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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, Joao Loureiro, Brian C Husband, 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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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, Joao Loureiro, Brian C Husband, Silvia CastroAbstract: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. 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. 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). 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. © The Author(s) 2020. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Niche differences may explain the geographic distribution of Cytotypes in Erysimum mediohispanicum
Plant Biology, 2017Co-Authors: A. J. Muñoz‐pajares, Mariana Castro, Joao Loureiro, Silvia Castro, F Perfectti, M Abdelaziz, P Biella, J M GómezAbstract:Polyploidization 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 have 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 climatic variables, population elevation, and soil properties to model ecological niches for the different Cytotypes. In addition, we have analysed the effect that ploidy level has on the floral phenotype. We have 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 has been 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. This article is protected by copyright. All rights reserved.
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Cytotype distribution at a diploid hexaploid contact zone in aster amellus asteraceae
Annals of Botany, 2012Co-Authors: Joao Loureiro, Silvia Castro, T Prochazka, 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.
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Cytotype distribution at a diploid–hexaploid contact zone in Aster amellus (Asteraceae)
Annals of Botany, 2012Co-Authors: Silvia Castro, Joao Loureiro, T Prochazka, 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.
Brian C Husband - 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, Joao Loureiro, Brian C Husband, 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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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, Joao Loureiro, Brian C Husband, Silvia CastroAbstract: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. 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. 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). 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. © The Author(s) 2020. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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population Cytotype structure in the polyploid galax urceolata diapensiaceae
Heredity, 1999Co-Authors: Tracy L Burton, Brian C HusbandAbstract:The geographical distributions of diploid and polyploid Galax urceolata overlap in the Blue Ridge Mountains, USA. As part of an investigation into the evolutionary forces governing the establishment of polyploids and their coexistence with diploids, we examined the population frequencies of diploids, triploids and tetraploids in the area of overlap. Ploidy was inferred from estimates of DNA content, using flow cytometry, for 1570 individuals sampled from 42 populations. Across the entire sampling area, diploids and tetraploids were most abundant (55% and 34% of individuals, respectively), whereas triploids were least abundant (11%). Cytotype frequencies differed significantly among the northern, central and southern regions of the range (G = 649.02, d.f. = 4, P < 0.0001), with diploids most frequent in the north-east and least frequent in the south-west. Twenty-six per cent of the populations contained three Cytotypes, 33% contained two, and 40% had a single Cytotype. Populations with two Cytotypes occurred in all possible Cytotype combinations, but when triploids were present, they were always in the minority. Uniform populations were either diploid (81%) or tetraploid (19%), but never triploid. Overall, populations are predominantly diploid or tetraploid but rarely evenly mixed, suggesting disruptive selection for chromosome number in G. urceolata. The contribution of ecological sorting and frequency-dependent mating success to the distribution of polyploids and diploids is discussed.
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Cytotype distribution at a diploid tetraploid contact zone in chamerion epilobium angustifolium onagraceae
American Journal of Botany, 1998Co-Authors: Brian C Husband, Douglas W SchemskeAbstract:In North America, the geographic distributions of diploid and tetraploid Chamerion (formerly Epilobium) angustifolium overlap in a narrow zone along the southern border of the boreal forest and along the Rocky Mountains. We examined the frequency and distribution of diploid and tetraploid Cytotypes in a narrow (5 km) zone of sympatry across an elevational gradient and in putatively uniform diploid and tetraploid reference populations on the Beartooth Pass, in the Rocky Mountains of southern Montana-northern Wyoming. All five reference populations sampled were dominated by a single Cytotype, but only one was completely uniform. In the zone of sympatry, 27 transects were sampled every 2 m for a total of 238 plants. Reproductive status (vegetative, flower buds, open flowers) was recorded, and the ploidy of each plant was determined by flow cytometry. Diploid and tetraploid plants predominated (36 and 55%, respectively) but were heterogeneously distributed among the transects. Six of the 27 transects were fixed for a single Cytotype (four transects, diploid; two transects, tetraploid), and in seven others either diploids or tetraploids predominated (frequency .75%). Triploids represented 9% of the total sample and occurred most frequently in transects containing both diploids and tetraploids ( G 5 3.4, df 5 2, P 5 0.07). Diploids were more often reproductive (in bud, flower, or fruit) than either triploids or tetraploids ( G 5 12.0, df 5 2, P , 0.001) and were the only Cytotype to have produced open flowers. These results suggest that the zone of sympatry is best characterized as a mosaic rather than a cline, with diploid and tetraploids in close proximity and that the distribution of polyploidy is regulated by ecological sorting in a heterogeneous physical environment.
Joao Loureiro - 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, Joao Loureiro, Brian C Husband, 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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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, Joao Loureiro, Brian C Husband, Silvia CastroAbstract: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. 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. 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). 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. © The Author(s) 2020. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Niche differences may explain the geographic distribution of Cytotypes in Erysimum mediohispanicum
Plant Biology, 2017Co-Authors: A. J. Muñoz‐pajares, Mariana Castro, Joao Loureiro, Silvia Castro, F Perfectti, M Abdelaziz, P Biella, J M GómezAbstract:Polyploidization 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 have 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 climatic variables, population elevation, and soil properties to model ecological niches for the different Cytotypes. In addition, we have analysed the effect that ploidy level has on the floral phenotype. We have 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 has been 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. This article is protected by copyright. All rights reserved.
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Cytotype distribution at a diploid hexaploid contact zone in aster amellus asteraceae
Annals of Botany, 2012Co-Authors: Joao Loureiro, Silvia Castro, T Prochazka, 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.
