The Experts below are selected from a list of 3540 Experts worldwide ranked by ideXlab platform
Christine A. Mcallister - One of the best experts on this subject based on the ideXlab platform.
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single nucleotide polymorphism discovery via genotyping by sequencing to assess population genetic structure and recurrent polyploidization in andropogon gerardii
American Journal of Botany, 2016Co-Authors: Christine A. Mcallister, Allison J MillerAbstract:PREMISE OF THE STUDY: Autopolyploidy, genome duplication within a single lineage, can result in multiple Cytotypes within a species. Geographic distributions of Cytotypes may reflect the evolutionary history of autopolyploid formation and subsequent population dynamics including stochastic (drift) and deterministic (differential selection among Cytotypes) processes. Here, we used a population genomic approach to investigate whether autopolyploidy occurred once or multiple times in Andropogon gerardii, a widespread, North American grass with two predominant Cytotypes. METHODS: Genotyping by sequencing was used to identify single nucleotide polymorphisms (SNPs) in individuals collected from across the geographic range of A. gerardii. Two independent approaches to SNP calling were used: the reference-free UNEAK pipeline and a reference-guided approach based on the sequenced Sorghum bicolor genome. SNPs generated using these pipelines were analyzed independently with genetic distance and clustering. KEY RESULTS: Analyses of the two SNP data sets showed very similar patterns of population-level clustering of A. gerardii individuals: a cluster of A. gerardii individuals from the southern Plains, a northern Plains cluster, and a western cluster. Groupings of individuals corresponded to geographic localities regardless of cytotype: 6x and 9x individuals from the same geographic area clustered together. CONCLUSIONS: SNPs generated using reference-guided and reference-free pipelines in A. gerardii yielded unique subsets of genomic data. Both data sets suggest that the 9x cytotype in A. gerardii likely evolved multiple times from 6x progenitors across the range of the species. Genomic approaches like GBS and diverse bioinformatics pipelines used here facilitate evolutionary analyses of complex systems with multiple ploidy levels.
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environmental correlates of cytotype distribution in andropogon gerardii poaceae
American Journal of Botany, 2015Co-Authors: Brent Bennett, Heidi Garrett, Jennifer Kidson, Blanda Matzenbacher, Anna Glotzbach, Christine A. Mcallister, Paul Kron, Russell Blaine, Allison J MillerAbstract:UNLABELLED: • PREMISE OF THE STUDY: Information about geographic distribution of Cytotypes can provide insight into the origin and maintenance of autopolyploid complexes and builds a foundation for understanding cytotype differentiation and the dynamics of mixed-ploidy populations. Here, we investigate environmental correlates of the geographic distributions of 6x and 9x individuals in the ecologically dominant grass Andropogon gerardii to examine the role of climate in shaping patterns of cytotype distribution in this species.• METHODS: Flow cytometry was used to estimate ploidy level in 352 individuals from 32 populations across North America. Ecological differentiation of Cytotypes was tested by relating BIOCLIM variables to cytotype distribution using principal components analysis and partial linear regression.• KEY RESULTS: Broad geographic sampling confirmed two primary Cytotypes-6x (hexaploid) and 9x (enneaploid)-and revealed that 9x plants are more common than previously thought. Enneaploids occur frequently in the southern portions of the range, with hexaploids dominating in northern regions. Mixed-ploidy populations were common (46.9%). Principal components analysis and partial linear regression indicated that reduced summer precipitation and increased variation in diurnal and seasonal temperature range were significant predictors of the frequency of 9x plants in a population.• CONCLUSIONS: Results indicate that (1) geographic distribution of 6x and 9x individuals is nonrandom; (2) environmental variables are associated with cytotype distribution in A. gerardii; and (3) nearly half of populations surveyed include both 6x and 9x individuals. The persistence of mixed-ploidy populations may reflect a combination of recurrent polyploid formation and the prevalence of clonal reproduction.
