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Li C, Wickell D, Kuo LY, Chen X, Nie B, Liao X, Peng D, Ji J, Jenkins J, Williams M, Shu S, Plott C, Barry K, Rajasekar S, Grimwood J, Han X, Sun S, Hou Z, He W, Dai G, Sun C, Schmutz J, Leebens-Mack JH, Li FW, Wang L. Extraordinary preservation of gene collinearity over three hundred million years revealed in homosporous lycophytes. Proc Natl Acad Sci U S A 2024; 121:e2312607121. [PMID: 38236735 PMCID: PMC10823260 DOI: 10.1073/pnas.2312607121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 12/11/2023] [Indexed: 01/23/2024] Open
Abstract
Homosporous lycophytes (Lycopodiaceae) are a deeply diverged lineage in the plant tree of life, having split from heterosporous lycophytes (Selaginella and Isoetes) ~400 Mya. Compared to the heterosporous lineage, Lycopodiaceae has markedly larger genome sizes and remains the last major plant clade for which no chromosome-level assembly has been available. Here, we present chromosomal genome assemblies for two homosporous lycophyte species, the allotetraploid Huperzia asiatica and the diploid Diphasiastrum complanatum. Remarkably, despite that the two species diverged ~350 Mya, around 30% of the genes are still in syntenic blocks. Furthermore, both genomes had undergone independent whole genome duplications, and the resulting intragenomic syntenies have likewise been preserved relatively well. Such slow genome evolution over deep time is in stark contrast to heterosporous lycophytes and is correlated with a decelerated rate of nucleotide substitution. Together, the genomes of H. asiatica and D. complanatum not only fill a crucial gap in the plant genomic landscape but also highlight a potentially meaningful genomic contrast between homosporous and heterosporous species.
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Affiliation(s)
- Cheng Li
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - David Wickell
- Boyce Thompson Institute, Ithaca, NY14853
- Plant Biology Section, Cornell University, Ithaca, NY14853
| | - Li-Yaung Kuo
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu300044, Taiwan
| | - Xueqing Chen
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Bao Nie
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Xuezhu Liao
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Dan Peng
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Jiaojiao Ji
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Jerry Jenkins
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL35806
| | - Mellissa Williams
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL35806
| | - Shengqiang Shu
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | - Christopher Plott
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL35806
| | - Kerrie Barry
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | - Shanmugam Rajasekar
- Arizona Genomics Institute, School of Plant Sciences, University of Arizona, Tucson, AZ85721
| | - Jane Grimwood
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL35806
| | - Xiaoxu Han
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Shichao Sun
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Zhuangwei Hou
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Weijun He
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
| | - Guanhua Dai
- Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, Yanji133000, China
| | - Cheng Sun
- College of Life Sciences, Capital Normal University, Beijing100048, China
| | - Jeremy Schmutz
- Genome Sequencing Center, HudsonAlpha Institute for Biotechnology, Huntsville, AL35806
- United States Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | | | - Fay-Wei Li
- Boyce Thompson Institute, Ithaca, NY14853
- Plant Biology Section, Cornell University, Ithaca, NY14853
| | - Li Wang
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen518000, China
- State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, Beijing100700, China
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2
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Harrington AD, Blake‐Mahmud J, Watkins JE. Antheridiogen controls spatial dynamics of sex expression in naturally occurring gametophytes of the tree fern Cyathea multiflora. AMERICAN JOURNAL OF BOTANY 2022; 109:1313-1325. [PMID: 35862812 PMCID: PMC9545132 DOI: 10.1002/ajb2.16040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 06/15/2023]
Abstract
PREMISE Antheridiogen systems are a set of pheromonal mechanisms that control sex expression in fern gametophytes. However, antheridiogen has rarely been studied outside of the laboratory, and little is known about its function in natural settings. Combining predictions based on field and laboratory study, we tested whether the sexual structure of gametophytic colonies of a tree fern were attributable to antheridiogen. METHODS Gametophytic colonies of the antheridiogen-producing tree fern Cyathea multiflora were collected at La Selva Biological Station in Costa Rica in January 2019. The sex of each gametophyte was determined, mapped, and spatial statistic approaches were used to examine the distribution of sex in each colony. RESULTS In all gametophytic colonies, males were most common, representing 62-68% of individuals. No hermaphroditic gametophytes were identified in any colony. A quadrat-based method showed female gametophytes were not clustered in each colony, while male gametophytes were clustered. In two of the colonies, the K(r) test statistic for males was greater than expected compared to random simulations of sex expression, indicating male sex expression was spatially associated with females. CONCLUSIONS This study provides the first documentation of spatial sex expression in natural settings of gametophytes of an antheridiogen-producing tree fern species. The profound impact of antheridiogen on gametophytic sex expression in field settings suggests this system is intimately tied to mating system, fitness, and genetic diversity in Cyathea multiflora.
