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Muralidhar P, Coop G, Veller C. Assortative mating enhances postzygotic barriers to gene flow via ancestry bundling. Proc Natl Acad Sci U S A 2022; 119:e2122179119. [PMID: 35858444 PMCID: PMC9335313 DOI: 10.1073/pnas.2122179119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 06/06/2022] [Indexed: 01/21/2023] Open
Abstract
Hybridization and subsequent genetic introgression are now known to be common features of the histories of many species, including our own. Following hybridization, selection often purges introgressed DNA genome-wide. While assortative mating can limit hybridization in the first place, it is also known to play an important role in postzygotic selection against hybrids and, thus, the purging of introgressed DNA. However, this role is usually thought of as a direct one: a tendency for mates to be conspecific reduces the sexual fitness of hybrids, reducing the transmission of introgressed ancestry. Here, we explore a second, indirect role of assortative mating as a postzygotic barrier to gene flow. Under assortative mating, parents covary in their ancestry, causing ancestry to be "bundled" in their offspring and later generations. This bundling effect increases ancestry variance in the population, enhancing the efficiency with which postzygotic selection purges introgressed DNA. Using whole-genome simulations, we show that the bundling effect can comprise a substantial portion of mate choice's overall effect as a postzygotic barrier to gene flow. We then derive a simple method for estimating the impact of the bundling effect from standard metrics of assortative mating. Applying this method to data from a diverse set of hybrid zones, we find that the bundling effect increases the purging of introgressed DNA by between 1.2-fold (in a baboon system with weak assortative mating) and 14-fold (in a swordtail system with strong assortative mating). Thus, assortative mating's bundling effect contributes substantially to the genetic isolation of species.
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Affiliation(s)
- Pavitra Muralidhar
- Department of Evolution and Ecology, University of California, 95616 Davis, CA
- Center for Population Biology, University of California, 95616 Davis, CA
| | - Graham Coop
- Department of Evolution and Ecology, University of California, 95616 Davis, CA
- Center for Population Biology, University of California, 95616 Davis, CA
| | - Carl Veller
- Department of Evolution and Ecology, University of California, 95616 Davis, CA
- Center for Population Biology, University of California, 95616 Davis, CA
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2
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Chybicki IJ, Oleksa A, Dering M. Identification of determinants of pollen donor fecundity using the hierarchical neighborhood model. Mol Ecol Resour 2020; 21:781-800. [PMID: 33290637 DOI: 10.1111/1755-0998.13307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 11/24/2020] [Accepted: 12/01/2020] [Indexed: 11/30/2022]
Abstract
Individual differences in male reproductive success drive genetic drift and natural selection, altering genetic variation and phenotypic trait distributions in future generations. Therefore, identifying the determinants of reproductive success is important for understanding the ecology and evolution of plants. Here, based on the spatially explicit mating model (the neighborhood model), we develop a hierarchical probability model that links co-dominant genotypes of offspring and candidate parents with phenotypic determinants of male reproductive success. The model accounts for pollen dispersal, genotyping errors as well as individual variation in selfing, pollen immigration, and differentiation of immigrant pollen pools. Unlike the classic neighborhood model approach, our approach is specially designed to account for excessive variation (overdispersion) in male fecundity. We implemented a Bayesian estimation method (the Windows computer program available at: https://www.ukw.edu.pl/pracownicy/plik/igor_chybicki/1806/) that, among others, allows for selecting phenotypic variables important for male fecundity and assessing the fraction of variance in fecundity (R2 ) explained by selected variables. Simulations showed that our method outperforms both the classic neighborhood model and the two-step approach, where fecundities and the effects of phenotypic variables are estimated separately. The analysis of two data examples showed that in wind-pollinated trees, male fecundity depends on both the amount of produced pollen and the ability to pollen spread. However, despite that the tree size was positively correlated with male fecundity, it explained only a fraction of the total variance in fecundity, indicating the presence of additional factors. Finally, case studies highlighted the importance of accounting for pollen dispersal in the estimation of fecundity determinants.
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Affiliation(s)
- Igor J Chybicki
- Department of Genetics, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Andrzej Oleksa
- Department of Genetics, Kazimierz Wielki University, Bydgoszcz, Poland
| | - Monika Dering
- Institute of Dendrology, Polish Academy of Sciences, Kórnik, Poland.,Department of Silviculture, Poznań University of Life Sciences, Poznań, Poland
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3
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Besnard G, Cheptou P, Debbaoui M, Lafont P, Hugueny B, Dupin J, Baali‐Cherif D. Paternity tests support a diallelic self-incompatibility system in a wild olive ( Olea europaea subsp. laperrinei, Oleaceae). Ecol Evol 2020; 10:1876-1888. [PMID: 32128122 PMCID: PMC7042767 DOI: 10.1002/ece3.5993] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/16/2019] [Accepted: 12/20/2019] [Indexed: 01/31/2023] Open
Abstract
Self-incompatibility (SI) is the main mechanism that favors outcrossing in plants. By limiting compatible matings, SI interferes in fruit production and breeding of new cultivars. In the Oleeae tribe (Oleaceae), an unusual diallelic SI system (DSI) has been proposed for three distantly related species including the olive (Olea europaea), but empirical evidence has remained controversial for this latter. The olive domestication is a complex process with multiple origins. As a consequence, the mixing of S-alleles from two distinct taxa, the possible artificial selection of self-compatible mutants and the large phenological variation of blooming may constitute obstacles for deciphering SI in olive. Here, we investigate cross-genotype compatibilities in the Saharan wild olive (O. e. subsp. laperrinei). As this taxon was geographically isolated for thousands of years, SI should not be affected by human selection. A population of 37 mature individuals maintained in a collection was investigated. Several embryos per mother were genotyped with microsatellites in order to identify compatible fathers that contributed to fertilization. While the pollination was limited by distance inside the collection, our results strongly support the DSI hypothesis, and all individuals were assigned to two incompatibility groups (G1 and G2). No self-fertilization was observed in our conditions. In contrast, crosses between full or half siblings were frequent (ca. 45%), which is likely due to a nonrandom assortment of related trees in the collection. Finally, implications of our results for orchard management and the conservation of olive genetic resources are discussed.
