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Kioukis A, Michalopoulou VA, Briers L, Pirintsos S, Studholme DJ, Pavlidis P, Sarris PF. Intraspecific diversification of the crop wild relative Brassica cretica Lam. using demographic model selection. BMC Genomics 2020; 21:48. [PMID: 31937246 PMCID: PMC6961386 DOI: 10.1186/s12864-019-6439-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 12/29/2019] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Crop wild relatives (CWRs) contain genetic diversity, representing an invaluable resource for crop improvement. Many of their traits have the potential to help crops to adapt to changing conditions that they experience due to climate change. An impressive global effort for the conservation of various CWR will facilitate their use in crop breeding for food security. The genus Brassica is listed in Annex I of the International Treaty on Plant Genetic Resources for Food and Agriculture. Brassica oleracea (or wild cabbage), a species native to southern and western Europe, has become established as an important human food crop plant because of its large reserves stored over the winter in its leaves. Brassica cretica Lam. (Bc) is a CWR in the brassica group and B. cretica subsp. nivea (Bcn) has been suggested as a separate subspecies. The species Bc has been proposed as a potential gene donor to brassica crops, including broccoli, cabbage, cauliflower, oilseed rape, etc. RESULTS: We sequenced genomes of four Bc individuals, including two Bcn and two Bc. Demographic analysis based on our whole-genome sequence data suggests that populations of Bc are not isolated. Classification of the Bc into distinct subspecies is not supported by the data. Using only the non-coding part of the data (thus, the parts of the genome that has evolved nearly neutrally), we find the gene flow between different Bc population is recent and its genomic diversity is high. CONCLUSIONS Despite predictions on the disruptive effect of gene flow in adaptation, when selection is not strong enough to prevent the loss of locally adapted alleles, studies show that gene flow can promote adaptation, that local adaptations can be maintained despite high gene flow, and that genetic architecture plays a fundamental role in the origin and maintenance of local adaptation with gene flow. Thus, in the genomic era it is important to link the selected demographic models with the underlying processes of genomic variation because, if this variation is largely selectively neutral, we cannot assume that a diverse population of crop wild relatives will necessarily exhibit the wide-ranging adaptive diversity required for further crop improvement.
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Affiliation(s)
- Antonios Kioukis
- Institute of Computer Science, Foundation for Research and Technology-Hellas, Heraklion, 70013, Crete, Greece
| | - Vassiliki A Michalopoulou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013, Crete, Greece
| | - Laura Briers
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Stergios Pirintsos
- Department of Biology, University of Crete, 714 09, Heraklion, Greece
- Botanical Garden, University of Crete, Gallos Campus, 741 00, Rethymnon, Greece
| | - David J Studholme
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
| | - Pavlos Pavlidis
- Institute of Computer Science, Foundation for Research and Technology-Hellas, Heraklion, 70013, Crete, Greece
| | - Panagiotis F Sarris
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013, Crete, Greece.
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
- Department of Biology, University of Crete, 714 09, Heraklion, Greece.
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102
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Royer AM, Waite-Himmelwright J, Smith CI. Strong Selection Against Early Generation Hybrids in Joshua Tree Hybrid Zone Not Explained by Pollinators Alone. FRONTIERS IN PLANT SCIENCE 2020; 11:640. [PMID: 32528500 PMCID: PMC7264850 DOI: 10.3389/fpls.2020.00640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 04/24/2020] [Indexed: 05/07/2023]
Abstract
Coevolution frequently plays an important role in diversification, but the role of obligate pollination mutualisms in the maintenance of hybrid zones has rarely been investigated. Like most members of the genus Yucca, the two species of Joshua tree (Yucca brevifolia and Yucca jaegeriana) are involved in a tightly coevolved mutualism with yucca moths. There is strong evidence of a history of coevolution between Joshua trees and their moth pollinators. We use a geographic clines approach in the Joshua tree hybrid zone to ask if selection by the moths may currently contribute to maintaining separation between these species. We compare genomic, phenotypic, and pollinator frequency clines to test whether pollinators maintain the hybrid zone or follow it as passive participants. The results reveal dramatic overlapping genomic and pollinator clines, consistent with a narrow hybrid zone maintained by strong selection. Wider phenotypic clines and a chloroplast genomic cline displaced opposite the expected direction suggest that pollinators are not the main source of selection maintaining the hybrid zone. Rather, it seems that high levels of reproductive isolation, likely acting through multiple barriers and involving many parts of the genome, keep the hybrid zone narrow.
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Affiliation(s)
- Anne M. Royer
- Biology Department, The University of Scranton, Scranton, PA, United States
- *Correspondence: Anne M. Royer,
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103
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Zhong S, Liu M, Wang Z, Huang Q, Hou S, Xu YC, Ge Z, Song Z, Huang J, Qiu X, Shi Y, Xiao J, Liu P, Guo YL, Dong J, Dresselhaus T, Gu H, Qu LJ. Cysteine-rich peptides promote interspecific genetic isolation in Arabidopsis. Science 2019; 364:364/6443/eaau9564. [PMID: 31147494 DOI: 10.1126/science.aau9564] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 01/14/2019] [Accepted: 04/25/2019] [Indexed: 12/21/2022]
Abstract
Reproductive isolation is a prerequisite for speciation. Failure of communication between female tissues of the pistil and paternal pollen tubes imposes hybridization barriers in flowering plants. Arabidopsis thaliana LURE1 (AtLURE1) peptides and their male receptor PRK6 aid attraction of the growing pollen tube to the ovule. Here, we report that the knockout of the entire AtLURE1 gene family did not affect fertility, indicating that AtLURE1-PRK6-mediated signaling is not required for successful fertilization within one Arabidopsis species. AtLURE1s instead function as pollen tube emergence accelerators that favor conspecific pollen over pollen from other species and thus promote reproductive isolation. We also identified maternal peptides XIUQIU1 to -4, which attract pollen tubes regardless of species. Cooperation between ovule attraction and pollen tube growth acceleration favors conspecific fertilization and promotes reproductive isolation.
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Affiliation(s)
- Sheng Zhong
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China.,The National Plant Gene Research Center (Beijing), Beijing 100101, People's Republic of China
| | - Meiling Liu
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Zhijuan Wang
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Qingpei Huang
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Saiying Hou
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Yong-Chao Xu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Zengxiang Ge
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Zihan Song
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Jiaying Huang
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Xinyu Qiu
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Yihao Shi
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Junyu Xiao
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Pei Liu
- Department of Ecology, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, People's Republic of China
| | - Ya-Long Guo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Juan Dong
- The Waksman Institute of Microbiology, Rutgers, the State University of New Jersey, Piscataway, NJ 08854, USA
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, Regensburg Center for Biochemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Hongya Gu
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China.,The National Plant Gene Research Center (Beijing), Beijing 100101, People's Republic of China
| | - Li-Jia Qu
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences at the College of Life Sciences, Peking University, Beijing 100871, People's Republic of China. .,The National Plant Gene Research Center (Beijing), Beijing 100101, People's Republic of China
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104
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Babiychuk E, Teixeira JG, Tyski L, Guimaraes JTF, Romeiro LA, da Silva EF, Dos Santos JF, Vasconcelos S, da Silva DF, Castilho A, Siqueira JO, Fonseca VLI, Kushnir S. Geography is essential for reproductive isolation between florally diversified morning glory species from Amazon canga savannahs. Sci Rep 2019; 9:18052. [PMID: 31792228 PMCID: PMC6889514 DOI: 10.1038/s41598-019-53853-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 11/06/2019] [Indexed: 11/29/2022] Open
Abstract
The variety, relative importance and eco-evolutionary stability of reproductive barriers are critical to understanding the processes of speciation and species persistence. Here we evaluated the strength of the biotic prezygotic and postzygotic isolation barriers between closely related morning glory species from Amazon canga savannahs. The flower geometry and flower visitor assemblage analyses supported pollination by the bees in lavender-flowered Ipomoea marabaensis and recruitment of hummingbirds as pollinators in red-flowered Ipomoea cavalcantei. Nevertheless, native bee species and alien honeybees foraged on flowers of both species. Real-time interspecific hybridization underscored functionality of the overlap in flower visitor assemblages, questioning the strength of prezygotic isolation underpinned by diversification in flower colour and geometry. Interspecific hybrids were fertile and produced offspring in nature. No significant asymmetry in interspecific hybridization and hybrid incompatibilities among offspring were found, indicating weak postmating and postzygotic isolation. The results suggested that despite floral diversification, the insular-type geographic isolation remains a major barrier to gene flow. Findings set a framework for the future analysis of contemporary evolution of plant-pollinator networks at the population, community, and ecosystem levels in tropical ecosystems that are known to be distinct from the more familiar temperate climate models.
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Affiliation(s)
- Elena Babiychuk
- Instituto Tecnológico Vale, Rua Boaventura da Silva 955, CEP 66055-090, Belém, Pará, Brazil.
| | | | - Lourival Tyski
- Parque Zoobotânico Vale, VALE S.A., Rod. Raimundo Mascarenhas, Km 26, S/N., Núcleo Urbano de Carajás, CEP 68516-000, Parauapebas, Pará, Brazil
| | | | - Luiza Araújo Romeiro
- Instituto Tecnológico Vale, Rua Boaventura da Silva 955, CEP 66055-090, Belém, Pará, Brazil
| | | | | | - Santelmo Vasconcelos
- Instituto Tecnológico Vale, Rua Boaventura da Silva 955, CEP 66055-090, Belém, Pará, Brazil
| | - Delmo Fonseca da Silva
- Parque Zoobotânico Vale, VALE S.A., Rod. Raimundo Mascarenhas, Km 26, S/N., Núcleo Urbano de Carajás, CEP 68516-000, Parauapebas, Pará, Brazil
| | - Alexandre Castilho
- Gerência de Meio Ambiente, Departamento de Ferrosos Corredor Norte, Vale S.A., Rua Guamá n 60, Núcleo Urbano, CEP 68516-000, Parauapebas, Pará, Brazil
| | - José Oswaldo Siqueira
- Instituto Tecnológico Vale, Rua Boaventura da Silva 955, CEP 66055-090, Belém, Pará, Brazil
| | | | - Sergei Kushnir
- Unaffiliated, Belém, Pará, Brazil.,Teagasc, Crop Science Department, Oak Park, Carlow, R93 XE12, Ireland
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105
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Benoit LK, Les DH, King UM, Na HR, Chen L, Tippery NP. Extensive interlineage hybridization in the predominantly clonal Hydrilla verticillata. AMERICAN JOURNAL OF BOTANY 2019; 106:1622-1637. [PMID: 31758546 DOI: 10.1002/ajb2.1392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/01/2019] [Indexed: 06/10/2023]
Abstract
PREMISE The submersed aquatic plant Hydrilla verticillata ("hydrilla") is important ecologically and economically due to its aggressive growth in both indigenous and nonindigenous regions. Substantial morphological variation has been documented in hydrilla, including the existence of monoecious and dioecious "biotypes." Whereas plastid sequence data have been used previously to explore intraspecific diversity, nuclear data have yet to be analyzed in a phylogenetic context. Molecular and morphological analyses were used to evaluate the genetic diversity and phylogenetic relationships of native and introduced populations. METHODS Nuclear (internal transcribed spacer-ITS; phytoene desaturase-PDS) and plastid (trnL-F) sequence data were evaluated phylogenetically using likelihood and Bayesian methods. Leaf morphologies were compared among clades that were identified in phylogenetic analyses. RESULTS Data from both ITS and PDS show multiple instances of polymorphic sequences that could be traced to two or more lineages, including both invasive biotypes in the Americas. Leaf morphological data support the distinctness of lineages and provide a metric for distinguishing monoecious and dioecious biotypes in the United States. CONCLUSIONS Nuclear molecular data indicate far greater genetic diversity than could be estimated using plastid markers. Substantially divergent copies of nuclear genes, found in multiple populations worldwide, likely result from interlineage hybridization. Invasive monoecious and dioecious hydrilla biotypes in the Americas are genetically distinct, with both biotypes resulting from admixture among Eurasian progenitors. Genetic similarity to populations in India and South Korea, respectively, implicates these as likely origins for the dioecious and monoecious biotypes.
