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Feng C, Zou S, Zhang J. Genetic architecture of microhabitat adaptation traits in a pair of sympatric Primulina species. BIOTECHNOL BIOTEC EQ 2023. [DOI: 10.1080/13102818.2023.2176169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Affiliation(s)
- Chen Feng
- Jiangxi Provincial Key Laboratory of ex situ Plant Conservation and Utilization, Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, Jiangxi, PR China
| | - Shuaiyu Zou
- Jiangxi Provincial Key Laboratory of ex situ Plant Conservation and Utilization, Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, Jiangxi, PR China
| | - Jie Zhang
- Jiangxi Provincial Key Laboratory of ex situ Plant Conservation and Utilization, Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, Jiangxi, PR China
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Afonso A, Castro S, Loureiro J, Arroyo J, Figueiredo A, Lopes S, Castro M. Ecological niches in the polyploid complex Linum suffruticosum s.l.. FRONTIERS IN PLANT SCIENCE 2023; 14:1148828. [PMID: 37152130 PMCID: PMC10154603 DOI: 10.3389/fpls.2023.1148828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/29/2023] [Indexed: 05/09/2023]
Abstract
Introduction The high frequency of polyploidy in the evolutionary history of many plant groups occurring in the Mediterranean region is likely a consequence of its dynamic paleogeographic and climatic history. Polyploids frequently have distinct characteristics that allow them to overcome the minority cytotype exclusion. Such traits may enable polyploid individuals to grow in habitats different from their parentals and/or expand to new areas, leading to spatial segregation. Therefore, the successful establishment of polyploid lineages has long been associated with niche divergence or niche partitioning and the ability of polyploids to cope with different, often more stressful, conditions. In this study, we aimed to explore the role of environmental variables associated with the current distribution patterns of cytotypes within the polyploid complex Linum suffruticosum s.l.. Methods The distribution and environmental niches of the five main cytotypes of Linum suffruticosum s.l. (diploids, tetraploids, hexaploids, octoploids and decaploids) were studied across its distribution range. Realized environmental niche of each cytotype was determined using niche modelling tools, such as maximum entropy modelling and niche equivalency and similarity tests. Results Differences in the environmental conditions of L. suffruticosum s.l. cytotypes were observed, with polyploids being associated with habitats of increased drought and soil pH, narrower temperature ranges and decreased soil water and cation exchange capacities. Diploids present the widest environmental niche, and polyploids occupy part of the diploid niche. Although some polyploids have equivalent potential ecological niches, cytotypes do not co-occur in nature. Additionally, the ecological niche of this polyploid complex is different between continents, with North African habitats being characterised by differences in soil texture, higher pH, and low cation exchange capacity, precipitation and soil water capacity and higher temperatures than habitats in southwest Europe. Discussion The different ecological conditions played a role in the distribution of cytotypes, but the mosaic distribution could not be entirely explained by the environmental variables included in this study. Other factors, such as reproductive isolation and competitive interactions among cytotypes, could further explain the current diversity and distribution patterns in white flax. This study provides relevant data on the niche requirements of each cytotype for further competition and reciprocal transplant experiments. further competition and reciprocal transplant experiments.
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Affiliation(s)
- Ana Afonso
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
- *Correspondence: Ana Afonso,
| | - Sílvia Castro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - João Loureiro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Juan Arroyo
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain
| | - Albano Figueiredo
- Centre of Studies in Geography and Spatial Planning (CEGOT), Department of Geography and Tourism, University of Coimbra, Coimbra, Portugal
| | - Sara Lopes
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Mariana Castro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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Zhang HP, Tao ZB, Trunschke J, Shrestha M, Scaccabarozzi D, Wang H, Ren ZX. Reproductive Isolation Among Three Nocturnal Moth-Pollinated Sympatric Habenaria Species (Orchidaceae). FRONTIERS IN PLANT SCIENCE 2022; 13:908852. [PMID: 35812980 PMCID: PMC9257206 DOI: 10.3389/fpls.2022.908852] [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: 03/31/2022] [Accepted: 05/16/2022] [Indexed: 06/15/2023]
Abstract
Comparison and quantification of multiple pre- and post-pollination barriers to interspecific hybridization are important to understand the factors promoting reproductive isolation. Such isolating factors have been studied recently in many flowering plant species which seek after the general roles and relative strengths of different pre- and post-pollination barriers. In this study, we quantified six isolating factors (ecogeographic isolation, phenological isolation, pollinator isolation, pollinia-pistil interactions, fruit production, and seed development) that could possibly be acting as reproductive barriers at different stages among three sympatric Habenaria species (H. limprichtii, H. davidii, and H. delavayi). These three species overlap geographically but occupy different microhabitats varying in soil water content. They were isolated through pollinator interactions both ethologically (pollinator preference) and mechanically (pollinia attachment site), but to a variable degree for different species pairs. Interspecific crosses between H. limprichtii and H. davidii result in high fruit set, and embryo development suggested weak post-pollination barriers, whereas bidirectional crosses of H. delavayi with either of the other two species fail to produce fruits. Our results revealed that pollinators were the most important isolating barrier including both ethological and mechanical mechanisms, to maintain the boundaries among these three sympatric Habenaria species. Our study also highlights the importance of a combination of pre-and post-pollination barriers for species co-existence in Orchidaceae.