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Affiliation(s)
- Aidan D. Harrington
- Plant and Microbial Biology Program, College of Biological SciencesUniversity of Minnesota Twin CitiesSt. PaulMN55108USA
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3
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Wang FG, Wang AH, Bai CK, Jin DM, Nie LY, Harris AJ, Che L, Wang JJ, Li SY, Xu L, Shen H, Gu YF, Shang H, Duan L, Zhang XC, Chen HF, Yan YH. Genome size evolution of the extant lycophytes and ferns. PLANT DIVERSITY 2022; 44:141-152. [PMID: 35505989 PMCID: PMC9043363 DOI: 10.1016/j.pld.2021.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 11/24/2021] [Accepted: 11/28/2021] [Indexed: 05/11/2023]
Abstract
Ferns and lycophytes have remarkably large genomes. However, little is known about how their genome size evolved in fern lineages. To explore the origins and evolution of chromosome numbers and genome size in ferns, we used flow cytometry to measure the genomes of 240 species (255 samples) of extant ferns and lycophytes comprising 27 families and 72 genera, of which 228 species (242 samples) represent new reports. We analyzed correlations among genome size, spore size, chromosomal features, phylogeny, and habitat type preference within a phylogenetic framework. We also applied ANOVA and multinomial logistic regression analysis to preference of habitat type and genome size. Using the phylogeny, we conducted ancestral character reconstruction for habitat types and tested whether genome size changes simultaneously with shifts in habitat preference. We found that 2C values had weak phylogenetic signal, whereas the base number of chromosomes (x) had a strong phylogenetic signal. Furthermore, our analyses revealed a positive correlation between genome size and chromosome traits, indicating that the base number of chromosomes (x), chromosome size, and polyploidization may be primary contributors to genome expansion in ferns and lycophytes. Genome sizes in different habitat types varied significantly and were significantly correlated with habitat types; specifically, multinomial logistic regression indicated that species with larger 2C values were more likely to be epiphytes. Terrestrial habitat is inferred to be ancestral for both extant ferns and lycophytes, whereas transitions to other habitat types occurred as the major clades emerged. Shifts in habitat types appear be followed by periods of genomic stability. Based on these results, we inferred that habitat type changes and multiple whole-genome duplications have contributed to the formation of large genomes of ferns and their allies during their evolutionary history.
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Affiliation(s)
- Fa-Guo Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Ai-Hua Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning, 530001, China
| | - Cheng-Ke Bai
- College of Life Sciences, Shaanxi Normal University, Xi'an, 710062, China
| | - Dong-Mei Jin
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, China
| | - Li-Yun Nie
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - AJ Harris
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- Department of Biology, Oberlin College, Oberlin, OH, 44074, USA
| | - Le Che
- College of Life Sciences, Shaanxi Normal University, Xi'an, 710062, China
| | - Juan-Juan Wang
- College of Life Sciences, Shaanxi Normal University, Xi'an, 710062, China
| | - Shi-Yu Li
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Lei Xu
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Hui Shen
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, China
| | - Yu-Feng Gu
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, China
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, the National Orchid Conservation Center of China and the Orchid Conservation & Research Center of Shenzhen, 518114, Shenzhen, China
- Life Science and Technology College, Harbin Normal University, Harbin, 150025, China
| | - Hui Shang
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, China
| | - Lei Duan
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
| | - Xian-Chun Zhang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Hong-Feng Chen
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
- Corresponding author.
| | - Yue-Hong Yan
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai, 201602, China
- Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, the National Orchid Conservation Center of China and the Orchid Conservation & Research Center of Shenzhen, 518114, Shenzhen, China
- Corresponding author. The National Orchid Conservation Center of China and the Orchid Conservation & Research Center of Shenzhen, 518114, Shenzhen, Guangdong, China.