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Affiliation(s)
- Lori K Benoit
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269-3043, USA
| | - Donald H Les
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269-3043, USA
| | - Ursula M King
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269-3043, USA
| | - Hye Ryun Na
- Northeastern Asia Biodiversity Institute, Seoul, 05677, Republic of Korea
| | - Lei Chen
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Nicholas P Tippery
- Department of Biological Sciences, University of Wisconsin-Whitewater, Whitewater, Wisconsin, 53190, USA
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106
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Kariyawasam T, Joo S, Lee J, Toor D, Gao AF, Noh KC, Lee JH. TALE homeobox heterodimer GSM1/GSP1 is a molecular switch that prevents unwarranted genetic recombination in Chlamydomonas. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 100:938-953. [PMID: 31368133 DOI: 10.1111/tpj.14486] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 07/23/2019] [Accepted: 07/24/2019] [Indexed: 06/10/2023]
Abstract
Eukaryotic sexual life cycles alternate between haploid and diploid stages, the transitions between which are delineated by cell fusion and meiotic division. Transcription factors in the TALE-class homeobox family, GSM1 and GSP1, predominantly control gene expression for the haploid-to-diploid transition during sexual reproduction in the unicellular green alga, Chlamydomonas reinhardtii. To understand the roles that GSM1 and GSP1 play in zygote development, we used gsm1 and gsp1 mutants and examined fused gametes that normally undergo the multiple organellar fusions required for the genetic unity of the zygotes. In gsm1 and gsp1 zygotes, no fusion was observed for the nucleus and chloroplast. Surprisingly, mitochondria and endoplasmic reticulum, which undergo dynamic autologous fusion/fission, did not undergo heterologous fusions in gsm1 or gsp1 zygotes. Furthermore, the mutants failed to resorb their flagella, an event that normally renders the zygotes immotile. When gsm1 and gsp1 zygotes resumed the mitotic cycle, their two nuclei fused prior to mitosis, but neither chloroplastic nor mitochondrial fusion took place, suggesting that these fusions are specifically turned on by GSM1/GSP1. Taken together, this study shows that organellar restructuring during zygotic diploidization does not occur by default but is triggered by a combinatorial switch, the GSM1/GSP1 dyad. This switch may represent an ancient mechanism that evolved to restrict genetic recombination during sexual development.
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Affiliation(s)
| | - Sunjoo Joo
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Jenny Lee
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Deepak Toor
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Ally F Gao
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Kyung-Chul Noh
- Department of Biology, Washington University, St. Louis, MO, USA
| | - Jae-Hyeok Lee
- Department of Botany, University of British Columbia, Vancouver, Canada
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107
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Karbstein K, Tomasello S, Prinz K. Desert-like badlands and surrounding (semi-)dry grasslands of Central Germany promote small-scale phenotypic and genetic differentiation in Thymus praecox. Ecol Evol 2019; 9:14066-14084. [PMID: 31938504 PMCID: PMC6953696 DOI: 10.1002/ece3.5844] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/23/2019] [Accepted: 10/24/2019] [Indexed: 11/08/2022] Open
Abstract
Environmental heterogeneity among sites can generate phenotypic and genetic variation facilitating differentiation and microevolution of plant populations. Badlands are desert-like, predominantly vegetation-poor habitats often embedded in (semi-)dry grasslands. The desert-like conditions of badlands demand extreme adaptation of plants, that is, phenotypic modifications in short-term and/or natural adaptation in long-term. However, detailed knowledge is missing about both plant phenotypic and genetic differentiation in this unique and widely occurring habitat type. The present study focused on the largest known badlands systems in Central Europe located in the "Drei Gleichen" region, a designated nature conservation area in Central Germany. Locations were suitable for this study in terms of having co-occurring badlands and (semi-)dry grassland habitats (sites) occupied by the pioneer plant Thymus praecox. Here, we studied the environmental preferences, morphological and functional trait variation, and genetic variation using microsatellite markers of T. praecox. Results revealed significant, mainly site-dependent environmental, phenotypic, and genetic differentiation. In general, individuals in badlands are shorter in height and have lower patch sizes (length × width), relative growth rates, and smaller stomata. The PCA additionally unveiled slightly increased leaf robustness, trichome density, decreased stomatal conductance, fewer females, and earlier phenology in badlands. We interpret differentiation patterns as adaptive responses to light, temperature, drought, and nutrient stress conditions supported by reviewed literature. Genetic differentiation was strongest between local badlands and grassland sites, and clearly weaker among locations and between sites (in total) as indicated by G ST, AMOVA, PCoA, and population structure. Our study supports the importance of small-scale microhabitat conditions as a driver of microevolutionary processes, and the population's need for sufficient phenotypic variation and genetic resources to deal with environmental changes. We demonstrated that badlands are an appropriate model system for testing plant response to extreme habitats and that more research is needed on these fascinating landscapes.
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Affiliation(s)
- Kevin Karbstein
- Institute of Ecology and Evolution of PlantsSystematic Botany with Herbarium Haussknecht and Botanical GardenFriedrich‐Schiller‐University JenaJenaGermany
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium)Albrecht‐von‐Haller Institute for Plant SciencesUniversity of GoettingenGoettingenGermany
| | - Salvatore Tomasello
- Department of Systematics, Biodiversity and Evolution of Plants (with Herbarium)Albrecht‐von‐Haller Institute for Plant SciencesUniversity of GoettingenGoettingenGermany
| | - Kathleen Prinz
- Institute of Ecology and Evolution of PlantsSystematic Botany with Herbarium Haussknecht and Botanical GardenFriedrich‐Schiller‐University JenaJenaGermany
- Landschaftspflegeverband Suedharz/Kyffhaeuser e.V.NordhausenGermany
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108
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Matsumoto TK, Miyazaki Y, Sueyoshi M, Senda Y, Yamada K, Hirobe M. Pre-pollination barriers between two sympatric Arisaema species in northern Shikoku Island, Japan. AMERICAN JOURNAL OF BOTANY 2019; 106:1612-1621. [PMID: 31729010 DOI: 10.1002/ajb2.1389] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 10/01/2019] [Indexed: 06/10/2023]
Abstract
PREMISE The genus Arisaema (Araceae) has rapidly diversified in Japan, and multiple species often coexist in the field. Although Japanese Arisaema species hybridize from artificial crossing, hybrid individuals are rare in mixed populations; suggesting the presence of effective pre-pollination barriers. We examined the following reproductive barriers between A. sikokianum and A. tosaense: habitat, phenology, and pollinator isolations. METHODS Habitat isolation was examined by interspecific comparisons of microhabitat conditions at a mixed site and of altitude at the sampling site of herbarium specimens. Phenological isolation was evaluated by comparing seasonal transition in apparent spathe condition and frequency of insect visitation. Pollinator isolation was examined by comparing floral visitor assemblages between the two Arisaema species. To avoid overestimation of pollinator isolation due to seasonal changes in insect assemblages, we also compared visitor assemblages between natural and late-flowering A. sikokianum, where the latter was experimentally introduced and blooming with a natural A. tosaense population. RESULTS Microhabitat conditions and sampling elevations of herbarium specimens overlapped between the two Arisaema species. At the population level, A. sikokianum and A. tosaense flowered for 39 and 52 days, respectively, with 13 days overlap. Insect visitation in A. sikokianum decreased before the seasonal overlap. Floral visitor assemblages differed between the two Arisaema species, while the difference between natural and late-flowering A. sikokianum was less distinct. CONCLUSIONS Phenological and pollinator isolation contribute to reproductive isolation between the two Arisaema species and should enable the two species to coexist in this area.
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Affiliation(s)
- Tetsuya K Matsumoto
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-Naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Yuko Miyazaki
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-Naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Masahiro Sueyoshi
- Center for Biodiversity, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, 305-8687, Japan
| | - Yoshihiro Senda
- Hiwa Museum for Natural History, Hiwa 1119-1, Hiwa, Shôbara, 727-0301, Japan
| | - Kazuhiro Yamada
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-Naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
| | - Muneto Hirobe
- Graduate School of Environmental and Life Science, Okayama University, Tsushima-Naka 1-1-1, Kita-ku, Okayama, 700-8530, Japan
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109
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Lucek K, Hohmann N, Willi Y. Postglacial ecotype formation under outcrossing and self-fertilization in Arabidopsis lyrata. Mol Ecol 2019; 28:1043-1055. [PMID: 30719799 DOI: 10.1111/mec.15035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 01/18/2019] [Accepted: 01/28/2019] [Indexed: 12/01/2022]
Abstract
The formation of ecotypes has been invoked as an important driver of postglacial biodiversity, because many species colonized heterogeneous habitats and experienced divergent selection. Ecotype formation has been predominantly studied in outcrossing taxa, while far less attention has been paid to the implications of mating system shifts. Here, we addressed whether substrate-related ecotypes exist in selfing and outcrossing populations of Arabidopsis lyrata subsp. lyrata and whether the genomic footprint differs between mating systems. The North American subspecies colonized both rocky and sandy habitats during postglacial range expansion and shifted the mating system from predominantly outcrossing to predominantly selfing in a number of regions. We performed an association study on pooled whole-genome sequence data of 20 selfing or outcrossing populations, which suggested genes involved in adaptation to substrate. Motivated by enriched gene ontology terms, we compared root growth between plants from the two substrates in a common environment and found that plants originating from sand grew roots faster and produced more side roots, independent of mating system. Furthermore, single nucleotide polymorphisms associated with substrate-related ecotypes were more clustered among selfing populations. Our study provides evidence for substrate-related ecotypes in A. lyrata and divergence in the genomic footprint between mating systems. The latter is the likely result of selfing populations having experienced divergent selection on larger genomic regions due to higher genome-wide linkage disequilibrium.
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Affiliation(s)
- Kay Lucek
- Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Nora Hohmann
- Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Yvonne Willi
- Department of Environmental Sciences, University of Basel, Basel, Switzerland
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110
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Moreira-Hernández JI, Muchhala N. Importance of Pollinator-Mediated Interspecific Pollen Transfer for Angiosperm Evolution. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2019. [DOI: 10.1146/annurev-ecolsys-110218-024804] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Understanding how pollen moves between species is critical to understanding speciation, diversification, and evolution of flowering plants. For co-flowering species that share pollinators, competition through interspecific pollen transfer (IPT) can profoundly impact floral evolution, decreasing female fitness via heterospecific pollen deposition on stigmas and male fitness via pollen misplacement during visits to heterospecific flowers. The pollination literature demonstrates that such reproductive interference frequently selects for reproductive character displacement in floral traits linked to pollinator attraction, pollen placement, and mating systems and has also revealed that IPT between given pairs of species is typically asymmetric. More recent work is starting to elucidate its importance to the speciation process, clarifying the link between IPT and current and historical patterns of hybridization, the evolution of phenotypic novelty through adaptive introgression, and the rise of reproductive isolation. Our review aims to stimulate further research on IPT as a ubiquitous mechanism that plays a central role in angiosperm diversification.
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Affiliation(s)
- Juan Isaac Moreira-Hernández
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri–St. Louis, St. Louis, Missouri 63121, USA;,
| | - Nathan Muchhala
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri–St. Louis, St. Louis, Missouri 63121, USA;,
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Hornych O, Ekrt L, Riedel F, Koutecký P, Košnar J. Asymmetric hybridization in Central European populations of the Dryopteris carthusiana group. AMERICAN JOURNAL OF BOTANY 2019; 106:1477-1486. [PMID: 31634425 DOI: 10.1002/ajb2.1369] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 08/30/2019] [Indexed: 06/10/2023]
Abstract
PREMISE Hybridization is a key process in plant speciation. Despite its importance, there is no detailed study of hybridization rates in fern populations. A proper estimate of hybridization rates is needed to understand factors regulating hybridization. METHODS We studied hybridization in the European Dryopteris carthusiana group, represented by one diploid and two tetraploid species and their hybrids. We sampled ~100 individuals per population in 40 mixed populations of the D. carthusiana group across Europe. All plants were identified by measuring genome size (DAPI staining) using flow cytometry. To determine the maternal parentage of hybrids, we sequenced the chloroplast region trnL-trnF of all taxa involved. RESULTS We found hybrids in 85% of populations. Triploid D. ×ambroseae occurred in every population that included both parent species and is most abundant when the parent species are equally abundant. By contrast, tetraploid D. ×deweveri was rare (15 individuals total) and triploid D. ×sarvelae was absent. The parentage of hybrid taxa is asymmetric. Despite expectations from previous studies, tetraploid D. dilatata is the predominant male parent of its triploid hybrid. CONCLUSIONS This is a thorough investigation of hybridization rates in natural populations of ferns. Hybridization rates differ greatly even among closely related fern taxa. In contrast to angiosperms, our data suggest that hybridization rates are highest in balanced parent populations and support the notion that some ferns possess very weak barriers to hybridization. Our results from sequencing cpDNA challenge established notions about the correlation of ploidy level and mating tendencies.