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Affiliation(s)
| | - Pierre‐Olivier Cheptou
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valery Montpellier 3MontpellierFrance
| | - Malik Debbaoui
- EDBUMR 5174CNRS‐IRD‐UPSUniversité Paul SabatierToulouse cedexFrance
| | - Pierre Lafont
- EDBUMR 5174CNRS‐IRD‐UPSUniversité Paul SabatierToulouse cedexFrance
| | - Bernard Hugueny
- EDBUMR 5174CNRS‐IRD‐UPSUniversité Paul SabatierToulouse cedexFrance
| | - Julia Dupin
- EDBUMR 5174CNRS‐IRD‐UPSUniversité Paul SabatierToulouse cedexFrance
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4
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Gleiser G, Chybicki IJ, González-Martínez SC, Aizen MA. Phenological match drives pollen-mediated gene flow in a temporally dimorphic tree. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20:93-100. [PMID: 29063726 DOI: 10.1111/plb.12651] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 10/18/2017] [Indexed: 06/07/2023]
Abstract
Variation in flowering phenology is common in natural populations, and is expected to be, together with inter-mate distance, an important driver of effective pollen dispersal. In populations composed of plants with temporally separated sexual phases (i.e. dichogamous or heterodichogamous populations), pollen-mediated gene flow is assumed to reflect phenological overlap between complementary sexual phases. In this study, we conducted paternity analyses to test this hypothesis in the temporally dimorphic tree Acer opalus. We performed spatially explicit analyses based on categorical and fractional paternity assignment, and included tree size, pair-wise genetic relatedness and morph type as additional predictors. Because differences between morphs in flowering phenology may also influence pollination distances, we modelled separate pollen dispersal kernels for the two morphs. Extended phenological overlap between male and female phases (mainly associated with inter-morph crosses) resulted in higher siring success after accounting for the effects of genetic relatedness, morph type and tree size, while reduced phenological overlap (mainly associated with intra-morph crosses) resulted in longer pollination distances achieved. Siring success also increased in larger trees. Mating patterns could not be predicted by phenology alone. However, as heterogeneity in flowering phenology was the single morph-specific predictor of siring success, it is expected to be key in maintaining the temporal dimorphism in A. opalus, by promoting not only a prevalent pattern of inter-morph mating, but also long-distance pollination resulting from intra-morph mating events.
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Affiliation(s)
- G Gleiser
- Laboratorio Ecotono, INIBIOMA, CONICET-Universidad Nacional del Comahue, Bariloche, Argentina
| | - I J Chybicki
- Department of Genetics, Kazimierz Wielki University, Bydgoszcz, Poland
| | | | - M A Aizen
- Laboratorio Ecotono, INIBIOMA, CONICET-Universidad Nacional del Comahue, Bariloche, Argentina
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Semizer-Cuming D, Kjær ED, Finkeldey R. Gene flow of common ash (Fraxinus excelsior L.) in a fragmented landscape. PLoS One 2017; 12:e0186757. [PMID: 29053740 PMCID: PMC5650178 DOI: 10.1371/journal.pone.0186757] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 10/06/2017] [Indexed: 12/24/2022] Open
Abstract
Gene flow dynamics of common ash (Fraxinus excelsior L.) is affected by several human activities in Central Europe, including habitat fragmentation, agroforestry expansion, controlled and uncontrolled transfer of reproductive material, and a recently introduced emerging infectious disease, ash dieback, caused by Hymenoscyphus fraxineus. Habitat fragmentation may alter genetic connectivity and effective population size, leading to loss of genetic diversity and increased inbreeding in ash populations. Gene flow from cultivated trees in landscapes close to their native counterparts may also influence the adaptability of future generations. The devastating effects of ash dieback have already been observed in both natural and managed populations in continental Europe. However, potential long-term effects of genetic bottlenecks depend on gene flow across fragmented landscapes. For this reason, we studied the genetic connectivity of ash trees in an isolated forest patch of a fragmented landscape in Rösenbeck, Germany. We applied two approaches to parentage analysis to estimate gene flow patterns at the study site. We specifically investigated the presence of background pollination at the landscape level and the degree of genetic isolation between native and cultivated trees. Local meteorological data was utilized to understand the effect of wind on the pollen and seed dispersal patterns. Gender information of the adult trees was considered for calculating the dispersal distances. We found that the majority of the studied seeds (55-64%) and seedlings (75-98%) in the forest patch were fathered and mothered by the trees within the same patch. However, we determined a considerable amount of pollen flow (26-45%) from outside of the study site, representing background pollination at the landscape level. Limited pollen flow was observed from neighbouring cultivated trees (2%). Both pollen and seeds were dispersed in all directions in accordance with the local wind directions. Whereas there was no positive correlation between pollen dispersal distance and wind speed, the correlation between seed dispersal distance and wind speed was significant (0.71, p < 0.001), indicating that strong wind favours long-distance dispersal of ash seeds. Finally, we discussed the implications of establishing gene conservation stands and the use of enrichment planting in the face of ash dieback.