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Affiliation(s)
- Hai-Ping Zhang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhi-Bin Tao
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences (CAS), Wuhan, China
| | - Judith Trunschke
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
| | - Mani Shrestha
- Department of Disturbance Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
| | - Daniela Scaccabarozzi
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China
- School of Molecular and Life Sciences, Curtin University, Bentley, WA, Australia
| | - Hong Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
- Lijiang Forest Biodiversity National Observation and Research Station, Lijiang, China
| | - Zong-Xin Ren
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences (CAS), Kunming, China
- University of Chinese Academy of Sciences, Beijing, China
- Lijiang Forest Biodiversity National Observation and Research Station, Lijiang, China
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Goff KA, Martinez Del Rio C, Kay KM. A greenhouse experiment partially supports inferences of ecogeographic isolation from niche models of Clarkia sister species. AMERICAN JOURNAL OF BOTANY 2021; 108:2002-2014. [PMID: 34661904 PMCID: PMC9298282 DOI: 10.1002/ajb2.1756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 07/10/2021] [Accepted: 07/12/2021] [Indexed: 06/13/2023]
Abstract
PREMISE Ecogeographic isolation, or geographic isolation caused by ecological divergence, is thought to be of primary importance in speciation, yet is difficult to demonstrate and quantify. To determine whether distributions are limited by divergent adaptation or historical contingency, the gold standard is to reciprocally transplant species between their geographic ranges. Alternatively, ecogeographic isolation is inferred from species distribution models and niche divergence tests using widely available environmental and occurrence data. METHODS We tested for ecogeographic isolation between two sister species of California annual wildflowers, Clarkia concinna and C. breweri, with a hybrid approach. We used niche models to predict water availability as the major axis of ecological divergence and then tested that with a greenhouse experiment. Specifically, we manipulated water availability in field soils for two populations of each species and predicted higher fitness in conditions representing home habitats to those representing the environment of each's sister species. RESULTS Water availability and soil representing C. concinna generally increased both species' fitness. Thus, water and soil may indeed limit C. concinna from colonizing the range of C. breweri, but not vice versa. We suggest that the competitive environment and pollinator availability, which are not directly captured with either approach, may be key biotic factors correlated with climate that contribute to unexplained ecogeographic isolation for C. breweri. CONCLUSIONS Ours is a valuable approach to assessing ecogeographic isolation, in that it balances feasibility with model validation, and our results have implications for species distribution modeling efforts geared toward predicting climate change responses.
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Affiliation(s)
- Kaleb A. Goff
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaSanta CruzCA95060USA
- Present address:
Kaleb A. Goff, Department of Plant and Microbial BiologyNorth Carolina State UniversityRaleighNC 27695USA
| | | | - Kathleen M. Kay
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaSanta CruzCA95060USA
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Van de Peer Y, Ashman TL, Soltis PS, Soltis DE. Polyploidy: an evolutionary and ecological force in stressful times. THE PLANT CELL 2021; 33:11-26. [PMID: 33751096 PMCID: PMC8136868 DOI: 10.1093/plcell/koaa015] [Citation(s) in RCA: 238] [Impact Index Per Article: 79.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/07/2020] [Indexed: 05/10/2023]
Abstract
Polyploidy has been hypothesized to be both an evolutionary dead-end and a source for evolutionary innovation and species diversification. Although polyploid organisms, especially plants, abound, the apparent nonrandom long-term establishment of genome duplications suggests a link with environmental conditions. Whole-genome duplications seem to correlate with periods of extinction or global change, while polyploids often thrive in harsh or disturbed environments. Evidence is also accumulating that biotic interactions, for instance, with pathogens or mutualists, affect polyploids differently than nonpolyploids. Here, we review recent findings and insights on the effect of both abiotic and biotic stress on polyploids versus nonpolyploids and propose that stress response in general is an important and even determining factor in the establishment and success of polyploidy.
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Affiliation(s)
| | - Tia-Lynn Ashman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
| | - Pamela S Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611
| | - Douglas E Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611
- Department of Biology, University of Florida, Gainesville, Florida 32611
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Laport RG, Minckley RL, Pilson D. Pollinator assemblage and pollen load differences on sympatric diploid and tetraploid cytotypes of the desert-dominant Larrea tridentata. AMERICAN JOURNAL OF BOTANY 2021; 108:297-308. [PMID: 33580499 PMCID: PMC7986067 DOI: 10.1002/ajb2.1605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 09/21/2020] [Indexed: 06/12/2023]
Abstract
PREMISE Whole-genome duplication (polyploidy) is an important force shaping flowering-plant evolution. Ploidy-specific plant-pollinator interactions represent important community-level biotic interactions that can lead to nonrandom mating and the persistence of mixed-ploidy populations. METHODS At a naturally occurring diploid-tetraploid contact zone of the autopolyploid desert shrub Larrea tridentata, we combined flower phenology analyses, collections of bees on plants of known cytotype, and flow cytometry analyses of bee-collected pollen loads to investigate whether (1) diploid and tetraploid plants have unique bee pollinator assemblages, (2) bee taxa exhibit ploidy-specific visitation and pollen collection biases, and (3) specialist and generalist bee taxa have ploidy-specific visitation and pollen collection biases. RESULTS Although bee assemblages overlapped, we found significant differences in bee visitation to co-occurring diploids and tetraploids, with the introduced honeybee (Apis mellifera) and one native species (Andrena species 12) more frequently visiting tetraploids. Consistent with bee assemblage differences, we found that diploid pollen was overrepresented among pollen loads on native bees, while pollen loads on A. mellifera did not deviate from the random expectation. However, mismatches between the ploidy of pollen loads and plants were common, consistent with ongoing intercytotype gene flow. CONCLUSIONS Our data are consistent with cytotype-specific bee visitation and suggest that pollinator behavior contributes to reduced diploid-tetraploid mating. Differences in bee visitation and pollen movement potentially contribute to an easing of minority cytotype exclusion and the facilitation of cytotype co-occurrence.
