1
|
Peris D, Condamine FL. The angiosperm radiation played a dual role in the diversification of insects and insect pollinators. Nat Commun 2024; 15:552. [PMID: 38253644 PMCID: PMC10803743 DOI: 10.1038/s41467-024-44784-4] [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: 02/23/2023] [Accepted: 01/04/2024] [Indexed: 01/24/2024] Open
Abstract
Interactions with angiosperms have been hypothesised to play a crucial role in driving diversification among insects, with a particular emphasis on pollinator insects. However, support for coevolutionary diversification in insect-plant interactions is weak. Macroevolutionary studies of insect and plant diversities support the hypothesis that angiosperms diversified after a peak in insect diversity in the Early Cretaceous. Here, we used the family-level fossil record of insects as a whole, and insect pollinator families in particular, to estimate diversification rates and the role of angiosperms on insect macroevolutionary history using a Bayesian process-based approach. We found that angiosperms played a dual role that changed through time, mitigating insect extinction in the Cretaceous and promoting insect origination in the Cenozoic, which is also recovered for insect pollinator families only. Although insects pollinated gymnosperms before the angiosperm radiation, a radiation of new pollinator lineages began as angiosperm lineages increased, particularly significant after 50 Ma. We also found that global temperature, increases in insect diversity, and spore plants were strongly correlated with origination and extinction rates, suggesting that multiple drivers influenced insect diversification and arguing for the investigation of different explanatory variables in further studies.
Collapse
Affiliation(s)
- David Peris
- Institut Botànic de Barcelona (CSIC-CMCNB), 08038, Barcelona, Spain.
| | - Fabien L Condamine
- CNRS, Institut des Sciences de l'Evolution de Montpellier, Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, France
| |
Collapse
|
2
|
Liu W, Xu X, Wang X. Unique Morphology of Sarcobatus baileyi Male Inflorescence and Its Botanical Implications. PLANTS (BASEL, SWITZERLAND) 2023; 12:plants12091917. [PMID: 37176975 PMCID: PMC10180837 DOI: 10.3390/plants12091917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 04/28/2023] [Accepted: 05/02/2023] [Indexed: 05/15/2023]
Abstract
A typical angiosperm flower is usually bisexual, with entomophilous plants having four whorls of organs: the calyx, corolla, stamens, and gynoecium. The flower is usually colorful, and thus, distinct from the dull-colored reproductive organs of gymnosperms; however, this formula is not applicable to all flowers. For example, the male flower of Sarcobatus baileyi is reduced into only a single stamen. Such unusual flowers are largely poorly documented and underappreciated. To fill such a lacuna in our knowledge of the male reproductive organ of S. baileyi, we collected and studied materials of the male inflorescence of S. baileyi (Sarcobataceae). The outcomes of our Micro-CT (micro computed tomography), SEM (scanning electron microscopy), and paraffin sectioning indicate that a male inflorescence of S. baileyi is more comparable with the cone of conifers; its male flowers lack the perianth, are directly attached to a central axis and sheltered by peltate indusium-like shields. To understand the evolutionary logic underlying such a rarely seen male inflorescence, we also studied and compared it with a female cone of Cupressus sempervirens. Although the genera Sarcobatus and Cupressus belong to two distinct major plant groups (angiosperms and gymnosperms), they apply the same propagule-protecting strategy.
Collapse
Affiliation(s)
- Wenzhe Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), School of Life Sciences, Northwest University, Xi'an 710069, China
| | - Xiuping Xu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Xin Wang
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and CAS Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China
| |
Collapse
|
3
|
Coiro M, Roberts EA, Hofmann CC, Seyfullah LJ. Cutting the long branches: Consilience as a path to unearth the evolutionary history of Gnetales. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1082639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The Gnetales are one of the most fascinating groups within seed plants. Although the advent of molecular phylogenetics has generated some confidence in their phylogenetic placement of Gnetales within seed plants, their macroevolutionary history still presents many unknowns. Here, we review the reasons for such unknowns, and we focus the discussion on the presence of “long branches” both in their molecular and morphological history. The increased rate of molecular evolution and genome instability as well as the numerous unique traits (both reproductive and vegetative) in the Gnetales have been obstacles to a better understanding of their evolution. Moreover, the fossil record of the Gnetales, though relatively rich, has not yet been properly reviewed and investigated using a phylogenetic framework. Despite these apparent blocks to progress we identify new avenues to enable us to move forward. We suggest that a consilience approach, involving different disciplines such as developmental genetics, paleobotany, molecular phylogenetics, and traditional anatomy and morphology might help to “break” these long branches, leading to a deeper understanding of this mysterious group of plants.
Collapse
|
4
|
A Flower Bud from the Lower Cretaceous of China. BIOLOGY 2022; 11:biology11111598. [DOI: 10.3390/biology11111598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/27/2022] [Accepted: 10/27/2022] [Indexed: 11/06/2022]
Abstract
Background: Although various angiosperms (including their flowers) have been reported from the Yixian Formation (Lower Cretaceous) of China, which is famous worldwide for its fossils of early angiosperms, no flower bud has hitherto been seen in the Early Cretaceous. Such a lack of examples hinders our understanding of the evolution of flowers. Methods: The specimen studied in the present paper was collected from an outcrop of the Yixian Formation (the Barremian-Aptian, Lower Cretaceous) of Dawangzhangzi in Lingyuan, Liaoning, China. The specimen was photographed using a Nikon D200 digital camera, its details were observed and photographed using a Nikon SMZ1500 stereomicroscope, and some of its details were observed using a Leo 1530 VP SEM. Results: We report a fossilized flower bud, Archaebuda lingyuanensis gen. et sp. nov, from the Yixian Formation of China. The debut of Archaebuda in the Yixian Formation provides first-hand material for debate on the early evolution of angiosperm flowers and underscores the great diversity of angiosperms in the Yixian Formation.
Collapse
|
5
|
Klymiuk AA, Rothwell GW, Stockey RA. A novel cupulate seed plant, Xadzigacalix quatsinoensis gen. et sp. nov., provides new insight into the Mesozoic radiation of gymnosperms. AMERICAN JOURNAL OF BOTANY 2022; 109:966-985. [PMID: 35435244 PMCID: PMC9328379 DOI: 10.1002/ajb2.1853] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 06/14/2023]
Abstract
PREMISE Anatomically preserved evidence for a novel clade of gymnosperms emphasizes diversity of seed plants immediately prior to the appearance of angiosperm fossils in the paleontological record. METHODS Cupulate seeds from the Early Cretaceous Apple Bay locality (Vancouver Island) are described from serial cellulose acetate peels and three-dimensional reconstruction. Phylogenetic context is assessed through the comparative analysis of gymnosperm seed producing fructifications and maximum parsimony analysis of a revised morphological data set for seed plant phylogeny. RESULTS Xadzigacalix quatsinoensis gen. et sp. nov. is characterized by an orthotropous ovule with an elongated micropyle and complex integument, enclosed within a radial cupule. The micropylar canal is elongated; and the nucellus extends into the micropyle to seal the post pollination ovule. Except at the apex of the micropyle, the seed is completely enclosed by a parenchymatous cupule with ca. 20 axially elongated secretory ducts. The cupulate seed is produced upon a triangular woody stele, consisting of a parenchymatous pith surrounded by radially aligned tracheids. The stele produces three short terete traces that terminate within the base of the cupule as transfusion tissue at the seed chalaza. CONCLUSIONS Organography, vascularization, nature of the integument and nucellus, and configuration of the micropylar canal distinguish Xadzigacalix quatsinoensis from all other gymnosperm clades. Cladistic analyses suggest the new plant may have affinities with gnetophytes or angiosperms. These results are complemented with a critical re-evaluation of ovulate structures for Mesozoic gymnosperms, providing new insight into plant diversity immediately antecedent to the explosive diversification of flowering plants.