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Affiliation(s)
- Ondřej Hornych
- Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, CZ-37005, Czech Republic
| | - Libor Ekrt
- Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, CZ-37005, Czech Republic
| | - Felix Riedel
- Botanischer Garten der Universität Potsdam, Maulbeerallee 3, Potsdam, D-14469, Germany
- Arboretum der Humboldt-Universität zu Berlin, Späthstrasse 80/81, Berlin, D-12437, Germany
| | - Petr Koutecký
- Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, CZ-37005, Czech Republic
| | - Jiří Košnar
- Faculty of Science, University of South Bohemia, Branišovská 1760, České Budějovice, CZ-37005, Czech Republic
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112
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Baena-Díaz F, Zemp N, Widmer A. Insights into the genetic architecture of sexual dimorphism from an interspecific cross between two diverging Silene (Caryophyllaceae) species. Mol Ecol 2019; 28:5052-5067. [PMID: 31605646 DOI: 10.1111/mec.15271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 08/15/2019] [Accepted: 09/23/2019] [Indexed: 12/15/2022]
Abstract
The evolution of sexual dimorphism in species with separate sexes is influenced by the resolution of sexual conflicts creating sex differences through genetic linkage or sex-biased expression. Plants with different degrees of sexual dimorphism are thus ideal to study the genetic basis of sexual dimorphism. In this study we explore the genetic architecture of sexual dimorphism between Silene latifolia and Silene dioica. These species have chromosomal sex determination and differ in the extent of sexual dimorphism. To test whether QTL for sexually dimorphic traits have accumulated on the sex chromosomes and to quantify their contribution to species differences, we create a linkage map and performed QTL analysis of life history, flower and vegetative traits using an unidirectional interspecific F2 hybrid cross. We found support for an accumulation of QTL on the sex chromosomes and that sex differences explained a large proportion of the variance between species, suggesting that both natural and sexual selection contributed to species divergence. Sexually dimorphic traits that also differed between species displayed transgressive segregation. We observed a reversal in sexual dimorphism in the F2 population, where males tended to be larger than females, indicating that sexual dimorphism is constrained within populations but not in recombinant hybrids. This study contributes to the understanding of the genetic basis of sexual dimorphism and its evolution in Silene.
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Affiliation(s)
| | | | - Alex Widmer
- Institute of Integrative Biology, ETH Zurich, Zürich, Switzerland
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113
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Paudel BR, Burd M, Shrestha M, Dyer AG, Li QJ. Reproductive isolation in alpine gingers: How do coexisting Roscoea (R. purpurea and R. tumjensis) conserve species integrity? Evolution 2019; 72:1840-1850. [PMID: 29992542 DOI: 10.1111/evo.13546] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 06/07/2018] [Indexed: 02/06/2023]
Abstract
Multiple barriers may contribute to reproductive isolation between closely related species. Understanding the relative strength of these barriers can illuminate the ecological factors that currently maintain species integrity and how these factors originally promoted speciation. Two Himalayan alpine gingers, Roscoea purpurea and R. tumjensis, occur sympatrically in central Nepal and have such similar morphology that it is not clear whether or how they maintain a distinct identity. Our quantitative measurements of the components of reproductive isolation show that they are, in fact, completely isolated by a combination of phenological displacement of flowering, earlier for R. tumjensis and later for R. purpurea, and complete fidelity of visitation by different pollinator species, bumblebees for R. tumjensis and a long-tongued fly for R. purpurea. Furthermore, the nectar of R. tumjensis flowers is available to the shorter tongued bumblebees while R. purpurea nectar is less accessible, requiring deep probing from long-tongued flies. Although flowering phenology is a strong current barrier that seemingly obviates any need for pollinator discrimination, this current pattern need not reflect selective forces occurring at the initial divergence of R. tumjensis. There has been considerable pollinator switching during the radiation of the Himalayan Roscoea, and the association of flowering time with type of pollinator in these sympatric species may have originated among the earliest or latest flowering individuals or populations of an ancestor to exploit either bumblebee activity early in the breeding season or long-tongued fly abundance later in the season. These two sympatric Roscoea species add to accumulating evidence of the primacy of prezygotic pollination traits in speciation among angiosperms even in the absence of postzygotic incompatibility.
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Affiliation(s)
- Babu Ram Paudel
- Current Address: Laboratory of Ecology and Evolutionary Biology, Yunnan University, Kunming, 650091, Yunnan, China.,Department of Botany, Prithvi Narayan Campus, Tribhuvan University, Pokhara, Nepal
| | - Martin Burd
- School of Biological Sciences, Monash University, Melbourne, VIC, 3800, Australia
| | - Mani Shrestha
- Faculty of information Technology, Monash University, Melbourne, VIC, 3800, Australia.,School of Media and Communications, RMIT University, Melbourne, VIC, 3001, Australia
| | - Adrian G Dyer
- School of Media and Communications, RMIT University, Melbourne, VIC, 3001, Australia.,Department of Physiology, Monash University, Melbourne, 3800, Australia
| | - Qing-Jun Li
- Current Address: Laboratory of Ecology and Evolutionary Biology, Yunnan University, Kunming, 650091, Yunnan, China
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Kumar A, Singh VJ, Krishnan SG, Vinod KK, Bhowmick PK, Nagarajan M, Ellur RK, Bollinedi H, Singh AK. WA-CMS-based iso-cytoplasmic restorers derived from commercial rice hybrids reveal distinct population structure and genetic divergence towards restorer diversification. 3 Biotech 2019; 9:299. [PMID: 31355108 DOI: 10.1007/s13205-019-1824-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 07/01/2019] [Indexed: 12/27/2022] Open
Abstract
One hundred diverse iso-cytoplasmic restorer (ICR) lines carrying WA cytoplasm indicated significant but moderate variability for agro-morphological traits as well as for the microsatellite-based allele patterns. There were two major groups of ICRs based on agro-morphological clustering. Simple sequence repeat (SSR) markers identified allelic variants with an average of 2.48 alleles per locus and the gene diversity (GD) ranged from 0.02 to 0.62 at different loci. ICR lines showed a genetic structure involving two sub-populations, POP1 and POP2. Both the subpopulations had the presence of admixture lines. Nearest ancestry-based grouping of ICRs by neighbour-joining (NJ) method showed near similar grouping as that of sub-population division. The POP2 was the largest group but with fewer admixed lines. POP1 was more distinct than POP2. Since the hybrid parents of the ICRs had limited diversity on maternal lineage, paternal lineage was concluded as the major contributor to the observed divergence and population differentiation. ICRs developed from certain hybrids were more genetically distinct than other hybrids. Even with the moderate variability, ICRs could be considered as a potential source of fertility restoration in hybrid development because of their distinct population structure and the full complement of restorer genes they contained. ICR lines with high per se performance can be utilized in hybrid rice development by estimating their combining ability.
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Affiliation(s)
- Amit Kumar
- 1Division of Genetics, ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, 110012 India
- Plant Breeding, ICAR-Research Complex for North Eastern Hill Region, Umiam, 793103 India
| | - Vikram Jeet Singh
- 1Division of Genetics, ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, 110012 India
| | - S Gopala Krishnan
- 1Division of Genetics, ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, 110012 India
| | - K K Vinod
- Rice Breeding and Genetics Research Centre, ICAR-IARI, Aduthurai, 612101 India
| | - Prolay Kumar Bhowmick
- 1Division of Genetics, ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, 110012 India
| | - M Nagarajan
- Rice Breeding and Genetics Research Centre, ICAR-IARI, Aduthurai, 612101 India
| | - Ranjith Kumar Ellur
- 1Division of Genetics, ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, 110012 India
| | - Haritha Bollinedi
- 1Division of Genetics, ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, 110012 India
| | - Ashok Kumar Singh
- 1Division of Genetics, ICAR-Indian Agricultural Research Institute (ICAR-IARI), New Delhi, 110012 India
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Callaway TD, Singh-Cundy A. HD-AGPs as Speciation Genes: Positive Selection on a Proline-Rich Domain in Non-Hybridizing Species of Petunia, Solanum, and Nicotiana. PLANTS (BASEL, SWITZERLAND) 2019; 8:E211. [PMID: 31288469 PMCID: PMC6681252 DOI: 10.3390/plants8070211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/18/2019] [Accepted: 07/04/2019] [Indexed: 11/16/2022]
Abstract
Transmitting tissue-specific proteins (TTS proteins) are abundant in the extracellular matrix of Nicotiana pistils, and vital for optimal pollen tube growth and seed set. We have identified orthologs from several species in the Solanaceae, including Petunia axillaris axillaris and Petunia integrifolia. We refer to TTS proteins and their orthologs as histidine domain-arabinogalactan proteins (HD-AGPs). HD-AGPs have distinctive domains, including a small histidine-rich region and a C-terminal PAC domain. Pairwise comparisons between HD-AGPs of 15 species belonging to Petunia, Nicotiana, and Solanum show that the his-domain and PAC domain are under purifying selection. In contrast, a proline-rich domain (HV2) is conserved among cross-hybridizing species, but variant in species-pairs that are reproductively isolated by post-pollination pre-fertilization reproductive barriers. In particular, variation in a tetrapeptide motif (XKPP) is systematically correlated with the presence of an interspecific reproductive barrier. Ka/Ks ratios are not informative at the infrageneric level, but the ratios reveal a clear signature of positive selection on two hypervariable domains (HV1 and HV2) when HD-AGPs from five solanaceous genera are compared. We propose that sequence divergence in the hypervariable domains of HD-AGPs reinforces sympatric speciation in incipient species that may have first diverged as a consequence of pollinator preferences or other ecological factors.
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Affiliation(s)
- Tara D Callaway
- Biology Department, Western Washington University, Bellingham, WA 98225, USA
| | - Anu Singh-Cundy
- Biology Department, Western Washington University, Bellingham, WA 98225, USA.
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116
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Ramírez-Aguirre E, Martén-Rodríguez S, Quesada-Avila G, Quesada M, Martínez-Díaz Y, Oyama K, Espinosa-García FJ. Reproductive isolation among three sympatric Achimenes species: pre- and post-pollination components. AMERICAN JOURNAL OF BOTANY 2019; 106:1021-1031. [PMID: 31299090 DOI: 10.1002/ajb2.1324] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 05/06/2019] [Indexed: 06/10/2023]
Abstract
PREMISE Closely related species occurring in sympatry may experience the negative consequences of interspecific pollen transfer if reproductive isolation (RI) barriers are not in place. We evaluated the importance of pre- and post-pollination RI barriers in three sympatric species of Achimenes (Gesneriaceae), including ecogeographic, phenological, floral isolation, self-pollination, and hybrid viability (fruit and seed set). METHODS We recorded geographic distribution throughout species ranges and assessed flowering phenology and pollinator visitation at one site in central Mexico. In the greenhouse, we measured floral traits involved in RI and quantified fruit and seed set for from self, intraspecific, and interspecific crosses. RESULTS Ecogeographic barriers were important in RI, but under sympatry, phenological and floral barriers contributed more to total RI. Phenological RI varied between species and years, while floral RI was 100% effective at preventing interspecific visitation. Species showed differences in floral morphology, color, and scents associated with specialized pollination systems (A. antirrhina-hummingbirds, A. flava-bees, A. patens-butterflies); heterospecific visitation events were restricted to rare secondary pollinators. Hybrid crosses consistently yielded progeny in lower numbers than intraspecific crosses. CONCLUSIONS This study indicated that neither autogamy nor early post-pollination barriers prevent interspecific pollen flow between Achimenes species. However, floral isolation, acting through a combination of attraction and reward traits, consistently ensures specificity of the pollination system. These results suggest that selection on floral traits to reduce the costs of hybrid progeny production may have played a role in evolution or maintenance of specialized pollination systems in Achimenes.