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Affiliation(s)
| | | | - Diana Pilson
- School of Biological SciencesUniversity of Nebraska‐LincolnLincolnNE68588USA
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Misiewicz TM, Simmons TS, Fine PVA. The contribution of multiple barriers to reproduction between edaphically divergent lineages in the Amazonian tree Protium subserratum (Burseraceae). Ecol Evol 2020; 10:6646-6663. [PMID: 32724539 PMCID: PMC7381562 DOI: 10.1002/ece3.6396] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/30/2020] [Accepted: 04/22/2020] [Indexed: 11/09/2022] Open
Abstract
Disentangling the strength and importance of barriers to reproduction that arise between diverging lineages is central to our understanding of species origin and maintenance. To date, the vast majority of studies investigating the importance of different barriers to reproduction in plants have focused on short-lived temperate taxa while studies of reproductive isolation in trees and tropical taxa are rare. Here, we systematically examine multiple barriers to reproduction in an Amazonian tree, Protium subserratum (Burseraceae) with diverging lineages of soil specialist ecotypes. Using observational, molecular, distributional, and experimental data, we aimed to quantify the contributions of individual prezygotic and postzygotic barriers including ecogeographic isolation, flowering phenology, pollinator assemblage, pollen adhesion, pollen germination, pollen tube growth, seed development, and hybrid fitness to total reproductive isolation between the ecotypes. We were able to identify five potential barriers to reproduction including ecogeographic isolation, phenological differences, differences in pollinator assemblages, differential pollen adhesion, and low levels of hybrid seed development. We demonstrate that ecogeographic isolation is a strong and that a combination of intrinsic and extrinsic prezygotic and postzygotic barriers may be acting to maintain near complete reproductive isolation between edaphically divergent populations of the tropical tree, P. subserratum.
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Affiliation(s)
- Tracy M. Misiewicz
- Department of Integrative Biology, University and Jepson HerbariaUniversity of CaliforniaBerkeleyCAUSA
| | - Tracey S. Simmons
- Department of Biological SciencesSan Jose State UniversitySan JoseCAUSA
| | - Paul V. A. Fine
- Department of Integrative Biology, University and Jepson HerbariaUniversity of CaliforniaBerkeleyCAUSA
- Department of Integrative BiologyEssig Museum of EntomologyUniversity and Jepson HerbariaUniversity of CaliforniaBerkeleyCAUSA
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Castro M, Loureiro J, Figueiredo A, Serrano M, Husband BC, Castro S. Different Patterns of Ecological Divergence Between Two Tetraploids and Their Diploid Counterpart in a Parapatric Linear Coastal Distribution Polyploid Complex. FRONTIERS IN PLANT SCIENCE 2020; 11:315. [PMID: 32265966 PMCID: PMC7098452 DOI: 10.3389/fpls.2020.00315] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 03/03/2020] [Indexed: 05/24/2023]
Abstract
Polyploidization is a widespread mechanism of evolutionary divergence in flowering plants. Ecological divergence of polyploid lineages has been proposed as a key process shaping the distribution of cytotypes in nature (niche shift hypothesis); however, evidence for the role of niche separation in replicated diploid-polyploid species pairs is still needed. This study aimed to assess the role of abiotic factors shaping current cytotype distributions. For that, we examined the distribution and environmental niches of two varieties recognized in diploid-tetraploid Jasione maritima across the species range and within a putative contact zone on the Iberian Peninsula. We counted chromosomes, screened for ploidy across Iberian Peninsula and characterized environmental requirements using niche modeling tools. We found that J. maritima var. maritima is composed by diploids with disjunct distribution in the west coast of France and northwest Iberian Peninsula, and by tetraploids in Iberian Peninsula, while var. sabularia is tetraploid. In the Iberian Peninsula, two parapatric contact zones along a linear coastal distribution were detected, one between diploid and tetraploid var. maritima, and the other between tetraploids of the two varieties. Environmental variables of diploid populations from France are distinct from those of southern diploid populations, which are more similar to tetraploids. In general, niche modeling results are congruent with the observed distribution patterns, although the results suggest a wider contact zone between varieties and cytotypes. Tetraploids of both varieties revealed different degrees of environmental divergence in comparison with their diploid counterpart. Tetraploid var. sabularia differed environmentally from diploids suggesting niche divergence. In contrast, tetraploid var. maritima overlapped with diploid environmental niche and currently occupies its entire predicted range, whereas diploids are restricted to northern areas of their suitable environment. Differences in ecological envelopes facilitate the recognition of functional units of biodiversity within polyploid groups, allowing the study of factors related to post-polyploidization divergence. Thus, whereas changes in environmental requirements may have allowed tetraploid var. sabularia to spread in habitats not favorable to diploids, other factors are involved with the distribution of diploid and tetraploid var. maritima.
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Affiliation(s)
- Mariana Castro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - João Loureiro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Albano Figueiredo
- Centre for Studies in Geography and Spatial Planning, Department of Geography and Tourism, Faculty of Arts and Humanities, University of Coimbra, Coimbra, Portugal
| | - Miguel Serrano
- Department of Botany, Faculty of Pharmacy, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Brian C. Husband
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - Sílvia Castro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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Christie K, Strauss SY. Reproductive isolation and the maintenance of species boundaries in two serpentine endemic Jewelflowers. Evolution 2019; 73:1375-1391. [PMID: 31152435 DOI: 10.1111/evo.13767] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/28/2019] [Accepted: 05/03/2019] [Indexed: 12/30/2022]
Abstract
Speciation occurs when reproductive barriers substantially reduce gene flow between lineages. Understanding how specific barriers contribute to reproductive isolation offers insight into the initial forces driving divergence and the evolutionary and ecological processes responsible for maintaining diversity. Here, we quantified multiple pre- and post-pollination isolating barriers in a pair of closely related California Jewelflowers (Streptanthus, Brassicaceae) living in an area of sympatry. S. breweri and S. hesperidis are restricted to similar serpentine habitats; however, populations are spatially isolated at fine-scales and rarely co-occur in intermixed stands. Several intrinsic postzygotic barriers were among the strongest we quantified, yet, postzygotic barriers currently contribute little to overall reproductive isolation due to the cumulative strength of earlier-acting extrinsic barriers, including spatial isolation, and flowering time and pollinator differences. Data from multiple years suggest that pre-pollination barriers may have different strengths depending on annual environmental conditions. Similarly, crossing data suggest that the strength of intrinsic isolation may vary among different population pairs. Estimates of total reproductive isolation in S. breweri and S. hesperidis are robust to uncertainty and variability in individual barrier strength estimates, demonstrating how multiple barriers can act redundantly to prevent gene flow between close relatives living in sympatry.