Collapse
Affiliation(s)
- Ashley A. Klymiuk
- Department of Biological SciencesUniversity of ManitobaWinnipegManitobaR3T 2N2Canada
- Gantz Family Collections Center, Field Museum, 1400 S Lake Shore DriveChicagoIL60605USA
| | - Gar W. Rothwell
- Department of Botany and Plant PathologyOregon State UniversityCorvallisOR97331−2902USA
- Department of Environmental and Plant Biology317 Porter Hall, Ohio UniversityAthensOH45701USA
| | - Ruth A. Stockey
- Department of Botany and Plant PathologyOregon State UniversityCorvallisOR97331−2902USA
| |
Collapse
|
6
|
Rudall PJ. Evolution and patterning of the ovule in seed plants. Biol Rev Camb Philos Soc 2021; 96:943-960. [PMID: 33432779 DOI: 10.1111/brv.12684] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 12/23/2020] [Accepted: 01/04/2021] [Indexed: 02/06/2023]
Abstract
The ovule and its developmental successor, the seed, together represent a highly characteristic feature of seed plants that has strongly enhanced the reproductive and dispersal potential of this diverse group of taxa. Ovules encompass multiple tissues that perform various roles within a highly constrained space, requiring a complex cascade of genes that generate localized cell proliferation and programmed cell death during different developmental stages. Many heritable morphological differences among lineages reflect relative displacement of these tissues, but others, such as the second (outer) integuments of angiosperms and Gnetales, represent novel and apparently profound and independent innovations. Recent studies, mostly on model taxa, have considerably enhanced our understanding of gene expression in the ovule. However, understanding its evolutionary history requires a comparative and phylogenetic approach that is problematic when comparing extant angiosperms not only with phylogenetically distant extant gymnosperms but also with taxa known only from fossils. This paper reviews ovule characters across a phylogenetically broad range of seed plants in a dynamic developmental context. It discusses both well-established and recent theories of ovule and seed evolution and highlights potential gaps in comparative data that will usefully enhance our understanding of evolutionary transitions and developmental mechanisms.
Collapse
Affiliation(s)
- Paula J Rudall
- Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, U.K
| |
Collapse
|
7
|
Schönenberger J, von Balthazar M, López Martínez A, Albert B, Prieu C, Magallón S, Sauquet H. Phylogenetic analysis of fossil flowers using an angiosperm-wide data set: proof-of-concept and challenges ahead. AMERICAN JOURNAL OF BOTANY 2020; 107:1433-1448. [PMID: 33026116 PMCID: PMC7702048 DOI: 10.1002/ajb2.1538] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 07/08/2020] [Indexed: 05/29/2023]
Abstract
PREMISE Significant paleobotanical discoveries in recent decades have considerably improved our understanding of the early evolution of angiosperms and their flowers. However, our ability to test the systematic placement of fossil flowers on the basis of phylogenetic analyses has remained limited, mainly due to the lack of an adequate, angiosperm-wide morphological data set for extant taxa. Earlier attempts to place fossil flowers phylogenetically were, therefore, forced to make prior qualitative assessments of the potential systematic position of fossils and to restrict phylogenetic analyses to selected angiosperm subgroups. METHODS We conduct angiosperm-wide molecular backbone analyses of 10 fossil flower taxa selected from the Cretaceous record. Our analyses make use of a floral trait data set built within the framework of the eFLOWER initiative. We provide an updated version of this data set containing data for 28 floral and two pollen traits for 792 extant species representing 372 angiosperm families. RESULTS We find that some fossils are placed congruently with earlier hypotheses while others are found in positions that had not been suggested previously. A few take up equivocal positions, including the stem branches of large clades. CONCLUSIONS Our study provides an objective approach to test for the phylogenetic position of fossil flowers across angiosperms. Such analyses may provide a complementary tool for paleobotanical studies, allowing for a more comprehensive understanding of fossil phylogenetic relationships in angiosperms. Ongoing work focused on extending the sampling of extant taxa and the number of floral traits will further improve the applicability and accuracy of our approach.
Collapse
Affiliation(s)
- Jürg Schönenberger
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 14ViennaA‐1030Austria
| | - Maria von Balthazar
- Department of Botany and Biodiversity ResearchUniversity of ViennaRennweg 14ViennaA‐1030Austria
| | - Andrea López Martínez
- Instituto de BiologíaUniversidad Nacional Autónoma de MéxicoCircuito Exterior, Ciudad Universitaria, CoyoacánMéxico City04510Mexico
| | - Béatrice Albert
- Ecologie Systématique EvolutionUniv. Paris‐SudCNRSAgroParisTechUniversité Paris‐SaclayOrsay91400France
| | - Charlotte Prieu
- Ecologie Systématique EvolutionUniv. Paris‐SudCNRSAgroParisTechUniversité Paris‐SaclayOrsay91400France
| | - Susana Magallón
- Instituto de BiologíaUniversidad Nacional Autónoma de MéxicoCircuito Exterior, Ciudad Universitaria, CoyoacánMéxico City04510Mexico
| | - Hervé Sauquet
- Ecologie Systématique EvolutionUniv. Paris‐SudCNRSAgroParisTechUniversité Paris‐SaclayOrsay91400France
- National Herbarium of New South Wales (NSW)Royal Botanic Gardens and Domain TrustSydneyNSW2000Australia
- Evolution and Ecology Research CentreSchool of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyAustralia
| |
Collapse
|
8
|
Bell D, Lin Q, Gerelle WK, Joya S, Chang Y, Taylor ZN, Rothfels CJ, Larsson A, Villarreal JC, Li FW, Pokorny L, Szövényi P, Crandall-Stotler B, DeGironimo L, Floyd SK, Beerling DJ, Deyholos MK, von Konrat M, Ellis S, Shaw AJ, Chen T, Wong GKS, Stevenson DW, Palmer JD, Graham SW. Organellomic data sets confirm a cryptic consensus on (unrooted) land-plant relationships and provide new insights into bryophyte molecular evolution. AMERICAN JOURNAL OF BOTANY 2020; 107:91-115. [PMID: 31814117 DOI: 10.1002/ajb2.1397] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
PREMISE Phylogenetic trees of bryophytes provide important evolutionary context for land plants. However, published inferences of overall embryophyte relationships vary considerably. We performed phylogenomic analyses of bryophytes and relatives using both mitochondrial and plastid gene sets, and investigated bryophyte plastome evolution. METHODS We employed diverse likelihood-based analyses to infer large-scale bryophyte phylogeny for mitochondrial and plastid data sets. We tested for changes in purifying selection in plastid genes of a mycoheterotrophic liverwort (Aneura mirabilis) and a putatively mycoheterotrophic moss (Buxbaumia), and compared 15 bryophyte plastomes for major structural rearrangements. RESULTS Overall land-plant relationships conflict across analyses, generally weakly. However, an underlying (unrooted) four-taxon tree is consistent across most analyses and published studies. Despite gene coverage patchiness, relationships within mosses, liverworts, and hornworts are largely congruent with previous studies, with plastid results generally better supported. Exclusion of RNA edit sites restores cases of unexpected non-monophyly to monophyly for Takakia and two hornwort genera. Relaxed purifying selection affects multiple plastid genes in mycoheterotrophic Aneura but not Buxbaumia. Plastid genome structure is nearly invariant across bryophytes, but the tufA locus, presumed lost in embryophytes, is unexpectedly retained in several mosses. CONCLUSIONS A common unrooted tree underlies embryophyte phylogeny, [(liverworts, mosses), (hornworts, vascular plants)]; rooting inconsistency across studies likely reflects substantial distance to algal outgroups. Analyses combining genomic and transcriptomic data may be misled locally for heavily RNA-edited taxa. The Buxbaumia plastome lacks hallmarks of relaxed selection found in mycoheterotrophic Aneura. Autotrophic bryophyte plastomes, including Buxbaumia, hardly vary in overall structure.