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Cytotype distribution at a diploid–hexaploid contact zone in Aster amellus (Asteraceae)
Annals of Botany, 2012Co-Authors: Silvia Castro, Joao Loureiro, T Prochazka, 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.
Zuzana Munzbergova - One of the best experts on this subject based on the ideXlab platform.
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Physiological and fitness differences between Cytotypes vary with stress in a grassland perennial herb
PLOS ONE, 2017Co-Authors: Zuzana Pavlíková, D. Holá, Blanka Vlasáková, Tomáš Procházka, Zuzana MunzbergovaAbstract:Understanding the consequences of polyploidization is a major step towards assessing the importance of this mode of speciation. Most previous studies comparing different Cytotypes, however, did so only within a single environment and considered only one group of traits. To take a step further, we need to explore multiple environments and a wide range of traits. The aim of this study was to assess response of diploid and autotetraploid individuals of Knautia arvensis (Dipsacaceae) to two stress conditions, shade or drought. We studied eleven photosynthetic, morphological and fitness parameters of the plants over three years in a common garden under ambient conditions and two types of stress. The results indicate strong differences in performance and physiology between Cytotypes in ambient conditions. Interestingly, higher fitness in diploids contrasted with more efficient photosynthesis in tetraploids in ambient conditions. However, stress, especially drought, strongly reduced fitness and disrupted function of the photosystems in both Cytotypes reducing the between Cytotype differences. The results indicate that drought stress reduced function of the photosynthetic processes in both Cytotypes but particularly in tetraploids, while fitness reduction was stronger in diploids. The photosynthesis related traits show higher plasticity in polyploids as theoretically expected, while the fitness related traits show higher plasticity in diploids especially in response to drought. This suggests that between Cytotype comparisons need to consider multiple traits and multiple environments to understand the breath of possible responses of different Cytotypes to stress. They also show that integrating results based on different traits is not straightforward and call for better mechanistic understanding of the relationships between species photosynthetic activity and fitness. Still, considering multiple environments and multiple species traits is crucial for understanding the drivers of niche differentiation between Cytotypes in future studies.
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Cytotype coexistence in the field cannot be explained by inter Cytotype hybridization alone linking experiments and computer simulations in the sexual species pilosella echioides asteraceae
BMC Evolutionary Biology, 2017Co-Authors: Jindřich Chrtek, Zuzana Munzbergova, Tomas Herben, Radka Rosenbaumova, Zuzana Dockalova, Jaroslav Zahradnicek, Jana Krejcikova, Pavel TravnicekAbstract:Abstract Background Processes driving ploidal diversity at the population level are virtually unknown. Their identification should use a combination of large-scale screening of ploidy levels in the field, pairwise crossing experiments and mathematical modelling linking these two types of data. We applied this approach to determine the drivers of frequencies of coexisting Cytotypes in mixed-ploidy field populations of the fully sexual plant species Pilosella echioides . We examined fecundity and ploidal diversity in seeds from all possible pairwise crosses among 2x, 3x and 4x plants. Using these data, we simulated the dynamics of theoretical panmictic populations of individuals whose progeny structure is identical to that determined by the hybridization experiment. Results The seed set differed significantly between the crossing treatments, being highest in crosses between diploids and tetraploids and lowest in triploid-triploid crosses. The number of progeny classes (with respect to embryo and endosperm ploidy) ranged from three in the 2x-2x cross to eleven in the 3x-3x cross. Our simulations demonstrate that, provided there is no difference in clonal growth and/or survival between Cytotypes, it is a clear case of minority Cytotype exclusion depending on the initial conditions with two stable states, neither of which corresponds to the ploidal structure in the field: (i) with prevalent diploids and lower proportions of other ploidies, and (ii) with prevalent tetraploids and 9% of hexaploids. By contrast, if clonal growth differs between Cytotypes, minority Cytotype exclusion occurs only if the role of sexual reproduction is high; otherwise differences in clonal growth are sufficient to maintain triploid prevalence (as observed in the field) independently of initial conditions. Conclusions The projections of our model suggest that the ploidal structure observed in the field can only be reached via a relatively high capacity for clonal growth (and proportionally lower sexual reproduction) in all Cytotypes combined with higher clonal growth in the prevailing Cytotype (3x).
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Cytotype distribution at a diploid hexaploid contact zone in aster amellus asteraceae
Annals of Botany, 2012Co-Authors: Joao Loureiro, Silvia Castro, T Prochazka, 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.
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Cytotype distribution at a diploid–hexaploid contact zone in Aster amellus (Asteraceae)
Annals of Botany, 2012Co-Authors: Silvia Castro, Joao Loureiro, T Prochazka, 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.
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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, Joao Loureiro, Brian C Husband, 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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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, Joao Loureiro, Brian C Husband, Silvia CastroAbstract: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. 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. 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). 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. © The Author(s) 2020. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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Niche differences may explain the geographic distribution of Cytotypes in Erysimum mediohispanicum
Plant Biology, 2017Co-Authors: A. J. Muñoz‐pajares, Mariana Castro, Joao Loureiro, Silvia Castro, F Perfectti, M Abdelaziz, P Biella, J M GómezAbstract:Polyploidization 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 have 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 climatic variables, population elevation, and soil properties to model ecological niches for the different Cytotypes. In addition, we have analysed the effect that ploidy level has on the floral phenotype. We have 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 has been 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. This article is protected by copyright. All rights reserved.