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environmental correlates of cytotype distribution in andropogon gerardii poaceae
American Journal of Botany, 2015Co-Authors: Brent Bennett, Heidi Garrett, Jennifer Kidson, Blanda Matzenbacher, Anna Glotzbach, Christine A. Mcallister, Paul Kron, Russell Blaine, Allison J MillerAbstract:UNLABELLED: • PREMISE OF THE STUDY: Information about geographic distribution of Cytotypes can provide insight into the origin and maintenance of autopolyploid complexes and builds a foundation for understanding cytotype differentiation and the dynamics of mixed-ploidy populations. Here, we investigate environmental correlates of the geographic distributions of 6x and 9x individuals in the ecologically dominant grass Andropogon gerardii to examine the role of climate in shaping patterns of cytotype distribution in this species.• METHODS: Flow cytometry was used to estimate ploidy level in 352 individuals from 32 populations across North America. Ecological differentiation of Cytotypes was tested by relating BIOCLIM variables to cytotype distribution using principal components analysis and partial linear regression.• KEY RESULTS: Broad geographic sampling confirmed two primary Cytotypes-6x (hexaploid) and 9x (enneaploid)-and revealed that 9x plants are more common than previously thought. Enneaploids occur frequently in the southern portions of the range, with hexaploids dominating in northern regions. Mixed-ploidy populations were common (46.9%). Principal components analysis and partial linear regression indicated that reduced summer precipitation and increased variation in diurnal and seasonal temperature range were significant predictors of the frequency of 9x plants in a population.• CONCLUSIONS: Results indicate that (1) geographic distribution of 6x and 9x individuals is nonrandom; (2) environmental variables are associated with cytotype distribution in A. gerardii; and (3) nearly half of populations surveyed include both 6x and 9x individuals. The persistence of mixed-ploidy populations may reflect a combination of recurrent polyploid formation and the prevalence of clonal reproduction.
Libor Ekrt - One of the best experts on this subject based on the ideXlab platform.
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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, 2019Co-Authors: Kristýna Hanusova, Martin Certner, Tomas Urfus, Petr Koutecký, Jiři Kosnar, Carl J Rothfels, Vlasta Jarolimova, Jan Ptacek, Libor EkrtAbstract:Author(s): Hanusova, Kristýna; Certner, Martin; Urfus, Tomas; Koutecký, Petr; Kosnar, Jiři; Rothfels, Carl J; Jarolimova, Vlasta; Ptacek, Jan; Ekrt, Libor | Abstract: Background and aimsPolyploidy 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.MethodsFlow 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 resultsAltogether, 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.ConclusionsHigh 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.
Allison J Miller - One of the best experts on this subject based on the ideXlab platform.
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single nucleotide polymorphism discovery via genotyping by sequencing to assess population genetic structure and recurrent polyploidization in andropogon gerardii
American Journal of Botany, 2016Co-Authors: Christine A. Mcallister, Allison J MillerAbstract:PREMISE OF THE STUDY: Autopolyploidy, genome duplication within a single lineage, can result in multiple Cytotypes within a species. Geographic distributions of Cytotypes may reflect the evolutionary history of autopolyploid formation and subsequent population dynamics including stochastic (drift) and deterministic (differential selection among Cytotypes) processes. Here, we used a population genomic approach to investigate whether autopolyploidy occurred once or multiple times in Andropogon gerardii, a widespread, North American grass with two predominant Cytotypes. METHODS: Genotyping by sequencing was used to identify single nucleotide polymorphisms (SNPs) in individuals collected from across the geographic range of A. gerardii. Two independent approaches to SNP calling were used: the reference-free UNEAK pipeline and a reference-guided approach based on the sequenced Sorghum bicolor genome. SNPs generated using these pipelines were analyzed independently with genetic distance and clustering. KEY RESULTS: Analyses of the two SNP data sets showed very similar patterns of population-level clustering of A. gerardii individuals: a cluster of A. gerardii individuals from the southern Plains, a northern Plains cluster, and a western cluster. Groupings of individuals corresponded to geographic localities regardless of cytotype: 6x and 9x individuals from the same geographic area clustered together. CONCLUSIONS: SNPs generated using reference-guided and reference-free pipelines in A. gerardii yielded unique subsets of genomic data. Both data sets suggest that the 9x cytotype in A. gerardii likely evolved multiple times from 6x progenitors across the range of the species. Genomic approaches like GBS and diverse bioinformatics pipelines used here facilitate evolutionary analyses of complex systems with multiple ploidy levels.