Collapse
Affiliation(s)
- David Bell
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
- UBC Botanical Garden and Centre for Plant Research, University of British Columbia, 6804 Marine Drive SW, Vancouver, British Columbia, V6T 1Z4, Canada
- Royal Botanic Garden, 20A Inverleith Row, Edinburgh, EH3 5LR, UK
| | - Qianshi Lin
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
- UBC Botanical Garden and Centre for Plant Research, University of British Columbia, 6804 Marine Drive SW, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Wesley K Gerelle
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
- UBC Botanical Garden and Centre for Plant Research, University of British Columbia, 6804 Marine Drive SW, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Steve Joya
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Ying Chang
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, 97331, USA
| | - Z Nathan Taylor
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
| | - Carl J Rothfels
- University Herbarium and Department of Integrative Biology, University of California Berkeley, Berkeley, California, 94702, USA
| | - Anders Larsson
- Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Juan Carlos Villarreal
- Department of Biology, Université Laval, Québec, G1V 0A6, Canada
- Smithsonian Tropical Research Institute, Panama City, Panama
| | - Fay-Wei Li
- Boyce Thompson Institute, Ithaca, New York, 14853, USA
- Plant Biology Section, Cornell University, Ithaca, New York, 14853, USA
| | - Lisa Pokorny
- Royal Botanic Gardens, Kew, Richmond, TW9 3DS, Surrey, UK
- Centre for Plant Biotechnology and Genomics (CBGP, UPM-INIA), 28223, Pozuelo de Alarcón (Madrid), Spain
| | - Péter Szövényi
- Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
| | | | - Lisa DeGironimo
- Department of Biology, College of Arts and Science, New York University, New York, New York, 10003, USA
| | - Sandra K Floyd
- School of Biological Sciences, Monash University, Melbourne, Victoria, 3800, Australia
| | - David J Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Michael K Deyholos
- Department of Biology, University of British Columbia, Kelowna, British Columbia, V1V 1V7, Canada
| | - Matt von Konrat
- Field Museum of Natural History, Chicago, Illinois, 60605, USA
| | - Shona Ellis
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
| | - A Jonathan Shaw
- Department of Biology, Duke University, Durham, North Carolina, 27708, USA
| | - Tao Chen
- Shenzhen Fairy Lake Botanical Garden, Chinese Academy of Sciences, Shenzhen, Guangdong, 518004, China
| | - Gane K-S Wong
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
- Department of Medicine, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
- BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen, 518083, China
| | | | - Jeffrey D Palmer
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
| | - Sean W Graham
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
- UBC Botanical Garden and Centre for Plant Research, University of British Columbia, 6804 Marine Drive SW, Vancouver, British Columbia, V6T 1Z4, Canada
| |
Collapse
|
9
|
Rudall PJ, Bateman RM. Leaf surface development and the plant fossil record: stomatal patterning in Bennettitales. Biol Rev Camb Philos Soc 2019; 94:1179-1194. [DOI: 10.1111/brv.12497] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 12/17/2018] [Accepted: 12/20/2018] [Indexed: 11/28/2022]
|
10
|
Fu Q, Diez JB, Pole M, García Ávila M, Liu ZJ, Chu H, Hou Y, Yin P, Zhang GQ, Du K, Wang X. An unexpected noncarpellate epigynous flower from the Jurassic of China. eLife 2018; 7:38827. [PMID: 30558712 PMCID: PMC6298773 DOI: 10.7554/elife.38827] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 11/04/2018] [Indexed: 11/28/2022] Open
Abstract
The origin of angiosperms has been a long-standing botanical debate. The great diversity of angiosperms in the Early Cretaceous makes the Jurassic a promising period in which to anticipate the origins of the angiosperms. Here, based on observations of 264 specimens of 198 individual flowers preserved on 34 slabs in various states and orientations, from the South Xiangshan Formation (Early Jurassic) of China, we describe a fossil flower, Nanjinganthus dendrostyla gen. et sp. nov.. The large number of specimens and various preservations allow for an evidence-based reconstruction of the flower. From the evidence of the combination of an invaginated receptacle and ovarian roof, we infer that the seeds of Nanjinganthus were completely enclosed. Evidence of an actinomorphic flower with a dendroid style, cup-form receptacle, and angiospermy, is consistent with Nanjinganthus being a bona fide angiosperm from the Jurassic, an inference that we hope will re-invigorate research into angiosperm origins. From oranges to apples, flowering plants produce most of the fruits and vegetables that we can see on display in a supermarket. While we may take little notice of the poppy fields and plum blossoms around us, how flowers came to be has been an intensely debated mystery. The current understanding, which is mainly based on previously available fossils, is that flowers appeared about 125 million years ago in the Cretaceous, an era during which many insects such as bees also emerged. But not everybody agrees that this is the case. Genetic analyses, for example, suggest that flowering plants are much more ancient. Another intriguing element is that flowers seemed to have arisen during the Cretaceous ‘out of nowhere’. Fossils are essential to help settle the debate but it takes diligence and luck to find something as fragile as a flower preserved in rocks for millions of years. In addition, digging out what could look like a bloom is not enough. It is only if the ovules (the cells that will become seeds when fertilized) of the plant are completely enclosed inside the ovary before pollination that researchers can definitely say that they have found a ‘true’ flower. Now, Fu et al. describe over 200 specimens of a new fossil flower that presents this characteristic, as well as other distinctive features such as petals and sepals – the leaf-like parts that protect a flower bud. Called Nanjinganthus, the plant dates back to more than 174 million years ago, making it the oldest known record of a ‘true’ flower by almost 50 million years. Contrary to mainstream belief, this would place the apparition of flowering plants to the Early Jurassic, the period that saw dinosaurs dominating the planet. This discovery may reshape our current understanding of the evolution of flowers.