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Affiliation(s)
- Devrim Semizer-Cuming
- Department of Forest Genetics and Forest Tree Breeding, Faculty of Forest Sciences and Forest Ecology, University of Göttingen, Göttingen, Germany
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Erik Dahl Kjær
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Reiner Finkeldey
- Department of Forest Genetics and Forest Tree Breeding, Faculty of Forest Sciences and Forest Ecology, University of Göttingen, Göttingen, Germany
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6
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Ison JL, Weis AE. Temporal population genetic structure in the pollen pool for flowering time: A field experiment with Brassica rapa (Brassicaceae). AMERICAN JOURNAL OF BOTANY 2017; 104:1569-1580. [PMID: 29885229 DOI: 10.3732/ajb.1700210] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 09/11/2017] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Assortative mating by flowering time can cause temporal genetic structure in species with heritable flowering times. A strong temporal structure, when coupled with a seasonal shift in selection, may lead to adaptive temporal clines. We implemented a prospective and retrospective method to estimate the temporal genetic structure in the pollen pool of Brassica rapa. METHODS The prospective method uses flowering schedules to estimate the seasonal shift in the pollen donors' phenotype. By examining the offspring generation, we can get a direct estimate of temporal genetic structure, i.e., a retrospective estimate. However, this estimate is problematic because of the phenotypic correlation of the trait of interest, flowering time, between dam and sire. We developed a novel retrospective method that isolates flowering time by holding the maternal contribution constant and sampled the pollen pool in eight open-pollinated field plots throughout the flowering season. KEY RESULTS We found temporal genetic structure for flowering time in seven of the eight field plots. Interestingly, the direct (retrospective) temporal structure estimate was 35% larger than the prospective estimate based on flowering schedules. Spatial clumping of pollen donors did not affect temporal structure, but structure intensified when heritability was experimentally enhanced. CONCLUSIONS Temporal genetic structure, especially for flowering time, likely occurs in many plant populations and may be underestimated using a prospective method. We discuss the genome-wide consequences of temporal genetic structure and the potential for adaptive temporal clines in plant populations.
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Affiliation(s)
- Jennifer L Ison
- Department of Biology, The College of Wooster, 1189 Beall Avenue, Wooster, Ohio 44691 USA
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
| | - Arthur E Weis
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
- Koffler Scientific Reserve at Jokers Hill, University of Toronto 17000 Dufferin Street, King City, Ontario, L7B 1K5, Canada
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Tambarussi EV, Boshier D, Vencovsky R, Freitas MLM, Sebbenn AM. Paternity analysis reveals significant isolation and near neighbor pollen dispersal in small Cariniana legalis Mart. Kuntze populations in the Brazilian Atlantic Forest. Ecol Evol 2015; 5:5588-600. [PMID: 27069608 PMCID: PMC4813111 DOI: 10.1002/ece3.1816] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 10/06/2015] [Accepted: 10/09/2015] [Indexed: 11/09/2022] Open
Abstract
Throughout the world, large trees are increasingly rare. Cariniana legalis is the tallest tree species of the Brazilian Atlantic Forest, reaching up to 60 m in height. Due to extensive deforestation of the Atlantic Forest, remnant C. legalis populations are small and spatially isolated, requiring the development of strategies for their conservation. For in situ and ex situ genetic conservation to be effective, it is important to understand the levels and patterns of spatial genetic structure (SGS), and gene flow. We investigated SGS and pollen flow in three small, physically isolated C. legalis stands using microsatellite loci. We measured, mapped, and sampled all C. legalis trees in the three stands: 65 trees from Ibicatu population, 22 trees from MGI, and 4 trees from MGII. We also collected and genotyped 600 seeds from Ibicatu, 250 seeds from MGI, and 200 seeds from MGII. Significant SGS was detected in Ibicatu up to 150 m, but substantial levels of external pollen flow were also detected in Ibicatu (8%), although not in MGI (0.4%) or MGII (0%). Selfing was highest in MGII (18%), the smallest group of trees, compared to MGI (6.4%) and Ibicatu (6%). In MGI and MGII, there was a strong pattern of mating among near‐neighbors. Seed collection strategies for breeding, in situ and ex situ conservation and ecological restoration, must ensure collection from seed trees located at distances greater than 350 m and from several forest fragments.
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Affiliation(s)
- Evandro V Tambarussi
- Escola Superior de Agricultura "Luiz de Queiroz" Universidade de São Paulo Av. Pádua Dias, 11 Caixa Postal 9 Piracicaba 13418-900 Brazil
| | - David Boshier
- Department of Plant Sciences South Parks Road Oxford OX1 3RB UK
| | - Roland Vencovsky
- Escola Superior de Agricultura "Luiz de Queiroz" Universidade de São Paulo Av. Pádua Dias, 11 Caixa Postal 9 Piracicaba 13418-900 Brazil
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McQuillan MA, Rice AM. Differential effects of climate and species interactions on range limits at a hybrid zone: potential direct and indirect impacts of climate change. Ecol Evol 2015; 5:5120-37. [PMID: 26640687 PMCID: PMC4662315 DOI: 10.1002/ece3.1774] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/08/2015] [Accepted: 09/17/2015] [Indexed: 01/20/2023] Open
Abstract
The relative contributions of climate versus interspecific interactions in shaping species distributions have important implications for closely related species at contact zones. When hybridization occurs within a contact zone, these factors regulate hybrid zone location and movement. While a hybrid zone's position may depend on both climate and interactions between the hybridizing species, little is known about how these factors interact to affect hybrid zone dynamics. Here, we utilize SDM (species distribution modeling) both to characterize the factors affecting the current location of a moving North American avian hybrid zone and to predict potential direct and indirect effects of climate change on future distributions. We focus on two passerine species that hybridize where their ranges meet, the Black‐capped (Poecile atricapillus) and Carolina (P. carolinensis) chickadee. Our contemporary climate models predict the occurrence of climatically suitable habitat extending beyond the hybrid zone for P. atricapillus only, suggesting that interspecific interactions primarily regulate this range boundary in P. atricapillus, while climatic factors regulate P. carolinensis. Year 2050 climate models predict a drastic northward shift in suitable habitat for P. carolinensis. Because of the greater importance of interspecific interactions for regulating the southern range limit of P. atricapillus, these climate‐mediated shifts in the distribution of P. carolinensis may indirectly lead to a range retraction in P. atricapillus. Together, our results highlight the ways climate change can both directly and indirectly affect species distributions and hybrid zone location. In addition, our study lends support to the longstanding hypothesis that abiotic factors regulate species' poleward range limits, while biotic factors shape equatorial range limits.