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Affiliation(s)
- Kyle Christie
- UC Davis Department of Evolution and Ecology, and Center for Population Biology, University of California, One Shields Avenue, Davis, California, 95616
| | - Sharon Y Strauss
- UC Davis Department of Evolution and Ecology, and Center for Population Biology, University of California, One Shields Avenue, Davis, California, 95616
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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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Gaynor ML, Marchant DB, Soltis DE, Soltis PS. Climatic niche comparison among ploidal levels in the classic autopolyploid system, Galax urceolata. AMERICAN JOURNAL OF BOTANY 2018; 105:1631-1642. [PMID: 30239980 DOI: 10.1002/ajb2.1161] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 07/04/2018] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Autopolyploidy, or whole-genome duplication within a species, leads to closely related cytotypes in one geographic location. One hypothesized mechanism by which autopolyploids become established is climatic niche divergence from their diploid progenitor. Here we tested this hypothesis in diploid, triploid, and tetraploid Galax urceolata (Diapensiaceae) and predicted the effects of climate change on the relative distributions of these cytotypes. METHODS We investigated whether climatic niche divergence has shaped the current distributions of Galax urceolata cytotypes in eastern North America using climatic niche modeling, multivariate analyses of environmental space, and geographic range analyses. We then projected the models of the three cytotypes onto an ensemble of future climate maps to determine how the distributions might be altered over time. KEY RESULTS All cytotypes are geographically sympatric; however, climatic niche contraction and a slight niche shift of the tetraploids was observed relative to that of the diploids. Climate projections for all diploid and tetraploid cytotypes showed substantial range contraction without much, or any, range shift, suggesting that Galax urceolata will likely go extinct in nature as mountain refugia become warmer. CONCLUSIONS Galax urceolata tetraploids occupy a slightly wetter habitat than that of their diploid progenitors. While we cannot take into account future adaptation, our models suggest extensive decreases in range distributions for both diploid and tetraploid G. urceolata based on climate change projections. Galax urceolata may therefore be under extreme threat due to loss of suitable habitat, and conservation efforts will be needed.
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Affiliation(s)
- Michelle L Gaynor
- Department of Biology, University of Central Florida, Orlando, Florida, 32816, USA
| | - D Blaine Marchant
- Department of Biology, University of Florida, Gainesville, Florida, 32611, USA
- Florida Museum of Natural History, University of Florida, Gainesville, Florida, 32611, USA
| | - Douglas E Soltis
- Department of Biology, University of Florida, Gainesville, Florida, 32611, USA
- Florida Museum of Natural History, University of Florida, Gainesville, Florida, 32611, USA
| | - Pamela S Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, Florida, 32611, USA
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Castro M, Castro S, Figueiredo A, Husband B, Loureiro J. Complex cytogeographical patterns reveal a dynamic tetraploid-octoploid contact zone. AOB PLANTS 2018; 10:ply012. [PMID: 29593853 PMCID: PMC5844219 DOI: 10.1093/aobpla/ply012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 02/13/2018] [Indexed: 05/24/2023]
Abstract
The distribution of cytotypes in mixed-ploidy species is crucial for evaluating ecological processes involved in the establishment and evolution of polyploid taxa. Here, we use flow cytometry and chromosome counts to explore cytotype diversity and distributions within a tetraploid-octoploid contact zone. We then use niche modelling and ploidy seed screening to assess the roles of niche differentiation among cytotypes and reproductive interactions, respectively, in promoting cytotype coexistence. Two cytotypes, tetraploids and octoploids, were dominant within the contact zone. They were most often distributed parapatrically or allopatrically, resulting in high geographic isolation. Still, 16.7 % of localities comprised two or more cytotypes, including the intermediate hexaploid cytotype. Tetraploids and octoploids had high environmental niche overlap and associated with similar climatic environments, suggesting they have similar ecological requirements. Given the geographical separation and habitat similarity among cytotypes, mixed-ploidy populations may be transitional and subject to the forces of minority cytotype exclusion which lead to pure-ploidy populations. However, seed ploidy analysis suggests that strong reproductive barriers may enforce assortative mating which favours stable cytotype coexistence. High cytogenetic diversity detected in the field suggests that unreduced gamete formation and hybridization events seem frequent in the studied polyploid complex and might be involved with the recurrent polyploid formation, governing, as well, the gene flow between cytogenetic entities.
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Affiliation(s)
- Mariana Castro
- CFE, Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, Coimbra, Portugal
| | - Sílvia Castro
- CFE, Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, Coimbra, Portugal
- Botanic Garden of the University of Coimbra, Calçada Martim de Freitas, Coimbra, Portugal
| | - Albano Figueiredo
- CEGOT, Departamento de Geografia e Turismo, Faculdade de Letras, Universidade de Coimbra, Largo da Porta Férrea, Coimbra, Portugal
| | - Brian Husband
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
| | - João Loureiro
- CFE, Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, Coimbra, Portugal
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Casazza G, Boucher FC, Minuto L, Randin CF, Conti E. Do floral and niche shifts favour the establishment and persistence of newly arisen polyploids? A case study in an Alpine primrose. ANNALS OF BOTANY 2017; 119:81-93. [PMID: 28025287 PMCID: PMC5218380 DOI: 10.1093/aob/mcw221] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/29/2016] [Accepted: 09/10/2016] [Indexed: 05/31/2023]
Abstract
BACKGROUND AND AIMS Polyploidization plays a key role in plant evolution. Despite the generally accepted 'minority-cytotype exclusion' theory, the specific mechanisms leading to successful establishment and persistence of new polyploids remain controversial. The majority of newly formed polyploids do not become established, because they are less common, have fewer potential mates or may not be able to compete successfully with co-occurring progenitors at lower ploidy levels. Changes in floral traits and ecological niches have been proposed as important mechanisms to overcome this initial frequency-dependent disadvantage. The aim of this study was to determine whether dodecaploids of the heterostylous P. marginata differ from their hexaploid progenitors in P. marginata and P. allionii for selected floral traits and ecological preferences that might be involved in establishment and persistence, providing a possible explanation for the origin of polyploidized populations. METHODS Floral morphological traits and ecological niche preferences among dodecaploids and their hexaploid progenitors in P. marginata and P. allionii ,: all restricted to the south-western Alps, were quantified and compared KEY RESULTS: Differences in floral traits were detected between dodecaploids and their closest relatives, but such differences might be too weak to counter the strength of minority cytotype disadvantage and are unlikely to enable the coexistence of different cytotypes. Furthermore, the results suggest the preservation of full distyly and no transition to selfing in dodecaploids. Finally, dodecaploids occur almost exclusively in environments that are predicted to be suitable also for their closest hexaploid relatives. CONCLUSIONS In light of the results, P. marginata dodecaploids have probably been able to establish and persist by occupying geographical areas not yet filled by their closest relatives without significant evolution in their climatic and pollination niches. Dispersal limitation and minority-cytotype exclusion probably maintain their current range disjunct from those of its close relatives.
