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Larue C, Klein EK, Petit RJ. Sexual interference revealed by joint study of male and female pollination success in chestnut. Mol Ecol 2023; 32:1211-1228. [PMID: 36484548 DOI: 10.1111/mec.16820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 10/31/2022] [Accepted: 11/30/2022] [Indexed: 12/13/2022]
Abstract
Most seed plants produce both pollen and ovules. In principle, pollen export could interfere with pollen import through self-pollination, resulting in ovule usurpation and reduced fruit set. Evidence for such interference exists under experimental settings but its importance under natural conditions is unknown. To test for sexual interference in nature, it is necessary to study together mating system, through paternity analyses, and fruit set, the proportion of flowers giving seeds or fruits. We developed a new model combining both processes, using chestnut (Castanea) as case study. We carried out a paternity analysis in an intensively studied plot of 273 trees belonging to three interfertile chestnut species and including a range of individuals with more or less functional stamens, resulting in a large data set of 1924 mating events. We then measured fruit set on 216 of these trees. Fruit set of male-fertile trees was much lower than that of male-sterile trees. Our process-based model shows that pollen is not limiting in the study site and hence cannot account for reduced fruit set. It also indicates that self-pollination is high (74%) but selfing rate is low (4%). Self-pollen is less competitive than cross-pollen, reducing sexual interference, but not sufficiently, as many ovules end up being self-fertilized, 95% of which abort before fruit formation, resulting in the loss of 46% of the fruit crop. These results suggest that the main cause of reduced reproductive potential in chestnut is sexual interference by self-pollen, raising questions on its evolutionary origins.
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Affiliation(s)
- Clément Larue
- University of Bordeaux, INRAE, BIOGECO, Cestas, France.,INVENIO, Maison Jeannette, Douville, France
| | | | - Rémy J Petit
- University of Bordeaux, INRAE, BIOGECO, Cestas, France
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2
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Du FK, Qi M, Zhang YY, Petit RJ. Asymmetric character displacement in mixed oak stands. THE NEW PHYTOLOGIST 2022; 236:1212-1224. [PMID: 35706383 DOI: 10.1111/nph.18311] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 05/28/2022] [Indexed: 06/15/2023]
Abstract
Ecological character displacement (ECD) refers to a pattern of increased divergence at sites where species ranges overlap caused by competition for resources. Although ECD is believed to be common, there are few in-depth studies that clearly establish its existence, especially in plants. Thus, we have compared leaf traits in allopatric and sympatric populations of two East Asian deciduous oaks: Quercus dentata and Quercus aliena. In contrast to previous studies, we define sympatry and allopatry at a local scale, thereby comparing populations that can or cannot directly interact. Using genetic markers, we found greater genetic divergence between the two oak species growing in mixed stands and inferred that long-term gene flow has predominantly occurred asymmetrically from the cold-tolerant species (Q. dentata) to the warm-demanding later colonizing species (Q. aliena). Analysis of leaf traits revealed greater divergence in mixed than in pure oak stands. This was mostly due to the later colonizing species being characterized by more resource-conservative traits in the presence of the other species. Controlling for relevant environmental differences did not alter these conclusions. These results suggest that asymmetric trait divergence can take place where species coexist, possibly due to the imbalance in demographic history of species resulting in asymmetric inter-specific selection pressures.
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Affiliation(s)
- Fang K Du
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, 100083, China
| | - Min Qi
- School of Ecology and Nature Conservation, Beijing Forestry University, Beijing, 100083, China
| | - Yuan-Ye Zhang
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, 361102, China
| | - Rémy J Petit
- Université de Bordeaux, INRAE, BIOGECO, F-33610, Cestas, France
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3
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Reutimann O, Gugerli F, Rellstab C. A species-discriminatory single-nucleotide polymorphism set reveals maintenance of species integrity in hybridizing European white oaks (Quercus spp.) despite high levels of admixture. ANNALS OF BOTANY 2020; 125:663-676. [PMID: 31912148 PMCID: PMC7102958 DOI: 10.1093/aob/mcaa001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 01/04/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND AND AIMS Hybridization and introgression play an important role in the evolution and diversification of plants. To assess the degree of past and current hybridization, the level of genetic admixture in populations needs to be investigated. Ongoing hybridization and blurred species separation have made it challenging to assign European white oak taxa based on leaf morphology and/or genetic markers and to assess the level of admixture. Therefore, there is a need for powerful markers that differentiate between taxa. Here, we established a condensed set of single-nucleotide polymorphism (SNP) markers to reliably differentiate between the three most common oak species in temperate European forests (Quercus robur, Q. petraea, Q. pubescens) and to assess the degree of admixture in a large set of selected Swiss populations. METHODS A training set of 194 presumably pure reference samples from Switzerland and Europe was used to assign 633 test individuals with two different approaches (population genetic-based/Bayesian vs. assumption-free/discriminative classifier) using 58 selected SNPs from coding regions. Admixture was calculated at the individual and population level with the Shannon diversity index based on individual assignment probabilities. KEY RESULTS Depending on the approach, 97.5-100 % of training individuals were assigned correctly, and additional analyses showed that the established SNP set could be further reduced while maintaining its discriminatory power. The two assignment approaches showed high overlap (99 %) in assigning training individuals and slightly less overlap in test individuals (84 %). Levels of admixture varied widely among populations. Mixed stands of Q. petraea and Q. pubescens revealed much higher degrees of admixture than mixed stands of the other two taxon pairs, accentuating high levels of gene flow between these two taxa in Switzerland. CONCLUSIONS Our set of SNPs warrants reliable taxon discrimination with great potential for further applications. We show that the three European white oak taxa have largely retained their species integrity in Switzerland despite high levels of admixture.