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Affiliation(s)
- Michael A McQuillan
- Department of Biological Sciences Lehigh University 111 Research Drive Bethlehem Pennsylvania 18015
| | - Amber M Rice
- Department of Biological Sciences Lehigh University 111 Research Drive Bethlehem Pennsylvania 18015
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9
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Weis AE, Turner KM, Petro B, Austen EJ, Wadgymar SM. Hard and soft selection on phenology through seasonal shifts in the general and social environments: A study on plant emergence time. Evolution 2015; 69:1361-1374. [PMID: 25929822 DOI: 10.1111/evo.12677] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 04/14/2015] [Indexed: 11/27/2022]
Abstract
The timing of transition out of one life-history phase determines where in the seasonal succession of environments the next phase is spent. Shifts in the general environment (e.g., seasonal climate) affect the expected fitness for particular transition dates. Variation in transition date also leads to temporal variation in the social environment. For instance, early transition may confer a competitive advantage over later individuals. If so, the social environment will impose frequency- and density-dependent selection components. In effect, the general environment imposes hard selection, whereas the social environment imposes soft selection on phenology. We examined hard and soft selection on seedling emergence time in an experiment on Brassica rapa. In monoculture (uniform social environment), early emergence results in up to a 1.5-fold increase in seed production. In bicultures (heterogeneous social environment), early-emerging plants capitalized on their head start, suppressing their late neighbors and increasing their fitness advantage to as much as 38-fold, depending on density. We devised a novel adaptation of contextual analysis to partition total selection (i.e., cov(ω, z)) into the hard and soft components. Hard and soft components had similar strengths at low density, whereas soft selection was five times stronger than hard at high density.
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Affiliation(s)
- Arthur E Weis
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,Koffler Scientific Reserve at Jokers Hill, University of Toronto, King Township, Ontario, Canada
| | - Kyle M Turner
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.,Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts
| | - Bergita Petro
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Emily J Austen
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Susana M Wadgymar
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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10
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Roumet M, Cayre A, Latreille M, Muller MH. Quantifying temporal isolation: a modelling approach assessing the effect of flowering time differences on crop-to-weed pollen flow in sunflower. Evol Appl 2015; 8:64-74. [PMID: 25667603 PMCID: PMC4310582 DOI: 10.1111/eva.12222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 09/15/2014] [Indexed: 01/08/2023] Open
Abstract
Flowering time divergence can be a crucial component of reproductive isolation between sympatric populations, but few studies have quantified its actual contribution to the reduction of gene flow. In this study, we aimed at estimating pollen-mediated gene flow between cultivated sunflower and a weedy conspecific sunflower population growing in the same field and at quantifying, how it is affected by the weeds' flowering time. For that purpose, we extended an existing mating model by including a temporal distance (i.e. flowering time difference between potential parents) effect on mating probabilities. Using phenological and genotypic data gathered on the crop and on a sample of the weedy population and its offspring, we estimated an average hybridization rate of approximately 10%. This rate varied strongly from 30% on average for weeds flowering at the crop flowering peak to 0% when the crop finished flowering and was affected by the local density of weeds. Our result also suggested the occurrence of other factors limiting crop-to-weed gene flow. This level of gene flow and its dependence on flowering time might influence the evolutionary fate of weedy sunflower populations sympatric to their crop relative.