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4
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Kinosian SP, Rowe CA, Wolf PG. Why Do Heterosporous Plants Have So Few Chromosomes? FRONTIERS IN PLANT SCIENCE 2022; 13:807302. [PMID: 35251082 PMCID: PMC8888854 DOI: 10.3389/fpls.2022.807302] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
The mechanisms controlling chromosome number, size, and shape, and the relationship of these traits to genome size, remain some of the least understood aspects of genome evolution. Across vascular plants, there is a striking disparity in chromosome number between homosporous and heterosporous lineages. Homosporous plants (comprising most ferns and some lycophytes) have high chromosome numbers compared to heterosporous lineages (some ferns and lycophytes and all seed plants). Many studies have investigated why homosporous plants have so many chromosomes. However, homospory is the ancestral condition from which heterospory has been derived several times. Following this phylogenetic perspective, a more appropriate question to ask is why heterosporous plants have so few chromosomes. Here, we review life history differences between heterosporous and homosporous plants, previous work on chromosome number and genome size in each lineage, known mechanisms of genome downsizing and chromosomal rearrangements, and conclude with future prospects for comparative research.
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Affiliation(s)
- Sylvia P. Kinosian
- Negaunee Institute for Plant Conservation Science, Chicago Botanic Garden, Glencoe, IL, United States
| | - Carol A. Rowe
- Earth System Science Center, The University of Alabama in Huntsville, Huntsville, AL, United States
| | - Paul G. Wolf
- Department of Biological Sciences, The University of Alabama in Huntsville, Huntsville, AL, United States
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5
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Lima LV, Sousa SMDE, Almeida TE, Salino A. State of the art in cytogenetics, insights into chromosome number evolution, and new C-value reports for the fern family Gleicheniaceae. AN ACAD BRAS CIENC 2021; 93:e20201881. [PMID: 34550205 DOI: 10.1590/0001-3765202120201881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 05/10/2021] [Indexed: 11/22/2022] Open
Abstract
Studies concerning the cytogenetics of Gleicheniaceae have been scarce, especially those employing evolutionary approaches. Two chromosome number evolutionary models have been hypothesized for Gleicheniaceae. One proposes that ancestral haploid numbers were small and that the chromosome numbers of extant species evolved through polyploidy. The other model proposes that, at the genus level, fern chromosome evolution occurred from ancestors with essentially the same high chromosome numbers seen in living lineages. Neither of those hypotheses has been tested based on phylogenetic frameworks. We sought to (i) present the state of the art of Gleicheniaceae chromosome numbers; (ii) test the two evolutionary models of chromosome numbers within a phylogenetic framework; (iii) test correlations between DNA contents and chromosome numbers in the family. We report here DNA C-values for five species, which increases the number of investigated taxa nearly twofold and report two new genera records. Ancestral state chromosome reconstruction corroborates the hypothesis that ancestral chromosome numbers in Gleicheniaceae were as high as those of extant lineages. Our results demonstrate the possible role of dysploidy in the evolutionary chromosome history of Gleicheniaceae at the genus level and suggest that the relationship between chromosome number and DNA content does not appear to be linear.
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Affiliation(s)
- Lucas Vieira Lima
- Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Departamento de Botânica, Laboratório de Sistemática Vegetal, Av. Antônio Carlos, 6627, 31270-901, Belo Horizonte, MG, Brazil
| | - Saulo Marçal DE Sousa
- Universidade Federal de Juiz de Fora, Instituto de Ciências Biológicas, Departamento de Biologia, Laboratório de Genética e Biotecnologia, Rua José Lourenço Kelmer, s/n, 36036-900 Juiz de Fora, MG, Brazil
| | - Thaís Elias Almeida
- Universidade Federal do Oeste do Pará, Herbário HSTM, Avenida Marechal Rondon, s/n, 68040-070 Santarém, PA, Brazil
| | - Alexandre Salino
- Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Departamento de Botânica, Laboratório de Sistemática Vegetal, Av. Antônio Carlos, 6627, 31270-901, Belo Horizonte, MG, Brazil
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6
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Wang J, Dong S, Yang L, Harris A, Schneider H, Kang M. Allopolyploid Speciation Accompanied by Gene Flow in a Tree Fern. Mol Biol Evol 2021; 37:2487-2502. [PMID: 32302390 DOI: 10.1093/molbev/msaa097] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Hybridization in plants may result in hybrid speciation or introgression and, thus, is now widely understood to be an important mechanism of species diversity on an evolutionary timescale. Hybridization is particularly common in ferns, as is polyploidy, which often results from hybrid crosses. Nevertheless, hybrid speciation as an evolutionary process in fern lineages remains poorly understood. Here, we employ flow cytometry, phylogeny, genomewide single nucleotide polymorphism data sets, and admixture and coalescent modeling to show that the scaly tree fern, Gymnosphaera metteniana is a naturally occurring allotetraploid species derived from hybridization between the diploids, G. denticulata and G. gigantea. Moreover, we detected ongoing gene flow between the hybrid species and its progenitors, and we found that G. gigantea and G. metteniana inhabit distinct niches, whereas climatic niches of G. denticulata and G. metteniana largely overlap. Taken together, these results suggest that either some degree of intrinsic genetic isolation between the hybrid species and its parental progenitors or ecological isolation over short distances may be playing an important role in the evolution of reproductive barriers. Historical climate change may have facilitated the origin of G. metteniana, with the timing of hybridization coinciding with a period of intensification of the East Asian monsoon during the Pliocene and Pleistocene periods in southern China. Our study of allotetraploid G. metteniana represents the first genomic-level documentation of hybrid speciation in scaly tree ferns and, thus, provides a new perspective on evolution in the lineage.
