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Brown MR, Abbott RJ, Twyford AD. The emerging importance of cross-ploidy hybridisation and introgression. Mol Ecol 2024; 33:e17315. [PMID: 38501394 DOI: 10.1111/mec.17315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 02/21/2024] [Accepted: 02/23/2024] [Indexed: 03/20/2024]
Abstract
Natural hybridisation is now recognised as pervasive in its occurrence across the Tree of Life. Resurgent interest in natural hybridisation fuelled by developments in genomics has led to an improved understanding of the genetic factors that promote or prevent species cross-mating. Despite this body of work overturning many widely held assumptions about the genetic barriers to hybridisation, it is still widely thought that ploidy differences between species will be an absolute barrier to hybridisation and introgression. Here, we revisit this assumption, reviewing findings from surveys of polyploidy and hybridisation in the wild. In a case study in the British flora, 203 hybrids representing 35% of hybrids with suitable data have formed via cross-ploidy matings, while a wider literature search revealed 59 studies (56 in plants and 3 in animals) in which cross-ploidy hybridisation has been confirmed with genetic data. These results show cross-ploidy hybridisation is readily overlooked, and potentially common in some groups. General findings from these studies include strong directionality of hybridisation, with introgression usually towards the higher ploidy parent, and cross-ploidy hybridisation being more likely to involve allopolyploids than autopolyploids. Evidence for adaptive introgression across a ploidy barrier and cases of cross-ploidy hybrid speciation shows the potential for important evolutionary outcomes.
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Affiliation(s)
- Max R Brown
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, UK
- School of Life Sciences, Anglia Ruskin University, Cambridge, UK
| | - Richard J Abbott
- School of Biology, University of St Andrews, St Andrews, Fife, UK
| | - Alex D Twyford
- Institute of Ecology and Evolution, University of Edinburgh, Edinburgh, UK
- Royal Botanical Garden Edinburgh, Edinburgh, UK
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Vaz de Sousa D, Greve M, Oberlander KC. Friends without benefits: Extensive cytotype sympatry and polyploid persistence in an African geophyte. AMERICAN JOURNAL OF BOTANY 2024:e16291. [PMID: 38439133 DOI: 10.1002/ajb2.16291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 12/08/2023] [Accepted: 12/08/2023] [Indexed: 03/06/2024]
Abstract
PREMISE Polyploidy is a major factor in plant adaptation and speciation. Multiple mechanisms contribute to autopolyploid frequency within populations, but uncertainties remain regarding mechanisms that facilitate polyploid establishment and persistence. Here we aimed to document and predict cytotype distributions of Oxalis obliquifolia Steud. ex A. Rich. across Gauteng, South Africa, and test for evidence of possible mechanisms, including morphological, phenological, and reproductive traits, that may potentially facilitate polyploid persistence. METHODS Over 320 O. obliquifolia plants from 25 sites were cytotyped using flow cytometry, and DNA ploidy was confirmed using meiotic chromosome squashes. Cytotypes were mapped and correlations with abiotic variables assessed using ordinations. To assess morphological and phenological associations with cytotype, we grew multiple cytotypes in a common garden, measured phenotypic traits and compared them using linear models and discriminant analyses. Intercytotype reproductive isolation was assessed using crossing experiments, and AMOVAs based on ITS DNA sequences tested for cytogeographic structure. RESULTS Six cytotypes were identified, and most sites had multiple cytotypes. Abiotic variables were not predictive of cytotype distribution. A clear gigas effect was present. Differences in flower size and phenology suggested pollinator interactions could play a role in polyploid persistence. Intercytotype crosses produced seed at low frequency. DNA data suggested diploids and polyploids were largely reproductively isolated in situ, and polyploidization events were not frequent enough to explain high cytotype sympatry. CONCLUSIONS Diploids and polyploids are behaving as separate species, despite little observable niche differentiation and non-zero potential intercytotype seed set. Tests on biotic interactions and intercytotype F1 fitness may provide insights into diploid and polyploid coexistence.
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Affiliation(s)
- Damian Vaz de Sousa
- Department of Plant and Soil Science, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
- H.G.W.J. Schweickerdt Herbarium, Department of Plant and Soil Science, University of Pretoria, Pretoria, South Africa
| | - Michelle Greve
- Department of Plant and Soil Science, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
| | - Kenneth C Oberlander
- H.G.W.J. Schweickerdt Herbarium, Department of Plant and Soil Science, University of Pretoria, Pretoria, South Africa
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Šemberová K, Svitok M, Marhold K, Suda J, Schmickl RE. Morphological and environmental differentiation as prezygotic reproductive barriers between parapatric and allopatric Campanula rotundifolia agg. cytotypes. ANNALS OF BOTANY 2023; 131:71-86. [PMID: 34559179 PMCID: PMC9904352 DOI: 10.1093/aob/mcab123] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 09/21/2021] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Reproductive isolation and local establishment are necessary for plant speciation. Polyploidy, the possession of more than two complete chromosome sets, creates a strong postzygotic reproductive barrier between diploid and tetraploid cytotypes. However, this barrier weakens between polyploids (e.g. tetraploids and hexaploids). Reproductive isolation may be enhanced by cytotype morphological and environmental differentiation. Moreover, morphological adaptations to local conditions contribute to plant establishment. However, the relative contributions of ploidy level and the environment to morphology have generally been neglected. Thus, the extent of morphological variation driven by ploidy level and the environment was modelled for diploid, tetraploid and hexaploid cytotypes of Campanula rotundifolia agg. Cytotype distribution was updated, and morphological and environmental differentiation was tested in the presence and absence of natural contact zones. METHODS Cytotype distribution was assessed from 231 localities in Central Europe, including 48 localities with known chromosome counts, using flow cytometry. Differentiation in environmental niche and morphology was tested for cytotype pairs using discriminant analyses. A structural equation model was used to explore the synergies between cytotype, environment and morphology. KEY RESULTS Tremendous discrepancies were revealed between the reported and detected cytotype distribution. Neither mixed-ploidy populations nor interploidy hybrids were detected in the contact zones. Diploids had the broadest environmental niche, while hexaploids had the smallest and specialized niche. Hexaploids and spatially isolated cytotype pairs differed morphologically, including allopatric tetraploids. While leaf and shoot morphology were influenced by environmental conditions and polyploidy, flower morphology depended exclusively on the cytotype. CONCLUSIONS Reproductive isolation mechanisms vary between cytotypes. While diploids and polyploids are isolated postzygotically, the environmental niche shift is essential between higher polyploids. The impact of polyploidy and the environment on plant morphology implies the adaptive potential of polyploids, while the exclusive relationship between flower morphology and cytotype highlights the role of polyploidy in reproductive isolation.
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Affiliation(s)
| | - Marek Svitok
- Faculty of Ecology and Environmental Sciences, Technical University in Zvolen, T. G. Masaryka, Zvolen, Slovakia
- Faculty of Science, Department of Ecosystem Biology, University of South Bohemia, Branišovská, České Budějovice, Czech Republic
| | - Karol Marhold
- Faculty of Science, Department of Botany, Charles University, Benátská, Prague, Czech Republic
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta, Bratislava, Slovakia
| | | | - Roswitha E Schmickl
- Faculty of Science, Department of Botany, Charles University, Benátská, Prague, Czech Republic
- Czech Academy of Sciences, Institute of Botany, Department of Evolutionary Plant Biology, Zámek, Průhonice, Czech Republic
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Schneider DJ, Levin RA, Miller JS. Reproductive isolation between diploid and tetraploid individuals in mixed-cytotype populations of Lycium australe. AMERICAN JOURNAL OF BOTANY 2023; 110:e16133. [PMID: 36706341 DOI: 10.1002/ajb2.16133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 12/28/2022] [Accepted: 12/29/2022] [Indexed: 06/18/2023]
Abstract
PREMISE Whole-genome duplication is considered a major mechanism of sympatric speciation due to the creation of strong and instantaneous reproductive barriers. Although postzygotic reproductive isolation between diploids and polyploids is often expected, the extent of reproductive incompatibility must be empirically determined and compared to patterns of genetic isolation to fully characterize the reproductive dynamics between cytotypes. METHODS We investigated reproductive compatibility between diploid and tetraploid Lycium australe in two mixed-cytotype populations using (1) controlled crossing experiments to evaluate fruit and seed production and (2) germination trials to test seed viability following homoploid and heteroploid crosses. We contrast these experiments with a single-nucleotide polymorphism (SNP) data set to measure genetic isolation between cytotypes and explore whether cytotype or population origin better explains patterns of genetic variation. Finally, we explore mating patterns using the observed germination rates of naturally produced seeds in each population. RESULTS Although homoploid and heteroploid crosses resulted in similar fruit and seed production, reproductive isolation between co-occurring diploids and tetraploids was nearly complete, due to low seed viability following heteroploid crosses. Of 191,182 total SNPs, 21,679 were present in ≥90% of individuals and replicate runs using unlinked SNPs revealed strong clustering by cytotype and differentiation of tetraploids based on population origin. CONCLUSIONS As often reported, diploid and tetraploid L. australe experience strong postzygotic isolation via hybrid seed inviability. Consistent with this result, cytotype explained a greater amount of variation in the SNP data set than population origin, despite some evidence of historical introgression.