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Affiliation(s)
- Marie Roumet
- INRA, UMR 1334, Amélioration Génétique et Adaptation des Plantes méditerranéennes et tropicales (AGAP) Montpellier Cedex 1, France ; ETH Zurich, Institute of Integrative Biology (IBZ) Zurich, Switzerland
| | - Adeline Cayre
- INRA, UMR 1334, Amélioration Génétique et Adaptation des Plantes méditerranéennes et tropicales (AGAP) Montpellier Cedex 1, France
| | - Muriel Latreille
- INRA, UMR 1334, Amélioration Génétique et Adaptation des Plantes méditerranéennes et tropicales (AGAP) Montpellier Cedex 1, France
| | - Marie-Hélène Muller
- INRA, UMR 1334, Amélioration Génétique et Adaptation des Plantes méditerranéennes et tropicales (AGAP) Montpellier Cedex 1, France
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11
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Thépot S, Restoux G, Goldringer I, Hospital F, Gouache D, Mackay I, Enjalbert J. Efficiently tracking selection in a multiparental population: the case of earliness in wheat. Genetics 2015; 199:609-23. [PMID: 25406468 PMCID: PMC4317666 DOI: 10.1534/genetics.114.169995] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 11/11/2014] [Indexed: 11/18/2022] Open
Abstract
Multiparental populations are innovative tools for fine mapping large numbers of loci. Here we explored the application of a wheat Multiparent Advanced Generation Inter-Cross (MAGIC) population for QTL mapping. This population was created by 12 generations of free recombination among 60 founder lines, following modification of the mating system from strict selfing to strict outcrossing using the ms1b nuclear male sterility gene. Available parents and a subset of 380 SSD lines of the resulting MAGIC population were phenotyped for earliness and genotyped with the 9K i-Select SNP array and additional markers in candidate genes controlling heading date. We demonstrated that 12 generations of strict outcrossing rapidly and drastically reduced linkage disequilibrium to very low levels even at short map distances and also greatly reduced the population structure exhibited among the parents. We developed a Bayesian method, based on allelic frequency, to estimate the contribution of each parent in the evolved population. To detect loci under selection and estimate selective pressure, we also developed a new method comparing shifts in allelic frequency between the initial and the evolved populations due to both selection and genetic drift with expectations under drift only. This evolutionary approach allowed us to identify 26 genomic areas under selection. Using association tests between flowering time and polymorphisms, 6 of these genomic areas appeared to carry flowering time QTL, 1 of which corresponds to Ppd-D1, a major gene involved in the photoperiod sensitivity. Frequency shifts at 4 of 6 areas were consistent with earlier flowering of the evolved population relative to the initial population. The use of this new outcrossing wheat population, mixing numerous initial parental lines through multiple generations of panmixia, is discussed in terms of power to detect genes under selection and association mapping. Furthermore we provide new statistical methods for use in future analyses of multiparental populations.
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Affiliation(s)
- Stéphanie Thépot
- Université Paris-Sud, Unité Mixte de Recherche 0320/Unité Mixte de Recherche 8120, Génétique Végétale, F-91190 Gif-sur-Yvette, France Institut National de la Recherche Agronomique, Unité Mixte de Recherche 0320/Unité Mixte de Recherche 8120, Génétique Végétale, F-91190 Gif-sur-Yvette, France
| | - Gwendal Restoux
- Unité d'Ecologie, Systématique et Evolution, Centre National de la Recherche Scientifique Unité Mixte de Recherche 8079, Université Paris-Sud, Orsay, France
| | - Isabelle Goldringer
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 0320/Unité Mixte de Recherche 8120, Génétique Végétale, F-91190 Gif-sur-Yvette, France
| | - Frédéric Hospital
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 1313 Génétique Animale et Biologie Intégrative, F-78352 Jouy en Josas, France
| | - David Gouache
- Arvalis, Institut du Végétal, Station Expérimentale, F-91720 Boigneville, France
| | - Ian Mackay
- National Institute of Agricultural Botany, Huntingdon Road, Cambridge CB3 0LE, United Kingdom
| | - Jérôme Enjalbert
- Institut National de la Recherche Agronomique, Unité Mixte de Recherche 0320/Unité Mixte de Recherche 8120, Génétique Végétale, F-91190 Gif-sur-Yvette, France
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12
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Weis AE, Nardone E, Fox GA. The strength of assortative mating for flowering date and its basis in individual variation in flowering schedule. J Evol Biol 2014; 27:2138-51. [DOI: 10.1111/jeb.12465] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 07/21/2014] [Accepted: 07/22/2014] [Indexed: 11/27/2022]
Affiliation(s)
- A. E. Weis
- Koffler Scientific Reserve at Jokers Hill; University of Toronto; King City ON Canada
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto ON Canada
| | - E. Nardone
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto ON Canada
| | - G. A. Fox
- Department of Integrative Biology; University of South Florida; Tampa FL USA
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Stabilizing selection on nectar concentration in wild Petunia axillaris, as revealed by genetic analysis of pollen dispersal. Evol Ecol 2014. [DOI: 10.1007/s10682-014-9714-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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14
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Hinsinger DD, Gaudeul M, Couloux A, Bousquet J, Frascaria-Lacoste N. The phylogeography of Eurasian Fraxinus species reveals ancient transcontinental reticulation. Mol Phylogenet Evol 2014; 77:223-37. [PMID: 24795215 DOI: 10.1016/j.ympev.2014.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 04/14/2014] [Accepted: 04/18/2014] [Indexed: 01/16/2023]
Abstract
To investigate the biogeographical history of ashes species of the Eurasian section Fraxinus and to test the hypothesis of ancient reticulations, we sequenced nuclear DNA (nETS and nITS, 1075 bp) for 533 samples and scored AFLP for 63 samples of Eurasian ashes within the section Fraxinus. The nITS phylogeny retrieved the classical view of the evolution of the section, whereas nETS phylogeny indicated an unexpected separation of F. angustifolia in two paraphyletic groups, respectively found in southeastern Europe and in the other parts of the Mediterranean basin. In the nETS phylogeny, the former group was closely related to F. excelsior, whereas the later was closely related to F. mandshurica, a species which is restricted nowadays to northeastern Asia. This topological incongruence between the two loci indicated the occurrence of an ancient reticulation between European and Asian ash species. Several other ancient reticulation events between the two European species and the other species of the section were supported by the posterior predictive checking method. Some of these reticulation events would have occurred during the Miocene, when climatic variations may have lead these species to expand their distribution range and come into contact. The recurrent reticulations observed among Eurasian ash species indicate that they should be considered as conspecific taxa, with subspecific status for some groups. Altogether, the results of the present study provide a rare documented evidence for the occurrence of multiple ancient reticulations within a group of temperate tree taxa with modern disjunct distributions in Eurasia. These ancient reticulation events indicate that the speciation process is slow in ashes, necessitating long periods of geographical isolation. The implications for speciation processes in temperate trees with similar life history and reproductive biology are discussed.