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Affiliation(s)
- Jing Wang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
| | - Shiyong Dong
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
| | - Lihua Yang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
| | - Aj Harris
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.,Department of Biology, Oberlin College, Oberlin, OH
| | - Harald Schneider
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, China
| | - Ming Kang
- Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
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7
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Huang CH, Qi X, Chen D, Qi J, Ma H. Recurrent genome duplication events likely contributed to both the ancient and recent rise of ferns. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2020; 62:433-455. [PMID: 31628713 DOI: 10.1111/jipb.12877] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 10/17/2019] [Indexed: 05/07/2023]
Abstract
Ferns, the second largest group of vascular plants, originated ~400 million years ago (Mya). They became dominant in the ancient Earth landscape before the angiosperms and are still important in current ecosystems. Many ferns have exceptionally high chromosome numbers, possibly resulting from whole-genome duplications (WGDs). However, WGDs have not been investigated molecularly across fern diversity. Here we detected and dated fern WGDs using a phylogenomic approach and by calculating synonymous substitution rates (Ks). We also investigated a possible correlation between proposed WGDs and shifts in species diversification rates. We identified 19 WGDs: three ancient events along the fern phylogenetic backbone that are shared by 66%-97% of extant ferns, with additional lineage-specific WGDs for eight orders, providing strong evidence for recurring genome duplications across fern evolutionary history. We also observed similar Ks peak values for more than half of these WGDs, with multiple WGDs occurring close to the Cretaceous (~145-66 Mya). Despite the repeated WGD events, the biodiversity of ferns declined during the Cretaceous, implying that other factors probably contributed to the floristic turnover from ferns to angiosperms. This study provides molecular evidence for recurring WGDs in ferns and offers important clues to the genomic evolutionary history of ferns.
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Affiliation(s)
- Chien-Hsun Huang
- Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering and State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, Institute of Plant Biology, Institute of Biodiversity Sciences, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Xinping Qi
- Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering and State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, Institute of Plant Biology, Institute of Biodiversity Sciences, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Duoyuan Chen
- Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering and State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, Institute of Plant Biology, Institute of Biodiversity Sciences, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Ji Qi
- Ministry of Education Key Laboratory of Biodiversity Sciences and Ecological Engineering and State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, Institute of Plant Biology, Institute of Biodiversity Sciences, Center for Evolutionary Biology, School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Hong Ma
- Department of Biology, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
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8
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Mishra N, Panda T, Lodhiyal N, Behera SK. Studies on the gametophytic development, mating behaviour and reproductive biology of Macrothelypteris torresiana (Gaudich.) Ching (Thelypteridaceae). Micron 2019; 124:102700. [PMID: 31185368 DOI: 10.1016/j.micron.2019.102700] [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: 04/12/2019] [Revised: 06/03/2019] [Accepted: 06/03/2019] [Indexed: 11/16/2022]
Abstract
Macrothelypteris torresiana is a terrestrial fern belongs to the family Thelypteridaceae. It is very imperative to know the germination and growth pattern of this fern to make strategy for ex- situ conservation. In the present study germination of spore, developmental pattern of prothallium with particular emphasis on emergence of antheridia as well as archegonia, their fertilization and development of sporophytes were studied. The spores were spheroidal or reniform with broadly winged fimbriate perispore having average size of 48 ± 3.6 × 39 ± 4.2 μm. The spores started germinating just after 6 days of plating and percentage of germination was 94%. The germination pattern of spore was Vittaria type and development of gametophyte was Aspidium type. After 27 days of plating, a very distinct cordate-shaped adult gametophyte with deep apical notch and unicellular papillate hairs throughout the gametophyte was developed. The rhizoids appeared away from the apical notch of the gametophyte. The gametophyte first developed archegonia on 32nd day, whereas antheridia were developed on 42nd day. In isolate culture the gametophytes did not develop any sporophyte whereas in composite culture juvenile sporophytes were emerged on 77th day. This suggests the plant has ability to reproduce only through inter-gametophytic selfing and crossing, hence decreasing the plant's capacity for colonization in a particular locality.