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Affiliation(s)
- Erandi Ramírez-Aguirre
- Laboratorio Nacional de Análisis y Síntesis Ecológica (LANASE), Escuela Nacional de Estudios Superiores (ENES), Unidad Morelia, Universidad Nacional Autónoma de México, Morelia, Michoacán, C.P. 58190, México
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México. Unidad de Posgrado, Coordinación del Posgrado en Ciencias Biológicas. Edificio D, 1º Piso. Circuito de Posgrados, Ciudad Universitaria Del., Coyoacán, C. P. 04510, México D.F
| | - Silvana Martén-Rodríguez
- Laboratorio Nacional de Análisis y Síntesis Ecológica (LANASE), Escuela Nacional de Estudios Superiores (ENES), Unidad Morelia, Universidad Nacional Autónoma de México, Morelia, Michoacán, C.P. 58190, México
| | - Gabriela Quesada-Avila
- Universidad Nacional de Costa Rica, Heredia, Costa Rica. Avenida 1, Calle 9. Apartado Postal, 86-3000
| | - Mauricio Quesada
- Laboratorio Nacional de Análisis y Síntesis Ecológica (LANASE), Escuela Nacional de Estudios Superiores (ENES), Unidad Morelia, Universidad Nacional Autónoma de México, Morelia, Michoacán, C.P. 58190, México
- Instituto de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro 8701, Morelia, Michoacán, C.P. 58190, México
| | - Yesenia Martínez-Díaz
- Laboratorio Nacional de Análisis y Síntesis Ecológica (LANASE), Escuela Nacional de Estudios Superiores (ENES), Unidad Morelia, Universidad Nacional Autónoma de México, Morelia, Michoacán, C.P. 58190, México
| | - Ken Oyama
- Laboratorio Nacional de Análisis y Síntesis Ecológica (LANASE), Escuela Nacional de Estudios Superiores (ENES), Unidad Morelia, Universidad Nacional Autónoma de México, Morelia, Michoacán, C.P. 58190, México
| | - Francisco J Espinosa-García
- Instituto de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro 8701, Morelia, Michoacán, C.P. 58190, México
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Kostyun JL, Gibson MJS, King CM, Moyle LC. A simple genetic architecture and low constraint allow rapid floral evolution in a diverse and recently radiating plant genus. THE NEW PHYTOLOGIST 2019; 223:1009-1022. [PMID: 30972773 DOI: 10.1111/nph.15844] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/02/2019] [Indexed: 06/09/2023]
Abstract
Genetic correlations among different components of phenotypes, especially those resulting from pleiotropy, can constrain or facilitate trait evolution. These factors could especially influence the evolution of traits that are functionally integrated, such as those comprising the flower. Indeed, pleiotropy is proposed as a main driver of repeated convergent trait transitions, including the evolution of phenotypically similar pollinator syndromes. We assessed the role of pleiotropy in the differentiation of floral and other reproductive traits between two species - Jaltomata sinuosa and J. umbellata (Solanaceae) - that have divergent suites of floral traits consistent with bee and hummingbird pollination, respectively. To do so, we generated a hybrid population and examined the genetic architecture (trait segregation and quantitative trait locus (QTL) distribution) underlying 25 floral and fertility traits. We found that most floral traits had a relatively simple genetic basis (few, predominantly additive, QTLs of moderate to large effect), as well as little evidence of antagonistic pleiotropy (few trait correlations and QTL colocalization, particularly between traits of different classes). However, we did detect a potential case of adaptive pleiotropy among floral size and nectar traits. These mechanisms may have facilitated the rapid floral trait evolution observed within Jaltomata, and may be a common component of rapid phenotypic change more broadly.
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Affiliation(s)
- Jamie L Kostyun
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
- Department of Plant Biology, The University of Vermont, Burlington, VT, 05405, USA
| | | | - Christian M King
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Leonie C Moyle
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
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118
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Yang R, Folk R, Zhang N, Gong X. Homoploid hybridization of plants in the Hengduan mountains region. Ecol Evol 2019; 9:8399-8410. [PMID: 31380098 PMCID: PMC6662326 DOI: 10.1002/ece3.5393] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 04/24/2019] [Accepted: 05/30/2019] [Indexed: 12/24/2022] Open
Abstract
The Hengduan Mountains Region (HMR) is a major global biodiversity hotspot. Complex tectonic and historical climatic conditions created opportunities for natural interspecific hybridization. Likewise, anthropogenic disturbance potentially raises the frequency of hybridization. Among species studies to date, the frequency of homoploid hybridization appears in the HMR. Of nine taxa in which natural hybridization has been detected, three groups are involved in homoploid hybrid speciation, and species pairs from the remaining six genera suggest that continuous gene flow occurs in hybrid zones. Reproductive isolation may greatly affect the dynamic and architecture of hybrid zones in the HMR. Asymmetrical hybridization and introgression can primarily be attributed to both prezygotic and postzygotic barriers. The frequent observation of such asymmetry may imply that reproductive barrier contributes to maintaining species boundaries in the alpine region. Ecological isolations with environmental disturbance may promote breeding barriers between parental species and hybrids. Hybrid zones may be an important phase for homoploid hybrid speciation. Hybrid zones potentially provided abundant genetic resources for the diversification of the HMR flora. The ecological and molecular mechanisms of control and mediation for natural hybridization will help biologists to understand the formation of biodiversity in the HMR. More researches from ecological and molecular aspects were required in future studies.
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Affiliation(s)
- Rui Yang
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of Botany, Chinese Academy of SciencesKunmingChina
- Key Laboratory of Economic Plants and BiotechnologyKunming Institute of Botany, Chinese Academy of SciencesKunmingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Ryan Folk
- Florida Museum of Natural HistoryUniversity of FloridaGainesvilleFloridaUSA
| | - Ningning Zhang
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of Botany, Chinese Academy of SciencesKunmingChina
- Key Laboratory of Economic Plants and BiotechnologyKunming Institute of Botany, Chinese Academy of SciencesKunmingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Xun Gong
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of Botany, Chinese Academy of SciencesKunmingChina
- Key Laboratory of Economic Plants and BiotechnologyKunming Institute of Botany, Chinese Academy of SciencesKunmingChina
- Yunnan Key Laboratory for Wild Plant ResourcesKunmingChina
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119
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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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120
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Levitan DR, Buchwalter R, Hao Y. The evolution of gametic compatibility and compatibility groups in the sea urchin
Mesocentrotus franciscanus
: An avenue for speciation in the sea. Evolution 2019; 73:1428-1442. [DOI: 10.1111/evo.13766] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/02/2019] [Accepted: 05/11/2019] [Indexed: 01/17/2023]
Affiliation(s)
- Don R. Levitan
- Department of Biological Science Florida State University Tallahassee Florida 32306
| | - Rebecca Buchwalter
- Department of Biological Science Florida State University Tallahassee Florida 32306
| | - Yueling Hao
- Department of Biological Science Florida State University Tallahassee Florida 32306
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121
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Richards TJ, Ortiz‐Barrientos D, McGuigan K. Natural selection drives leaf divergence in experimental populations of Senecio lautus under natural conditions. Ecol Evol 2019; 9:6959-6967. [PMID: 31380026 PMCID: PMC6662321 DOI: 10.1002/ece3.5263] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 04/21/2019] [Accepted: 04/23/2019] [Indexed: 11/11/2022] Open
Abstract
Leaf morphology is highly variable both within and between plant species. This study employs a combination of common garden and reciprocal transplant experiments to determine whether differences in leaf shape between Senecio lautus ecotypes has evolved as an adaptive response to divergent ecological conditions.We created a synthetic population of hybrid genotypes to segregate morphological variation between three ecotypes and performed reciprocal transplants where this hybrid population was transplanted into the three adjacent native environments. We measured nine leaf morphology traits across the experimental and natural populations at these sites.We found significant divergence in multivariate leaf morphology toward the native character in each environment, suggesting environmental conditions at each site exert selective pressure that results in a phenotypic shift toward the local phenotype of the wild populations.These associations suggest that differences in leaf morphology between S. lautus ecotypes have arisen as a result of divergent selection on leaf shape or associated traits that confer an adaptive advantage in each environment, which has led to the formation of morphologically distinct ecotypes.
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Affiliation(s)
- Thomas J. Richards
- School of Biological Sciences St LuciaUniversity of QueenslandSt LuciaQueenslandAustralia
- Department of Plant BiologySwedish University of Agricultural SciencesLinnean Center for Plant BiologyUppsalaSweden
| | | | - Katrina McGuigan
- School of Biological Sciences St LuciaUniversity of QueenslandSt LuciaQueenslandAustralia
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122
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Volis S, Zhang YH, Deng T, Dorman M, Blecher M, Abbott RJ. Divergence and reproductive isolation between two closely related allopatric Iris species. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Sergei Volis
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Yong-Hong Zhang
- Life Science Department, Yunnan Normal University, Kunming, China
| | - Tao Deng
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Michael Dorman
- Geography Department, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Michael Blecher
- En Gedi Nature Reserve, Israel Nature and Parks Authority, Dead Sea, Israel
| | - Richard J Abbott
- School of Biology, Harold Mitchell Building, University of St Andrews, St Andrews, Fife, UK
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123
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Nováková E, Zablatzká L, Brus J, Nesrstová V, Hanáček P, Kalendar R, Cvrčková F, Majeský Ľ, Smýkal P. Allelic Diversity of Acetyl Coenzyme A Carboxylase accD/ bccp Genes Implicated in Nuclear-Cytoplasmic Conflict in the Wild and Domesticated Pea ( Pisum sp.). Int J Mol Sci 2019; 20:E1773. [PMID: 30974846 PMCID: PMC6480052 DOI: 10.3390/ijms20071773] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 04/04/2019] [Accepted: 04/08/2019] [Indexed: 01/09/2023] Open
Abstract
Reproductive isolation is an important component of species differentiation. The plastid accD gene coding for the acetyl-CoA carboxylase subunit and the nuclear bccp gene coding for the biotin carboxyl carrier protein were identified as candidate genes governing nuclear-cytoplasmic incompatibility in peas. We examined the allelic diversity in a set of 195 geographically diverse samples of both cultivated (Pisum sativum, P. abyssinicum) and wild (P. fulvum and P. elatius) peas. Based on deduced protein sequences, we identified 34 accD and 31 bccp alleles that are partially geographically and genetically structured. The accD is highly variable due to insertions of tandem repeats. P. fulvum and P. abyssinicum have unique alleles and combinations of both genes. On the other hand, partial overlap was observed between P. sativum and P. elatius. Mapping of protein sequence polymorphisms to 3D structures revealed that most of the repeat and indel polymorphisms map to sequence regions that could not be modeled, consistent with this part of the protein being less constrained by requirements for precise folding than the enzymatically active domains. The results of this study are important not only from an evolutionary point of view but are also relevant for pea breeding when using more distant wild relatives.
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Affiliation(s)
- Eliška Nováková
- Department of Botany, Faculty of Sciences, Palacký University, 78371 Olomouc, Czech Republic.
| | - Lenka Zablatzká
- Department of Botany, Faculty of Sciences, Palacký University, 78371 Olomouc, Czech Republic.
| | - Jan Brus
- Department of Geoinformatics, Faculty of Sciences, Palacký University, 78371 Olomouc, Czech Republic.
| | - Viktorie Nesrstová
- Department of Mathematical Analysis and Applications of Mathematics, Palacký University, 78371 Olomouc, Czech Republic.
| | - Pavel Hanáček
- Department of Plant Biology, Faculty of Agronomy, Mendel University, 61300 Brno, Czech Republic.
| | - Ruslan Kalendar
- National Center for Biotechnology, Astana 010000, Kazakhstan.