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Affiliation(s)
- Gabriele Casazza
- DISTAV, University of Genoa, Corso Europa 26, I-16132 Genoa, Italy
| | - Florian C Boucher
- Department of Systematic and Evolutionary Botany and Botanic Garden, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
- Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa
| | - Luigi Minuto
- DISTAV, University of Genoa, Corso Europa 26, I-16132 Genoa, Italy
| | - Christophe F Randin
- Department of Ecology & Evolution, University of Lausanne, Biophore, CH-1015 Lausanne, Switzerland
| | - Elena Conti
- Department of Systematic and Evolutionary Botany and Botanic Garden, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
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Milano ER, Lowry DB, Juenger TE. The Genetic Basis of Upland/Lowland Ecotype Divergence in Switchgrass ( Panicum virgatum). G3 (BETHESDA, MD.) 2016; 6:3561-3570. [PMID: 27613751 PMCID: PMC5100855 DOI: 10.1534/g3.116.032763] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 08/30/2016] [Indexed: 12/29/2022]
Abstract
The evolution of locally adapted ecotypes is a common phenomenon that generates diversity within plant species. However, we know surprisingly little about the genetic mechanisms underlying the locally adapted traits involved in ecotype formation. The genetic architecture underlying locally adapted traits dictates how an organism will respond to environmental selection pressures, and has major implications for evolutionary ecology, conservation, and crop breeding. To understand the genetic architecture underlying the divergence of switchgrass (Panicum virgatum) ecotypes, we constructed a genetic mapping population through a four-way outbred cross between two northern upland and two southern lowland accessions. Trait segregation in this mapping population was largely consistent with multiple independent loci controlling the suite of traits that characterizes ecotype divergence. We assembled a joint linkage map using ddRADseq, and mapped quantitative trait loci (QTL) for traits that are divergent between ecotypes, including flowering time, plant size, physiological processes, and disease resistance. Overall, we found that most QTL had small to intermediate effects. While we identified colocalizing QTL for multiple traits, we did not find any large-effect QTL that clearly controlled multiple traits through pleiotropy or tight physical linkage. These results indicate that ecologically important traits in switchgrass have a complex genetic basis, and that similar loci may underlie divergence across the geographic range of the ecotypes.
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Affiliation(s)
- Elizabeth R Milano
- Department of Integrative Biology, The University of Texas at Austin, Texas 78712
| | - David B Lowry
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Thomas E Juenger
- Department of Integrative Biology, The University of Texas at Austin, Texas 78712
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Blaine Marchant D, Soltis DE, Soltis PS. Patterns of abiotic niche shifts in allopolyploids relative to their progenitors. THE NEW PHYTOLOGIST 2016; 212:708-718. [PMID: 27399976 DOI: 10.1111/nph.14069] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/23/2016] [Indexed: 05/05/2023]
Abstract
Polyploidy has extensive genetic, physiological, morphological, and ecological ramifications. While the patterns underlying the genetic and morphological consequences of polyploidy are being rapidly elucidated, the effects on ecological niche are still largely unknown. This study investigated 13 allopolyploid systems in North America (10 ferns and three angiosperms) using digitized natural history museum specimens. The abiotic niches of the allopolyploids were compared with those of their diploid progenitors using ecological niche modeling, niche analyses, and multivariate analyses. We identified four patterns of niche shifts through our analyses: niche expansion, niche contraction, niche intermediacy, and niche novelty. The classification of these shifts depended on the amount of niche overlap and breadth between the polyploid and progenitors. The most common niche shift was niche intermediacy in which the polyploid inhabited a geographic range between that of the progenitors and had a high degree of niche overlap. Each polyploid had at least partial geographic sympatry and abiotic niche overlap with one of its progenitors, suggesting that biotic and/or microclimate factors may play a larger role in polyploid establishment than previously hypothesized. This study provides a baseline for future comparisons of the diverse outcomes of genome merger and duplication on abiotic niche preference.
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Affiliation(s)
- D Blaine Marchant
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA.
- Florida Museum of Natural History, Gainesville, FL, 32611, USA.
| | - Douglas E Soltis
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
- Florida Museum of Natural History, Gainesville, FL, 32611, USA
- Genetics Institute, University of Florida, Gainesville, FL, 32611, USA
| | - Pamela S Soltis
- Florida Museum of Natural History, Gainesville, FL, 32611, USA
- Genetics Institute, University of Florida, Gainesville, FL, 32611, USA
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Visger CJ, Germain-Aubrey CC, Patel M, Sessa EB, Soltis PS, Soltis DE. Niche divergence between diploid and autotetraploid Tolmiea. AMERICAN JOURNAL OF BOTANY 2016; 103:1396-1406. [PMID: 27507838 DOI: 10.3732/ajb.1600130] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/10/2016] [Indexed: 06/06/2023]
Abstract
PREMISE OF STUDY Polyploidy is common in eukaryotes and is of major evolutionary importance over both short and long time-scales. Compared to allopolyploids, autopolyploids remain understudied; they are often morphologically cryptic and frequently remain taxonomically unrecognized, although there is increasing recognition of the high frequency of autopolyploidy in angiosperms. While autopolyploidy can serve as an instant speciation mechanism, little is known about the ecological consequences of this process. We describe the ecological divergence of a diploid-autotetraploid species pair in Tolmiea. METHODS We investigated whether abiotic niche divergence has shaped the current allopatric distribution of diploid T. diplomenziesii and its autotetraploid derivative, T. menziesii, in the Pacific Northwest of North America. We employed field measures of light availability, as well as niche modeling and a principal component analysis of environmental space. Within a common garden, we also investigated physiological responses to changes in soil moisture. KEY RESULTS Diploid and autotetraploid Tolmiea inhabit significantly different climatic niche spaces. The climatic niche divergence between these two species is best explained by a shift in precipitation availability, and we found evidence of differing physiological response to water availability between these species. CONCLUSIONS We found that spatial segregation of T. diplomenziesii and T. menziesii was accompanied by adaptation to changes in climatic regime. Tolmiea menziesii is not a nascent autotetraploid, having persisted long enough to be established throughout the Pacific Northwest, and therefore both polyploidization and subsequent evolution have contributed to the observed differences between T. menziesii and T. diplomenziesii.