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Affiliation(s)
- Derek J Schneider
- Department of Biology, Amherst College, Amherst, Massachusetts, 01002, USA
| | - Rachel A Levin
- Department of Biology, Amherst College, Amherst, Massachusetts, 01002, USA
| | - Jill S Miller
- Department of Biology, Amherst College, Amherst, Massachusetts, 01002, USA
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Mráz P, Španiel S, Skokanová K, Šingliarová B. Temporal stability of spatial cytotype structure in mixed-ploidy populations of Centaurea stoebe. AOB PLANTS 2022; 14:plac052. [PMID: 36439406 PMCID: PMC9683110 DOI: 10.1093/aobpla/plac052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
Spatial segregation of cytotypes reduces the negative effect of frequency-dependent mating on the fitness of minority cytotype(s) and thus allows its establishment and coexistence with the majority cytotype in mixed-ploidy populations. Despite its evolutionary importance, the stability of spatial segregation is largely unknown. Furthermore, closely related sympatric cytotypes that differ in their life histories might exhibit contrasting spatial dynamics over time. We studied the temporal stability of spatial structure at a secondary contact zone of co-occurring monocarpic diploids and polycarpic tetraploids of Centaurea stoebe, whose tetraploid cytotype has undergone a rapid range expansion in Europe and became invasive in North America. Eleven years after the initial screening, we re-assessed the microspatial distribution of diploids and tetraploids and their affinities to varying vegetation-cover density in three mixed-ploidy populations in Central Europe. We found that overall, spatial patterns and frequencies of both cytotypes in all sites were very similar over time, with one exception. At one site, in one previously purely 2x patch, diploids completely disappeared due to intensive succession by shrubby vegetation. The remaining spatial patterns, however, showed the same cytotype clumping and higher frequency of 2x despite subtle changes in vegetation-cover densities. In contrast to the expected expansion of polycarpic tetraploids having higher colonization ability when compared to diploids, the tetraploids remained confined to their former microsites and showed no spatial expansion. Spatial patterns of coexisting diploids and tetraploids, which exhibit contrasting life histories, did not change over more than a decade. Such temporal stability is likely caused by relatively stable habitat conditions and very limited seed dispersal. Our results thus imply that in the absence of a disturbance regime connected with frequent human- or animal-mediated seed dispersal, spatial patterns may be very stable over time, thus contributing to the long-term coexistence of cytotypes.
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Affiliation(s)
- Patrik Mráz
- Herbarium Collections & Department of Botany, Faculty of Sciences, Charles University, Benátská 2, CZ-128 01 Prague, Czechia
| | | | - Katarína Skokanová
- Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 23 Bratislava, Slovakia
| | - Barbora Šingliarová
- Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 23 Bratislava, Slovakia
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Becker FW, Oberlander KC, Trávníček P, Dreyer LL. Inconsistent expression of the gigas effect in polyploid Oxalis. AMERICAN JOURNAL OF BOTANY 2022; 109:1607-1621. [PMID: 36193941 DOI: 10.1002/ajb2.16077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 09/02/2022] [Accepted: 09/02/2022] [Indexed: 06/16/2023]
Abstract
PREMISE It is well-known that whole genome duplication (WGD) has played a significant role in the evolution of plants. The best-known phenotypic effect of WGD is the gigas effect, or the enlargement of polyploid plant traits. WGD is often linked with increased weediness, which could be a result of fitness advantages conferred by the gigas effect. As a result, the gigas effect could potentially explain polyploid persistence and abundance. We test whether a gigas effect is present in the polyploid-rich geophyte Oxalis, at both organ and cellular scales. METHODS We measured traits in conspecific diploid and polyploid accessions of 24 species across the genus. In addition, we measured the same and additional traits in 20 populations of the weedy and highly ploidy-variable species Oxalis purpurea L., including measures of clonality and selfing as a proxy for weediness. Ploidy level was determined using flow cytometry. RESULTS We found substantial variation and no consistent ploidy-related size difference, both between and within species, and across traits. Oxalis purpurea polyploids did, however, produce significantly more underground biomass and more bulbils than diploids, consistent with a potential role of WGD in the weediness of this species. CONCLUSIONS Our results suggest a more nuanced role for the gigas effect, at least in Oxalis. It may be temporary, short-lived, and inconsistently expressed and retained on evolutionary time scales, but in the short term can contribute to lineage success via increased vegetative reproduction.
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Affiliation(s)
- Frederik W Becker
- Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Kenneth C Oberlander
- H. G. W. J. Schweickerdt Herbarium, Department of Plant and Soil Sciences, Plant Sciences Complex, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Pavel Trávníček
- Institute of Botany, Academy of Sciences of the Czech Republic, Průhonice, Czech Republic, and Department of Botany, Charles University, Praha, Czech Republic
| | - Léanne L Dreyer
- Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
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Zheng W, Yan LJ, Burgess KS, Luo YH, Zou JY, Qin HT, Wang JH, Gao LM. Natural hybridization among three Rhododendron species (Ericaceae) revealed by morphological and genomic evidence. BMC PLANT BIOLOGY 2021; 21:529. [PMID: 34763662 PMCID: PMC8582147 DOI: 10.1186/s12870-021-03312-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 11/02/2021] [Indexed: 06/08/2023]
Abstract
BACKGROUND Natural hybridization can influence the adaptive response to selection and accelerate species diversification. Understanding the composition and structure of hybrid zones may elucidate patterns of hybridization processes that are important to the formation and maintenance of species, especially for taxa that have experienced rapidly adaptive radiation. Here, we used morphological traits, ddRAD-seq and plastid DNA sequence data to investigate the structure of a Rhododendron hybrid zone and uncover the hybridization patterns among three sympatric and closely related species. RESULTS Our results show that the hybrid zone is complex, where bi-directional hybridization takes place among the three sympatric parental species: R. spinuliferum, R. scabrifolium, and R. spiciferum. Hybrids between R. spinuliferum and R. spiciferum (R. ×duclouxii) comprise multiple hybrid classes and a high proportion of F1 generation hybrids, while a novel hybrid taxon between R. spinuliferum and R. scabrifolium dominated the F2 generation, but no backcross individuals were detected. The hybrid zone showed basically coincident patterns of population structure between genomic and morphological data. CONCLUSIONS Natural hybridization exists among the three Rhododendron species in the hybrid zone, although patterns of hybrid formation vary between hybrid taxa, which may result in different evolutionary outcomes. This study represents a unique opportunity to dissect the ecological and evolutionary mechanisms associated with adaptive radiation of Rhododendron species in a biodiversity hotspot.
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Affiliation(s)
- Wei Zheng
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, Yunnan, China
- University of Chinese Academy of Sciences, 10049, Beijing, China
| | - Li-Jun Yan
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, Yunnan, China
- University of Chinese Academy of Sciences, 10049, Beijing, China
- College of Vocational and Technical Education, Yunnan Normal University, 650092, Kunming, Yunnan, China
| | - Kevin S Burgess
- Department of Biology, Columbus State University, University System of Georgia, 31907-5645, Columbus, GA, USA
| | - Ya-Huang Luo
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, Yunnan, China
| | - Jia-Yun Zou
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, Yunnan, China
- University of Chinese Academy of Sciences, 10049, Beijing, China
| | - Han-Tao Qin
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, Yunnan, China
- University of Chinese Academy of Sciences, 10049, Beijing, China
| | - Ji-Hua Wang
- The Flower Research Institute, Yunnan Academy of Agricultural Sciences, 650205, Kunming, China.
| | - Lian-Ming Gao
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 650201, Kunming, Yunnan, China.
- Lijiang Forest Biodiversity National Observation and Research Station, Kunming Institute of Botany, Chinese Academy of Sciences, 674100, Lijiang, Yunnan, China.
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Wang Z, Zhong C, Li D, Yan C, Yao X, Li Z. Cytotype distribution and chloroplast phylogeography of the Actinidia chinensis complex. BMC PLANT BIOLOGY 2021; 21:325. [PMID: 34229602 PMCID: PMC8259359 DOI: 10.1186/s12870-021-03099-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Plant phylogeographic studies of species in subtropical China have mainly focused on rare and endangered species, whereas few studies have been conducted on taxa with relatively wide distribution, especially polyploid species. We investigated the cytotype and haplotype distribution pattern of the Actinidia chinensis complex, a widespread geographically woody liana with variable ploidy in subtropical China comprising two varieties, with three chloroplast fragments DNA (ndhF-rpl132, rps16-trnQ and trnE-trnT). Macroevolutionary, microevolutionary and niche modeling tools were also combined to disentangle the origin and the demographic history of the species or cytotypes. RESULTS The ploidy levels of 3338 individuals from 128 populations sampled throughout the species distribution range were estimated with flow cytometry. The widespread cytotypes were diploids followed by tetraploids and hexaploids, whereas triploids and octoploids occurred in a few populations. Thirty-one chloroplast haplotypes were detected. The genetic diversity and genetic structure were found to be high between varieties (or ploidy races) chinensis and deliciosa. Our results revealed that these two varieties inhabit significantly different climatic niche spaces. Ecological niche models (ENMs) indicate that all varieties' ranges contracted during the Last Inter Glacial (LIG), and expanded eastward or northward during the Last Glacial Maximum (LGM). CONCLUSIONS Pliocene and Plio-Pleistocene climatic fluctuations and vicariance appear to have played key roles in shaping current population structure and historical demography in the A. chinensis complex. The polyploidization process also appears to have played an important role in the historical demography of the complex through improving their adaptability to environmental changes.