- Department of Agricultural Sciences, Viikki Plant Science Centre and Helsinki Sustainability Centre, University of Helsinki, FI-00014 Helsinki, Finland.
| | - Fatima Cvrčková
- Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic.
| | - Ľuboš Majeský
- Department of Botany, Faculty of Sciences, Palacký University, 78371 Olomouc, Czech Republic.
| | - Petr Smýkal
- Department of Botany, Faculty of Sciences, Palacký University, 78371 Olomouc, Czech Republic.
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124
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Sobel JM, Stankowski S, Streisfeld MA. Variation in ecophysiological traits might contribute to ecogeographic isolation and divergence between parapatric ecotypes of
Mimulus aurantiacus. J Evol Biol 2019; 32:604-618. [DOI: 10.1111/jeb.13442] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 03/06/2019] [Accepted: 03/11/2019] [Indexed: 12/11/2022]
Affiliation(s)
- James M. Sobel
- Department of Biological Sciences Binghamton University (SUNY) Binghamton New York
| | - Sean Stankowski
- Institute of Ecology and Evolution University of Oregon Eugene Oregon
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125
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Aguilar-Rodríguez PA, Tschapka M, García-Franco JG, Krömer T, MacSwiney G MC. Bromeliads going batty: pollinator partitioning among sympatric chiropterophilous Bromeliaceae. AOB PLANTS 2019; 11:plz014. [PMID: 31186827 PMCID: PMC6537948 DOI: 10.1093/aobpla/plz014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 03/08/2019] [Indexed: 06/09/2023]
Abstract
Pollinators can be a limited resource and natural selection should favour differences in phenotypic characteristics to reduce competition among plants. Bats are important pollinators of many Neotropical plants, including the Bromeliaceae; however, the pre-pollination mechanisms for isolation among sympatric bat-pollinated bromeliads are unknown. Here, we studied the mechanisms for reproductive segregation between Pitcairnia recurvata, Pseudalcantarea viridiflora, Werauhia noctiflorens and W. nutans. The study was conducted at Los Tuxtlas Biosphere Reserve, in Veracruz, Mexico We carried out ex situ and in situ manual pollination treatments to determine the breeding system by assessing fruiting and seedling success and sampled bat visitors using mist-nets and infrared cameras. We determined the nocturnal nectar production pattern, estimating the energetic content of this reward. All four bromeliads are self-compatible, but only P. recurvata appears to require pollinators, because the physical separation between anthers and stigma prevents self-pollination, it is xenogamous and presents a strictly nocturnal anthesis. The bats Anoura geoffroyi, Glossophaga soricina and Hylonycteris underwoodi are probable pollinators of three of the studied bromeliads. We did not record any animal visiting the fourth species. The flowering season of each species is staggered throughout the year, with minimal overlap, and the floral morphology segregates the locations on the body of the bat where the pollen is deposited. The most abundant nectar per flower is provided by P. viridiflora, but P. recurvata offers the best reward per hectare, considering the density of flowering plants. Staggered flowering, different pollen deposition sites on the body of the pollinator and differences in the reward offered may have evolved to reduce the competitive costs of sharing pollinators while providing a constant supply of food to maintain a stable nectarivorous bat community.
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Affiliation(s)
- Pedro Adrián Aguilar-Rodríguez
- Centro de Investigaciones Tropicales, Universidad Veracruzana, José María Morelos, Col. Centro, C.P. Xalapa, Veracruz, México
- Department of Zoology, Tel Aviv University, Tel Aviv, Israel
| | - Marco Tschapka
- Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Albert Einstein Allee 11, D Ulm, Germany
- Smithsonian Tropical Research Institute, Balboa Ancón, Apartado, Panamá, Republica de Panamáa
| | - José G García-Franco
- Red de Ecología Funcional, Instituto de Ecología, A.C., Carretera Antigua a Coatepec No. 351, El Haya, C.P. Xalapa, Veracruz, México
| | - Thorsten Krömer
- Centro de Investigaciones Tropicales, Universidad Veracruzana, José María Morelos, Col. Centro, C.P. Xalapa, Veracruz, México
| | - M Cristina MacSwiney G
- Centro de Investigaciones Tropicales, Universidad Veracruzana, José María Morelos, Col. Centro, C.P. Xalapa, Veracruz, México
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126
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Carrió E, Güemes J. Can the problem of hybridization in threatened species be evaluated using a fieldwork research? A case study in snapdragons. J Nat Conserv 2019. [DOI: 10.1016/j.jnc.2019.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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127
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Liao WJ, Zhu BR, Li YF, Li XM, Zeng YF, Zhang DY. A comparison of reproductive isolation between two closely related oak species in zones of recent and ancient secondary contact. BMC Evol Biol 2019; 19:70. [PMID: 30841907 PMCID: PMC6404273 DOI: 10.1186/s12862-019-1399-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 02/22/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Much of the debate over the evolutionary consequences of hybridization on genetic divergence and speciation results from the breakdown or reinforcement of reproductive barriers in secondary hybrid zones. Among hybrid populations established for different lengths of time following secondary contact, stronger reproductive barriers are generally expected to occur in zones with longer contact. However, in plants no detailed investigation of recent and ancient zones of secondary contact has been conducted despite the importance of such a comparative study. Here, we compare pre- and postzygotic reproductive barriers between two closely related oak species, Quercus mongolica and Q. liaotungensis, in such a situation. RESULTS The recorded flowering times of both species overlapped in both contact zones. The fruit set at 10 and 30 days after interspecific hand pollination was not significantly lower than that after intraspecific pollination whenever Q. mongolica or Q. liaotungensis comprised the maternal parents in both populations. These results indicated that neither prezygotic phenological barriers nor interspecific incompatibility could have resulted in the reproductive isolation between the two species in both hybrid zones. However, the proportion of hybrid seeds produced by both species in the ancient zone was significantly lower than that recorded in the recent zone of secondary contact. In addition, the proportion of hybrid seeds simulated to form, assuming both random mating and an absence of postpollination barriers, was significantly higher than that detected in the ancient contact zone but not in the recent contact zone. These results suggest stronger early-acting postzygotic isolation between the two oak species in the ancient relative to the recent contact zone. CONCLUSIONS Our comparative study demonstrated that postzygotic barriers during seed maturity were the main contributing factor to total reproductive isolation, particularly in the ancient contact zone, which aided species delimitation. In the recently formed secondary contact zone, pre- and postzygotic barriers were not well developed, and a high frequency of natural hybridization was evident. To our knowledge this study provides the first comparison of reproductive isolation between the ancient and recent secondary contact zones in plants and helps to clarify the evolutionary consequences of hybridization in a temporal context.
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Affiliation(s)
- Wan-Jin Liao
- State Key Laboratory of Earth Surface Processes and Resource Ecology and MOE Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, 100875 China
| | - Bi-Ru Zhu
- State Key Laboratory of Earth Surface Processes and Resource Ecology and MOE Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, 100875 China
| | - Yue-Fei Li
- State Key Laboratory of Earth Surface Processes and Resource Ecology and MOE Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, 100875 China
| | - Xiao-Meng Li
- State Key Laboratory of Earth Surface Processes and Resource Ecology and MOE Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, 100875 China
| | - Yan-Fei Zeng
- Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091 China
| | - Da-Yong Zhang
- State Key Laboratory of Earth Surface Processes and Resource Ecology and MOE Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, 100875 China
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128
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Nadir S, Li W, Zhu Q, Khan S, Zhang XL, Zhang H, Wei ZF, Li MT, Zhou L, Li CY, Chen LJ, Lee DS. A novel discovery of a long terminal repeat retrotransposon-induced hybrid weakness in rice. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:1197-1207. [PMID: 30576523 PMCID: PMC6382335 DOI: 10.1093/jxb/ery442] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 12/04/2018] [Indexed: 06/09/2023]
Abstract
Hybrid weakness is a post-zygotic hybridization barrier frequently observed in plants, including rice. In this study, we describe the genomic variation among three temperate japonica rice (Oryza sativa ssp. japonica) varieties 'Aranghyangchalbyeo' ('CH7'), 'Sanghaehyangheolua' ('CH8') and 'Shinseonchalbyeo' ('CH9'), carrying different hybrid weakness genes. The reciprocal progeny obtained from crossing any two varieties displayed characteristic hybrid weakness traits. We mapped and cloned a new locus, Hwc3 (hybrid weakness 3), on chromosome 4. Sequence analysis identified that a long terminal repeat (LTR) retrotransposon was inserted into the promoter region of the Hwc3 gene in 'CH7'. A 4-kb DNA fragment from 'CH7' containing the Hwc3 gene with the inserted LTR retrotransposon was able to induce hybrid weakness in hybrids with 'CH8' plants carrying the Hwc1 gene by genetic complementation. We investigated the differential gene expression profile of F1 plants exhibiting hybrid weakness and detected that the genes associated with energy metabolism were significantly down-regulated compared with the parents. Based on our results, we propose that LTR retrotransposons could be a potential cause of hybrid weakness in intrasubspecific hybrids in japonica rice. Understanding the molecular mechanisms underlying intrasubspecific hybrid weakness is important for increasing our knowledge on reproductive isolation and could have significant implications for rice improvement and hybrid breeding.
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Affiliation(s)
- Sadia Nadir
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
- Department of Chemistry, University of Science and Technology, Bannu, KPK, Pakistan
- Centre for Mountain Ecosystem Studies, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Wei Li
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
| | - Qian Zhu
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
| | - Sehroon Khan
- Centre for Mountain Ecosystem Studies, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
- World Agroforestry Centre, East and Central Asia, Kunming, Yunnan, China
| | - Xiao-Ling Zhang
- Agricultural College of Kunming University, Kunming, Yunnan, China
| | - Hui Zhang
- College of Agronomy and Biotechnology, Yunnan Agriculture University, Kunming, Yunnan, China
| | - Zhen-Fei Wei
- Maize Research Institute, Shanxi Academy of Agriculture Sciences, Xinzhou, Shanxi, China
| | - Meng-Ting Li
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
| | - Li Zhou
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
| | - Cheng-Yun Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Li-Juan Chen
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Dong-Sun Lee
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan, China
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129
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Skeels A, Cardillo M. Reconstructing the Geography of Speciation from Contemporary Biodiversity Data. Am Nat 2019; 193:240-255. [DOI: 10.1086/701125] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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130
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Maxwell CS, Mattox K, Turissini DA, Teixeira MM, Barker BM, Matute DR. Gene exchange between two divergent species of the fungal human pathogen, Coccidioides. Evolution 2019; 73:42-58. [PMID: 30414183 PMCID: PMC6430640 DOI: 10.1111/evo.13643] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 10/15/2018] [Accepted: 10/18/2018] [Indexed: 12/12/2022]
Abstract
The fungal genus Coccidioides is composed of two species, Coccidioides immitis and Coccidioides posadasii. These two species are the causal agents of coccidioidomycosis, a pulmonary disease also known as valley fever. The two species are thought to have shared genetic material due to gene exchange in spite of their long divergence. To quantify the magnitude of shared ancestry between them, we analyzed the genomes of a population sample from each species. Next, we inferred what is the expected size of shared haplotypes that might be inherited from the last common ancestor of the two species and find a cutoff to find what haplotypes have conclusively been exchanged between species. Finally, we precisely identified the breakpoints of the haplotypes that have crossed the species boundary and measure the allele frequency of each introgression in this sample. We find that introgressions are not uniformly distributed across the genome. Most, but not all, of the introgressions segregate at low frequency. Our results show that divergent species can share alleles, that species boundaries can be porous, and highlight the need for a systematic exploration of gene exchange in fungal species.