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Affiliation(s)
- Clayton J Visger
- Department of Biology, University of Florida, Gainesville, Florida 32611 USA Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA
| | | | - Maya Patel
- Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA
| | - Emily B Sessa
- Department of Biology, University of Florida, Gainesville, Florida 32611 USA Genetics Institute, University of Florida, Gainesville, Florida 32608 USA
| | - Pamela S Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA Genetics Institute, University of Florida, Gainesville, Florida 32608 USA
| | - Douglas E Soltis
- Department of Biology, University of Florida, Gainesville, Florida 32611 USA Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA Genetics Institute, University of Florida, Gainesville, Florida 32608 USA
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Laport RG, Minckley RL, Ramsey J. Ecological distributions, phenological isolation, and genetic structure in sympatric and parapatric populations of the Larrea tridentata polyploid complex. AMERICAN JOURNAL OF BOTANY 2016; 103:1358-1374. [PMID: 27440793 DOI: 10.3732/ajb.1600105] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 05/20/2016] [Indexed: 06/06/2023]
Abstract
PREMISE OF THE STUDY Polyploidy is widely recognized as a mechanism of diversification. Contributions of polyploidy to specific pre- and postzygotic barriers-and classifications of polyploid speciation as "ecological" vs. "non-ecological"-are more contentious. Evaluation of these issues requires comprehensive studies that test ecological characteristics of cytotypes as well as the coincidence of genetic structure with cytotype distributions. METHODS We investigated a classical example of autopolyploid speciation, Larrea tridentata, at multiple areas of cytotype co-occurrence. Habitat and phenological differences were compared between diploid, tetraploid, and hexaploid populations on the basis of edaphic, community composition, and flowering time surveys. Frequency of hybridization between diploids and tetraploids was investigated using a diploid-specific chloroplast DNA (cpDNA) marker; genetic structure for all cytotypes was assessed using amplified fragment length polymorphisms (AFLPs). KEY RESULTS Across contact zones, we found cytotypes in habitats distinguished by soil and vegetation. We observed modest differences in timing and production of flowers, indicating a degree of assortative mating that was asymmetric between cytotypes. Nonetheless, cpDNA analyses in diploid-tetraploid contact zones suggested that ∼5% of tetraploid plants had hybrid origins involving unilateral sexual polyploidization. Genetic structure of AFLPs largely coincided with cytotype distributions in diploid-tetraploid contact zones. In contrast, there was little structure in areas of contact between tetraploids and hexaploids, suggesting intercytotype gene flow or recurrent hexaploid formation. CONCLUSIONS Diploid, tetraploid, and hexaploid cytotypes of L. tridentata are segregated by environmental distributions and flowering phenology in contact zones, with diploid and tetraploid populations having corresponding differences in genetic structure.
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Affiliation(s)
- Robert G Laport
- University of Nebraska-Lincoln, School of Biological Sciences, Lincoln, Nebraska 68588 USA
| | - Robert L Minckley
- University of Rochester, Department of Biology, River Campus, Rochester, New York 14627 USA
| | - Justin Ramsey
- Black Hills State University, School of Natural Sciences, Spearfish, South Dakota 57799 USA
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Soltis DE, Visger CJ, Marchant DB, Soltis PS. Polyploidy: Pitfalls and paths to a paradigm. AMERICAN JOURNAL OF BOTANY 2016; 103:1146-66. [PMID: 27234228 DOI: 10.3732/ajb.1500501] [Citation(s) in RCA: 164] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 02/25/2016] [Indexed: 05/22/2023]
Abstract
Investigators have long searched for a polyploidy paradigm-rules or principles that might be common following polyploidization (whole-genome duplication, WGD). Here we attempt to integrate what is known across the more thoroughly investigated polyploid systems on topics ranging from genetics to ecology. We found that while certain rules may govern gene retention and loss, systems vary in the prevalence of gene silencing vs. homeolog loss, chromosomal change, the presence of a dominant genome (in allopolyploids), and the relative importance of hybridization vs. genome doubling per se. In some lineages, aspects of polyploidization are repeated across multiple origins, but in other species multiple origins behave more stochastically in terms of genetic and phenotypic change. Our investigation also reveals that the path to synthesis is hindered by numerous gaps in our knowledge of even the best-known systems. Particularly concerning is the absence of linkage between genotype and phenotype. Moreover, most recent studies have focused on the genetic and genomic attributes of polyploidy, but rarely is there an ecological or physiological context. To promote a path to a polyploidy paradigm (or paradigms), we propose a major community goal over the next 10-20 yr to fill the gaps in our knowledge of well-studied polyploids. Before a meaningful synthesis is possible, more complete data sets are needed for comparison-systems that include comparable genetic, genomic, chromosomal, proteomic, as well as morphological, physiological, and ecological data. Also needed are more natural evolutionary model systems, as most of what we know about polyploidy continues to come from a few crop and genetic models, systems that often lack the ecological context inherent in natural systems and necessary for understanding the drivers of biodiversity.