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Affiliation(s)
- Niranjan Mishra
- CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226 001, India
| | - Tribhuban Panda
- Kalahandi Institute for Tribology and Ethnobiology, Jilingdara, Kalahandi, Odisha, India
| | - Neelu Lodhiyal
- Department of Botany, DSB Campus, Kumaun University, Nainital, Uttarakhand, India
| | - Sandip Kumar Behera
- CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226 001, India.
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9
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Clark J, Hidalgo O, Pellicer J, Liu H, Marquardt J, Robert Y, Christenhusz M, Zhang S, Gibby M, Leitch IJ, Schneider H. Genome evolution of ferns: evidence for relative stasis of genome size across the fern phylogeny. THE NEW PHYTOLOGIST 2016; 210:1072-82. [PMID: 26756823 DOI: 10.1111/nph.13833] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 11/16/2015] [Indexed: 05/06/2023]
Abstract
The genome evolution of ferns has been considered to be relatively static compared with angiosperms. In this study, we analyse genome size data and chromosome numbers in a phylogenetic framework to explore three hypotheses: the correlation of genome size and chromosome number, the origin of modern ferns from ancestors with high chromosome numbers, and the occurrence of several whole-genome duplications during the evolution of ferns. To achieve this, we generated new genome size data, increasing the percentage of fern species with genome sizes estimated to 2.8% of extant diversity, and ensuring a comprehensive phylogenetic coverage including at least three species from each fern order. Genome size was correlated with chromosome number across all ferns despite some substantial variation in both traits. We observed a trend towards conservation of the amount of DNA per chromosome, although Osmundaceae and Psilotaceae have substantially larger chromosomes. Reconstruction of the ancestral genome traits suggested that the earliest ferns were already characterized by possessing high chromosome numbers and that the earliest divergences in ferns were correlated with substantial karyological changes. Evidence for repeated whole-genome duplications was found across the phylogeny. Fern genomes tend to evolve slowly, albeit genome rearrangements occur in some clades.
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Affiliation(s)
- James Clark
- Department of Life Sciences, Natural History Museum, London, SW7 5BD, UK
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Oriane Hidalgo
- Royal Botanic Gardens, Kew, Richmond, Surrey, TW8 3DS, UK
| | - Jaume Pellicer
- Royal Botanic Gardens, Kew, Richmond, Surrey, TW8 3DS, UK
| | - Hongmei Liu
- Shenzhen Key Laboratory of Southern Subtropical Plant Diversity, Fairylake Botanical Garden, Shenzhen & The Chinese Academy of Sciences, Shenzhen, 518004, China
| | - Jeannine Marquardt
- Department of Life Sciences, Natural History Museum, London, SW7 5BD, UK
| | - Yannis Robert
- 18, Rue des Capucines, F-97431, La Plaine des Palmistes, La Réunion, France
| | - Maarten Christenhusz
- Royal Botanic Gardens, Kew, Richmond, Surrey, TW8 3DS, UK
- Plant Gateway, 5 Talbot Street, Hertford, Hertfordshire, SG13 7BX, UK
| | - Shouzhou Zhang
- Shenzhen Key Laboratory of Southern Subtropical Plant Diversity, Fairylake Botanical Garden, Shenzhen & The Chinese Academy of Sciences, Shenzhen, 518004, China
| | - Mary Gibby
- Department of Science, Royal Botanic Garden Edinburgh, Edinburgh, EH3 5LR, UK
| | - Ilia J Leitch
- Royal Botanic Gardens, Kew, Richmond, Surrey, TW8 3DS, UK
| | - Harald Schneider
- Department of Life Sciences, Natural History Museum, London, SW7 5BD, UK
- School of Life Sciences, Sun Yatsen University, Guangzhou, 510275, Guangdong, China
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Relationships and origins of the Dryopteris varia (L.) Kuntze species complex (Dryopteridaceae) in Korea inferred from nuclear and chloroplast DNA sequences. BIOCHEM SYST ECOL 2013. [DOI: 10.1016/j.bse.2013.05.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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11
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Palaeoploidization and adaptation: An evolutionary strategy among pteridophytes with a reference to Ophioglossum L. THE NUCLEUS 2013. [DOI: 10.1007/s13237-013-0085-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Wang L, Schneider H, Wu Z, He L, Zhang X, Xiang Q. Indehiscent sporangia enable the accumulation of local fern diversity at the Qinghai-Tibetan Plateau. BMC Evol Biol 2012; 12:158. [PMID: 22929005 PMCID: PMC3560248 DOI: 10.1186/1471-2148-12-158] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 08/27/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Indehiscent sporangia are reported for only a few of derived leptosporangiate ferns. Their evolution has been likely