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Affiliation(s)
- Colin S Maxwell
- Biology Department, University of North Carolina, Chapel Hill, North Carolina
| | - Kathleen Mattox
- Biology Department, University of North Carolina, Chapel Hill, North Carolina
| | - David A Turissini
- Biology Department, University of North Carolina, Chapel Hill, North Carolina
| | - Marcus M Teixeira
- Núcleo de Medicina Tropical, Faculdade de Medicina, University of Brasília, Brasília, Brazil
| | - Bridget M Barker
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona
| | - Daniel R Matute
- Biology Department, University of North Carolina, Chapel Hill, North Carolina
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131
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Giesbers AKJ, den Boer E, Ulen JJWEH, van Kaauwen MPW, Visser RGF, Niks RE, Jeuken MJW. Patterns of Transmission Ratio Distortion in Interspecific Lettuce Hybrids Reveal a Sex-Independent Gametophytic Barrier. Genetics 2019; 211:263-276. [PMID: 30401697 PMCID: PMC6325705 DOI: 10.1534/genetics.118.301566] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 10/30/2018] [Indexed: 11/18/2022] Open
Abstract
Interspecific crosses can result in progeny with reduced vitality or fertility due to genetic incompatibilities between species, a phenomenon known as hybrid incompatibility (HI). HI is often caused by a bias against deleterious allele combinations, which results in transmission ratio distortion (TRD). Here, we determined the genome-wide distribution of HI between wild lettuce, Lactuca saligna, and cultivated lettuce, L. sativa, in a set of backcross inbred lines (BILs) with single introgression segments from L. saligna introgressed into a L. sativa genetic background. Almost all BILs contained an introgression segment in a homozygous state except a few BILs, for which we were able to obtain only a single heterozygous introgression. Their inbred progenies displayed severe TRD with a bias toward the L. sativa allele and complete nontransmission of the homozygous L. saligna introgression, i.e., absolute HI. These HI might be caused by deleterious heterospecific allele combinations at two loci. We used an multilocus segregating interspecific F2 population to identify candidate conspecific loci that can nullify the HI in BILs. Segregation analysis of developed double-introgression progenies showed nullification of three HI and proved that these HI are explained by nuclear pairwise incompatibilities. One of these digenic HI showed 29% reduced seed set and its pattern of TRD pointed to a sex-independent gametophytic barrier. Namely, this HI was caused by complete nontransmission of one heterospecific allele combination at the haploid stage, surprisingly in both male and female gametophytes. Our study shows that two-locus incompatibility systems contribute to reproductive barriers among Lactuca species.
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Affiliation(s)
- Anne K J Giesbers
- Plant Breeding, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
| | - Erik den Boer
- Plant Breeding, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
| | | | | | - Richard G F Visser
- Plant Breeding, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
| | - Rients E Niks
- Plant Breeding, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
| | - Marieke J W Jeuken
- Plant Breeding, Wageningen University and Research, 6708 PB Wageningen, The Netherlands
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132
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Roda F, Hopkins R. Correlated evolution of self and interspecific incompatibility across the range of a Texas wildflower. THE NEW PHYTOLOGIST 2019; 221:553-564. [PMID: 29992588 DOI: 10.1111/nph.15340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 06/10/2018] [Indexed: 06/08/2023]
Abstract
Selection to prevent interspecific mating can cause an increase or a decrease in self-pollination in sympatric populations. Characterizing the geographical variation in self and interspecific incompatibilities within a species can reveal if and how the evolution of self and interspecific mate choice are linked. We used controlled pollinations to characterize the variation in self and interspecific incompatibility across 29 populations of Phlox drummondii. We evaluated seed set from these pollinations and described the developmental timing of variation in pollen-pistil compatibility. There is extensive quantitative variation in self-incompatibility and interspecific-incompatibility with its close congener P. cuspidata. Phlox drummondii populations that co-occur and hybridize with P. cuspidata have significantly higher interspecific incompatibility and self-incompatibility than geographically isolated P. drummondii populations. The strength of self and interspecific incompatibility is significantly correlated among individuals and the strength of both incompatibilities is explained by the success of pollen adhesion to the stigma. The correlated strength of self and interspecific incompatibility across the range of P. drummondii and the concurrent developmental timing of the pollen-pistil interaction, suggests these incompatibilities have an overlapping molecular mechanism. The geographical distribution of variation in incompatibilities indicates that this mechanistic link between incompatibilities may affect the evolution of mate choice in plants.
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Affiliation(s)
- Federico Roda
- Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, 1300 Centre St, Boston, MA, 02131, USA
| | - Robin Hopkins
- Department of Organismic and Evolutionary Biology, Harvard University, 22 Divinity Avenue, Cambridge, MA, 02138, USA
- The Arnold Arboretum, Harvard University, 1300 Centre St, Boston, MA, 02131, USA
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133
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Karrenberg S, Liu X, Hallander E, Favre A, Herforth-Rahmé J, Widmer A. Ecological divergence plays an important role in strong but complex reproductive isolation in campions (Silene). Evolution 2018; 73:245-261. [PMID: 30499144 DOI: 10.1111/evo.13652] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 11/13/2018] [Accepted: 01/16/2018] [Indexed: 12/27/2022]
Abstract
New species arise through the evolution of reproductive barriers between formerly interbreeding lineages. Yet, comprehensive assessments of potential reproductive barriers, which are needed to make inferences on processes driving speciation, are only available for a limited number of systems. In this study, we estimated individual and cumulative strengths of seven prezygotic and six postzygotic reproductive barriers between the recently diverged taxa Silene dioica (L.) Clairv. and S. latifolia Poiret using both published and new data. A combination of multiple partial reproductive barriers resulted in near-complete reproductive isolation between S. dioica and S. latifolia, consistent with earlier estimates of gene flow between the taxa. Extrinsic barriers associated with adaptive ecological divergence were most important, while intrinsic postzygotic barriers had moderate individual strength but contributed only little to total reproductive isolation. These findings are in line with ecological divergence as driver of speciation. We further found extensive variation in extrinsic reproductive isolation, ranging from sites with very strong selection against migrants and hybrids to intermediate sites where substantial hybridization is possible. This situation may allow for, or even promote, heterogeneous genetic divergence.
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Affiliation(s)
- Sophie Karrenberg
- Department of Ecology and Genetics, Uppsala University, Norbyvägen 18 D, 75236, Uppsala, Sweden
| | - Xiaodong Liu
- Department of Ecology and Genetics, Uppsala University, Norbyvägen 18 D, 75236, Uppsala, Sweden
| | - Emelie Hallander
- Department of Ecology and Genetics, Uppsala University, Norbyvägen 18 D, 75236, Uppsala, Sweden.,Current Address: Swedish Board of Agriculture, Vallgatan 8, 551 82, Jönköping, Sweden
| | - Adrien Favre
- Department of Diversity and Evolution of Higher Plants, Institute of Ecology, Evolution and Diversity, Goethe-University, 60439, Frankfurt am Main, Germany.,Senckenberg Research Institute and Natural History Museum, Senckenberganlage 25, 60325, Frankfurt am Main, Germany
| | - Joelle Herforth-Rahmé
- ETH Zurich, Institute of Integrative Biology, Universitätstrasse 16, 8092, Zürich, Switzerland.,Current Address: Research Institute of Organic Agriculture FiBL, Department of Soil Sciences, Ackerstrasse 113, Box 219, 5070, Frick, Switzerland
| | - Alex Widmer
- ETH Zurich, Institute of Integrative Biology, Universitätstrasse 16, 8092, Zürich, Switzerland
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134
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Nadir S, Khan S, Zhu Q, Henry D, Wei L, Lee DS, Chen L. An overview on reproductive isolation in Oryza sativa complex. AOB PLANTS 2018; 10:ply060. [PMID: 30538811 PMCID: PMC6280023 DOI: 10.1093/aobpla/ply060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 11/21/2018] [Indexed: 05/27/2023]
Abstract
Reproductive isolation is generally regarded as the essence of the speciation process. Studying closely related species is convenient for understanding the genetic basis of reproductive isolation. Therefore, the present review is restricted to the species and subspecies of the Oryza sativa complex, which includes the two domestic rice cultivars and six wild species. Although closely related, these rice species are separated from each other by a range reproductive barriers. This review presents a comprehensive understanding of the forces that shaped the formation of reproductive barriers among and between the species of the O. sativa complex. We suggest the possibility that domestication and artificial breeding in these rice species can lead to the early stages of speciation. Understanding the evolutionary and molecular mechanisms underlying reproductive isolation in rice will increase our knowledge in speciation and would also offer practical significance for the implementation of crop improvement strategies.
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Affiliation(s)
- Sadia Nadir
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
- Department of Chemistry, University of Science and Technology, Bannu, Khyber Pakhtunkhwa, Pakistan
- Centre for Mountain Ecosystem Studies, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Sehroon Khan
- Centre for Mountain Ecosystem Studies, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Qian Zhu
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
| | - Doku Henry
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
- Biotechnology Lab Complex, CSIR-Crops Research Institute, Ghana
| | - Li Wei
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
| | - Dong Sun Lee
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan, China
| | - LiJuan Chen
- Rice Research Institute, Yunnan Agriculture University, Kunming, Yunnan, China
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, Kunming, Yunnan, China
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135
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Jacquemyn H, Waud M, Brys R. Mycorrhizal divergence and selection against immigrant seeds in forest and dune populations of the partially mycoheterotrophic Pyrola rotundifolia. Mol Ecol 2018; 27:5228-5237. [PMID: 30427084 DOI: 10.1111/mec.14940] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 10/17/2018] [Accepted: 10/24/2018] [Indexed: 11/29/2022]
Abstract
Plant populations occupying different habitats may diverge from each other over time and gradually accumulate genetic and morphological differences, ultimately resulting in ecotype or even species formation. In plant species that critically rely on mycorrhizal fungi, differences in mycorrhizal communities can contribute to ecological isolation by reducing or even inhibiting germination of immigrant seeds. In this study, we investigated whether the mycorrhizal communities available in the soil and associating with the roots of seedlings and adult plants of the partially mycoheterotrophic Pyrola rotundifolia differed between populations growing in sand dunes and forests. In addition, reciprocal germination experiments were performed to test whether native seeds showed higher germination than immigrant seeds. Our results showed that the mycorrhizal communities differed significantly between forest and dune populations, and that within populations seedlings and adults also associated with different mycorrhizal communities. In both forest and dune populations, mycorrhizal communities were dominated by members of the Thelephoraceae, but dune populations showed a higher incidence of members of the Inocybaceae, whereas forest populations showed a high abundance of members of the Russulaceae. Reciprocal germination experiments showed that native seeds showed a higher germination success than immigrant seeds and this effect was most pronounced in dune populations. Overall, these results demonstrate that plants of P. rotundifolia growing in dune and forest habitats associate with different mycorrhizal communities and that reduced germination of non-native seeds may contribute to reproductive isolation. We conclude that selection against immigrants may constitute an important reproductive barrier at early stages of the speciation process.
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Affiliation(s)
- Hans Jacquemyn
- Department of Biology, Plant Conservation and Population Biology, KU Leuven, Leuven, Belgium
| | - Michael Waud
- Department of Biology, Plant Conservation and Population Biology, KU Leuven, Leuven, Belgium
| | - Rein Brys
- Research Institute for Forest and Nature, Geraardsbergen, Belgium
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136
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Uy JAC, Irwin DE, Webster MS. Behavioral Isolation and Incipient Speciation in Birds. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2018. [DOI: 10.1146/annurev-ecolsys-110617-062646] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Behavioral changes, such as those involved in mating, foraging, and migration, can generate reproductive barriers between populations. Birds, in particular, are known for their great diversity in these behaviors, and so behavioral isolation is often proposed to be the major driver of speciation. Here, we review empirical evidence to evaluate the importance of behavioral isolation in the early stages of avian speciation. Experimentally measured mating preferences indicate that changes in mating behavior can result in premating barriers, with their strength depending on the extent of divergence in mating signals. Differences in migratory and foraging behavior also can play important roles in generating reproductive barriers in the early stages of speciation. However, because premating behavioral isolation is imperfect, extrinsic postzygotic barriers, in the form of selection against hybrids having intermediate phenotypes, also play an important role in avian diversification, especially in completing the speciation process.