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Affiliation(s)
- Douglas E Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA Department of Biology, University of Florida, Gainesville, Florida 32611 USA Genetics Institute, University of Florida, Gainesville, Florida 32608 USA
| | - Clayton J Visger
- Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA Department of Biology, University of Florida, Gainesville, Florida 32611 USA
| | - D Blaine Marchant
- Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA Department of Biology, University of Florida, Gainesville, Florida 32611 USA
| | - Pamela S Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611 USA Genetics Institute, University of Florida, Gainesville, Florida 32608 USA
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Fine PVA, Baraloto C. Habitat Endemism in White‐sand Forests: Insights into the Mechanisms of Lineage Diversification and Community Assembly of the Neotropical Flora. Biotropica 2016. [DOI: 10.1111/btp.12301] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Paul V. A. Fine
- Department of Integrative Biology and University and Jepson Herbaria University of California 3040 Valley Life Sciences Building #3140 Berkeley CA 94720 U.S.A
| | - Christopher Baraloto
- INRA UMR Ecologie des Forêts de Guyane 97310 Kourou French Guiana
- Department of Biological Sciences and International Center for Tropical Botany Florida International University Miami FL 33199 U.S.A
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20
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Naczk AM, Kolanowska M. Glacial Refugia and Future Habitat Coverage of Selected Dactylorhiza Representatives (Orchidaceae). PLoS One 2015; 10:e0143478. [PMID: 26599630 PMCID: PMC4657909 DOI: 10.1371/journal.pone.0143478] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Accepted: 11/05/2015] [Indexed: 12/01/2022] Open
Abstract
The intensively discussed taxonomic complexity of the Dactylorhiza genus is probably correlated with its migration history during glaciations and interglacial periods. Previous studies on past processes affecting the current distribution of Dactylorhiza species as well as the history of the polyploid complex formation were based only on molecular data. In the present study the ecological niche modeling (ENM) technique was applied in order to describe the distribution of potential refugia for the selected Dactylorhiza representatives during the Last Glacial Maximum. Additionally, future changes in their potential habitat coverage were measured with regard to three various climatic change scenarios. The maximum entropy method was used to create models of suitable niche distribution. A database of Dactylorhiza localities was prepared on the grounds of information collected from literature and data gathered during field works. Our research indicated that the habitats of majority of the studied taxa will decrease by 2080, except for D. incarnata var. incarnata, for which suitable habitats will increase almost two-fold in the global scale. Moreover, the potential habitats of some taxa are located outside their currently known geographical ranges, e.g. the Aleutian Islands, the western slopes of the Rocky Mountains, Newfoundland, southern Greenland and Iceland. ENM analysis did not confirm that the Balkans, central Europe or central Russia served as the most important refugia for individual representatives of the Dactylorhiza incarnata/maculata complex. Our study rather indicated that the Black Sea coast, southern Apennines and Corsica were the main areas characterized by habitats suitable for most of the taxa.
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Affiliation(s)
- Aleksandra M. Naczk
- Department of Molecular Evolution, University of Gdańsk, Wita Stwosza 59, PL 80–308, Gdańsk, Poland
| | - Marta Kolanowska
- Department of Plant Taxonomy and Nature Conservation, University of Gdańsk, Wita Stwosza 59, PL 80–308, Gdańsk, Poland
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21
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Machado S, Gottschalk MS, Robe LJ. Historical patterns of niche dynamics in Neotropical species of the Drosophila subgenus (Drosophilidae, Diptera). Evol Ecol 2015. [DOI: 10.1007/s10682-015-9805-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Roccaforte K, Russo SE, Pilson D. Hybridization and reproductive isolation between diploid Erythronium mesochoreum and its tetraploid congener E. albidum (Liliaceae). Evolution 2015; 69:1375-1389. [PMID: 25903102 DOI: 10.1111/evo.12666] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 04/13/2015] [Indexed: 11/28/2022]
Abstract
Polyploidy has played an important role in angiosperm diversification, but how polyploidy contributes to reproductive isolation remains poorly understood. Most work has focused on postzygotic reproductive barriers, and the influence of ploidy differences on prezygotic barriers is understudied. To address these gaps, we quantified hybrid occurrence, interspecific self-compatibility differences, and the contributions of multiple pre- and postzygotic barriers to reproductive isolation between diploid Erythronium mesochoreum (Liliaceae) and its tetraploid congener Erythronium albidum. Reproductive isolation between the study species was nearly complete, and naturally occurring hybrids were infrequent and largely sterile. Although postzygotic barriers effected substantial reproductive isolation when considered in isolation, the study species' spatial distributions and pollinator assemblages overlapped little, such that interspecific pollen transfer is likely uncommon. We did not find evidence that E. albidum and E. mesochoreum differed in mating systems, indicating that self-incompatibility release may not have fostered speciation in this system. Ultimately, we demonstrate that E. albidum and E. mesochoreum are reproductively isolated by multiple, hierarchically-operating barriers, and we add to the currently limited number of studies demonstrating that early acting barriers such as pollinator-mediated isolation can be important for effecting and sustaining reproductive isolation in diploid-polyploid systems.
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Affiliation(s)
- Kathy Roccaforte
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, 68588.,Current Address: Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, 66045
| | - Sabrina E Russo
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, 68588
| | - Diana Pilson
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, 68588
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Sobel JM, Streisfeld MA. Strong premating reproductive isolation drives incipient speciation in Mimulus aurantiacus. Evolution 2015; 69:447-61. [PMID: 25545789 DOI: 10.1111/evo.12589] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 11/20/2014] [Indexed: 01/15/2023]
Abstract
Determining which forms of reproductive isolation have the biggest impact on the process of divergence is a major goal of speciation research. These barriers are often divided into those that affect the potential for hybridization (premating isolation), and those that occur after mating (postmating isolation), and much debate has surrounded the relative importance of these categories. Within the species Mimulus aurantiacus, red- and yellow-flowered ecotypes occur in the southwest corner of California, and a hybrid zone occurs where their ranges overlap. We show that premating barriers are exclusively responsible for isolation in this system, with both ecogeographic and pollinator isolation contributing significantly to total isolation. Postmating forms of reproductive isolation have little or no impact on gene flow, indicating that hybrids likely contribute to introgression at neutral loci. Analysis of molecular variation across thousands of restriction-site associated DNA sequencing (RAD-seq) markers reveals that the genomes of these taxa are largely undifferentiated. However, structure analysis shows that these taxa are distinguishable genetically, likely due to the impact of loci underlying differentiated adaptive phenotypes. These data exhibit the power of divergent natural selection to maintain highly differentiated phenotypes in the face of gene flow during the early stages of speciation.