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Affiliation(s)
- Zhi Wang
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan, 430074, Hubei, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Caihong Zhong
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan, 430074, Hubei, China
| | - Dawei Li
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan, 430074, Hubei, China
| | - Chunlin Yan
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan, 430074, Hubei, China
| | - Xiaohong Yao
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan, 430074, Hubei, China.
| | - Zuozhou Li
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan, 430074, Hubei, China.
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Sutherland BL, Galloway LF. Variation in heteroploid reproduction and gene flow across a polyploid complex: One size does not fit all. Ecol Evol 2021; 11:9676-9688. [PMID: 34306653 PMCID: PMC8293777 DOI: 10.1002/ece3.7791] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/18/2021] [Accepted: 03/18/2021] [Indexed: 11/17/2022] Open
Abstract
Whole-genome duplication is considered an important speciation mechanism in plants. However, its effect on reproductive isolation between higher cytotypes is not well understood. We used backcrosses between different ploidy levels and surveys of mixed-ploidy contact zones to determine how reproductive barriers differed with cytotype across a polyploid complex. We backcrossed F1 hybrids derived from 2X-4X and 4X-6X crosses in the Campanula rotundifolia autopolyploid complex, measured backcross fitness, and estimated backcross DNA cytotype. We then sampled four natural mixed-ploidy contact zones (two 2X-4X and two 4X-6X), estimated ploidy, and genotyped individuals across each contact zone. Reproductive success and capacity for gene flow was markedly lower for 2X-4X than 4X-6X hybrids. In fact, 3X hybrids could not backcross; all 2X-4X backcross progeny resulted from neotetraploid F1 hybrids. Further, no 3X individuals were found in 2X-4X contact zones, and 2X and 4X individuals were genetically distinct. By contrast, backcrosses of 5X hybrids were relatively successful, particularly when crossed to 6X individuals. In 4X-6X contact zones, 5X individuals and aneuploids were common and all cytotypes were largely genetically similar and spatially intermixed. Taken together, these results provide strong evidence that reproduction is low between 2X and 4X cytotypes, primarily occurring via unreduced gamete production, but that reproduction and gene flow are ongoing between 4X and 6X cytotypes. Further, it suggests whole-genome duplication can result in speciation between diploids and polyploids, but is less likely to create reproductive barriers between different polyploid cytotypes, resulting in two fundamentally different potentials for speciation across polyploid complexes.
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Affiliation(s)
- Brittany L. Sutherland
- Department of BiologyUniversity of VirginiaCharlottesvilleVAUSA
- Department of BiologyUniversity of Louisiana at LafayetteLafayetteLAUSA
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Delomas TA, Willis SC, Parker BL, Miller D, Anders P, Schreier A, Narum S. Genotyping single nucleotide polymorphisms and inferring ploidy by amplicon sequencing for polyploid, ploidy-variable organisms. Mol Ecol Resour 2021; 21:2288-2298. [PMID: 34008918 DOI: 10.1111/1755-0998.13431] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 04/21/2021] [Accepted: 05/11/2021] [Indexed: 11/30/2022]
Abstract
Whole genome duplication is hypothesized to have played a critical role in the evolution of several major taxa, including vertebrates, and while many lineages have rediploidized, some retain polyploid genomes. Additionally, variation in ploidy can occur naturally or be artificially induced within select plant and animal species. Modern genetic techniques have not been widely applied to polyploid or ploidy-variable species, in part due to the difficulty of obtaining genotype data from polyploids. In this study, we demonstrate a strategy for developing an amplicon sequencing panel of single nucleotide polymorphisms for high-throughput genotyping of polyploid organisms. We then develop a method to infer ploidy of individuals from amplicon sequencing data that is generalized to apply to any ploidy and does not require prior identification of heterozygous genotypes. Combining these two techniques will allow researchers to both infer ploidy and generate ploidy-aware genotypes with the same amplicon sequencing panel. We demonstrate this approach with white sturgeon Acipenser transmontanus, a ploidy-variable (octoploid, decaploid and dodecaploid) imperiled species under conservation management in the Pacific Northwest and obtained a panel of 325 loci. These loci were validated by examining inheritance in known-cross families, and the ploidy inference method was validated with known ploidy samples. We provide scripts that adapt existing pipelines to genotype polyploids and an R package for application of the ploidy inference method. We expect that these techniques will empower studies of genetic variation and inheritance in polyploid organisms that vary in ploidy level, either naturally or as a result of artificial propagation practices.
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Affiliation(s)
- Thomas A Delomas
- Pacific States Marine Fisheries Commission/Idaho Department of Fish and Game, Eagle Fish Genetics Laboratory, Eagle, ID, USA
| | - Stuart C Willis
- Hagerman Genetics Lab, Columbia River Inter-Tribal Fish Commission, Hagerman, ID, USA
| | - Blaine L Parker
- Columbia River Inter-Tribal Fish Commission, Portland, OR, USA
| | | | | | - Andrea Schreier
- Genomic Variation Laboratory, Department of Animal Science, University of California Davis, Davis, CA, USA
| | - Shawn Narum
- Hagerman Genetics Lab, Columbia River Inter-Tribal Fish Commission, Hagerman, ID, USA
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Morgan EJ, Čertner M, Lučanová M, Kubíková K, Marhold K, Kolář F. Niche similarity in diploid-autotetraploid contact zones of Arabidopsis arenosa across spatial scales. AMERICAN JOURNAL OF BOTANY 2020; 107:1375-1388. [PMID: 32974906 DOI: 10.1002/ajb2.1534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 06/21/2020] [Indexed: 06/11/2023]
Abstract
PREMISE Whole genome duplication is a major evolutionary event, but its role in ecological divergence remains equivocal. When populations of different ploidy (cytotypes) overlap in space, "contact zones" are formed, allowing the study of evolutionary mechanisms contributing toward ploidy divergence. Multiple contact zones per species' range are often described but rarely leveraged as natural replicates. We explored whether the strength of niche differentiation of diploid and autotetraploid Arabidopsis arenosa varies over distinct contact zones and if the frequency of triploids decreases from seedling to adult stage. METHODS We characterized ploidy composition and habitat preferences in 264 populations across three contact zones using climatic niche modeling. Ecological differences of cytotypes were also assessed using local vegetation surveys at 110 populations within two contact zones, and at the finer scale within five mixed-ploidy sites. This was complemented by flow cytometry of seedlings. RESULTS We found no niche differences between diploid and tetraploid populations within contact zones for either climatic or local environmental variables. Comparisons of cytotypes within mixed-ploidy sites found weak niche differences that were inconsistent in direction. Triploid individuals were virtually absent (0.14%) in the field, and they were at a similarly low frequency (0.2%) in ex situ germinated seedlings. CONCLUSIONS This study demonstrates the strength in investigating different spatial scales across several contact zones when addressing ecological niche differentiation between ploidies. The lack of consistent habitat differentiation of ploidies across the scales and locations supports the recently emerging picture that processes other than ecological differentiation may underlie ploidy coexistence in diploid-autopolyploid systems.
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Affiliation(s)
- Emma J Morgan
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 01, Prague, Czech Republic
| | - Martin Čertner
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 01, Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43, Průhonice, Czech Republic
| | - Magdalena Lučanová
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 01, Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43, Průhonice, Czech Republic
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 31, CZ-370 05, České Budějovice, Czech Republic
| | - Kateřina Kubíková
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 01, Prague, Czech Republic
| | - Karol Marhold
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 01, Prague, Czech Republic
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 23, Bratislava, Slovak Republic
| | - Filip Kolář
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 01, Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43, Průhonice, Czech Republic
- Institute of Botany, University of Innsbruck, Sternwartestrasse 15, AT-6020, Innsbruck, Austria
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12
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Román-Palacios C, Molina-Henao YF, Barker MS. Polyploids increase overall diversity despite higher turnover than diploids in the Brassicaceae. Proc Biol Sci 2020; 287:20200962. [PMID: 32873209 PMCID: PMC7542780 DOI: 10.1098/rspb.2020.0962] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 08/10/2020] [Indexed: 12/21/2022] Open
Abstract
Although polyploidy is widespread across the plant Tree of Life, its long-term evolutionary significance is still poorly understood. Here, we examine the effects of polyploidy in explaining the large-scale evolutionary patterns within angiosperms by focusing on a single family exhibiting extensive interspecific variation in chromosome numbers. We inferred ploidy from haploid chromosome numbers for 80% of species in the most comprehensive species-level chronogram for the Brassicaceae. After evaluating a total of 94 phylogenetic models of diversification, we found that ploidy influences diversification rates across the Brassicaceae. We also found that despite diversifying at a similar rate to diploids, polyploids have played a significant role in driving present-day differences in species richness among clades. Overall, in addition to highlighting the complexity in the evolutionary consequences of polyploidy, our results suggest that rare successful polyploids persist while significantly contributing to the long-term evolution of clades. Our findings further indicate that polyploidy has played a major role in driving the long-term evolution of the Brassicaceae and highlight the potential of polyploidy in shaping present-day diversity patterns across the plant Tree of Life.