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environmental correlates of cytotype distribution in andropogon gerardii poaceae
American Journal of Botany, 2015Co-Authors: Brent Bennett, Heidi Garrett, Jennifer Kidson, Blanda Matzenbacher, Anna Glotzbach, Christine A. Mcallister, Paul Kron, Russell Blaine, Allison J MillerAbstract:UNLABELLED: • PREMISE OF THE STUDY: Information about geographic distribution of Cytotypes can provide insight into the origin and maintenance of autopolyploid complexes and builds a foundation for understanding cytotype differentiation and the dynamics of mixed-ploidy populations. Here, we investigate environmental correlates of the geographic distributions of 6x and 9x individuals in the ecologically dominant grass Andropogon gerardii to examine the role of climate in shaping patterns of cytotype distribution in this species.• METHODS: Flow cytometry was used to estimate ploidy level in 352 individuals from 32 populations across North America. Ecological differentiation of Cytotypes was tested by relating BIOCLIM variables to cytotype distribution using principal components analysis and partial linear regression.• KEY RESULTS: Broad geographic sampling confirmed two primary Cytotypes-6x (hexaploid) and 9x (enneaploid)-and revealed that 9x plants are more common than previously thought. Enneaploids occur frequently in the southern portions of the range, with hexaploids dominating in northern regions. Mixed-ploidy populations were common (46.9%). Principal components analysis and partial linear regression indicated that reduced summer precipitation and increased variation in diurnal and seasonal temperature range were significant predictors of the frequency of 9x plants in a population.• CONCLUSIONS: Results indicate that (1) geographic distribution of 6x and 9x individuals is nonrandom; (2) environmental variables are associated with cytotype distribution in A. gerardii; and (3) nearly half of populations surveyed include both 6x and 9x individuals. The persistence of mixed-ploidy populations may reflect a combination of recurrent polyploid formation and the prevalence of clonal reproduction.
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environmental correlates of cytotype distribution in andropogon gerardii poaceae
American Journal of Botany, 2015Co-Authors: Brent Bennett, Heidi Garrett, Jennifer Kidson, Blanda Matzenbacher, Anna Glotzbach, Christine A. Mcallister, Paul Kron, Russell Blaine, Allison J MillerAbstract:UNLABELLED: • PREMISE OF THE STUDY: Information about geographic distribution of Cytotypes can provide insight into the origin and maintenance of autopolyploid complexes and builds a foundation for understanding cytotype differentiation and the dynamics of mixed-ploidy populations. Here, we investigate environmental correlates of the geographic distributions of 6x and 9x individuals in the ecologically dominant grass Andropogon gerardii to examine the role of climate in shaping patterns of cytotype distribution in this species.• METHODS: Flow cytometry was used to estimate ploidy level in 352 individuals from 32 populations across North America. Ecological differentiation of Cytotypes was tested by relating BIOCLIM variables to cytotype distribution using principal components analysis and partial linear regression.• KEY RESULTS: Broad geographic sampling confirmed two primary Cytotypes-6x (hexaploid) and 9x (enneaploid)-and revealed that 9x plants are more common than previously thought. Enneaploids occur frequently in the southern portions of the range, with hexaploids dominating in northern regions. Mixed-ploidy populations were common (46.9%). Principal components analysis and partial linear regression indicated that reduced summer precipitation and increased variation in diurnal and seasonal temperature range were significant predictors of the frequency of 9x plants in a population.• CONCLUSIONS: Results indicate that (1) geographic distribution of 6x and 9x individuals is nonrandom; (2) environmental variables are associated with cytotype distribution in A. gerardii; and (3) nearly half of populations surveyed include both 6x and 9x individuals. The persistence of mixed-ploidy populations may reflect a combination of recurrent polyploid formation and the prevalence of clonal reproduction.
Martin Certner - One of the best experts on this subject based on the ideXlab platform.
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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, 2019Co-Authors: Kristýna Hanusova, Martin Certner, Tomas Urfus, Petr Koutecký, Jiři Kosnar, Carl J Rothfels, Vlasta Jarolimova, Jan Ptacek, Libor EkrtAbstract:Author(s): Hanusova, Kristýna; Certner, Martin; Urfus, Tomas; Koutecký, Petr; Kosnar, Jiři; Rothfels, Carl J; Jarolimova, Vlasta; Ptacek, Jan; Ekrt, Libor | Abstract: Background and aimsPolyploidy 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.MethodsFlow 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 resultsAltogether, 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.ConclusionsHigh 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.
