Naturally occurring triploid birch hybrids from woodlands in Iceland are partially fertile

Anamthawat‐Jónsson, Kesara; Karlsdóttir, Lilja; Thórsson, Æ. Th.; Jóhannsson, Magnús

doi:10.1007/s11056-020-09816-z

Cited by 12 publications

(13 citation statements)

References 56 publications

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“…But recent studies have shown that fluorescence microscopy is a much better alternative, as the method is straightforward to perform and offers more specific analysis, both in terms of pollen species identification and pollen viability screening 38,39 . Pollen autofluorescence can differentiate between live (allergenic) and dead or aborted pollen grains, and in the case of Betula pollen (Figure 3), we have proved that the autofluorescence method is good for this purpose 18 . It has been demonstrated that the major Fagales allergens (in this case, the birch Bet v1) represent cytoplasmic proteins, which cannot be detected on the surface of dry pollen 40 .…”

Section: Resultsmentioning

confidence: 69%

“…Indeed, we have demonstrated, by evaluating pollen viability and seed germination, that natural triploid birch hybrids are not completely sterile. 18 We found that 8−9% of pollen from triploid hybrids was viable, and 0.5−6% of seed produced by triploids germinated. This confirms both male and female fertility of triploid Betula hybrids.…”

Section: Introductionmentioning

confidence: 79%

“…These triploid hybrids, if they are not sterile, can mediate gene flow between the parental species via backcrossing. Indeed, we have demonstrated, by evaluating pollen viability and seed germination, that natural triploid birch hybrids are not completely sterile 18 . We found that 8−9% of pollen from triploid hybrids was viable, and 0.5−6% of seed produced by triploids germinated.…”

Section: Introductionmentioning

confidence: 83%

“…Normal development of the exine wall, thus red autofluorescence, is associated with pollen viability. The emission of double autofluorescence, i.e., red exine wall versus green cytoplasm, can be used to infer pollen viability 18 . Scale bar represents 5 µm.…”

Section: Introductionmentioning

confidence: 99%

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Microscopical palynology: Birch woodland expansion and species hybridisation coincide with periods of climate warming during the Holocene epoch in Iceland

Anamthawat‐Jónsson

Karlsdóttir

Thórsson

et al. 2023

Journal of Microscopy

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Introgressive hybridisation between arctic dwarf birch (Betula nana) and European downy birch (B. pubescens) is relatively common in natural woodlands in Iceland. As dwarf birch is a diploid species and downy tree birch a tetraploid species, their hybrids are triploid. In the introgression process, triploid hybrids, which are partially fertile, can backcross with the parental species, producing progenies comprising introgressed diploid, triploid and tetraploid plants.Triploid plants produce both normal triporate pollen (with three pores) and abnormal, aborted pollen, due to dysfunctional meiosis. The type of pollen abnormality that can be detected and quantified is non-triporate pollen (with four or more pores in the pollen wall). We therefore used the presence of non-triporate pollen as a marker to trace birch hybridisation in the past. In the current study we examined fossil pollen in samples from Holocene sediments from three locations: Grímsnes (SW), Eyjafjördur (N) and Thistilsfjördur (NE Iceland). All three peat monoliths had the starting age of 10.3 cal. ka BP. Ages were calibrated based on known tephra layers and by radiocarbon dating. The size of Betula pollen grains was measured, and the species proportions calculated from size. Nontriporate grains were detected in samples from all three locations and throughout the Holocene, but with different frequencies. The peaks of intense hybridisation followed birch woodland expansion in two major periods of the Holocene, both coinciding with a warming of climate. The first period occurred in the Early Holocene, around 9.5-7 cal. ka BP, when the climate warmed rapidly after deglaciation. The second period occurred around 5-3.5 cal. ka BP, well within the mid-Holocene Northern Hemisphere warming. A new wave of birch hybridisation appears to have started in the last few decades as the climate has warmed.Birch woodlands are likely to become more widespread. Introgressed shrub birch is likely to be more competitive over dwarf birch.

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Section: Resultsmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Microscopical palynology: Birch woodland expansion and species hybridisation coincide with periods of climate warming during the Holocene epoch in Iceland

Anamthawat‐Jónsson

Karlsdóttir

Thórsson

et al. 2023

Journal of Microscopy

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“…However, introgression from B. mcallisterii to B. luminifera is very little with the highest admixture value of 5.3%, much lower than the level of introgression from B. nana to B. pubescens , which shows the highest admixture value of 16.9% (Zohren et al, 2016). One possible explanation is that triploids between B. mcallisterii and B. luminifera may produce less viable gametes than triploids between B. nana and B. pubescens , which were reported to produce a small proportion of viable gametes (Anamthawat-Jónsson et al, 2021). Alternatively, we may have failed to sample the introgressed individuals.…”

Section: Discussionmentioning

confidence: 99%

A nearly 30-years living collection from the Royal Botanic Garden Edinburgh is a new species: a case study ofBetula mcallisteriisp. nov. (sect.Acuminatae, Betulaceae) and its little hybridization withBetula luminifera

Zhang

Ding

Wang

2022

Preprint

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Species description meets challenges arising from various species concepts. Integrating different sources of information and multiple lines of evidence are important for species recognition and discovery. Here we use morphology, restriction site-associated DNA sequencing and flow cytometry to study the species status of the unidentifiedBetulasamples collected in this study and to assess the extent of hybridization between the unidentifiedBetulasamples andB. luminiferain natural populations. Molecular analyses show the unidentifiedBetulasamples as a distinct lineage and reveal very little genetic admixture between the unidentified samples andB. luminifera. Unexpectedly, the unidentified samples formed a well-supported monophyletic clade with the living collection ofB. luminifera19933472 in the Royal Botanic Garden Edinburgh which was introduced from Southwest China. Flow cytometry shows that the unidentified samples andB. luminifera19933472 are diploid. Our data indicates thatB. luminifera19933472 and the unidentifiedBetulasamples should be recognized as a new species, namelyB. mcallisterii. The very little introgression betweenB. mcallisteriiandB. luminiferaindicates a strong reproductive barrier. Our research shows the importance of gathering information from wild populations and the value of an integrative approach in species discovery.

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Paleopalynology of Holocene birch hybridization in Iceland

Anamthawat-Jonsson

2024

BIO Web Conf.

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Naturally occurring triploid birch hybrids from woodlands in Iceland are partially fertile

Cited by 12 publications

References 56 publications

Microscopical palynology: Birch woodland expansion and species hybridisation coincide with periods of climate warming during the Holocene epoch in Iceland

Microscopical palynology: Birch woodland expansion and species hybridisation coincide with periods of climate warming during the Holocene epoch in Iceland

A nearly 30-years living collection from the Royal Botanic Garden Edinburgh is a new species: a case study ofBetula mcallisteriisp. nov. (sect.Acuminatae, Betulaceae) and its little hybridization withBetula luminifera

Paleopalynology of Holocene birch hybridization in Iceland

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