Collapse
Affiliation(s)
- Qiang Fu
- CAS Key Laboratory of Economic Stratigraphy and Paleogeography, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, China
| | | | - Mike Pole
- Queensland Herbarium, Brisbane Botanical Gardens Mt Coot-tha, Toowong, Australia
| | - Manuel García Ávila
- Departamento de Geociencias, Universidad de Vigo, Vigo, Spain.,Facultade de Bioloxía, Asociación Paleontolóxica Galega, Universidade de Vigo, Vigo, Spain
| | - Zhong-Jian Liu
- State Forestry Administration Key Laboratory of Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Hang Chu
- Tianjin Center, China Geological Survey, Tianjin, China
| | - Yemao Hou
- Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
| | - Pengfei Yin
- Key Laboratory of Vertebrate Evolution and Human Origin of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, China
| | - Guo-Qiang Zhang
- State Forestry Administration Key Laboratory of Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Kaihe Du
- Jiangsu Key Laboratory for Supramolecular Medicinal Materials and Applications, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Xin Wang
- CAS Key Laboratory of Economic Stratigraphy and Paleogeography, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, China
| |
Collapse
|
11
|
Savoretti A, Bippus AC, Stockey RA, Rothwell GW, Tomescu AMF. Grimmiaceae in the Early Cretaceous: Tricarinella crassiphylla gen. et sp. nov. and the value of anatomically preserved bryophytes. ANNALS OF BOTANY 2018; 121:1275-1286. [PMID: 29444206 PMCID: PMC6007789 DOI: 10.1093/aob/mcy015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 01/22/2018] [Indexed: 06/08/2023]
Abstract
Background and Aims Widespread and diverse in modern ecosystems, mosses are rare in the fossil record, especially in pre-Cenozoic rocks. Furthermore, most pre-Cenozoic mosses are known from compression fossils, which lack detailed anatomical information. When preserved, anatomy significantly improves resolution in the systematic placement of fossils. Lower Cretaceous (Valanginian) deposits on Vancouver Island (British Columbia, Canada) contain a diverse anatomically preserved flora including numerous bryophytes, many of which have yet to be characterized. Among them is the grimmiaceous moss described here. Methods One fossil moss gametophyte preserved in a carbonate concretion was studied in serial sections prepared using the cellulose acetate peel technique. Key Results Tricarinella crassiphylla gen. et sp. nov. is a moss with tristichous phyllotaxis and strongly keeled leaves. The combination of an acrocarpous condition (inferred based on a series of morphological features), a central conducting strand, a homogeneous leaf costa and a lamina with bistratose portions and sinuous cells, and multicellular gemmae, supports placement of Tricarinella in family Grimmiaceae. Tricarinella is similar to Grimmia, a genus that exhibits broad morphological variability. However, tristichous phyllotaxis and especially the lamina, bistratose at the base but not in distal portions of the leaf, set Tricarinella apart as a distinct genus. Conclusions Tricarinella crassiphylla marks the oldest record for both family Grimmiaceae and sub-class Dicranidae, providing a hard minimum age (136 million years) for these groups. The fact that this fossil could be placed in an extant family, despite a diminutive size, emphasizes the considerable resolving power of anatomically preserved bryophyte fossils, even when recovered from allochthonous assemblages of marine sediments, such as the Apple Bay flora. Discovery of Tricarinella re-emphasizes the importance of paleobotanical studies as the only approach allowing access to a significant segment of biodiversity, the extinct biodiversity, which is unattainable by other means of investigation.
Collapse
Affiliation(s)
- Adolfina Savoretti
- Instituto de Botánica Darwinion, San Isidro and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Alexander C Bippus
- Department of Biological Sciences, Humboldt State University, Arcata, CA, USA
| | - Ruth A Stockey
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Gar W Rothwell
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
- Department of Environmental and Plant Biology, Ohio University, Athens, OH, USA
| | | |
Collapse
|
12
|
Bomfleur B, Grimm GW, McLoughlin S. The fossil Osmundales (Royal Ferns)-a phylogenetic network analysis, revised taxonomy, and evolutionary classification of anatomically preserved trunks and rhizomes. PeerJ 2017; 5:e3433. [PMID: 28713650 PMCID: PMC5508817 DOI: 10.7717/peerj.3433] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 05/17/2017] [Indexed: 12/03/2022] Open
Abstract
The Osmundales (Royal Fern order) originated in the late Paleozoic and is the most ancient surviving lineage of leptosporangiate ferns. In contrast to its low diversity today (less than 20 species in six genera), it has the richest fossil record of any extant group of ferns. The structurally preserved trunks and rhizomes alone are referable to more than 100 fossil species that are classified in up to 20 genera, four subfamilies, and two families. This diverse fossil record constitutes an exceptional source of information on the evolutionary history of the group from the Permian to the present. However, inconsistent terminology, varying formats of description, and the general lack of a uniform taxonomic concept renders this wealth of information poorly accessible. To this end, we provide a comprehensive review of the diversity of structural features of osmundalean axes under a standardized, descriptive terminology. A novel morphological character matrix with 45 anatomical characters scored for 15 extant species and for 114 fossil operational units (species or specimens) is analysed using networks in order to establish systematic relationships among fossil and extant Osmundales rooted in axis anatomy. The results lead us to propose an evolutionary classification for fossil Osmundales and a revised, standardized taxonomy for all taxa down to the rank of (sub)genus. We introduce several nomenclatural novelties: (1) a new subfamily Itopsidemoideae (Guaireaceae) is established to contain Itopsidema, Donwelliacaulis, and Tiania; (2) the thamnopteroid genera Zalesskya, Iegosigopteris, and Petcheropteris are all considered synonymous with Thamnopteris; (3) 12 species of Millerocaulis and Ashicaulis are assigned to modern genera (tribe Osmundeae); (4) the hitherto enigmatic Aurealcaulis is identified as an extinct subgenus of Plenasium; and (5) the poorly known Osmundites tuhajkulensis is assigned to Millerocaulis. In addition, we consider Millerocaulis stipabonettiorum a possible member of Palaeosmunda and Millerocaulis estipularis as probably constituting the earliest representative of the (Todea-)Leptopteris lineage (subtribe Todeinae) of modern Osmundoideae.