Silvia Castro - One of the best experts on this subject based on the ideXlab platform.
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the role of multiple reproductive barriers strong post pollination interactions govern cytotype isolation in a tetraploid octoploid contact zone
Annals of Botany, 2020Co-Authors: Mariana Castro, Brian C Husband, Joao Loureiro, Silvia CastroAbstract:BACKGROUND AND AIMS: Polyploidy is an important contributor to sympatric speciation and assortative mating is a key mechanism driving cytotype interactions at contact zones. While strong reproductive barriers can mediate the coexistence of different Cytotypes in sympatry, positive frequency-dependent mating disadvantage ultimately drives the transition to single-ploidy populations. However, comprehensive estimates of reproductive isolation among Cytotypes and across multiple barriers are rare. We quantify the strength of isolation across multiple reproductive stages in a tetraploid-octoploid contact zone to understand the potential for coexistence. METHODS: Assortative mating due to flowering asynchrony, pollinator behaviour, morphological overlap, self-fertilization and gametic competition between tetraploid and octoploid Gladiolus communis in a contact zone in Western Iberian Peninsula were assessed in natural and experimental populations to quantify reproductive isolation (RI) between Cytotypes. KEY RESULTS: Tetraploids and octoploids have a high degree of overlap in flowering time, similar floral morphology, and are visited by generalist insects without cytotype foraging preferences, resulting in weak pre-pollination reproductive isolation (RI from 0.00 to 0.21). In contrast, post-pollination isolation resulting from gametic selection was a strong barrier to inter-cytotype mating, with ploidy composition in stigmatic pollen loads determining the levels of RI (RI from 0.54 to 1.00). Between-cytotype cross-incompatibility was relatively high (RI from 0.54 to 0.63) as was isolation acquired through self-pollination (RI of 0.59 in tetraploids and 0.39 in octoploids). CONCLUSIONS: Total RI was high for both tetraploids (RI from 0.90 to 1.00) and octoploids (RI from 0.78 to 0.98). Such high rates of assortative mating will enable cytotype coexistence in mixed-ploidy populations by weakening the impacts of minority cytotype exclusion. This study reveals the key role of gametic selection in cytotype siring success and highlights the importance of comprehensive estimates across multiple reproductive barriers to understand cytotype interactions at contact zones.
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cytotype distribution at a diploid hexaploid contact zone in aster amellus asteraceae
Annals of Botany, 2012Co-Authors: Tomáš Procházka, Joao Loureiro, Silvia Castro, Zuzana MunzbergovaAbstract:† Background and Aims The present study aims to assess the diversity and distribution of Cytotypes of Aster amellus in central and eastern Europe, contributing with data to improve understanding of the evolutionary dynamics of the contact zone between diploids and hexaploids of this polyploid complex. † Methods Large-scale cytotype screening of 4720 individuals collected in 229 populations was performed using 4 ′ ,6-diamidino-2-phenylindole (DAPI) flow cytometry. Fine-scale cytotype screening was performed in the mixed-ploidy population. Reproductive variables, such as number of florets per flower head, seed set and seedling emergence, as well as ploidy level of seeds and seedlings were recorded in this population. † Key Results The diploid‐hexaploid contact zone is large and complex, reaching the Czech Republic in the west, Austria in the south, Poland in the north-east and Romania in the extreme east of the surveyed areas. Most populations presented only one cytotype, either diploid or hexaploid. In several areas of the contact zone both Cytotypes were found to grow in parapatry. One mixed-ploidy population of diploids and hexaploids was detected for the first time, but no signs of hybridization were detected. In this population, diploids had a significantly lower reproductive success, and significantly higher production of intercytotype offspring, being in reproductive disadvantage in comparison with hexaploids. † Conclusions The contact zone of diploid and hexaploid A. amellus in central and eastern Europe seems to be highly dynamic and diffuse, with both primary and secondary contacts being possible. The obtained results suggest the origin of hexaploids through diploids, overall supporting previous hypotheses that this species is autopolyploid. Data from the only mixed-ploidy population detected so far suggest that the minority cytotype exclusion is an important evolutionary mechanisms driving the prevalence of single-cytotype populations, and thus contributing to the current distributional patterns of the Cytotypes of A. amellus.