caused by conditions in which promotion of self-fertilization is an evolutionary advantageous strategy such as the colonization of isolated regions and responds to stressful habitat conditions. The Lepisorus clathratus complex provides the opportunity to test this hypothesis because these derived ferns include specimens with regular dehiscent and irregular indehiscent sporangia. The latter occurs preferably in well-defined regions in the Himalaya. Previous studies have shown evidence for multiple origins of indehiscent sporangia and the persistence of populations with indehiscent sporangia at extreme altitudinal ranges of the Qinghai-Tibetan Plateau (QTP). RESULTS Independent phylogenetic relationships reconstructed using DNA sequences of the uniparentally inherited chloroplast genome and two low-copy nuclear genes confirmed the hypothesis of multiple origins of indehiscent sporangia and the restriction of particular haplotypes to indehiscent sporangia populations in the Lhasa and Nyingchi regions of the QTP. In contrast, the Hengduan Mountains were characterized by high haplotype diversity and the occurrence of accessions with and without indehiscent sporangia. Evidence was found for polyploidy and reticulate evolution in this complex. The putative case of chloroplast capture in the Nyingchi populations provided further evidence for the promotion of isolated but persistent populations by indehiscent sporangia. CONCLUSIONS The presented results confirmed the hypothesis that indehiscent sporangia promote the establishment of persistent population in different regions of the QTP. These results are consistent with the expectations of reproductive reassurance by promotion of self-fertilization that played a critical role in the assembly of populations in isolated locations and/or extreme habitats.
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Affiliation(s)
- Li Wang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
- Department of Botany, Natural History Museum, London, United Kingdom
- Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Harald Schneider
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
- Department of Botany, Natural History Museum, London, United Kingdom
| | - Zhiqiang Wu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Lijuan He
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
- Graduate University of Chinese Academy of Sciences, Beijing, China
| | - Xianchun Zhang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
| | - Qiaoping Xiang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, China
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Wang T, Su Y, Li Y. Population genetic variation in the tree fern Alsophila spinulosa (Cyatheaceae): effects of reproductive strategy. PLoS One 2012; 7:e41780. [PMID: 22911855 PMCID: PMC3404049 DOI: 10.1371/journal.pone.0041780] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/25/2012] [Indexed: 11/29/2022] Open
Abstract
Background Essentially all ferns can perform both sexual and asexual reproduction. Their populations represent suitable study objects to test the population genetic effects of different reproductive systems. Using the diploid homosporous fern Alsophila spinulosa as an example species, the main purpose of this study was to assess the relative impact of sexual and asexual reproduction on the level and structure of population genetic variation. Methodology/Principal Findings Inter-simple sequence repeats analysis was conducted on 140 individuals collected from seven populations (HSG, LCH, BPC, MPG, GX, LD, and ZHG) in China. Seventy-four polymorphic bands discriminated a total of 127 multilocus genotypes. Character compatibility analysis revealed that 50.0 to 70.0% of the genotypes had to be deleted in order to obtain a tree-like structure in the data set from populations HSG, LCH, MPG, BPC, GX, and LD; and there was a gradual decrease of conflict in the data set when genotypes with the highest incompatibility counts were successively deleted. In contrast, in population ZHG, only 33.3% of genotypes had to be removed to achieve complete compatibility in the data set, which showed a sharp decline in incompatibility upon the deletion of those genotypes. All populations examined possessed similar levels of genetic variation. Population ZHG was not found to be more differentiated than the other populations. Conclusions/Significance Sexual recombination is the predominant source of genetic variation in most of the examined populations of A. spinulosa. However, somatic mutation contributes most to the genetic variation in population ZHG. This change of the primary mode of reproduction does not cause a significant difference in the population genetic composition. Character compatibility analysis represents an effective approach to separate the role of sexual and asexual components in shaping the genetic pattern of fern populations.