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Affiliation(s)
- Cristian Román-Palacios
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Y. Franchesco Molina-Henao
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- The Arnold Arboretum, Harvard University, Boston, MA 02131, USA
- Departamento de Biología, Universidad del Valle, Cali, Valle 760032, Colombia
| | - Michael S. Barker
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
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13
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Sutherland BL, Miranda-Katz T, Galloway LF. Strength in numbers? Cytotype frequency mediates effect of reproductive barriers in mixed-ploidy arrays. Evolution 2020; 74:2281-2292. [PMID: 32776511 DOI: 10.1111/evo.14077] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 05/14/2020] [Accepted: 05/18/2020] [Indexed: 01/14/2023]
Abstract
When differentiated lineages come into contact, their fates depend on demographic and reproductive factors. These factors have been well-studied in taxa of the same ploidy, but less is known about sympatric lineages that differ in ploidy, particularly with respect to demographic factors. We assessed prezygotic, postzygotic, and total reproductive isolation in naturally pollinated arrays of diploid-tetraploid and tetraploid-hexaploid population mixes of Campanula rotundifolia by measuring pollinator transitions, seed yield, germination rate, and proportion of hybrid offspring. Four frequencies of each cytotype were tested, and pollinators consistently overvisited rare cytotypes. Seed yield and F1 hybrid production were greater in 4X-6X arrays than 2X-4X arrays, whereas germination rates were similar, creating two distinct patterns of reproductive isolation. In 2X-4X arrays, postzygotic isolation was near complete (3% hybrid offspring), and prezygotic isolation associated with pollinator preference is expected to facilitate the persistence of minority cytotypes. However, in 4X-6X arrays where postzygotic isolation permitted hybrid formation (44% hybrids), pollinator behavior drove patterns of reproductive isolation, with rare cytotypes being more isolated and greater gene flow expected from rare into common cytotypes. In polyploid complexes, both the specific cytotypes in contact and local cytotype frequency, likely reflecting spatial demography, will influence likelihood of gene exchange.
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Affiliation(s)
- Brittany L Sutherland
- Mountain Lake Biological Station and Department of Biology, University of Virginia, Charlottesville, Virginia, 22904
| | - Tomas Miranda-Katz
- Mountain Lake Biological Station and Department of Biology, University of Virginia, Charlottesville, Virginia, 22904
| | - Laura F Galloway
- Mountain Lake Biological Station and Department of Biology, University of Virginia, Charlottesville, Virginia, 22904
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14
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Beirinckx L, Vanschoenwinkel B, Triest L. Hidden Hybridization and Habitat Differentiation in a Mediterranean Macrophyte, the Euryhaline Genus Ruppia. FRONTIERS IN PLANT SCIENCE 2020; 11:830. [PMID: 32754168 PMCID: PMC7366321 DOI: 10.3389/fpls.2020.00830] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 05/22/2020] [Indexed: 06/11/2023]
Abstract
In many aquatic plant taxa, classification based on morphology has always been difficult. Molecular markers revealed that the complexity in several of these aquatic taxa could be addressed to recurrent hybridization events and cryptic species diversity. The submerged macrophyte genus Ruppia is one of these aquatic genera with a complex taxonomy due to the absence of clear distinguishable traits and several hybridization events. Two species co-exist throughout Europe, R. maritima and R. spiralis (previously known as R. cirrhosa), but recent molecular studies also found several indications of hybridization, introgression and chloroplast capture between these species. However, the full extent and frequency of hybridization and introgression in this genus has not been studied so far, nor is it clear how these hybrid lineages can co-exist locally with their parental species. In this paper, we wanted to detect whether a single coastal wetland where both species co-exist can act as a Ruppia hybrid zone. As a case study, we chose the Camargue, a Mediterranean coastal wetland that harbors a wide diversity in aquatic habitats, especially in terms of salinity and hydro-regime. We sampled several Ruppia populations within this wetland. To identify each sample and reconstruct the local genetic structure of the two parental species and their hybrids, we used both chloroplast and nuclear microsatellite markers. Afterward, we tested whether different species had different habitat preferences. Our results confirmed that R. maritima and R. spiralis are two strongly divergent species with different reproductive ecologies and different habitat preferences. This prevents frequent hybridization and consequently we could not detect any trace of a recent hybridization event. However, we found several populations of later-generation hybrids, including a population of R. maritima x hybrid backcrosses. The hybrid populations occupy a different habitat and are genetically distinct from their parental species, although they tend to be morphological similar to parental R. maritima. Although local hybridization and introgression in Ruppia is less frequent than we expected, the taxonomy of Ruppia is complicated due to ancient hybridizations and several back-crossings.
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Affiliation(s)
- Lise Beirinckx
- Ecology and Biodiversity Research Group, Plant Biology and Nature Management, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Bram Vanschoenwinkel
- Community Ecology Laboratory, Department of Biology, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- Centre for Environmental Management, University of the Free State, Bloemfontein, South Africa
| | - Ludwig Triest
- Ecology and Biodiversity Research Group, Plant Biology and Nature Management, Vrije Universiteit Brussel (VUB), Brussels, Belgium
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15
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Nardi FD, Hülber K, Moser D, Alonso‐Marcos H, Tribsch A, Dobeš C. Occurrence of apomictic conspecifics and ecological preferences rather than colonization history govern the geographic distribution of sexual Potentilla puberula. Ecol Evol 2020; 10:7306-7319. [PMID: 32760530 PMCID: PMC7391561 DOI: 10.1002/ece3.6455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/20/2020] [Accepted: 05/11/2020] [Indexed: 11/24/2022] Open
Abstract
The geographic distribution of sexual-apomictic taxa (i.e., comprising individuals usually reproducing either sexually or asexually via seeds) is traditionally thought to be driven by their ecological preferences and colonization histories. Where sexuals and apomicts get into contact with each other, competitive and reproductive interactions can interfere with these factors, an aspect which hitherto received little attention in biogeographic studies. We disentangled and quantified the relative effects of the three factors on the distribution of tetraploid sexuals in Potentilla puberula in a latitudinal transect through the Eastern European Alps, in which they are codistributed with penta-, hepta-, and octoploid apomictic conspecifics. Effects were explored by means of binomial generalized linear regression models combining a single with a multiple predictor approach. Postglacial colonization history was inferred from population genetic variation (AFLPs and cpDNA) and quantified using a cost distance metric. The study was based on 235 populations, which were purely sexual, purely apomictic, or of mixed reproductive mode. The occurrence of apomicts explained most of the variation in the distribution of sexuals (31%). Specifically, the presence of sexual tetraploids was negatively related to the presence of each of the three apomictic cytotypes. Effects of ecological preferences were substantial too (7% and 12% of the total variation explained by ecological preferences alone, or jointly with apomicts' occurrence, respectively). In contrast, colonization history had negligible effects on the occurrence of sexuals. Taken together, our results highlight the potentially high impact of reproductive interactions on the geographic distribution of sexual and apomictic conspecifics and that resultant mutual exclusion interrelates to ecological differentiation, a situation potentially promoting their local coexistence.