Collapse
Affiliation(s)
- Benjamin Bomfleur
- Institut für Geologie und Paläontologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
- Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden
| | - Guido W. Grimm
- Department für Paläontologie, Universität Wien, Wien, Austria
- Orléans, France
| | - Stephen McLoughlin
- Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden
| |
Collapse
|
13
|
Liu ZJ, Wang X. Yuhania: a unique angiosperm from the Middle Jurassic of Inner Mongolia, China. HISTORICAL BIOLOGY 2017; 29:431-441. [PMID: 28392623 PMCID: PMC5359780 DOI: 10.1080/08912963.2016.1178740] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 04/12/2016] [Indexed: 05/10/2023]
Abstract
Despite increasing claims of pre-Cretaceous angiosperms, whether there really are angiosperms in the Jurassic is apparently still an open question for many people before further evidence is available. This question can only be answered by studying more Jurassic plant fossils. Here we report a fossil angiosperm, Yuhania daohugouensis gen. et sp. nov, from the Middle Jurassic of Inner Mongolia, China. The plant includes connected stem, leaves, flowers, aggregate fruits, fruitlets, and seeds within fruitlets. The leaves are helically arranged along the curving stem, linear in shape, with 5-6 parallel veins. The aggregate fruit is pedicellate, composed of over 20 carpels/fruitlets helically arranged. Each fruitlet encloses a seed. The reproductive organs in various stages are found in the same plant, allowing us to understand the development of Yuhania. The occurrence of Yuhania in the Middle Jurassic re-confirms the Jurassic history for angiosperms that has been suggested by other independent research and adds to the on-going study on the early evolution of angiosperms.
Collapse
Affiliation(s)
- Zhong-Jian Liu
- Shenzhen Key Laboratory for Orchid Conservation and Utilization, National Orchid Conservation Center of China and Orchid Conservation & Research Center of Shenzhen, Shenzhen518114, China
| | - Xin Wang
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, CAS, Nanjing210008, China
| |
Collapse
|
14
|
Liu ZJ, Wang X. A perfect flower from the Jurassic of China. HISTORICAL BIOLOGY 2016; 28:707-719. [PMID: 27134345 PMCID: PMC4841032 DOI: 10.1080/08912963.2015.1020423] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 02/03/2015] [Accepted: 02/04/2015] [Indexed: 05/10/2023]
Abstract
Flower, enclosed ovule and tetrasporangiate anther are three major characters distinguishing angiosperms from other seed plants. Morphologically, typical flowers are characterised by an organisation with gynoecium and androecium surrounded by corolla and calyx. Theoretically, flowers are derived from their counterparts in ancient ancestral gymnosperms. However, as for when, how and from which groups, there is no consensus among botanists yet. Although angiosperm-like pollen and angiosperms have been claimed in the Triassic and Jurassic, typical flowers with the aforesaid three key characters are still missing in the pre-Cretaceous age, making many interpretations of flower evolution tentative. Thus searching for flower in the pre-Cretaceous has been a tantalising task for palaeobotanists for a long time. Here, we report a typical flower, Euanthus paniigen. et sp. nov., from the Middle-Late Jurassic of Liaoning, China. Euanthus has sepals, petals, androecium with tetrasporangiate dithecate anthers and gynoecium with enclosed ovules, organised just like in perfect flowers of extant angiosperms. The discovery of Euanthus implies that typical angiosperm flowers have already been in place in the Jurassic, and provides a new insight unavailable otherwise for the evolution of flowers.
Collapse
Affiliation(s)
- Zhong-Jian Liu
- Shenzhen Key Laboratory for Orchid Conservation and Utilization, National Orchid Conservation Center of China and Orchid Conservation and Research Center of Shenzhen, Shenzhen518114, P.R. China
| | - Xin Wang
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Nanjing210008, P.R. China
- Palaeontological Center, Bohai University, Jinzhou121013, P.R. China
- Corresponding author.
| |
Collapse
|
15
|
Rothwell GW, Stockey RA. Phylogenetic diversification of Early Cretaceous seed plants: The compound seed cone of Doylea tetrahedrasperma. AMERICAN JOURNAL OF BOTANY 2016; 103:923-937. [PMID: 27208360 DOI: 10.3732/ajb.1600030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 03/07/2016] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Discovery of cupulate ovules of Doylea tetrahedrasperma within a compact, compound seed cone highlights the rich diversity of fructification morphologies, pollination biologies, postpollination enclosure of seeds, and systematic diversity of Early Cretaceous gymnosperms. METHODS Specimens were studied using the cellulose acetate peel technique, three-dimensional reconstructions (in AVIZO), and morphological phylogenetic analyses (in TNT). KEY RESULTS Doylea tetrahedrasperma has bract/fertile short shoot complexes helically arranged within a compact, compound seed cone. Complexes diverge from the axis as a single unit and separate distally into a free bract tip and two sporophylls. Each sporophyll bears a single, abaxial seed, recurved toward the cone axis, that is enveloped after pollinaton by sporophyll tissue, forming a closed cupule. Ovules are pollinated by bisaccate grains captured by micropylar pollination horns. CONCLUSIONS The unique combination of characters shown by D. tetrahedrasperma includes the presence of cupulate seeds borne in conifer-like compound seed cones, an ovuliferous scale analogue structurally equivalent to the ovulate stalk of Ginkgo biloba, gymnospermous pollination, and nearly complete enclosure of mature seeds. These features characterize the Doyleales ord. nov., clearly distinguish it from the seed fern order Corystospermales, and allow for recognition of another recently described Early Cretaceous seed plant as a second species in genus Doylea. A morphological phylogenetic analysis highlights systematic relationships of the Doyleales ord. nov. and emphasizes the explosive phylogenetic diversification of gymnosperms that was underway at the time when flowering plants may have originated and/or first began to radiate.
Collapse
Affiliation(s)
- Gar W Rothwell
- Department of Botany and Plant Pathology, 2082 Cordley Hall, Oregon State University, Corvallis, Oregon 97331, USA Department of Environmental and Plant Biology, Ohio University, Athens, Ohio 45701, USA
| | - Ruth A Stockey
- Department of Botany and Plant Pathology, 2082 Cordley Hall, Oregon State University, Corvallis, Oregon 97331, USA
| |
Collapse
|
16
|
Tomescu AMF, Wyatt SE, Hasebe M, Rothwell GW. Early evolution of the vascular plant body plan - the missing mechanisms. CURRENT OPINION IN PLANT BIOLOGY 2014; 17:126-36. [PMID: 24507504 DOI: 10.1016/j.pbi.2013.11.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 11/12/2013] [Accepted: 11/27/2013] [Indexed: 05/03/2023]
Abstract
The complex body plan of modern vascular plants evolved by modification of simple systems of branching axes which originated from the determinate vegetative axis of a bryophyte-grade ancestor. Understanding body plan evolution and homologies has implications for land plant phylogeny and requires resolution of the specific developmental changes and their evolutionary sequence. The branched sporophyte may have evolved from a sterilized bryophyte sporangium, but prolongation of embryonic vegetative growth is a more parsimonious explanation. Research in the bryophyte model system Physcomitrella points to mechanisms regulating sporophyte meristem maintenance, indeterminacy, branching and the transition to reproductive development. These results can form the basis for hypotheses to identify and refine the nature and sequence of changes in development that occurred during the evolution of the indeterminate branched sporophyte from an unbranched bryophyte-grade sporophyte.