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Affiliation(s)
- Damien D Hinsinger
- AgroParisTech, UMR 8079, 91405 Orsay, France; Centre national de la recherche scientifique, UMR 8079, 910405 Orsay, France; Université Paris-Sud, UMR 8079, F-91000 Orsay, France; Chaire de recherche du Canada en génomique forestière et environnementale, Centre d'étude de la forêt et Institut de biologie intégrative et des systèmes, Université Laval, Québec, Québec G1V 0A6, Canada.
| | - Myriam Gaudeul
- Muséum National d'Histoire Naturelle, UMR CNRS 7205 'Origine, Structure et Evolution de la Biodiversité', 16 rue Buffon, CP 39, F-75005 Paris, France.
| | - Arnaud Couloux
- Genoscope, Centre National de Séquençage, 2 rue Gaston Crémieux, CP 5706, F-91057 Evry Cedex, France.
| | - Jean Bousquet
- Chaire de recherche du Canada en génomique forestière et environnementale, Centre d'étude de la forêt et Institut de biologie intégrative et des systèmes, Université Laval, Québec, Québec G1V 0A6, Canada.
| | - Nathalie Frascaria-Lacoste
- AgroParisTech, UMR 8079, 91405 Orsay, France; Centre national de la recherche scientifique, UMR 8079, 910405 Orsay, France; Université Paris-Sud, UMR 8079, F-91000 Orsay, France.
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15
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Chunco AJ. Hybridization in a warmer world. Ecol Evol 2014; 4:2019-31. [PMID: 24963394 PMCID: PMC4063493 DOI: 10.1002/ece3.1052] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 03/01/2014] [Accepted: 03/11/2014] [Indexed: 01/09/2023] Open
Abstract
Climate change is profoundly affecting the evolutionary trajectory of individual species and ecological communities, in part through the creation of novel species assemblages. How climate change will influence competitive interactions has been an active area of research. Far less attention, however, has been given to altered reproductive interactions. Yet, reproductive interactions between formerly isolated species are inevitable as populations shift geographically and temporally as a result of climate change, potentially resulting in introgression, speciation, or even extinction. The susceptibility of hybridization rates to anthropogenic disturbance was first recognized in the 1930s. To date, work on anthropogenically mediated hybridization has focused primarily on either physical habitat disturbance or species invasion. Here, I review recent literature on hybridization to identify how ecological responses to climate change will increase the likelihood of hybridization via the dissolution of species barriers maintained by habitat, time, or behavior. Using this literature, I identify several cases where novel hybrid zones have recently formed, likely as a result of changing climate. Future research should focus on identifying areas and taxonomic groups where reproductive species interactions are most likely to be influenced by climate change. Furthermore, a better understanding of the evolutionary consequences of climate-mediated secondary contact is urgently needed. Paradoxically, hybridization is both a major conservation concern and an important source of novel genetic and phenotypic variation. Hybridization may therefore both contribute to increasing rates of extinction and stimulate the creation of novel phenotypes that will speed adaptation to novel climates. Predicting which result will occur following secondary contact will be an important contribution to conservation for many species.
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Affiliation(s)
- Amanda J Chunco
- Department of Environmental Studies, Elon University CB 2015, Elon, North Carolina 27244
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16
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Thomasset M, Hodkinson TR, Restoux G, Frascaria-Lacoste N, Douglas GC, Fernández-Manjarrés JF. Thank you for not flowering: conservation genetics and gene flow analysis of native and non-native populations of Fraxinus (Oleaceae) in Ireland. Heredity (Edinb) 2014; 112:596-606. [PMID: 24424162 DOI: 10.1038/hdy.2013.141] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 09/02/2013] [Accepted: 11/22/2013] [Indexed: 11/09/2022] Open
Abstract
The risks of gene flow between interfertile native and introduced plant populations are greatest when there is no spatial isolation of pollen clouds and phenological patterns overlap completely. Moreover, invasion probabilities are further increased if introduced populations are capable of producing seeds by selfing. Here we investigated the mating system and patterns of pollen-mediated gene flow among populations of native ash (Fraxinus excelsior) and mixed plantations of non-native ash (F. angustifolia and F. excelsior) as well as hybrid ash (F. excelsior × F. angustifolia) in Ireland. We analysed the flowering phenology of the mother trees and genotyped with six microsatellite loci in progeny arrays from 132 native and plantation trees (1493 seeds) and 444 potential parents. Paternity analyses suggested that plantation and native trees were pollinated by both native and introduced trees. No signs of significant selfing in the introduced trees were observed and no evidence of higher male reproductive success was found for introduced trees compared with native ones either. A small but significant genetic structure was found (φft=0.05) and did not correspond to an isolation-by-distance pattern. However, we observed a significant temporal genetic structure related to the different phenological groups, especially with early and late flowering native trees; each phenological group was pollinated with distinctive pollen sources. Implications of these results are discussed in relation to the conservation and invasiveness of ash and the spread of resistance genes against pathogens such as the fungus Chalara fraxinea that is destroying common ash forests in Europe.