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Affiliation(s)
- J. Albert C. Uy
- Department of Biology, University of Miami, Coral Gables, Florida 33146, USA
| | - Darren E. Irwin
- Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Michael S. Webster
- Cornell Lab of Ornithology and Department of Neurobiology and Behavior, Cornell University, Ithaca, New York 14850, USA
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137
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Cuevas E, Espino J, Marques I. Reproductive isolation between Salvia elegans and S. fulgens, two hummingbird-pollinated sympatric sages. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20:1075-1082. [PMID: 30004608 DOI: 10.1111/plb.12874] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/09/2018] [Indexed: 06/08/2023]
Abstract
The integrity of species in sympatric contact sites is dependent on the existence of reproductive isolating mechanisms, which restrict gene flow between them. However, we know little about the mechanisms that enable the coexistence of species with similar floral morphologies. Here, we evaluated several reproductive isolation barriers between Salvia elegans and S. fulgens, two sympatric sages with a similar ornithophilous floral syndrome, offering nectar as the main reward. Over 3 years, we evaluated broad-scale geographic isolation, floral phenologies and floral visitors as pre-pollination barriers, and fruit set, seed number and seed germination as post-pollination barriers. We found considerable geographic isolation and significant altitudinal differences between the two sages. The flowering period of both sages always overlapped extensively during the 3 years of this study, but hummingbirds were highly specific, visiting one or the other Salvia species and showing aggressive territorial behaviour. Interspecific experimental crosses revealed that hybrid seeds might be formed although strong asymmetric barriers were found depending on the species acting as the maternal donor. Despite the low level of flowering asynchrony, reproductive isolation was remarkably high in the two sages. Geographic isolation and pollinator fidelity were the main factors responsible for maintaining species integrity. Despite an extensive review, we found very few studies quantifying the efficiency of isolation barriers in Neotropical plants or even the importance of hummingbirds as pollinators.
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Affiliation(s)
- E Cuevas
- Facultad de Biología, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico
| | - J Espino
- Facultad de Biología, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico
| | - I Marques
- UBC Botanical Garden & Centre for Plant Research and Department of Botany, University of British Columbia, Vancouver, BC, Canada
- CE3C - Centre for Ecology, Evolution and Environmental Changes, Campo Grande, Portugal
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138
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Luo J, Sun X, Cormack BP, Boeke JD. Karyotype engineering by chromosome fusion leads to reproductive isolation in yeast. Nature 2018; 560:392-396. [PMID: 30069047 DOI: 10.1038/s41586-018-0374-x] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Accepted: 06/25/2018] [Indexed: 11/09/2022]
Abstract
Extant species have wildly different numbers of chromosomes, even among taxa with relatively similar genome sizes (for example, insects)1,2. This is likely to reflect accidents of genome history, such as telomere-telomere fusions and genome duplication events3-5. Humans have 23 pairs of chromosomes, whereas other apes have 24. One human chromosome is a fusion product of the ancestral state6. This raises the question: how well can species tolerate a change in chromosome numbers without substantial changes to genome content? Many tools are used in chromosome engineering in Saccharomyces cerevisiae7-10, but CRISPR-Cas9-mediated genome editing facilitates the most aggressive engineering strategies. Here we successfully fused yeast chromosomes using CRISPR-Cas9, generating a near-isogenic series of strains with progressively fewer chromosomes ranging from sixteen to two. A strain carrying only two chromosomes of about six megabases each exhibited modest transcriptomic changes and grew without major defects. When we crossed a sixteen-chromosome strain with strains with fewer chromosomes, we noted two trends. As the number of chromosomes dropped below sixteen, spore viability decreased markedly, reaching less than 10% for twelve chromosomes. As the number of chromosomes decreased further, yeast sporulation was arrested: a cross between a sixteen-chromosome strain and an eight-chromosome strain showed greatly reduced full tetrad formation and less than 1% sporulation, from which no viable spores could be recovered. However, homotypic crosses between pairs of strains with eight, four or two chromosomes produced excellent sporulation and spore viability. These results indicate that eight chromosome-chromosome fusion events suffice to isolate strains reproductively. Overall, budding yeast tolerates a reduction in chromosome number unexpectedly well, providing a striking example of the robustness of genomes to change.
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Affiliation(s)
- Jingchuan Luo
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA.,Department of Molecular Biology & Genetics, JHU School of Medicine, Baltimore, MD, USA
| | - Xiaoji Sun
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA
| | - Brendan P Cormack
- Department of Molecular Biology & Genetics, JHU School of Medicine, Baltimore, MD, USA
| | - Jef D Boeke
- Institute for Systems Genetics, NYU Langone Health, New York, NY, USA.
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139
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Liang H, Ren ZX, Tao ZB, Zhao YH, Bernhardt P, Li DZ, Wang H. Impact of pre- and post-pollination barriers on pollen transfer and reproductive isolation among three sympatric Pedicularis (Orobanchaceae) species. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20:662-673. [PMID: 29673012 DOI: 10.1111/plb.12833] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 04/11/2018] [Indexed: 06/08/2023]
Abstract
Pedicularis is the largest genus in the Orobanchaceae (>300) with many species co-occurring and co-blooming in subalpine to alpine meadows in the Himalayas. Although it is well known that different Pedicularis species place pollen on different parts of the same bumblebee's body, thus reducing interspecific pollen transfer, it is not known whether post-pollination components also contribute to reproductive isolation (RI). In this study, we quantified the individual strengths and absolute contributions of six pre- and post-pollination components of RI between three sympatric species in two pairs; Pedicularis gruina × Pedicularis tenuisecta (gru × ten) and Pedicularis comptoniifolia × Pedicularis tenuisecta (com × ten). All three Pedicularis species shared the same Bombus species. Individual foragers showed a high, but incomplete, floral constancy for each species. Therefore, pre-pollination barriers were potentially 'leaky' as Bombus species showed a low but consistent frequency of interspecific visitation. The RI strength of pre-pollination was lower in com × ten than in gru × ten. In contrast, post-pollination barriers completely blocked gene flow between both sets of species pairs. Two post-pollination recognition sites were identified. Late acting rejection of interspecific pollen tube growth occurred in com♀ × ten♂, while seeds produced in bi-directional crosses of gru × ten failed to germinate. We propose that, although floral isolation based on pollen placement on pollinators in the genus Pedicularis is crucial to avoid interspecific pollen transfer, the importance of this mode of interspecific isolation may be exaggerated. Post-pollination barriers may play even larger roles for currently established populations of co-blooming and sympatric species in this huge genus in the Himalayas.
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Affiliation(s)
- H Liang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Kunming College of Life Sciences, University of Chinese Academy of Sciences, Kunming, China
| | - Z-X Ren
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Z-B Tao
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Kunming College of Life Sciences, University of Chinese Academy of Sciences, Kunming, China
| | - Y-H Zhao
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - P Bernhardt
- Department of Biology, Saint Louis University, St. Louis, MI, USA
| | - D-Z Li
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - H Wang
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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140
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Tao Z, Ren Z, Bernhardt P, Liang H, Li H, Zhao Y, Wang H, Li D. Does reproductive isolation reflect the segregation of color forms in Spiranthes sinensis (Pers.) Ames complex (Orchidaceae) in the Chinese Himalayas? Ecol Evol 2018; 8:5455-5469. [PMID: 29938065 PMCID: PMC6010815 DOI: 10.1002/ece3.4067] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 03/09/2018] [Accepted: 03/12/2018] [Indexed: 01/16/2023] Open
Abstract
Isolation between species, or taxa sharing a common lineage, depends primarily on the relative strengths of various reproductive barriers. Previous studies on reproductive isolation between orchids emphasized mechanical and ethological barriers in flowers of species showing food and/or sexual mimicry. In this study, we investigated and quantified a series of prepollination and postpollination barriers between pink and white forms of Spiranthes sinensis sl, a nectar-secreting complex. We generated ML trees based on trnS-G and matK to explore phylogenetic relationships in this species complex. Spiranthes sinensis sl segregated from some other congeners, but the white form constituted a distinct clade in relation to the pink form. The white form secreted 2-Phenylethanol as it is a single-scent compound and was pollinated almost exclusively by native, large-bodied Apis cerana and Bombus species (Apidae). Apis cerana showed a high floral constancy to this form. The scentless, pink form was pollinated primarily by smaller bees in the genera Ceratina (Apidae), and members of the family Halictidae, with infrequent visits by A. cerana and Bombus species. Fruit set and the production of large embryos following interform pollination treatments were significantly lower compared to intraform pollination results for the white form. Our results suggested that pollinator isolation, based on color and scent cues, may result in greater floral constancy in white populations when both forms are sympatric as two different, guilds of pollinators forage selectively preventing or reducing prospective gene flow. Postpollination barriers appear weaker than prepollination barriers but they also play a role in interform isolation, especially in the white form. Our findings suggest that floral color forms in S. sinensis do not represent an unbalanced polymorphism. Interpretations of the evolutionary status of these forms are discussed.
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Affiliation(s)
- Zhi‐Bin Tao
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunmingChina
- Kunming College of Life SciencesUniversity of Chinese Academy of SciencesKunmingChina
| | - Zong‐Xin Ren
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunmingChina
| | | | - Huan Liang
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunmingChina
- Kunming College of Life SciencesUniversity of Chinese Academy of SciencesKunmingChina
| | - Hai‐Dong Li
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunmingChina
| | - Yan‐Hui Zhao
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunmingChina
| | - Hong Wang
- Key Laboratory for Plant Diversity and Biogeography of East AsiaKunming Institute of BotanyChinese Academy of SciencesKunmingChina
| | - De‐Zhu Li
- Germplasm Bank of Wild SpeciesKunming Institute of BotanyChinese Academy of SciencesKunmingChina
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141
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Suni SS, Hopkins R. The relationship between postmating reproductive isolation and reinforcement in Phlox. Evolution 2018; 72:1387-1398. [PMID: 29774945 DOI: 10.1111/evo.13507] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 04/09/2018] [Accepted: 04/14/2018] [Indexed: 02/06/2023]
Abstract
The process of speciation involves the accumulation of reproductive isolation (RI) between diverging lineages. Selection can favor increased RI via the process of reinforcement, whereby costs to hybridization impose selection for increased prezygotic RI. Reinforcement results in phenotypic divergence within at least one taxon, as a result of costly hybridization between sympatric taxa. The strength of selection driving reinforcement is determined by the cost of hybridization and the frequency of hybridization. We investigated the cost of hybridization by quantifying postmating RI barriers among Phlox species that comprise one of the best-studied cases of reinforcement. We determined if the strength of RI differs among lineages that have and have not undergone reinforcement, how much variability there is within species in RI, and whether RI is associated with phylogenetic relatedness. We found high RI for the species that underwent phenotypic divergence due to reinforcement; however, RI was also high between other species pairs. We found extensive variability in RI among individuals within species, and no evidence that the strength of RI was associated with phylogenetic relatedness. We suggest that phenotypic divergence due to reinforcement is associated with the frequency of hybridization and introgression, and not the cost of hybridization in this clade.
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Affiliation(s)
- Sevan S Suni
- The Arnold Arboretum of Harvard University, 1300 Centre Street, Boston, MA 02131
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA
- Present Address: The University of San Francisco, 2130 Fulton Street, San Francisco, CA 94117
| | - Robin Hopkins
- The Arnold Arboretum of Harvard University, 1300 Centre Street, Boston, MA 02131
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA
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142
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Serrato-Capuchina A, Matute DR. The Role of Transposable Elements in Speciation. Genes (Basel) 2018; 9:E254. [PMID: 29762547 PMCID: PMC5977194 DOI: 10.3390/genes9050254] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 01/20/2023] Open
Abstract
Understanding the phenotypic and molecular mechanisms that contribute to genetic diversity between and within species is fundamental in studying the evolution of species. In particular, identifying the interspecific differences that lead to the reduction or even cessation of gene flow between nascent species is one of the main goals of speciation genetic research. Transposable elements (TEs) are DNA sequences with the ability to move within genomes. TEs are ubiquitous throughout eukaryotic genomes and have been shown to alter regulatory networks, gene expression, and to rearrange genomes as a result of their transposition. However, no systematic effort has evaluated the role of TEs in speciation. We compiled the evidence for TEs as potential causes of reproductive isolation across a diversity of taxa. We find that TEs are often associated with hybrid defects that might preclude the fusion between species, but that the involvement of TEs in other barriers to gene flow different from postzygotic isolation is still relatively unknown. Finally, we list a series of guides and research avenues to disentangle the effects of TEs on the origin of new species.
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Affiliation(s)
- Antonio Serrato-Capuchina
- Biology Department, Genome Sciences Building, University of North Carolina, Chapel Hill, NC 27514, USA.
| | - Daniel R Matute
- Biology Department, Genome Sciences Building, University of North Carolina, Chapel Hill, NC 27514, USA.