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Affiliation(s)
- Flavia Domizia Nardi
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
- Department of BiosciencesUniversity of SalzburgSalzburgAustria
| | - Karl Hülber
- Department of Conservation Biology, Vegetation Ecology and Landscape EcologyUniversity of ViennaViennaAustria
| | - Dietmar Moser
- Department of Conservation Biology, Vegetation Ecology and Landscape EcologyUniversity of ViennaViennaAustria
| | - Henar Alonso‐Marcos
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
- Department of Conservation Biology, Vegetation Ecology and Landscape EcologyUniversity of ViennaViennaAustria
| | - Andreas Tribsch
- Department of BiosciencesUniversity of SalzburgSalzburgAustria
| | - Christoph Dobeš
- Department of Forest GeneticsAustrian Research Centre for ForestsViennaAustria
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16
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Wilson J, Perry A, Shepherd JR, Durán-Castillo M, Jeffree CE, Cavers S. Invasion, isolation and evolution shape population genetic structure in Campanula rotundifolia. AOB PLANTS 2020; 12:plaa011. [PMID: 32284842 PMCID: PMC7141102 DOI: 10.1093/aobpla/plaa011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 03/09/2020] [Indexed: 05/13/2023]
Abstract
The distribution and genetic structure of most plant species in Britain and Ireland bear the imprint of the last ice age. These patterns were largely shaped by random processes during recolonization but, in angiosperms, whole-genome duplication may also have been important. We investigate the distribution of cytotypes of Campanula rotundifolia, considering DNA variation, postglacial colonization, environmental partitioning and reproductive barriers. Cytotypes and genome size variation from across the species' range were determined by flow cytometry and genetic variation was assessed using cpDNA markers. A common garden study examined growth and flowering phenology of tetraploid, pentaploid and hexaploid cytotypes and simulated a contact zone for investigation of reproductive barriers. Irish populations were entirely hexaploid. In Britain, hexaploids occurred mostly in western coastal populations which were allopatric with tetraploids, and in occasional sympatric inland populations. Chloroplast markers resolved distinct genetic groups, related to cytotype and geographically segregated; allopatric hexaploids were distinct from tetraploids, whereas sympatric hexaploids were not. Genome downsizing occurred between cytotypes. Progeny of open-pollinated clones from the contact zone showed that maternal tetraploids rarely produced progeny of other cytotypes, whereas the progeny of maternal hexaploids varied, with frequent pentaploids and aneuploids. The presence of distinctive hexaploid chloroplast types in Ireland, Scottish islands and western mainland Britain indicates that its establishment preceded separation of these land masses by sea-level rise c. 16 000 years BP. This group did not originate from British tetraploids and probably diverged before postglacial invasion from mainland Europe. The combination of cytotype, molecular, contact zone and common garden data shows an overall pattern reflecting postglacial colonization events, now maintained by geographic separation, together with more recent occasional local in situ polyploidisation. Reproductive barriers favour the persistence of the tetraploid to the detriment of the hexaploid.
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Affiliation(s)
- Julia Wilson
- UK Centre for Ecology & Hydrology, Penicuik, Midlothian, Scotland, UK
- Corresponding author’s email address:
| | - Annika Perry
- UK Centre for Ecology & Hydrology, Penicuik, Midlothian, Scotland, UK
| | | | - Mario Durán-Castillo
- Royal Botanic Garden Edinburgh, Edinburgh, Scotland, UK
- Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP), Campeche, Mexico
| | - Christopher E Jeffree
- Institute of Molecular Plant Sciences, Daniel Rutherford Building, The King’s Buildings, University of Edinburgh, Edinburgh, Scotland, UK
| | - Stephen Cavers
- UK Centre for Ecology & Hydrology, Penicuik, Midlothian, Scotland, UK
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17
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Levin DA. Has the Polyploid Wave Ebbed? FRONTIERS IN PLANT SCIENCE 2020; 11:251. [PMID: 32211006 PMCID: PMC7077508 DOI: 10.3389/fpls.2020.00251] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 02/18/2020] [Indexed: 05/13/2023]
Abstract
There was a wave of whole genome duplications (WGD) during and subsequent to the K-Pg interface, which was followed by an increase in the proportion of species that were polyploid. I consider why this wave of polyploid speciation has continued to rise through the divergent evolution of polyploid lineages, and through rounds of homoploid and heteroploid chromosomal change. I also consider why the polyploid speciation wave is likely to rise in the next millennium. I propose that the speed of polyploid genesis through ploidal increase and through diversification among polyploids likely will be greater than the speed of diploid speciation. The increase in polyploid diversity is expected to lag well behind episodes of WGD, owing to the very long period required for species diversification either by lineage splitting or additional rounds of polyploidy, in addition to the long period of genomic adjustment to higher ploidal levels in neopolyploids.
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Affiliation(s)
- Donald A. Levin
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, United States
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18
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Melichárková A, Šlenker M, Zozomová-Lihová J, Skokanová K, Šingliarová B, Kačmárová T, Caboňová M, Kempa M, Šrámková G, Mandáková T, Lysák MA, Svitok M, Mártonfiová L, Marhold K. So Closely Related and Yet So Different: Strong Contrasts Between the Evolutionary Histories of Species of the Cardamine pratensis Polyploid Complex in Central Europe. FRONTIERS IN PLANT SCIENCE 2020; 11:588856. [PMID: 33391302 PMCID: PMC7775393 DOI: 10.3389/fpls.2020.588856] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 11/19/2020] [Indexed: 05/04/2023]
Abstract
Recurrent polyploid formation and weak reproductive barriers between independent polyploid lineages generate intricate species complexes with high diversity and reticulate evolutionary history. Uncovering the evolutionary processes that formed their present-day cytotypic and genetic structure is a challenging task. We studied the species complex of Cardamine pratensis, composed of diploid endemics in the European Mediterranean and diploid-polyploid lineages more widely distributed across Europe, focusing on the poorly understood variation in Central Europe. To elucidate the evolution of Central European populations we analyzed ploidy level and genome size variation, genetic patterns inferred from microsatellite markers and target enrichment of low-copy nuclear genes (Hyb-Seq), and environmental niche differentiation. We observed almost continuous variation in chromosome numbers and genome size in C. pratensis s.str., which is caused by the co-occurrence of euploid and dysploid cytotypes, along with aneuploids, and is likely accompanied by inter-cytotype mating. We inferred that the polyploid cytotypes of C. pratensis s.str. are both of single and multiple, spatially and temporally recurrent origins. The tetraploid Cardamine majovskyi evolved at least twice in different regions by autopolyploidy from diploid Cardamine matthioli. The extensive genome size and genetic variation of Cardamine rivularis reflects differentiation induced by the geographic isolation of disjunct populations, establishment of triploids of different origins, and hybridization with sympatric C. matthioli. Geographically structured genetic lineages identified in the species under study, which are also ecologically divergent, are interpreted as descendants from different source populations in multiple glacial refugia. The postglacial range expansion was accompanied by substantial genetic admixture between the lineages of C. pratensis s.str., which is reflected by diffuse borders in their contact zones. In conclusion, we identified an interplay of diverse processes that have driven the evolution of the species studied, including allopatric and ecological divergence, hybridization, multiple polyploid origins, and genetic reshuffling caused by Pleistocene climate-induced range dynamics.
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Affiliation(s)
- Andrea Melichárková
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Marek Šlenker
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Judita Zozomová-Lihová
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Katarína Skokanová
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Barbora Šingliarová
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Tatiana Kačmárová
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Michaela Caboňová
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Matúš Kempa
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Gabriela Šrámková
- Department of Botany, Faculty of Science, Charles University, Prague, Czechia
| | - Terezie Mandáková
- Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czechia
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czechia
| | - Martin A. Lysák
- Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czechia
- National Centre for Biomolecular Research (NCBR), Faculty of Science, Masaryk University, Brno, Czechia
| | - Marek Svitok
- Department of Biology and General Ecology, Faculty of Ecology and Environmental Sciences, Technical University in Zvolen, Zvolen, Slovakia
- Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | | | - Karol Marhold
- Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia
- Department of Botany, Faculty of Science, Charles University, Prague, Czechia
- *Correspondence: Karol Marhold,
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19
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Hanušová K, Čertner M, Urfus T, Koutecký P, Košnar J, Rothfels CJ, Jarolímová V, Ptáček J, Ekrt L. Widespread co-occurrence of multiple ploidy levels in fragile ferns (Cystopteris fragilis complex; Cystopteridaceae) probably stems from similar ecology of cytotypes, their efficient dispersal and inter-ploidy hybridization. ANNALS OF BOTANY 2019; 123:845-855. [PMID: 30541055 PMCID: PMC6526313 DOI: 10.1093/aob/mcy219] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 11/09/2018] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS Polyploidy has played an important role in the evolution of ferns. However, the dearth of data on cytotype diversity, cytotype distribution patterns and ecology in ferns is striking in comparison with angiosperms and prevents an assessment of whether cytotype coexistence and its mechanisms show similar patterns in both plant groups. Here, an attempt to fill this gap was made using the ploidy-variable and widely distributed Cystopteris fragilis complex. METHODS Flow cytometry was used to assess DNA ploidy level and monoploid genome size (Cx value) of 5518 C. fragilis individuals from 449 populations collected over most of the species' global distributional range, supplemented with data from 405 individuals representing other related species from the complex. Ecological preferences of C. fragilis tetraploids and hexaploids were compared using field-recorded parameters and database-extracted climate data. KEY RESULTS Altogether, five different ploidy levels (2x, 4x, 5x, 6x, 8x) were detected and three species exhibited intraspecific ploidy-level variation: C. fragilis, C. alpina and C. diaphana. Two predominant C. fragilis cytotypes, tetraploids and hexaploids, co-occur over most of Europe in a diffuse, mosaic-like pattern. Within this contact zone, 40 % of populations were mixed-ploidy and most also contained pentaploid hybrids. Environmental conditions had only a limited effect on the distribution of cytotypes. Differences were found in the Cx value of tetraploids and hexaploids: between-cytotype divergence was higher in uniform-ploidy than in mixed-ploidy populations. CONCLUSIONS High ploidy-level diversity and widespread cytotype coexistence in the C. fragilis complex match the well-documented patterns in some angiosperms. While ploidy coexistence in C. fragilis is not driven by environmental factors, it could be facilitated by the perennial life-form of the species, its reproductive modes and efficient wind dispersal of spores. Independent origins of hexaploids and/or inter-ploidy gene flow may be expected in mixed-ploidy populations according to Cx value comparisons.