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Affiliation(s)
- Ting Wang
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei, China
| | - Yingjuan Su
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
- * E-mail:
| | - Yuan Li
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
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de Groot GA, Verduyn B, Wubs ERJ, Erkens RHJ, During HJ. Inter-and intraspecific variation in fern mating systems after long-distance colonization: the importance of selfing. BMC PLANT BIOLOGY 2012; 12:3. [PMID: 22217252 PMCID: PMC3305374 DOI: 10.1186/1471-2229-12-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 01/04/2012] [Indexed: 05/21/2023]
Abstract
BACKGROUND Previous studies on the reproductive biology of ferns showed that mating strategies vary among species, and that polyploid species often show higher capacity for self-fertilization than diploid species. However, the amount of intraspecific variation in mating strategy and selfing capacity has only been assessed for a few species. Yet, such variation may have important consequences during colonization, as the establishment of any selfing genotypes may be favoured after long-distance dispersal (an idea known as Baker's law). RESULTS We examined intra-and interspecific variation in potential for self-fertilization among four rare fern species, of which two were diploids and two were tetraploids: Asplenium scolopendrium (2n), Asplenium trichomanes subsp. quadrivalens (4n), Polystichum setiferum (2n) and Polystichum aculeatum (4n). Sporophyte production was tested at different levels of inbreeding, by culturing gametophytes in isolation, as well as in paired cultures with a genetically different gametophyte. We tested gametophytes derived from various genetically different sporophytes from populations in a recently planted forest colonized through long-distance dispersal (Kuinderbos, the Netherlands), as well as from older, less disjunct populations.Sporophyte production in isolation was high for Kuinderbos genotypes of all four species. Selfing capacity did not differ significantly between diploids and polyploids, nor between species in general. Rather selfing capacity differed between genotypes within species. Intraspecific variation in mating system was found in all four species. In two species one genotype from the Kuinderbos showed enhanced sporophyte production in paired cultures. For the other species, including a renowned out crosser, selfing capacity was consistently high. CONCLUSIONS Our results for four different species suggest that intraspecific variation in mating system may be common, at least among temperate calcicole ferns, and that genotypes with high selfing capacity may be present among polyploid as well as diploid ferns. The surprisingly high selfing capacity of all genotypes obtained from the Kuinderbos populations might be due to the isolated position of these populations. These populations may have established through single-spore colonization, which is only possible for genotypes capable of self-fertilization. Our results therewith support the idea that selection for selfing genotypes may occur during long-distance colonization, even in normally outcrossing, diploid ferns.
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Affiliation(s)
- G Arjen de Groot
- Ecology and Biodiversity group, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Betty Verduyn
- Ecology and Biodiversity group, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - ER Jasper Wubs
- Ecology and Biodiversity group, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Roy HJ Erkens
- Ecology and Biodiversity group, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Heinjo J During
- Ecology and Biodiversity group, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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Nitta JH, Ebihara A, Ito M. Reticulate evolution in the Crepidomanes minutum species complex (Hymenophyllaceae). AMERICAN JOURNAL OF BOTANY 2011; 98:1782-800. [PMID: 22012924 DOI: 10.3732/ajb.1000484] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
PREMISE OF THE STUDY Hybridization is an important mechanism of speciation in plants and often results in complexes that comprise multiple sexual diploids and their hybrid offspring. However, the intricacy of these systems has prevented a thorough understanding of many groups. The Crepidomanes minutum species complex (Hymenophyllaceae) is a widely distributed, morphologically variable fern species complex. Although prior reports of apogamy and polyploidy suggest hybridization, it has never been the focus of a phylogenetic study. METHODS Morphology, nuclear (gapCp), and chloroplast (rbcL) DNA sequences, cytology, field observation, and spore counts were used to infer phylogeny and trace hybrid origins. KEY RESULTS The C. minutum species complex is composed of at least three major clades: the African clade, clade 1 (East Asia and the Pacific), and clade 2 (Southeast Asia and the South Pacific). Clades 1 and 2 differ strikingly in morphological variation (uniform in clade 1 vs. highly variable in clade 2) and occurrence of hybrids (rare in clade 1 vs. frequent in clade 2). Apogamy and polyploidy were confirmed as likely mechanisms of hybrid stabilization in clade 2. Despite the large genetic distance between clades 1 and 2, several specimens were observed with gapCp sequences from both; diploid genome size and sexual reproduction indicate maintenance of genetic diversity via introgression or incomplete lineage sorting, rather than ongoing hybridization, in these specimens. CONCLUSIONS The C. minutum species complex is a reticulate network including multiple diploid lineages and their stabilized hybrid crosses. Additional sampling focused on reproductive mode and ploidy level is needed to delimit diploid species and hybrids.