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143
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Liu X, Karrenberg S. Genetic architecture of traits associated with reproductive barriers in Silene: Coupling, sex chromosomes and variation. Mol Ecol 2018; 27:3889-3904. [PMID: 29577481 DOI: 10.1111/mec.14562] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 01/22/2018] [Accepted: 01/31/2018] [Indexed: 01/02/2023]
Abstract
The evolution of reproductive barriers and their underlying genetic architecture is of central importance for the formation of new species. Reproductive barriers can be controlled either by few large-effect loci suggesting strong selection on key traits, or by many small-effect loci, consistent with gradual divergence or with selection on polygenic or multiple traits. Genetic coupling between reproductive barrier loci further promotes divergence, particularly divergence with ongoing gene flow. In this study, we investigated the genetic architectures of ten morphological, phenological and life history traits associated with reproductive barriers between the hybridizing sister species Silene dioica and S. latifolia; both are dioecious with XY-sex determination. We used quantitative trait locus (QTL) mapping in two reciprocal F2 crosses. One to six QTLs per trait, including nine major QTLs (PVE > 20%), were detected on 11 of the 12 linkage groups. We found strong evidence for coupling of QTLs for uncorrelated traits and for an important role of sex chromosomes in the genetic architectures of reproductive barrier traits. Unexpectedly, QTLs detected in the two F2 crosses differed largely, despite limited phenotypic differences between them and sufficient statistical power. The widely dispersed genetic architectures of traits associated with reproductive barriers suggest gradual divergence or multifarious selection. Coupling of the underlying QTLs likely promoted divergence with gene flow in this system. The low congruence of QTLs between the two crosses further points to variable and possibly redundant genetic architectures of traits associated with reproductive barriers, with important implications for the evolutionary dynamics of divergence and speciation.
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Affiliation(s)
- Xiaodong Liu
- Department of Ecology and Genetics, Evolutionary Biology Center, Uppsala University, Uppsala, Sweden
| | - Sophie Karrenberg
- Department of Ecology and Genetics, Evolutionary Biology Center, Uppsala University, Uppsala, Sweden
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144
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Fishman L, Sweigart AL. When Two Rights Make a Wrong: The Evolutionary Genetics of Plant Hybrid Incompatibilities. ANNUAL REVIEW OF PLANT BIOLOGY 2018; 69:707-731. [PMID: 29505737 DOI: 10.1146/annurev-arplant-042817-040113] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Hybrids between flowering plant species often exhibit reduced fitness, including sterility and inviability. Such hybrid incompatibilities create barriers to genetic exchange that can promote reproductive isolation between diverging populations and, ultimately, speciation. Additionally, hybrid breakdown opens a window into hidden molecular and evolutionary processes occurring within species. Here, we review recent work on the mechanisms and origins of hybrid incompatibility in flowering plants, including both diverse genic interactions and chromosomal incompatibilities. Conflict and coevolution among and within plant genomes contributes to the evolution of some well-characterized genic incompatibilities, but duplication and drift also play important roles. Inversions, while contributing to speciation by suppressing recombination, rarely cause underdominant sterility. Translocations cause severe F1 sterility by disrupting meiosis in heterozygotes, making their fixation in outcrossing sister species a paradox. Evolutionary genomic analyses of both genic and chromosomal incompatibilities, in the context of population genetic theory, can explicitly test alternative scenarios for their origins.
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Affiliation(s)
- Lila Fishman
- Division of Biological Sciences, University of Montana, Missoula, Montana 59812, USA;
| | - Andrea L Sweigart
- Department of Genetics, University of Georgia, Athens, Georgia 30602, USA;
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145
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Christie K, Strauss SY. Along the speciation continuum: Quantifying intrinsic and extrinsic isolating barriers across five million years of evolutionary divergence in California jewelflowers. Evolution 2018; 72:1063-1079. [DOI: 10.1111/evo.13477] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Accepted: 02/27/2018] [Indexed: 12/11/2022]
Affiliation(s)
- Kyle Christie
- Department of Evolution and Ecology and Center for Population Biology University of California One Shields Avenue Davis California 95616
| | - Sharon Y. Strauss
- Department of Evolution and Ecology and Center for Population Biology University of California One Shields Avenue Davis California 95616
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146
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Hybridization and differential introgression associated with environmental shifts in a mistletoe species complex. Sci Rep 2018; 8:5591. [PMID: 29615778 PMCID: PMC5882953 DOI: 10.1038/s41598-018-23707-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 03/12/2018] [Indexed: 12/22/2022] Open
Abstract
Host specialization after host shifting is traditionally viewed as the pathway to speciation in parasitic plants. However, geographical and environmental changes can also influence parasite speciation, through hybridization processes. Here we investigated the impact of past climatic fluctuations, environment, and host shifts on the genetic structure and patterns of hybridization and gene flow between Psittacanthus calyculatus and P. schiedeanus, a Mesoamerican species complex. Using microsatellites (408 individuals), we document moderate genetic diversity but high genetic differentiation between widespread parental clusters, calyculatus in dry pine-oak forests and schiedeanus in cloud forests. Bayesian analyses identified a third cluster, with admixture between parental clusters in areas of xeric and tropical dry forests and high levels of migration rates following secondary contact. Coincidently host associations in these areas differ from those in areas of parental species, suggesting that past hybridization played a role in environmental and host shifts. Overall, the observed genetic and geographic patterns suggest that these Psittacanthus populations could have entered a distinct evolutionary pathway. The results provide evidence for highlights on the importance of the Pleistocene climate changes, habitat differences, and potential host shifts in the evolutionary history of Neotropical mistletoes.
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147
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148
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Neri J, Wendt T, Palma-Silva C. Natural hybridization and genetic and morphological variation between two epiphytic bromeliads. AOB PLANTS 2018; 10:plx061. [PMID: 29308124 PMCID: PMC5751037 DOI: 10.1093/aobpla/plx061] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 11/22/2017] [Indexed: 05/18/2023]
Abstract
Reproductive isolation is of fundamental importance for maintaining species boundaries in sympatry. Here, we examine the genetic and morphological differences between two closely related bromeliad species: Vriesea simplex and Vriesea scalaris. Furthermore, we examined the occurrence of natural hybridization and discuss the action of reproductive isolation barriers. Nuclear genomic admixture suggests hybridization in sympatric populations, although interspecific gene flow is low among species in all sympatric zones (Nem < 0.5). Thus, morphological and genetic divergence (10.99 %) between species can be maintained despite ongoing natural hybridization. Cross-evaluation of our genetic and morphological data suggests that species integrity is maintained by the simultaneous action of multiple barriers, such as divergent reproductive systems among species, differences in floral traits and low hybrid seed viability.
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Affiliation(s)
- Jordana Neri
- Programa de Pós Graduação em Botânica, Departamento de Botânica, Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista, São Cristóvão, Rio de Janeiro, RJ, Brazil
| | - Tânia Wendt
- Departamento de Botânica, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Clarisse Palma-Silva
- Programa de Pós Graduação em Ecologia, Departamento de Ecologia – Universidade Estadual Paulista Julio Mesquita Filho, Rio Claro, SP, Brazil
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149
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Roth M, Florez-Rueda AM, Griesser S, Paris M, Städler T. Incidence and developmental timing of endosperm failure in post-zygotic isolation between wild tomato lineages. ANNALS OF BOTANY 2018; 121:107-118. [PMID: 29280998 PMCID: PMC5786209 DOI: 10.1093/aob/mcx133] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 10/04/2017] [Indexed: 05/19/2023]
Abstract
BACKGROUND AND AIMS Defective hybrid seed development in angiosperms might mediate the rapid establishment of intrinsic post-zygotic isolation between closely related species. Extensive crosses within and among three lineages of wild tomatoes (Solanum section Lycopersicon) were performed to address the incidence, developmental timing and histological manifestations of hybrid seed failure. These lineages encompass different, yet fairly recent, divergence times and both allopatric and partially sympatric pairs. METHODS Mature seeds were scored visually 2 months after hand pollinations, and viable-looking seeds were assessed for germination success. Using histological sections from early-developing seeds from a sub-set of crosses, the growth of three major seed compartments (endosperm, embryo and seed coat) was measured at critical developmental stages up to 21 d after pollination, with a focus on the timing and histological manifestations of endosperm misdevelopment in abortive hybrid seeds. KEY RESULTS For two of three interspecific combinations including the most closely related pair that was also studied histologically, almost all mature seeds appeared 'flat' and proved inviable; histological analyses revealed impaired endosperm proliferation at early globular embryo stages, concomitant with embryo arrest and seed abortion in both cross directions. The third interspecific combination yielded a mixture of flat, inviable and plump, viable seeds; many of the latter germinated and exhibited near-normal juvenile phenotypes or, in some instances, hybrid necrosis and impaired growth. CONCLUSIONS The overall results suggest that near-complete hybrid seed failure can evolve fairly rapidly and without apparent divergence in reproductive phenology/biology. While the evidence accrued here is largely circumstantial, early-acting disruptions of normal endosperm development are most probably the common cause of seed failure regardless of the type of endosperm (nuclear or cellular).
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Affiliation(s)
- Morgane Roth
- Plant Ecological Genetics, Institute of Integrative Biology & Zurich–Basel Plant Science Center, ETH Zurich, Zurich, Switzerland
| | - Ana M Florez-Rueda
- Plant Ecological Genetics, Institute of Integrative Biology & Zurich–Basel Plant Science Center, ETH Zurich, Zurich, Switzerland
| | - Stephan Griesser
- Plant Ecological Genetics, Institute of Integrative Biology & Zurich–Basel Plant Science Center, ETH Zurich, Zurich, Switzerland
| | - Margot Paris
- Plant Ecological Genetics, Institute of Integrative Biology & Zurich–Basel Plant Science Center, ETH Zurich, Zurich, Switzerland
| | - Thomas Städler
- Plant Ecological Genetics, Institute of Integrative Biology & Zurich–Basel Plant Science Center, ETH Zurich, Zurich, Switzerland
- For correspondence. Email
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Esposito F, Vereecken NJ, Gammella M, Rinaldi R, Laurent P, Tyteca D. Characterization of sympatric Platanthera bifolia and Platanthera chlorantha (Orchidaceae) populations with intermediate plants. PeerJ 2018; 6:e4256. [PMID: 29379684 PMCID: PMC5787349 DOI: 10.7717/peerj.4256] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/20/2017] [Indexed: 12/25/2022] Open
Abstract
Platanthera bifolia and P. chlorantha are terrestrial and rewarding orchids with a wide Eurasian distribution. Although genetically closely related, they exhibit significant morphological, phenological and ecological differences that maintain reproductive isolation between the species. However, where both species co-occur, individuals with intermediate phenotypic traits, often considered as hybrids, are frequently observed. Here, we combined neutral genetic markers (AFLPs), morphometrics and floral scent analysis (GC-MS) to investigate two mixed Platanthera populations where morphologically intermediate plants were found. Self-pollination experiments revealed a low level of autogamy and artificial crossings combined with assessments of fruit set and seed viability, showed compatibility between the two species. The results of the genetic analyses showed that morphologically intermediate plants had similar genetic patterns as the P. bifolia group. These results are corroborated also by floral scent analyses, which confirmed a strong similarity in floral scent composition between intermediate morphotypes and P. bifolia. Therefore, this study provided a much more detailed picture of the genetic structure of a sympatric zone between two closely allied species and supports the hypothesis that intermediate morphotypes in sympatry could reflect an adaptive evolution in response to local pollinator-mediated selection.
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Affiliation(s)
- Fabiana Esposito
- Earth and Life Institute—Biodiversity Research Centre, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Nicolas J. Vereecken
- Agroecology Lab, Brussels Bioengineering School, Université libre de Bruxelles (ULB), Brussels, Belgium
| | | | - Rosita Rinaldi
- Department of Biology, University of Naples Federico II, Napoli, Italy
| | - Pascal Laurent
- Unit of General Chemistry, Université Libre de Bruxelles, Brussels, Belgium
| | - Daniel Tyteca
- Earth and Life Institute—Biodiversity Research Centre, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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