Collapse
Affiliation(s)
- Alexandru M F Tomescu
- Department of Biological Sciences, Humboldt State University, Arcata, CA 95521, USA.
| | - Sarah E Wyatt
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
| | - Mitsuyasu Hasebe
- National Institute for Basic Biology and Department of Basic Biology, School of Life Science, The Graduate School for Advanced Studies, Okazaki 444-8585, Japan
| | - Gar W Rothwell
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA; Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| |
Collapse
|
17
|
Little SA, Jacobs B, McKechnie SJ, Cooper RL, Christianson ML, Jernstedt JA. Branch architecture in Ginkgo biloba: wood anatomy and long shoot-short shoot interactions. AMERICAN JOURNAL OF BOTANY 2013; 100:1923-1935. [PMID: 24061214 DOI: 10.3732/ajb.1300123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
PREMISE Ginkgo, centrally placed in seed plant phylogeny, is considered important in many phylogenetic and evolutionary studies. Shoot dimorphism of Ginkgo has been long noted, but no work has yet been done to evaluate the relationships between overall branch architecture and wood ring characters, shoot growth, and environmental conditions. • METHODS Branches, sampled from similar canopy heights, were mapped with the age of each long shoot segment determined by counting annual leaf-scar series on its short shoots. Transverse sections were made for each long shoot segment and an adjacent short shoot; wood ring thickness, number of rings, and number of tracheids/ring were determined. Using branch maps, we identified wood rings for each long shoot segment to year and developmental context of each year (distal short shoot growth only vs. at least one distal long shoot). Climate data were also analyzed in conjunction with developmental context. • KEY RESULTS Significantly thicker wood rings occur in years with distal long shoot development. The likelihood that a branch produced long shoots in a given year was lower with higher maximum annual temperature. Annual maximum temperature was negatively correlated with ring thickness in microsporangiate trees only. Annual minimum temperatures were correlated differently with ring thickness of megasporangiate and microsporangiate trees, depending on the developmental context. There were no significant effects associated with precipitation. • CONCLUSIONS Overall, developmental context alone predicts wood ring thickness about as well as models that include temperature. This suggests that although climatic factors may be strongly correlated with wood ring data among many gymnosperm taxa, at least for Ginkgo, correlations with climate data are primarily due to changes in proportions of shoot developmental types (LS vs. SS) across branches.
Collapse
Affiliation(s)
- Stefan A Little
- Department of Plant Sciences, One Shields Avenue, University of California, Davis, California 95616, USA
| | | | | | | | | | | |
Collapse
|
18
|
Yang Y, Lin L, Wang Q. Chengia laxispicata gen. et sp. nov., a new ephedroid plant from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China: evolutionary, taxonomic, and biogeographic implications. BMC Evol Biol 2013; 13:72. [PMID: 23530702 PMCID: PMC3626868 DOI: 10.1186/1471-2148-13-72] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 03/20/2013] [Indexed: 11/10/2022] Open
Abstract
Background The extant Gnetales include three monotypic families, namely, Ephedraceae (Ephedra), Gnetaceae (Gnetum), and Welwitschiaceae (Welwitschia), all of which possess compound female cones that comprise a main axis and 1 to multiple pairs/whorls of bracts subtending a female reproductive unit or having lower pairs/whorls of bracts sterile. However, the evolutionary origin of such a reproductive architecture in Gnetales is controversial in the light of the competing anthophyte versus gnetifer hypotheses of seed plant relationships. Hence, macrofossils demonstrating the structure of compound female cones of the Gnetales should be important to decipher the early evolution of the order. Results A new ephedroid plant Chengia laxispicata gen. et sp. nov. is described from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China. The fossil represents a part of a leafy shooting system with reproductive organs attached. The main shoot bears internodes and swollen nodes, from which lateral branches arise oppositely. Reproductive organs consist of female spikes terminal to twigs or axillary to linear leaves. Spikes are loosely arranged, having prominent nodes and internodes. Bracts of the spikes are decussately opposite and comprise 4—8 pairs of bracts. Each bract subtends an ellipsoid seed. Seeds are sessile, with a thin outer envelope and a distal micropylar tube. Conclusions Chengia laxispicata gen. et sp. nov. provides a missing link between archetypal fertile organs in the crown lineage of the Gnetales and compound female cones of the extant Ephedraceae. Combined with a wealth of Ephedra and ephedroid macrofossils from the Early Cretaceous, we propose a reduction and sterilization hypothesis that the female cone of the extant Ephedraceae may have stemmed from archetypal fertile organs in the crown lineage of the Gnetales. These have undergone sequentially intermediate links similar to female cones of Cretaceous Siphonospermum, Chengia, and Liaoxia by reduction and sterilization of the lower fertile bracts, shortenings of internodes and peduncles as well as loss of reproductive units in all inferior bracts. The basal family Ephedraceae including Ephedra of the extant Gnetales was demonstrated to have considerable diversity by the Early Cretaceous, so an emended familial diagnosis is given here. The Jehol Biota in Northeast China and adjacent areas contains a plethora of well-preserved macrofossils of Ephedra and ephedroids that show different evolutionary stages including primitive and derived characters of Ephedraceae, so Northeast China and adjacent areas may represent either the centre of origination or one of the centres for early diversification of the family.
Collapse
Affiliation(s)
- Yong Yang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China
| | | | | |
Collapse
|
19
|
Sims HJ. The evolutionary diversification of seed size: using the past to understand the present. Evolution 2012; 66:1636-49. [PMID: 22519796 DOI: 10.1111/j.1558-5646.2011.01527.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Devonian origin of seed plants and subsequent morphological diversification of seeds during the late Paleozoic represents an adaptive radiation into unoccupied ecological niche space. A plant's seed size is correlated with its life-history strategy, growth form, and seed dispersal syndrome. The fossil record indicates that the oldest seed plants had relatively small seeds, but the Mississippian seed size envelope increased significantly with the diversification of larger seeded lineages. Fossil seeds equivalent to the largest extant gymnosperm seeds appeared by the Pennsylvanian, concurrent with morphological diversification of growth forms and dispersal syndromes as well as the clade's radiation into new environments. Wang's Analysis of Skewness indicates that the evolutionary trend of increasing seed size resulted from primarily passive processes in Pennsylvanian seed plants. The distributions of modern angiosperms indicate a more diverse system of active and some passive processes, unbounded by Paleozoic limits; multiple angiosperm lineages independently evolved though the upper and lower bounds. Quantitative measures of preservation suggest that, although our knowledge of Paleozoic seeds is far from complete, the evolutionary trend in seed size is unlikely to be an artifact of taphonomy.