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Affiliation(s)
- M Thomasset
- 1] School of Natural Sciences, Trinity College Dublin, Dublin, Ireland [2] Teagasc, Kinsealy Research Centre, Dublin, Ireland
| | - T R Hodkinson
- 1] School of Natural Sciences, Trinity College Dublin, Dublin, Ireland [2] Trinity Centre for Biodiversity Research, Trinity College Dublin, Dublin, Ireland
| | - G Restoux
- Laboratoire d'Ecologie Systématique et Evolution, UMR 8079, Université Paris-Sud, Orsay, France
| | - N Frascaria-Lacoste
- 1] Laboratoire d'Ecologie Systématique et Evolution, UMR 8079, Université Paris-Sud, Orsay, France [2] AgroParisTech, Paris, France [3] CNRS, UMR 8079, Orsay, France
| | - G C Douglas
- Teagasc, Kinsealy Research Centre, Dublin, Ireland
| | - J F Fernández-Manjarrés
- 1] Laboratoire d'Ecologie Systématique et Evolution, UMR 8079, Université Paris-Sud, Orsay, France [2] AgroParisTech, Paris, France [3] CNRS, UMR 8079, Orsay, France
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17
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Gauzere J, Klein EK, Oddou-Muratorio S. Ecological determinants of mating system within and between three Fagus sylvatica populations along an elevational gradient. Mol Ecol 2013; 22:5001-15. [PMID: 23952125 DOI: 10.1111/mec.12435] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 06/21/2013] [Accepted: 06/24/2013] [Indexed: 11/26/2022]
Abstract
Studies addressing the variation of mating system between plant populations rarely account for the variability of these parameters between individuals within populations, although this variability is often non-negligible. Here, we propose a new direct method based on paternity analyses (Mixed Effect Mating Model) to estimate individual migration (mi ) and selfing rates (si ) together with the pollen dispersal kernel. Using this method and the KINDIST approach, we investigated the variation of mating system parameters within and between three populations of Fagus sylvatica along an elevational gradient. Among the mother trees, si varied from 0% to 48%, mi varied from 12% to 86% and the effective number of pollen donors (Nepi ) varied from 2 to 364. The mating patterns differed along the gradient, the top population showing higher m and lower s, and a trend to higher Nep than the bottom populations. The phenological lag shaped long-distance pollen flow both within population (by increasing mi at mother-tree level) and between populations (by increasing m at high elevation). Rather than the mate density, the canopy density was detected as a major mating system determinant within population; it acted as a barrier to pollen flow, decreasing the proportion of long-distance pollen flow and increasing si . Overall, the effects of ecological factors on mating system were not the same within vs. between populations across the gradient, and these factors also differed from those traditionally found to shape variation at range-wide scale, highlighting the interest of multiscale approaches.
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Affiliation(s)
- Julie Gauzere
- INRA, UR629 Ecologie des Forêts Méditerranéennes (URFM), F-84914, Avignon, France; INRA, UR546 Biostatistique et Processus Spatiaux (BioSP), F-84914, Avignon, France
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18
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Chybicki IJ, Burczyk J. Seeing the forest through the trees: comprehensive inference on individual mating patterns in a mixed stand of Quercus robur and Q. petraea. ANNALS OF BOTANY 2013; 112:561-74. [PMID: 23788747 PMCID: PMC3718219 DOI: 10.1093/aob/mct131] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS Sexual reproduction is one of the most important moments in a life cycle, determining the genetic composition of individual offspring. Controlled pollination experiments often show high variation in the mating system at the individual level, suggesting a persistence of individual variation in natural populations. Individual variation in mating patterns may have significant adaptive implications for a population and for the entire species. Nevertheless, field data rarely address individual differences in mating patterns, focusing rather on averages. This study aimed to quantify individual variation in the different components of mating patterns. METHODS Microsatellite data were used from 421 adult trees and 1911 seeds, structured in 72 half-sib families collected in a single mixed stand of Quercus robur and Q. petraea in northern Poland. Using a Bayesian approach, mating patterns were investigated, taking into account pollen dispersal, male fecundity, possible hybridization and heterogeneity in immigrant pollen pools. KEY RESULTS Pollen dispersal followed a heavy-tailed distribution (283 m on average). In spite of high pollen mobility, immigrant pollen pools showed strong genetic structuring among mothers. At the individual level, immigrant pollen pools showed highly variable divergence rates, revealing that sources of immigrant pollen can vary greatly among particular trees. Within the stand, the distribution of male fecundity appeared highly skewed, with a small number of dominant males, resulting in a ratio of census to effective density of pollen donors of 5·3. Male fecundity was not correlated with tree diameter but showed strong cline-like spatial variation. This pattern can be attributed to environmental variation. Quercus petraea revealed a greater preference (74 %) towards intraspecific mating than Q. robur (36 %), although mating preferences varied among trees. CONCLUSIONS Mating patterns can reveal great variation among individuals, even within a single even-age stand. The results show that trees can mate assortatively, with little respect for spatial proximity. Such selective mating may be a result of variable combining compatibility among trees due to genetic and/or environmental factors.
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Affiliation(s)
- Igor J Chybicki
- Department of Genetics, Institute of Experimental Biology, Kazimierz Wielki University, 85064 Bydgoszcz, Poland.
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19
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Ruhsam M, Hollingsworth PM, Ennos RA. Patterns of mating, generation of diversity, and fitness of offspring in a Geum hybrid swarm. Evolution 2013; 67:2728-40. [PMID: 24033179 DOI: 10.1111/evo.12147] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 04/16/2013] [Indexed: 12/01/2022]
Abstract
To understand the evolutionary consequences of hybridization between the outcrossing plant Geum rivale (Rosaceae) and the selfer Geum urbanum, we tested the predictions of two simple models that assume either (A) low or (B) high pollen fitness in hybrids. Model A predicts only four genotypic classes (G. rivale, G. rivale backcross [BC(R)], F1, and Geum urbanum) and asymmetric introgression from inbreeding to outbreeding species. Model B predicts additional genotypic classes and potential generation of novel inbreeding lines in the hybrid swarm. Amplified fragment length polymorphism (AFLP) analysis of adults revealed only the four genotypes predicted by model A. However, microsatellite analysis of parent-progeny arrays demonstrated production of selfed offspring by F1 and BC(R) maternal parents and contribution of these genotypes to outcross pollen pools, as predicted by model B. Moreover, AFLP and morphological analysis showed that the offspring generation comprised genotypes and phenotypes covering the entire spectrum of variation between the two parental species, in line with model B. A common garden experiment indicated no systematic reduction in fitness of offspring derived from hybrid parents. The genetic structure of the adults in the Geum hybrid swarm cannot be explained by restricted mating patterns but may result from ecological selection acting on a diverse offspring population.