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Affiliation(s)
| | - Felix Gugerli
- Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
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Cavender-Bares J. Diversification, adaptation, and community assembly of the American oaks (Quercus), a model clade for integrating ecology and evolution. THE NEW PHYTOLOGIST 2019; 221:669-692. [PMID: 30368821 DOI: 10.1111/nph.15450] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 07/10/2018] [Indexed: 05/26/2023]
Abstract
Contents Summary 669 I. Model clades for the study and integration of ecology and evolution 670 II. Oaks: an important model clade 671 III. Insights from the history of the American oaks for understanding community assembly and ecosystem dominance 673 IV. Bridging the gap between micro- and macroevolutionary processes relevant to ecology 679 V. How do we reconcile evidence for adaptive evolution with niche conservatism and long-term stasis? 682 VI. High plasticity and within-population genetic variation contribute to population persistence 683 VII. Emerging technologies for tracking functional change 685 VIII. Conclusions 685 Acknowledgements 686 References 686 SUMMARY: Ecologists and evolutionary biologists are concerned with explaining the diversity and composition of the natural world and are aware of the inextricable linkages between ecological and evolutionary processes that maintain the Earth's life support systems. Yet examination of these linkages remains challenging due to the contrasting nature of focal systems and research approaches. Model clades provide a critical means to integrate ecology and evolution, as illustrated by the oaks (genus Quercus), an important model clade, given their ecological dominance, remarkable diversity, and growing phylogenetic, genomic, and ecological data resources. Studies of the clade reveal that their history of sympatric parallel adaptive radiation continues to influence community assembly today, highlighting questions on the nature and extent of coexistence mechanisms. Flexible phenology and hydraulic traits, despite evolutionary stasis, may have enabled adaptation to a wide range of environments within and across species, contributing to their high abundance and diversity. The oaks offer fundamental insights at the intersection of ecology and evolution on the role of diversification in community assembly processes, on the importance of flexibility in key functional traits in adapting to new environments, on factors contributing to persistence of long-lived organisms, and on evolutionary legacies that influence ecosystem function.
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Affiliation(s)
- Jeannine Cavender-Bares
- Department of Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN, 55108, USA
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Chybicki IJ. NMπ-improved re-implementation of NM+, a software for estimating gene dispersal and mating patterns. Mol Ecol Resour 2017; 18:159-168. [DOI: 10.1111/1755-0998.12710] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 07/21/2017] [Accepted: 07/31/2017] [Indexed: 11/26/2022]
Affiliation(s)
- Igor J. Chybicki
- Department of Genetics; Kazimierz Wielki University; Bydgoszcz Poland
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Truffaut L, Chancerel E, Ducousso A, Dupouey JL, Badeau V, Ehrenmann F, Kremer A. Fine-scale species distribution changes in a mixed oak stand over two successive generations. THE NEW PHYTOLOGIST 2017; 215:126-139. [PMID: 28444962 PMCID: PMC5624485 DOI: 10.1111/nph.14561] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/01/2017] [Indexed: 05/12/2023]
Abstract
Large-scale tree distribution changes have received considerable attention but underlying demo-genetic mechanisms are less well documented. We used a diachronic approach to track species shifts in a mixed oak stand (Quercus petraea-Quercus robur) at a fine spatiotemporal scale. Species assignment was made using single nucleotide polymorphism (SNP) fingerprints employing clustering and parentage analysis. Mating patterns and reproductive success were assessed by parentage analysis. Plot-based inventories of soil parameters and sapling densities provided ecological and demographic information, respectively. Sapling density and reproductive success was higher in Q. petraea than in Q. robur, and were correlated with a spatial expansion of Q. petraea (50% to 67% of the area). Admixed trees resulting from hybridization and backcrossing between the two species were more frequent under the Q. robur canopy. We suspect that species' differential responses to ongoing environmental changes and interspecific competition are the predominant factors accounting for the recruitment success of Q. petraea, while human interference, differential reproduction and hybridization (and backcrossings) are probably of more limited importance. We anticipate in mixed Q. petraea-Q. robur stands, under current ongoing environmental change, that these processes will be enhanced, at least in the western part of the distribution of the two species.