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Affiliation(s)
- Joel H Nitta
- Department of System Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
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Perrie LR, Shepherd LD, De Lange PJ, Brownsey PJ. Parallel polyploid speciation: distinct sympatric gene-pools of recurrently derived allo-octoploid Asplenium ferns. Mol Ecol 2010; 19:2916-32. [PMID: 20579287 DOI: 10.1111/j.1365-294x.2010.04705.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Although polyploidy is widespread, its significance to the generation of biodiversity remains unclear. Many polyploids have been derived recurrently. For a particular polyploid, gene-flow between the products of independent origin is typical where they come into contact. Here, we use AFLP DNA-fingerprinting and chloroplast DNA sequences to demonstrate parallel polyploid speciation within both of the ferns Asplenium cimmeriorum and A. gracillimum. Both of these taxa comprise at least two allopolyploids, recurrently derived from the same progenitor pair. Each of these allopolyploids remain genetically distinguishable even with extensive sympatry, and could therefore be considered distinct species. To our knowledge, parallel speciation on this scale amongst recurrent polyploids has not been previously reported. With their parallel origins, these 'evolutionary replicates' provide an unrivalled opportunity to investigate how the reproductive barriers and ecological differentiation necessary for speciation arise following polyploidy.
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Affiliation(s)
- Leon R Perrie
- Museum of New Zealand Te Papa Tongarewa, PO Box 467, Wellington, New Zealand.
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Hennequin S, Ebihara A, Dubuisson JY, Schneider H. Chromosome number evolution in Hymenophyllum (Hymenophyllaceae), with special reference to the subgenus Hymenophyllum. Mol Phylogenet Evol 2010; 55:47-59. [DOI: 10.1016/j.ympev.2010.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 12/15/2009] [Accepted: 01/03/2010] [Indexed: 10/20/2022]
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Aagaard S, Greilhuber J, Zhang XC, Wikström N. Occurrence and evolutionary origins of polyploids in the clubmoss genus Diphasiastrum (Lycopodiaceae). Mol Phylogenet Evol 2009; 52:746-54. [DOI: 10.1016/j.ympev.2009.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 04/12/2009] [Accepted: 05/04/2009] [Indexed: 10/20/2022]
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Taylor TN, Kerp H, Hass H. Life history biology of early land plants: deciphering the gametophyte phase. Proc Natl Acad Sci U S A 2005; 102:5892-7. [PMID: 15809414 PMCID: PMC556298 DOI: 10.1073/pnas.0501985102] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ca. 400-million-year-old Rhynie chert biota represents a benchmark for studies of early terrestrial ecosystems. The exquisite preservation of the organisms documents an ancient biodiversity that also includes various levels of biological interaction. Absent from the picture until recently has been detailed information about the development of the gametophyte phase and the alternation of generations of the macroplants in this ecosystem. Here, we trace the development of the gametophyte phase of Aglaophyton, an early land plant with an unusual complement of structural and morphological characters. Mature gametophytes consist of a fleshy protocorm attached to the substrate by basal rhizoids; arising from the upper surface are one to several upright gametangiophores bearing multiple gametangia. Stomata are present on the upper surface of the protocorm and gametangiophore, and endomycorrhizal fungi extend throughout the gametophyte. Gametophytes are unisexual, producing either antheridiophores or archegoniophores. There is no evidence that gametophytes later become hermaphroditic. The sexual dimorphism of the Rhynie chert gametophytes is inconsistent with theoretical ideas about the haploid phase of early land plants. The gametophyte phase of early land plants can now be considered within an ecological and evolutionary framework that, in turn, can be used to develop hypotheses about some aspects of the population dynamics and growth of these early land plants.
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Affiliation(s)
- Thomas N Taylor
- Department of Ecology and Evolutionary Biology and Natural History Museum and Biodiversity Research Center, University of Kansas, Lawrence, KS 66045-7534, USA.
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