Collapse
Affiliation(s)
- Hallie J Sims
- Department of Geoscience, University of Iowa, Iowa City, Iowa 52242, USA.
| |
Collapse
|
20
|
Abstract
• Plants have utterly transformed the planet, but testing hypotheses of causality requires a reliable time-scale for plant evolution. While clock methods have been extensively developed, less attention has been paid to the correct interpretation and appropriate implementation of fossil data. • We constructed 17 calibrations, consisting of minimum constraints and soft maximum constraints, for divergences between model representatives of the major land plant lineages. Using a data set of seven plastid genes, we performed a cross-validation analysis to determine the consistency of the calibrations. Six molecular clock analyses were then conducted, one with the original calibrations, and others exploring the impact on divergence estimates of changing maxima at basal nodes, and prior probability densities within calibrations. • Cross-validation highlighted Tracheophyta and Euphyllophyta calibrations as inconsistent, either because their soft maxima were overly conservative or because of undetected rate variation. Molecular clock analyses yielded estimates ranging from 568-815 million yr before present (Ma) for crown embryophytes and from 175-240 Ma for crown angiosperms. • We reject both a post-Jurassic origin of angiosperms and a post-Cambrian origin of land plants. Our analyses also suggest that the establishment of the major embryophyte lineages occurred at a much slower tempo than suggested in most previous studies. These conclusions are entirely compatible with current palaeobotanical data, although not necessarily with their interpretation by palaeobotanists.
Collapse
Affiliation(s)
- John T Clarke
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - Rachel C M Warnock
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK
| | - Philip C J Donoghue
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK
| |
Collapse
|
21
|
Endress PK. Angiosperm ovules: diversity, development, evolution. ANNALS OF BOTANY 2011; 107:1465-89. [PMID: 21606056 PMCID: PMC3108811 DOI: 10.1093/aob/mcr120] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 03/29/2011] [Accepted: 04/11/2011] [Indexed: 05/18/2023]
Abstract
BACKGROUND Ovules as developmental precursors of seeds are organs of central importance in angiosperm flowers and can be traced back in evolution to the earliest seed plants. Angiosperm ovules are diverse in their position in the ovary, nucellus thickness, number and thickness of integuments, degree and direction of curvature, and histological differentiations. There is a large body of literature on this diversity, and various views on its evolution have been proposed over the course of time. Most recently evo-devo studies have been concentrated on molecular developmental genetics in ovules of model plants. SCOPE The present review provides a synthetic treatment of several aspects of the sporophytic part of ovule diversity, development and evolution, based on extensive research on the vast original literature and on experience from my own comparative studies in a broad range of angiosperm clades. CONCLUSIONS In angiosperms the presence of an outer integument appears to be instrumental for ovule curvature, as indicated from studies on ovule diversity through the major clades of angiosperms, molecular developmental genetics in model species, abnormal ovules in a broad range of angiosperms, and comparison with gymnosperms with curved ovules. Lobation of integuments is not an atavism indicating evolution from telomes, but simply a morphogenetic constraint from the necessity of closure of the micropyle. Ovule shape is partly dependent on locule architecture, which is especially indicated by the occurrence of orthotropous ovules. Some ovule features are even more conservative than earlier assumed and thus of special interest in angiosperm macrosystematics.
Collapse
Affiliation(s)
- Peter K Endress
- Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland.
| |
Collapse
|
22
|
Affiliation(s)
- James A Doyle
- Department of Evolution and Ecology, University of California, Davis, CA 95616, USA.
| |
Collapse
|
23
|
Rydin C, Friis EM. A new early Cretaceous relative of Gnetales: Siphonospermum simplex gen. et sp. nov. from the Yixian formation of northeast China. BMC Evol Biol 2010; 10:183. [PMID: 20565755 PMCID: PMC2900273 DOI: 10.1186/1471-2148-10-183] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Accepted: 06/17/2010] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Knowledge on fossil and evolutionary history of the Gnetales has expanded rapidly; Ephedra and ephedroids as well as the Gnetum-Welwitschia clade are now well documented in the Early Cretaceous. However, hypotheses on evolutionary relationships among living and fossil species are hampered by restricted knowledge of morphological variation in living groups and recent studies indicate that gnetalean diversity and character evolution may be more complex than previously assumed and involve additional extinct groups (Bennettitales, Erdtmanithecales and unassigned fossil taxa). RESULTS Here we describe a new fossil related to Gnetales, Siphonospermum simplex from the Early Cretaceous Yixian Formation, an impression/compression of a reproductive shoot. The slender main axis bears one pair of opposite and linear leaves with primary parallel venation. The reproductive units are ovoid, without supporting bracts and borne on one median and two lateral branches. The most conspicuous feature of the fossil is the long, thread-like micropylar tube formed by the integument. Each ovule is surrounded by two different layers representing one or two seed envelopes; an inner sclerenchymatous layer and an outer probably parenchymatous layer. CONCLUSIONS The vegetative and reproductive features of Siphonospermum simplex exclude a relationship to any other group than the Gnetales. A combination of opposite phyllotaxis, linear leaves and ovules surrounded by seed envelope(s) and with a long exposed micropylar tube are known only for extant and extinct Gnetales. Siphonospermum simplex constitutes a new lineage within the Gnetales. Its morphology cannot be directly linked to any previously known plant, but the organization of the reproductive units indicates that it belongs to the Gnetum-Welwitschia clade. Based on the absence of cone bracts and the inferred histology of the seed envelope(s) it could be related to Gnetum, however, there are also affinities with the ephedran lineage, some of which are likely plesiomorphic features, others perhaps not. Phylogeny and character evolution in the Bennettitales, Erdtmanithecales and Gnetales are currently only partly understood and under debate; the exact systematic position of Siphonospermum simplex, i.e., its position within the Gnetales, cannot be resolved with certainty.
Collapse
Affiliation(s)
- Catarina Rydin
- University of Zürich, Institute of Systematic Botany, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Else Marie Friis
- Swedish Museum of Natural History, Department of Palaeobotany, Box 50007, SE-104 05 Stockholm, Sweden
| |
Collapse
|
24
|
Abstract
The evolution of the seed represents a remarkable life-history transition for photosynthetic organisms. Here, we review the recent literature and historical understanding of how and why seeds evolved. Answering the 'how' question involves a detailed understanding of the developmental morphology and anatomy of seeds, as well as the genetic programs that determine seed size. We complement this with a special emphasis on the evolution of dormancy, the characteristic of seeds that allows for long 'distance' time travel. Answering the 'why' question involves proposed hypotheses of how natural selection has operated to favor the seed life-history phenomenon. The recent flurry of research describing the comparative biology of seeds is discussed. The review will be divided into sections dealing with: (1) the development and anatomy of seeds; (2) the endosperm; (3) dormancy; (4) early seed-like structures and the transition to seeds; and (5) the evolution of seed size (mass). In many cases, a special distinction is made between angiosperm and gymnosperm seeds. Finally, we make some recommendations for future research in seed biology.