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Affiliation(s)
- Kristýna Hanušová
- Department of Botany, Faculty of Science, Charles University, Benátská, Praha, Czech Republic
| | - Martin Čertner
- Department of Botany, Faculty of Science, Charles University, Benátská, Praha, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek, Průhonice, Czech Republic
| | - Tomáš Urfus
- Department of Botany, Faculty of Science, Charles University, Benátská, Praha, Czech Republic
| | - Petr Koutecký
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská, České Budějovice, Czech Republic
| | - Jiří Košnar
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská, České Budějovice, Czech Republic
| | - Carl J Rothfels
- University Herbarium and Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - Vlasta Jarolímová
- Institute of Botany, The Czech Academy of Sciences, Zámek, Průhonice, Czech Republic
| | - Jan Ptáček
- Department of Botany, Faculty of Science, Charles University, Benátská, Praha, Czech Republic
| | - Libor Ekrt
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská, České Budějovice, Czech Republic
- For correspondence. E-mail
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20
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Šingliarová B, Zozomová-Lihová J, Mráz P. Polytopic origin and scale-dependent spatial segregation of cytotypes in primary diploid–autopolyploid contact zones ofPilosella rhodopea(Asteraceae). Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/bly199] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Barbora Šingliarová
- Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta, Bratislava, Slovakia
| | - Judita Zozomová-Lihová
- Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta, Bratislava, Slovakia
| | - Patrik Mráz
- Herbarium and Department of Botany, Charles University, Benátská,Prague, Czech Republic
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21
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Molina-Henao YF, Hopkins R. Autopolyploid lineage shows climatic niche expansion but not divergence in Arabidopsis arenosa. AMERICAN JOURNAL OF BOTANY 2019; 106:61-70. [PMID: 30609009 DOI: 10.1002/ajb2.1212] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/24/2018] [Indexed: 06/09/2023]
Abstract
PREMISE OF THE STUDY Successful establishment of neopolyploids, and therefore polyploid speciation, is thought to be contingent on environmental niche shifts from their progenitors. We explore this niche shift hypothesis in the obligate outcrosser Arabidopsis arenosa complex, which includes diploid and recently formed autotetraploid populations. METHODS To characterize the climatic niches for both cytotypes in Arabidopsis arenosa, we first gathered climatic data from localities with known ploidy types. We then estimated the climatic niches for diploids and autotetraploids and calculated niche overlap. Using this niche overlap statistic, we tested for niche equivalency and similarity. We explored differences in niches by estimating and comparing niche optimum and breadth and then calculated indices of niche expansion and unfilling. KEY RESULTS Climatic niche overlap between diploids and autotetraploids is substantial. Although the two niche models are not significantly divergent, they are not identical as they differ in both optimum and breadth along two environmental gradients. Autotetraploids fill nearly the entire niche space of diploids and have expanded into novel environments. CONCLUSIONS We find climatic niche expansion but not divergence, together with a moderate change in the niche optimum, in the autotetraploid lineage of Arabidopsis arenosa. These results indicate that the climatic niche shift hypothesis alone cannot explain the coexistence of tetraploid and diploid cytotypes.
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Affiliation(s)
- Y Franchesco Molina-Henao
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, Boston, MA, 02131, USA
- Departamento de Biología, Universidad del Valle, Cali, Valle, 760032, Colombia
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, Boston, MA, 02131, USA
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22
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Baduel P, Bray S, Vallejo-Marin M, Kolář F, Yant L. The “Polyploid Hop”: Shifting Challenges and Opportunities Over the Evolutionary Lifespan of Genome Duplications. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00117] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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23
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Garmendia A, Merle H, Ruiz P, Ferriol M. Distribution and ecological segregation on regional and microgeographic scales of the diploid Centaurea aspera L., the tetraploid C. seridis L., and their triploid hybrids (Compositae). PeerJ 2018; 6:e5209. [PMID: 30002989 PMCID: PMC6034602 DOI: 10.7717/peerj.5209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/20/2018] [Indexed: 11/20/2022] Open
Abstract
Although polyploidy is considered a ubiquitous process in plants, the establishment of new polyploid species may be hindered by ecological competition with parental diploid taxa. In such cases, the adaptive processes that result in the ecological divergence of diploids and polyploids can lead to their co-existence. In contrast, non-adaptive processes can lead to the co-existence of diploids and polyploids or to differentiated distributions, particularly when the minority cytotype disadvantage effect comes into play. Although large-scale studies of cytotype distributions have been widely conducted, the segregation of sympatric cytotypes on fine scales has been poorly studied. We analysed the spatial distribution and ecological requirements of the tetraploid Centaurea seridis and the diploid Centaurea aspera in east Spain on a large scale, and also microspatially in contact zones where both species hybridise and give rise to sterile triploid hybrids. On the fine scale, the position of each Centaurea individual was recorded along with soil parameters, accompanying species cover and plant richness. On the east Spanish coast, a slight latitudinal gradient was found. Tetraploid C. seridis individuals were located northerly and diploid C. aspera individuals southerly. Tetraploids were found only in the habitats with strong anthropogenic disturbance. In disturbed locations with well-developed semi-fixed or fixed dunes, diploids and tetraploids could co-exist and hybridise. However, on a fine scale, although taxa were spatially segregated in contact zones, they were not ecologically differentiated. This finding suggests the existence of non-adaptive processes that have led to their co-existence. Triploid hybrids were closer to diploid allogamous mothers (C. aspera) than to tetraploid autogamous fathers (C. seridis). This may result in a better ability to compete for space in the tetraploid minor cytotype, which might facilitate its long-term persistence.
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Affiliation(s)
- Alfonso Garmendia
- Instituto Agroforestal Mediterráneo, Universitat Politècnica de València, Valencia, Spain
| | - Hugo Merle
- Departamento de Ecosistemas Agroforestales, Universitat Politècnica de València, Valencia, Spain
| | - Pablo Ruiz
- Departamento de Ecosistemas Agroforestales, Universitat Politècnica de València, Valencia, Spain
| | - Maria Ferriol
- Instituto Agroforestal Mediterráneo, Universitat Politècnica de València, Valencia, Spain
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Muñoz-Pajares AJ, Perfectti F, Loureiro J, Abdelaziz M, Biella P, Castro M, Castro S, Gómez JM. Niche differences may explain the geographic distribution of cytotypes in Erysimum mediohispanicum. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20 Suppl 1:139-147. [PMID: 28741843 DOI: 10.1111/plb.12605] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 07/18/2017] [Indexed: 05/26/2023]
Abstract
Polyploidisation has played an important role in plant diversification, and variation in ploidy level may be found not only between species of the same genus, but also within a single species. Although establishing the adaptive significance of polyploidy to explain the geographic distribution of cytotypes is challenging, the occurrence of different cytotypes in different ecological niches may suggest an adaptive role of genome duplication. We studied the adaptive significance of the geographic distribution of cytotypes across the entire distribution range of the endemic Erysimum mediohispanicum (Brassicaceae). For that, we have used climate variables, population elevation and soil properties to model ecological niches for the different cytotypes. In addition, we analysed the effect that ploidy level has on the floral phenotype. We found a clear geographic pattern in the distribution of cytotypes, with diploid individuals occurring in the southernmost part of the distribution range, while tetraploids were found in the northern area. A contact (mosaic) zone between both cytotypes was identified, but diploids and tetraploids occur in sympatry in only one population (although in a highly unbalanced proportion). Gene flow between different cytotypes seems to be negligible, as evident from an almost complete absence of triploids and other minority cytotypes. Niches occupied by both cytotypes showed subtle, but significant differences, even in the contact zone. Precipitation was higher in regions occupied by tetraploid individuals, which present wider corolla tubes and thinner but taller stalks than diploids. Our findings highlight the potential role of polyploidy in the ecological adaptation of E. mediohispanicum to both abiotic factors and biotic interactions.