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Affiliation(s)
- Laura Truffaut
- INRA, UMR 1202 BIOGECO, F-33610 Cestas, France
- Université de Bordeaux, UMR 1202 BIOGECO, F-33615 Pessac,
France
| | - Emilie Chancerel
- INRA, UMR 1202 BIOGECO, F-33610 Cestas, France
- Université de Bordeaux, UMR 1202 BIOGECO, F-33615 Pessac,
France
| | - Alexis Ducousso
- INRA, UMR 1202 BIOGECO, F-33610 Cestas, France
- Université de Bordeaux, UMR 1202 BIOGECO, F-33615 Pessac,
France
| | - Jean Luc Dupouey
- INRA Université de Lorraine UMR 1137 ‘Ecologie et
Ecophysiologie Forestières’, route d’Amance, F-54280
Champenoux, France
| | - Vincent Badeau
- INRA Université de Lorraine UMR 1137 ‘Ecologie et
Ecophysiologie Forestières’, route d’Amance, F-54280
Champenoux, France
| | - François Ehrenmann
- INRA, UMR 1202 BIOGECO, F-33610 Cestas, France
- Université de Bordeaux, UMR 1202 BIOGECO, F-33615 Pessac,
France
| | - Antoine Kremer
- INRA, UMR 1202 BIOGECO, F-33610 Cestas, France
- Université de Bordeaux, UMR 1202 BIOGECO, F-33615 Pessac,
France
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Beatty GE, Montgomery WI, Spaans F, Tosh DG, Provan J. Pure species in a continuum of genetic and morphological variation: sympatric oaks at the edge of their range. ANNALS OF BOTANY 2016; 117:541-9. [PMID: 26929202 PMCID: PMC4817430 DOI: 10.1093/aob/mcw002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/17/2015] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Studies on oaks (Quercus spp.) have often been hampered by taxonomic confusion, a situation further compounded by the occurrence of extensive interspecific hybridization. In the present study, a combination of genetic and morphological analyses was used to examine sympatric populations of Q. petraea and Q. robur at the north-western edge of their ranges in Northern Ireland, since it had previously been suggested that hybridization could facilitate the apparent rapid, long-distance dispersal of oaks following the glaciations. METHODS Samples were collected from 24 sites across Northern Ireland that had been previously designated as ancient or semi-natural woodland. Genotypes were obtained from a total of 950 trees using 12 nuclear microsatellite loci, and admixture coefficients were calculated based on a Bayesian clustering approach. Individuals were also classified as Q. petraea,Q. robur or hybrids based on two objective morphometric characters shown previously to delineate pure individuals effectively. Genetically 'pure' individuals of both species, as defined by the Bayesian clustering, were also genotyped for five chloroplast microsatellites. KEY RESULTS Genetic and morphological analyses both indicated the presence of pure individuals of both species, as well as a continuum of intermediates. There was a good agreement between the molecular and morphological classification, with a generally clear separation between pure individuals. CONCLUSIONS Despite millennia of hybridization and introgression, genetically and morphologically pure individuals of both Q. petraea and Q. robur can be found at the edge of their range, where both species occur sympatrically. The high proportion of individuals exhibiting introgression compared with previous studies may reflect the historical role of hybridization in facilitating dispersal following the glaciations. This is further supported by the significantly higher chloroplast diversity in Q. robur compared with Q. petraea.
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Affiliation(s)
- Gemma E Beatty
- School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK, Quercus, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK and Institute for Global Food Security, Queen's University Belfast
| | - W Ian Montgomery
- School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK, Quercus, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK and Institute for Global Food Security, Queen's University Belfast
| | - Florentine Spaans
- School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK, Quercus, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK and
| | - David G Tosh
- School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK, Quercus, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK and
| | - Jim Provan
- School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK, Quercus, School of Biological Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK and Institute for Global Food Security, Queen's University Belfast
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8
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Allergen of the Month--English Oak. Ann Allergy Asthma Immunol 2016; 115:A13. [PMID: 26505935 DOI: 10.1016/j.anai.2015.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ortiz-Barrientos D, Baack EJ. Species integrity in trees. Mol Ecol 2014; 23:4188-91. [PMID: 25155715 DOI: 10.1111/mec.12867] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Revised: 07/14/2014] [Accepted: 07/17/2014] [Indexed: 11/28/2022]
Abstract
From California sequoia, to Australian eucalyptus, to the outstanding diversity of Amazonian forests, trees are fundamental to many processes in ecology and evolution. Trees define the communities that they inhabit, are host to a multiplicity of other organisms and can determine the ecological dynamics of other plants and animals. Trees are also at the heart of major patterns of biodiversity such as the latitudinal gradient of species diversity and thus are important systems for studying the origin of new plant species. Although the role of trees in community assembly and ecological succession is partially understood, the origin of tree diversity remains largely opaque. For instance, the relative importance of differing habitats and phenologies as barriers to hybridization between closely related species is still largely uncharacterized in trees. Consequently, we know very little about the origin of trees species and their integrity. Similarly, studies on the interplay between speciation and tree community assembly are in their infancy and so are studies on how processes like forest maturation modifies the context in which reproductive isolation evolves. In this issue of Molecular Ecology, Lindtke et al. (2014) and Lagache et al. (2014) overcome some traditional difficulties in studying mating systems and sexual isolation in the iconic oaks and poplars, providing novel insights about the integrity of tree species and on how ecology leads to variation in selection on reproductive isolation over time and space.
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