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Affiliation(s)
- James M Sobel
- Department of Biological Sciences, Binghamton University, State University of New York, Binghamton, New York, 13902
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Visser V, Molofsky J. Ecological niche differentiation of polyploidization is not supported by environmental differences among species in a cosmopolitan grass genus. AMERICAN JOURNAL OF BOTANY 2015; 102:36-49. [PMID: 25587146 DOI: 10.3732/ajb.1400432] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
UNLABELLED • PREMISE OF THE STUDY Polyploidization frequently results in the creation of new plant species, the establishment of which is thought to often be facilitated by ecological niche differentiation from the diploid species. We tested this hypothesis using the cosmopolitan grass genus Phalaris (Poaceae), consisting of 19 species that range from diploid to tetraploid to hexaploid. Specifically, we tested whether (1) polyploids occupy more extreme environments and/or (2) have broader niche breadths and/or (3) whether the polyploid species' distributions indicate a niche shift from diploid species.• METHODS We employed a bootstrapping approach using distribution data for each species and eight environmental variables to investigate differences between species in the means, extremes, and breadths of each environmental variable. We used a kernel smoothing technique to quantify niche overlap between species.• KEY RESULTS Although we found some support for the three hypotheses for a few diploid-polyploid pairs and for specific environmental variables, none of these hypotheses were generally supported.• CONCLUSIONS Our results suggest that these commonly held hypotheses about the effects of polyploidization on ecological distributions are not universally applicable. Correlative biogeographic studies like ours provide a necessary first step for suggesting specific hypotheses that require experimental verification. A combination of genetic, physiological, and ecological studies will be required to achieve a better understanding of the role of polyploidization in niche evolution.
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Affiliation(s)
- Vernon Visser
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa
| | - Jane Molofsky
- Department of Plant Biology, University of Vermont, Burlington, Vermont 05405 USA
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Ramsey J, Ramsey TS. Ecological studies of polyploidy in the 100 years following its discovery. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130352. [PMID: 24958925 PMCID: PMC4071525 DOI: 10.1098/rstb.2013.0352] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Polyploidy is a mutation with profound phenotypic consequences and thus hypothesized to have transformative effects in plant ecology. This is most often considered in the context of geographical and environmental distributions-as achieved from divergence of physiological and life-history traits-but may also include species interactions and biological invasion. This paper presents a historical overview of hypotheses and empirical data regarding the ecology of polyploids. Early researchers of polyploidy (1910 s-1930 s) were geneticists by training but nonetheless savvy to its phenotypic effects, and speculated on the importance of genome duplication to adaptation and crop improvement. Cytogenetic studies in the 1930 s-1950 s indicated that polyploids are larger (sturdier foliage, thicker stems and taller stature) than diploids while cytogeographic surveys suggested that polyploids and diploids have allopatric or parapatric distributions. Although autopolyploidy was initially regarded as common, influential writings by North American botanists in the 1940 s and 1950 s argued for the principle role of allopolyploidy; according to this view, genome duplication was significant for providing a broader canvas for hybridization rather than for its phenotypic effects per se. The emphasis on allopolyploidy had a chilling effect on nascent ecological work, in part due to taxonomic challenges posed by interspecific hybridization. Nonetheless, biosystematic efforts over the next few decades (1950s-1970s) laid the foundation for ecological research by documenting cytotype distributions and identifying phenotypic correlates of polyploidy. Rigorous investigation of polyploid ecology was achieved in the 1980s and 1990 s by population biologists who leveraged flow cytometry for comparative work in autopolyploid complexes. These efforts revealed multi-faceted ecological and phenotypic differences, some of which may be direct consequences of genome duplication. Several classical hypotheses about the ecology of polyploids remain untested, however, and allopolyploidy--regarded by most botanists as the primary mode of genome duplication--is largely unstudied in an ecological context.
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Affiliation(s)
- Justin Ramsey
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Tara S Ramsey
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
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Weiss-Schneeweiss H, Emadzade K, Jang TS, Schneeweiss G. Evolutionary consequences, constraints and potential of polyploidy in plants. Cytogenet Genome Res 2013; 140:137-50. [PMID: 23796571 PMCID: PMC3859924 DOI: 10.1159/000351727] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Polyploidy, the possession of more than 2 complete genomes, is a major force in plant evolution known to affect the genetic and genomic constitution and the phenotype of an organism, which will have consequences for its ecology and geography as well as for lineage diversification and speciation. In this review, we discuss phylogenetic patterns in the incidence of polyploidy including possible underlying causes, the role of polyploidy for diversification, the effects of polyploidy on geographical and ecological patterns, and putative underlying mechanisms as well as chromosome evolution and evolution of repetitive DNA following polyploidization. Spurred by technological advances, a lot has been learned about these aspects both in model and increasingly also in nonmodel species. Despite this enormous progress, long-standing questions about polyploidy still cannot be unambiguously answered, due to frequently idiosyncratic outcomes and insufficient integration of different organizational levels (from genes to ecology), but likely this will change in the near future. See also the sister article focusing on animals by Choleva and Janko in this themed issue.
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Affiliation(s)
- H. Weiss-Schneeweiss
- Department of Systematic and Evolutionary Botany University of Vienna, Rennweg 14 AT–1030 Vienna (Austria)
| | - K. Emadzade
- Department of Systematic and Evolutionary Botany University of Vienna, Rennweg 14 AT–1030 Vienna (Austria)
| | - T.-S. Jang
- Department of Systematic and Evolutionary Botany University of Vienna, Rennweg 14 AT–1030 Vienna (Austria)
| | - G.M. Schneeweiss
- Department of Systematic and Evolutionary Botany University of Vienna, Rennweg 14 AT–1030 Vienna (Austria)
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