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Affiliation(s)
- A J Muñoz-Pajares
- Plant Biology, CIBIO/InBio, Centro de Investigação em Biodiversidade e Recursos Genéticos, Laboratório Associado, Universidade do Porto, Vairão, Portugal
- Departamento de Genetica, Universidad de Granada, Granada, Spain
| | - F Perfectti
- Departamento de Genetica, Universidad de Granada, Granada, Spain
| | - J Loureiro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - M Abdelaziz
- Departamento de Genetica, Universidad de Granada, Granada, Spain
| | - P Biella
- Departamento de Ecologıa, Universidad de Granada, Granada, Spain
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre of the Academy of Sciences of the Czech Republic, České Budějovice, Czech Republic
| | - M Castro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - S Castro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - J M Gómez
- Departamento de Ecologıa, Universidad de Granada, Granada, Spain
- Estación Experimental de Zonas Aridas (EEZA-CSIC), Almería, Spain
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25
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Kolář F, Čertner M, Suda J, Schönswetter P, Husband BC. Mixed-Ploidy Species: Progress and Opportunities in Polyploid Research. TRENDS IN PLANT SCIENCE 2017; 22:1041-1055. [PMID: 29054346 DOI: 10.1016/j.tplants.2017.09.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 09/12/2017] [Accepted: 09/18/2017] [Indexed: 05/07/2023]
Abstract
Mixed-ploidy species harbor a unique form of genomic and phenotypic variation that influences ecological interactions, facilitates genetic divergence, and offers insights into the mechanisms of polyploid evolution. However, there have been few attempts to synthesize this literature. We review here research on the cytotype distribution, diversity, and dynamics of intensively studied mixed-ploidy species and consider the implications for understanding mechanisms of polyploidization such as cytotype formation, establishment, coexistence, and post-polyploid divergence. In general, mixed-ploidy species are unevenly represented among families: they exhibit high cytotype diversity, often within populations, and frequently comprise rare and odd-numbered ploidies. Odd-ploidies often occur in association with asexuality. We highlight research hypotheses and opportunities that take advantage of the unique properties of ploidy variation.
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Affiliation(s)
- Filip Kolář
- Department of Botany, Faculty of Science, Charles University, Benátská 2, Praha, CZ-128 00, Czech Republic; Institute of Botany, The Czech Academy of Sciences, Zámek 1, Průhonice, CZ-252 43, Czech Republic
| | - Martin Čertner
- Department of Botany, Faculty of Science, Charles University, Benátská 2, Praha, CZ-128 00, Czech Republic; Institute of Botany, The Czech Academy of Sciences, Zámek 1, Průhonice, CZ-252 43, Czech Republic
| | - Jan Suda
- Department of Botany, Faculty of Science, Charles University, Benátská 2, Praha, CZ-128 00, Czech Republic; Institute of Botany, The Czech Academy of Sciences, Zámek 1, Průhonice, CZ-252 43, Czech Republic
| | - Peter Schönswetter
- Institute of Botany, University of Innsbruck, Sternwartestraße 15, A-6020 Innsbruck, Austria
| | - Brian C Husband
- Department of Integrative Biology, University of Guelph, Guelph, ON, N0B 2K0 Canada.
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26
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Čertner M, Fenclová E, Kúr P, Kolář F, Koutecký P, Krahulcová A, Suda J. Evolutionary dynamics of mixed-ploidy populations in an annual herb: dispersal, local persistence and recurrent origins of polyploids. ANNALS OF BOTANY 2017; 120:303-315. [PMID: 28398545 PMCID: PMC5737363 DOI: 10.1093/aob/mcx032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 03/08/2017] [Indexed: 05/18/2023]
Abstract
Background and Aims Despite the recent wealth of studies targeted at contact zones of cytotypes in various species, some aspects of polyploid evolution are still poorly understood. This is especially the case for the frequency and success rate of spontaneous neopolyploidization or the temporal dynamics of ploidy coexistence, requiring massive ploidy screening and repeated observations, respectively. To fill this gap, an extensive study of spatio-temporal patterns of ploidy coexistence was initiated in the widespread annual weed Tripleurospermum inodorum (Asteraceae). Methods DNA flow cytometry along with confirmatory chromosome counts was employed to assess ploidy levels of 11 018 adult individuals and 1263 ex situ germinated seedlings from 1209 Central European populations. The ploidy screening was conducted across three spatial scales and supplemented with observations of temporal development of 37 mixed-ploidy populations. Key Results The contact zone between the diploid and tetraploid cytotypes has a diffuse, mosaic-like structure enabling common cytotype coexistence from the within-population to the landscape level. A marked difference in monoploid genome size between the two cytotypes enabled the easy distinction of neotetraploid mutants from long-established tetraploids. Neotetraploids were extremely rare (0·03 %) and occurred solitarily. Altogether five ploidy levels (2 x -6 x ) and several aneuploids were discovered; the diversity in nuclear DNA content was highest in early ontogenetic stages (seedlings) and among individuals from mixed-ploidy populations. In spite of profound temporal oscillations in cytotype frequencies in mixed-ploidy populations, both diploids and tetraploids usually persisted up to the last census. Conclusions Diploids and tetraploids commonly coexist at all spatial scales and exhibit considerable temporal stability in local ploidy mixtures. Mixed-ploidy populations containing fertile triploid hybrids probaby act as effective generators of cytogenetic novelty and may facilitate inter-ploidy gene flow. Neopolyploid mutants were incapable of local establishment.
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Affiliation(s)
- Martin Čertner
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00 Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43 Průhonice, Czech Republic
| | - Eliška Fenclová
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00 Prague, Czech Republic
| | - Pavel Kúr
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00 Prague, Czech Republic
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, CZ-370 05 České Budějovice, Czech Republic
| | - Filip Kolář
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00 Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43 Průhonice, Czech Republic
- National Centre for Biosystematics, Natural History Museum, University of Oslo, NO-0318 Oslo, Norway
| | - Petr Koutecký
- Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, CZ-370 05 České Budějovice, Czech Republic
| | - Anna Krahulcová
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43 Průhonice, Czech Republic
| | - Jan Suda
- Department of Botany, Faculty of Science, Charles University, Benátská 2, CZ-128 00 Prague, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, CZ-252 43 Průhonice, Czech Republic
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27
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Winkler M, Escobar García P, Gattringer A, Sonnleitner M, Hülber K, Schönswetter P, Schneeweiss GM. A novel method to infer the origin of polyploids from Amplified Fragment Length Polymorphism data reveals that the alpine polyploid complex of Senecio carniolicus (Asteraceae) evolved mainly via autopolyploidy. Mol Ecol Resour 2017; 17:877-892. [PMID: 27978605 DOI: 10.1111/1755-0998.12641] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 11/24/2016] [Accepted: 12/06/2016] [Indexed: 11/30/2022]
Abstract
Despite its evolutionary and ecological relevance, the mode of polyploid origin has been notoriously difficult to be reconstructed from molecular data. Here, we present a method to identify the putative parents of polyploids and thus to infer the mode of their origin (auto- vs. allopolyploidy) from Amplified Fragment Length Polymorphism (AFLP) data. To this end, we use Cohen's d of distances between in silico polyploids, generated within a priori defined scenarios of origin from a priori delimited putative parental entities (e.g. taxa, genetic lineages), and natural polyploids. Simulations show that the discriminatory power of the proposed method increases mainly with increasing divergence between the lower-ploid putative ancestors and less so with increasing delay of polyploidization relative to the time of divergence. We apply the new method to the Senecio carniolicus aggregate, distributed in the European Alps and comprising two diploid, one tetraploid and one hexaploid species. In the eastern part of its distribution, the S. carniolicus aggregate was inferred to comprise an autopolyploid series, whereas for western populations of the tetraploid species, an allopolyploid origin involving the two diploid species was the most likely scenario. Although this suggests that the tetraploid species has two independent origins, other evidence (ribotype distribution, morphology) is consistent with the hypothesis of an autopolyploid origin with subsequent introgression by the second diploid species. Altogether, identifying the best among alternative scenarios using Cohen's d can be straightforward, but particular scenarios, such as allopolyploid origin vs. autopolyploid origin with subsequent introgression, remain difficult to be distinguished.
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Affiliation(s)
- Manuela Winkler
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna, A-1030, Austria.,GLORIA Co-ordination, Center for Global Change and Sustainability, University of Natural Resources and Life Sciences Vienna (BOKU) & Institute for Interdisciplinary Mountain Research, Austrian Academy of Sciences, Silbergasse 30/3, Vienna, A-1190, Austria
| | - Pedro Escobar García
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna, A-1030, Austria
| | - Andreas Gattringer
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna, A-1030, Austria
| | - Michaela Sonnleitner
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna, A-1030, Austria
| | - Karl Hülber
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna, A-1030, Austria.,Vienna Institute for Nature Conservation & Analyses, Giessergasse 6/7, Vienna, A-1090, Austria
| | - Peter Schönswetter
- Institute of Botany, University of Innsbruck, Sternwartestrasse 15, Innsbruck, A-6020, Austria
| | - Gerald M Schneeweiss
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna, A-1030, Austria
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28
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Sutherland BL, Galloway LF. Postzygotic isolation varies by ploidy level within a polyploid complex. THE NEW PHYTOLOGIST 2017; 213:404-412. [PMID: 27533526 DOI: 10.1111/nph.14116] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/12/2016] [Indexed: 05/20/2023]
Abstract
Whole genome duplication is considered to be a significant contributor to angiosperm speciation due to accumulation of rapid, strong interploid reproductive isolation. However, recent work suggests that interploid reproductive isolation may not be complete, especially among higher order cytotypes. This study evaluates postzygotic reproductive isolation among three cytotypes within a polyploid complex. We conducted reciprocal crosses using two diploid and two hexaploid populations each crossed to tetraploid populations spanning the geographic and phylogenetic range of the Campanula rotundifolia polyploid complex. Interploid and intrapopulation crosses were scored for fruit set, seed number, germination proportion and pollen viability. Postzygotic isolation was calculated for each cross as the product of these fitness components. A subset of offspring was cytotyped via flow cytometry. Postzygotic isolation was significantly lower in tetraploid-hexaploid crosses than diploid-tetraploid crosses, mostly due to substantially higher germination among tetraploid-hexaploid crosses. Tetraploid-hexaploid crosses produced pentaploids exclusively, whereas diploid-tetraploid crosses produced both triploids and tetraploids in high frequencies. Postzygotic isolation was weaker among higher order polyploids than between diploids and tetraploids, and unreduced gametes may facilitate diploid-tetraploid reproduction. This incomplete postzygotic isolation could allow ongoing interploid gene flow, especially among higher order polyploids, which may slow divergence and speciation in polyploid complexes.
