus (Drob.) Tzvelev, 2n = 28, SSYY. All hybrids were highly sterile. Hybrids between E. panormitanus and P. spicata, E. caninus, and E. dentatus ssp. ugamicus averaged 3.93, 3.70, and 7.28 bivalents per cell, respectively. Meiotic data in this series of F1 hybrids and karyotype analysis of E. panormitanus suggested that the genomic formula for E. panormitanus can tentatively be written as SpSpYpYp, indicating that both genomes are modified forms of the S and Y genomes found in the East Asian SY polyploids.Key words: Triticeae, Elymus, phylogeny, hybrids, intergeneric.

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

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.

Natural hybridization and introgression between Rana nigromaculata and Rana porosa porosa in central Japan

1997 ◽  
Vol 18 (3) ◽  
pp. 249-257 ◽  
Author(s):  
Masayuki Sumida ◽  
Tatsuo Ishihara
Keyword(s):  
Morphological Characters ◽  
Natural Hybridization ◽  
Reproductive Capacity ◽  
F1 Hybrids ◽  
Gene Introgression ◽  
Central Japan ◽  
Backcross Hybrid ◽  
Rana Nigromaculata ◽  
Frog Species ◽  
Hybridization And Introgression

AbstractIn order to elucidate the extent of natural hybridization and gene introgression between two Japanese pond frog species, Rana nigromaculata and Rana porosa porosa, 16 pond frogs from the Sengokuhara population in the Hakone district in central Japan were analyzed for morphological characters, allozymes, mtDNA and reproductive capacity. The results revealed that they consisted of pure Rana nigromaculata, F1 hybrids and a backcross hybrid.

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

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.

Intergeneric hybrids between Triticum aestivum and three crested wheatgrasses: Agropyron mongolicum, A. michnoi, and A. desertorum

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 663-667 ◽  
Author(s):  
Qin Chen ◽  
Joseph Jahier ◽  
Yvonne Cauderon
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Adult Stage ◽  
Meiotic Chromosome ◽  
Intergeneric Hybrids ◽  
Species Hybrid ◽  
Hybrid Necrosis ◽  
Hybrid Plants ◽  
High Degree ◽  
First Time

Three hybridizations of Triticum aestivum cv. Chinese Spring (CS) (2n = 42) with Agropyron mongolicum (2n = 14), A. michnoi (2n = 28), and A. desertorum (2n = 28) are reported for the first time. Hybrid embryos were obtained at frequencies of 0.24, 1.13, and 2.05%, respectively. The hybrid plants obtained from pollinating CS by A. mongolicum had the expected chromosome number of 2n = 4x = 28, but as a result of hybrid necrosis, none could be raised to the adult stage. Hybrids CS × A. michnoi and CS × A. desertorum both had 2n = 5x = 35 chromosomes. The average meiotic chromosome pairing per cell was 7.04 I + 12.14 II + 1.06 III + 0.07 IV + 0.02 V + 0.02 VI and 9.29 I + 11.05 II + 1.14 III + 0.05 IV, respectively. Their analysis leads to the conclusions that (i) the two Agropyron genomes in the hybrids share a high degree of homology, thus revealing that tetraploid Agropyron species are true autoploids (genome constitution PPPP) and (ii) gene(s) in the Agropyron species suppress the activity of the homoeologous pairing control system of wheat. The possibility of gene transfer from Agropyron to wheat is discussed.Key words: intergeneric hybrids, Triticum aestivum, Agropyron species, hybrid necrosis, chromosome pairing.

Investigations in the Triticinae II. The cytology and fertility of intergeneric and interspecific F1 hybrids and their derived amphidiploids

1953 ◽  
Vol 43 (1) ◽  
pp. 105-115 ◽  
Author(s):  
G. D. H. Bell ◽  
Leo Sachs
Keyword(s):  
Chromosome Pairing ◽  
Intergeneric Hybrids ◽  
F1 Hybrids ◽  
Cytological Evidence ◽  
Structural Chromosome ◽  
Multivalent Formation ◽  
Bivalent Formation ◽  
Low Incidence ◽  
High Degree ◽  
Differential Affinity

1. Chromosome pairing has been studied in twenty-two different sterile F1 hybrids involving the genera Aegilops, Agropyron and Triticum, together with their colchicine derived amphidiploids having chromosome numbers of 2n = 42, 56 and 70. Cytological evidence has been correlated with male and female fertility, while chromosome pairing in the parents has been studied in relation to their amphidiploids.2. Some of the sterile F1 hybrids showed little or no pairing, while in others the pairing was appreciable. There was an association of the amount of pairing with the parental combinations used in the production of the hybrids in that the interspecific hybrids were characterized by a relatively high degree of pairing, particularly those with 28 chromosomes, while the intergeneric hybrids either lacked pairing or showed a low incidence.3. In the A1 amphidiploid generation, chromosome pairing was in all cases high, and in some cases almost complete. In all cases multivalent formation in the amphidiploid was lower than bivalent formation in its undoubted F1 hybrid. Different amphidiploids showed various degrees of differential affinity. Univalent formation occurred in some amphidiploids, while bivalent formation in some was increased by a loss of chromosomes.4. In all cases there was a reduction in chiasmata per nucleus and chiasmata per bivalent in the amphidiploid compared with its parent species. Reduction values were not directly associated with any increase in chromosome number of the amphidiploid, nor with the presence of multivalents.5. No confirmation could be obtained of the view that multivalent formation in amphidiploids is a more generally sensitive index of chromosome homology than bivalent formation in the undoubted F1 hybrid. The absence of multivalents in an amphidiploid does not disprove the existence of structural chromosome homologies between the two parents.

Readjustment of the Standard ASUDAS to Encompass Dental Morphological Variations in Plio-Pleistocene Hominins

2018 ◽  
Vol 30 (1-2) ◽  
pp. 32-48
Author(s):  
M. Louail ◽  
S. Prat
Keyword(s):  
Phylogenetic Relationships ◽  
Homo Sapiens ◽  
Initial Study ◽  
Morphological Characters ◽  
State University ◽  
Arizona State University ◽  
Dental Anthropology ◽  
Morphological Variations ◽  
Fossil Hominins ◽  
Fossil Hominin

The standard ASUDAS scoring system (Arizona State University Dental Anthropology System) is used to assess dental morphological variations in modern humans. It is also frequently used to study, score, and compare morphological variations in fossil hominin taxa and to examine their phylogenetic relationships. However, using ASUDAS in studies of this type is under debate because it is based on modern Homo sapiens populations and does not appear to cover all variations observed in fossil Plio-Pleistocene homi- nins. Our observations and coding of 178 dentals casts of Plio-Pleistocene specimens based on ASUDAS and from the literature have confirmed the need to adapt the standard system to fossil hominins. In this initial study, we propose that the scoring procedures for some morphological characters need to be readjusted, while others could be standardized following the ASUDAS system.

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