Collapse
Affiliation(s)
- Ada Linkies
- Botany/Plant Physiology, Institute for Biology II, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany (http://www.seedbiology.de)
| | - Kai Graeber
- Botany/Plant Physiology, Institute for Biology II, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany (http://www.seedbiology.de)
| | - Charles Knight
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93401, USA
| | - Gerhard Leubner-Metzger
- Botany/Plant Physiology, Institute for Biology II, Faculty of Biology, University of Freiburg, Schänzlestr. 1, D-79104 Freiburg, Germany (http://www.seedbiology.de)
| |
Collapse
|
25
|
Whole fossil plants of Ephedra and their implications on the morphology, ecology and evolution of Ephedraceae (Gnetales). ACTA ACUST UNITED AC 2010. [DOI: 10.1007/s11434-010-3069-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
26
|
Rudall PJ, Bateman RM. Defining the limits of flowers: the challenge of distinguishing between the evolutionary products of simple versus compound strobili. Philos Trans R Soc Lond B Biol Sci 2010; 365:397-409. [PMID: 20047867 DOI: 10.1098/rstb.2009.0234] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recent phylogenetic reconstructions suggest that axially condensed flower-like structures evolved iteratively in seed plants from either simple or compound strobili. The simple-strobilus model of flower evolution, widely applied to the angiosperm flower, interprets the inflorescence as a compound strobilus. The conifer cone and the gnetalean 'flower' are commonly interpreted as having evolved from a compound strobilus by extreme condensation and (at least in the case of male conifer cones) elimination of some structures present in the presumed ancestral compound strobilus. These two hypotheses have profoundly different implications for reconstructing the evolution of developmental genetic mechanisms in seed plants. If different flower-like structures evolved independently, there should intuitively be little commonality of patterning genes. However, reproductive units of some early-divergent angiosperms, including the extant genus Trithuria (Hydatellaceae) and the extinct genus Archaefructus (Archaefructaceae), apparently combine features considered typical of flowers and inflorescences. We re-evaluate several disparate strands of comparative data to explore whether flower-like structures could have arisen by co-option of flower-expressed patterning genes into independently evolved condensed inflorescences, or vice versa. We discuss the evolution of the inflorescence in both gymnosperms and angiosperms, emphasising the roles of heterotopy in dictating gender expression and heterochrony in permitting internodal compression.
Collapse
Affiliation(s)
- Paula J Rudall
- Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond Surrey TW9 3DS, UK.
| | | |
Collapse
|
27
|
The discovery of whole-plant fossil cycad from the Upper Triassic in western Liaoning and its significance. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/s11434-009-0384-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
28
|
Wilson JP. Green Life Through Time
Paleobotany
The Biology and Evolution of Fossil Plants. 2nd ed.
by Thomas N. Taylor, Edith L. Taylor, and Michael Krings
Academic (Elsevier), Burlington, MA, 2009. 1252 pp. $125, £62.99, €91.95. ISBN 9780123739728. Science 2009. [DOI: 10.1126/science.1174659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
An expansion and update of Taylor and Taylor's classic 1993 book, this lavishly illustrated volume offers a comprehensive survey of fossil plants and fungi.
Collapse
Affiliation(s)
- Jonathan P. Wilson
- The reviewer is at the Division of Geological and Planetary Sciences, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| |
Collapse
|
29
|
|
30
|
Graham SW, Iles WJD. Different gymnosperm outgroups have (mostly) congruent signal regarding the root of flowering plant phylogeny. AMERICAN JOURNAL OF BOTANY 2009; 96:216-227. [PMID: 21628185 DOI: 10.3732/ajb.0800320] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We examined multiple plastid genes from a diversity of gymnosperm lineages to explore the consistency of signal among different outgroups for rooting flowering plant phylogeny. For maximum parsimony (MP), most outgroups attach on a branch of the underlying ingroup tree that leads to Amborella. Maximum likelihood (ML) analyses either root angiosperms on a nearby branch or find split support for these neighboring root placements, depending on the outgroup. The inclusion of two species of Hydatellaceae, recently recognized as an ancient line of angiosperms, does not aid in inference of the root. Cost profiles for placing the root in suboptimal locations are highly correlated across most outgroup comparisons, even comparing MP and ML profiles. Those for Gnetales are the most deviant of all those considered. This divergent outgroup either attaches on a long eudicot branch with moderate bootstrap support in MP analyses or supports no particular root location in ML analysis. Removing the most rapidly evolving sites in rate classifications based on two divergent angiosperm root placements with Gnetales yields strongly conflicting root placements in MP analysis, despite substantial overlap in the estimated sets of conservative sites. However, the generally high consistency in rooting signal among distantly related gymnosperm clades suggests that the long branch connecting angiosperms to their extant relatives may not interfere substantially with inference of the angiosperm root.
Collapse
Affiliation(s)
- Sean W Graham
- UBC Botanical Garden & Centre for Plant Research (Faculty of Land and Food Systems), 2357 Main Mall, and Department of Botany, 6270 University Boulevard, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
| | | |
Collapse
|
31
|
Stockey RA, Rothwell GW. Distinguishing angiophytes from the earliest angiosperms: A Lower Cretaceous (Valanginian-Hauterivian) fruit-like reproductive structure. AMERICAN JOURNAL OF BOTANY 2009; 96:323-335. [PMID: 21628191 DOI: 10.3732/ajb.0800295] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A remarkably diverse Lower Cretaceous (Valanginian-Hauterivian) flora at Apple Bay, Vancouver Island, preserves seed plants at an important time of floristic evolutionary transition, about the same time as the earliest flowering plant megafossils. The fossils are permineralized in carbonate concretions and include tetrahedral seeds within cupule- or carpel-like structures. These enclosing structures, composed of elongate sclerenchyma cells with spiral thickenings that grade externally to a few layers of parenchyma, are vascularized by one collateral vascular bundle and lack trichomes. They apparently broke open to release the tightly enclosed seeds by valves. Seeds are similar to those of the Triassic seed fern Petriellaea, but are about 100 million years younger and differ in size, vascularization, integumentary anatomy, seed attachment, and number of seeds/cupule. These new seeds are described as Doylea tetrahedrasperma gen. et sp. nov., tentatively assigned to Corystospermales. Inverted cupules are reminiscent of an outer angiosperm integument rather than a carpel. Like fruits, cupules opened to release seeds at maturity, thereby foretelling several aspects of angiospermy. They show that nearly total ovule enclosure, a level of organization approaching angiospermy, was achieved by advanced seed ferns during the Mesozoic.
Collapse
Affiliation(s)
- Ruth A Stockey
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
| | | |
Collapse
|
32
|
Stockey RA, Graham SW, Crane PR. Introduction to the Darwin special issue: The abominable mystery1. AMERICAN JOURNAL OF BOTANY 2009; 96:3-4. [PMID: 21628173 DOI: 10.3732/ajb.0800402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Affiliation(s)
- Ruth A Stockey
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9 Canada
| | | | | |
Collapse
|