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Affiliation(s)
| | - Laura F Galloway
- Department of Biology, University of Virginia, Charlottesville, VA, 22904-4328, USA
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Guo W, Yang J, Sun XD, Chen GJ, Yang YP, Duan YW. Divergence in Eco-Physiological Responses to Drought Mirrors the Distinct Distribution of Chamerion angustifolium Cytotypes in the Himalaya-Hengduan Mountains Region. FRONTIERS IN PLANT SCIENCE 2016; 7:1329. [PMID: 27630654 PMCID: PMC5005327 DOI: 10.3389/fpls.2016.01329] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Accepted: 08/18/2016] [Indexed: 05/08/2023]
Abstract
Polyploid species generally occupy harsher habitats (characterized by cold, drought and/or high altitude) than diploids, but the converse was observed for Chamerion angustifolium, in which diploid plants generally inhabit higher altitudes than their polyploid derivatives. Plants at high altitudes may experience cold-induced water stress, and we therefore examined the physiological responses of diploid and hexaploid C. angustifolium to water stress to better understand the ecological differentiation of plants with different ploidy levels. We conducted a common garden experiment by subjecting seedlings of different ploidy levels to low, moderate, and severe water stress. Fourteen indicators of physiological fitness were measured, and the anatomical characteristics of the leaves of each cytotype were determined. Both cytotypes were influenced by drought, and diploids exhibited higher fitness in terms of constant root:shoot ratio (R:S ratio) and maximum quantum yield of PS II (Fv/Fm ), less reduced maximal photosynthetic rate (A max), transpiration rate (E), intercellular CO2 concentration (C i) and stomatal conductance (g s), and higher long-term water use efficiency (WUEL) under severe water stress than did hexaploids. Analysis of leaf anatomy revealed morphological adjustments for tolerating water deficiency in diploids, in the form of closely packed mesophyll cells and small conduits in the midvein. Our results indicate that diploid C. angustifolium is more tolerant of drought than hexaploid plants, ensuring the successful survival of the diploid at high altitudes. This eco-physiological divergence may facilitate the species with different cytotypes to colonize new and large geographic ranges with heterogeneous environmental conditions.
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Affiliation(s)
- Wen Guo
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
- Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
- University of the Chinese Academy of SciencesBeijing, China
- Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
| | - Jie Yang
- School of Life Sciences, Yunnan Normal UniversityKunming, China
| | - Xu-Dong Sun
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
- Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
- Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
| | - Guang-Jie Chen
- Key Laboratory of Plateau Lake Ecology and Global Change, School of Tourism and Geography, Yunnan Normal UniversityKunming, China
| | - Yong-Ping Yang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
- Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
- Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
| | - Yuan-Wen Duan
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
- Plant Germplasm and Genomics Center, Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
- Institute of Tibetan Plateau Research at Kunming, Kunming Institute of Botany, Chinese Academy of SciencesKunming, China
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30
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Sonnleitner M, Hülber K, Flatscher R, Escobar García P, Winkler M, Suda J, Schönswetter P, Schneeweiss GM. Ecological differentiation of diploid and polyploid cytotypes of Senecio carniolicus sensu lato (Asteraceae) is stronger in areas of sympatry. ANNALS OF BOTANY 2016; 117:269-76. [PMID: 26658487 PMCID: PMC4724049 DOI: 10.1093/aob/mcv176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/07/2015] [Accepted: 10/06/2015] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS Ecological differentiation is recognized as an important factor for polyploid speciation, but little is known regarding whether the ecological niches of cytotypes differ between areas of sympatry and areas where single cytotypes occur (i.e. niche displacement). METHODS Ecological niches of four groups of Senecio carniolicus sensu lato (s.l.) (western and eastern diploid lineages, tetraploids and hexaploids) were characterized via Landolt indicator values of the accompanying vascular plant species and tested using multivariate and univariate statistics. KEY RESULTS The four groups of S. carniolicus s.l. were ecologically differentiated mainly with respect to temperature, light and soil (humus content, nutrients, moisture variability). Niche breadths did not differ significantly. In areas of sympatry hexaploids shifted towards sites with higher temperature, less light and higher soil humus content as compared with homoploid sites, whereas diploids and tetraploids shifted in the opposite direction. In heteroploid sites of tetraploids and the western diploid lineage the latter shifted towards sites with lower humus content but higher aeration. CONCLUSIONS Niche displacement can facilitate the formation of stable contact zones upon secondary contact of polyploids and their lower-ploid ancestors and/or lead to convergence of the cytotypes' niches after they have attained non-overlapping ranges. Niche displacement is essential for understanding ecological consequences of polyploidy.
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Affiliation(s)
- Michaela Sonnleitner
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria
| | - Karl Hülber
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria, Vienna Institute for Nature Conservation & Analyses, Giessergasse 6/7, A-1090 Vienna, Austria,
| | - Ruth Flatscher
- Institute of Botany, University of Innsbruck, Sternwartestrasse 15, A-6020 Innsbruck, Austria
| | - Pedro Escobar García
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria
| | - Manuela Winkler
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria, GLORIA co-ordination, University of Natural Resources and Life Sciences Vienna (BOKU), Center for Global Change and Sustainability & Austrian Academy of Sciences, Institute for Interdisciplinary Mountain Research, Silbergasse 30/3, A-1190 Vienna, Austria
| | - Jan Suda
- Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, Prague, CZ-128 01, Czech Republic and Institute of Botany, The Czech Academy of Sciences, Průhonice 1, CZ-252 43, Czech Republic
| | - Peter Schönswetter
- Institute of Botany, University of Innsbruck, Sternwartestrasse 15, A-6020 Innsbruck, Austria
| | - Gerald M Schneeweiss
- Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria
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31
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Flatscher R, García PE, Hülber K, Sonnleitner M, Winkler M, Saukel J, Schneeweiss GM, Schönswetter P. Underestimated diversity in one of the world's best studied mountain ranges: The polyploid complex of Senecio carniolicus (Asteraceae) contains four species in the European Alps. PHYTOTAXA 2015; 213:1-21. [PMID: 26190915 PMCID: PMC4503339 DOI: 10.11646/phytotaxa.213.1.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Senecio carniolicus (Asteraceae) is an intricate polyploid complex distributed in the European Alps (di-, tetra- and hexaploids) and Carpathians (hexaploids only). Molecular genetic, ecological, and crossing data allowed four evolutionary groups within S. carniolicus to be identified. Here, we establish that these four groups (two vicariant diploid lineages, tetraploids and hexaploids) are also morphologically differentiated. As a consequence, we draw taxonomic conclusions by characterizing four species, including the more narrowly circumscribed S. carniolicus (lectotypified here), the taxonomically elevated S. insubricus comb. nov. (lectotypified here), and the two newly described species S. disjunctus and S. noricus.
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Affiliation(s)
- Ruth Flatscher
- Division of Systematics and Evolutionary Botany, Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria; ,
| | - Pedro Escobar García
- Division of Systematics and Evolutionary Botany, Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria; , ; Department of Botany, Natural History Museum, Burgring 7, A-1010 Vienna, Austria;
| | - Karl Hülber
- Division of Conservation Biology, Vegetation Ecology and Landscape Ecology, Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, Vienna, Austria; ; Vienna Institute for Nature Conservation & Analyses, Giessergasse 6/7, A-1090 Vienna, Austria
| | - Michaela Sonnleitner
- Division of Systematics and Evolutionary Botany, Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria; ,
| | - Manuela Winkler
- Division of Systematics and Evolutionary Botany, Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria; , ; GLORIA co-ordination, University of Natural Resources and Life Sciences Vienna, Center for Global Change and Sustainability & Austrian Academy of Sciences, Institute for Interdisciplinary Mountain Research, Silbergasse 30, A-1190 Vienna, Austria;
| | - Johannes Saukel
- Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria;
| | - Gerald M Schneeweiss
- Division of Systematics and Evolutionary Botany, Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, 1030 Vienna, Austria; ,
| | - Peter Schönswetter
- Institute of Botany, University of Innsbruck, Sternwartestrasse 15, A-6020 Innsbruck, Austria;
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