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Affiliation(s)
- Markus Ruhsam
- University of Edinburgh, Institute of Evolutionary Biology, Ashworth Laboratories, Edinburgh, EH3 9JT, United Kingdom; Royal Botanic Garden Edinburgh, Edinburgh, EH3 5LR, United Kingdom.
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20
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Chybicki IJ. Note on the Applicability of the F-model in Analysis of Pollen Pool Heterogeneity. J Hered 2013; 104:578-85. [DOI: 10.1093/jhered/est029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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21
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De Cauwer I, Arnaud JF, Klein EK, Dufay M. Disentangling the causes of heterogeneity in male fecundity in gynodioecious Beta vulgaris ssp. maritima. THE NEW PHYTOLOGIST 2012; 195:676-687. [PMID: 22691102 DOI: 10.1111/j.1469-8137.2012.04191.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Variation among individuals in reproductive success is advocated as a major process driving evolution of sexual polymorphisms in plants, such as gynodioecy where females and hermaphrodites coexist. In gynodioecious Beta vulgaris ssp. maritima, sex determination involves cytoplasmic male sterility (CMS) genes and nuclear restorers of male fertility. Both restored CMS and non-CMS hermaphrodites co-occur. Genotype-specific differences in male fitness are theoretically expected to explain the maintenance of cytonuclear polymorphism. Using genotypic information on seedlings and flowering plants within two metapopulations, we investigated whether male fecundity was influenced by ecological, phenotypic and genetic factors, while taking into account the shape and scale of pollen dispersal. Along with spatially restricted pollen flow, we showed that male fecundity was affected by flowering synchrony, investment in reproduction, pollen production and cytoplasmic identity of potential fathers. Siring success of non-CMS hermaphrodites was higher than that of restored CMS hermaphrodites. However, the magnitude of the difference in fecundity depended on the likelihood of carrying restorer alleles for non-CMS hermaphrodites. Our results suggest the occurrence of a cost of silent restorers, a condition supported by scarce empirical evidence, but theoretically required to maintain a stable sexual polymorphism in gynodioecious species.
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Affiliation(s)
- I De Cauwer
- Laboratoire de Génétique et Évolution des Populations Végétales, UMR CNRS 8198, Bâtiment SN2, Université des Sciences et Technologies de Lille - Lille 1, F-59655 Villeneuve d'Ascq Cedex, France
- Present address: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - J-F Arnaud
- Laboratoire de Génétique et Évolution des Populations Végétales, UMR CNRS 8198, Bâtiment SN2, Université des Sciences et Technologies de Lille - Lille 1, F-59655 Villeneuve d'Ascq Cedex, France
| | - E K Klein
- INRA, UR 546, Biostatistique et Processus Spatiaux, Domaine St Paul, Site Agroparc, F-84914 Avignon Cedex 9, France
| | - M Dufay
- Laboratoire de Génétique et Évolution des Populations Végétales, UMR CNRS 8198, Bâtiment SN2, Université des Sciences et Technologies de Lille - Lille 1, F-59655 Villeneuve d'Ascq Cedex, France
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22
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Lukac M, Gooding MJ, Griffiths S, Jones HE. Asynchronous flowering and within-plant flowering diversity in wheat and the implications for crop resilience to heat. ANNALS OF BOTANY 2012; 109:843-50. [PMID: 22186277 PMCID: PMC3286278 DOI: 10.1093/aob/mcr308] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 11/23/2011] [Indexed: 05/24/2023]
Abstract
BACKGROUND AND AIMS Self-pollination dominates in wheat, with a small level of out-crossing due to flowering asynchrony and male sterility. However, the timing and synchrony of male and female flowering in wheat is a crucial determinant of seed set and may be an important factor affecting gene flow and resilience to climate change. Here, a methodology is presented for assessing the timing and synchrony of flowering in wheat, Triticum aestivum. METHODS From the onset of flowering until the end of anthesis, the anther and stigma activity of each floret was assessed on the first five developing ears in potted plants grown under ambient conditions and originating from 'Paragon' or 'Spark-Rialto' backgrounds. At harvest maturity, seed presence, size and weight was recorded for each floret scored. KEY RESULTS AND CONCLUSIONS The synchrony between pollen dehiscence and stigma collapse within a flower was dependent on its relative position in a spike and within a floret. Determined on the basis of synchrony within each flower, the level of pollination by pollen originating from other flowers reached approx. 30 % and did not change throughout the duration of flowering. A modelling exercise parameterized by flowering observations indicated that the temporal and spatial variability of anther activity within and between spikes may influence the relative resilience of wheat to sudden, extreme climatic events which has direct relevance to predicted future climate scenarios in the UK.
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Affiliation(s)
- Martin Lukac
- Department of Agriculture, Development and Policy, University of Reading, UK.
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23
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Effects of male fecundity, interindividual distance and anisotropic pollen dispersal on mating success in a Scots pine (Pinus sylvestris) seed orchard. Heredity (Edinb) 2011; 108:312-21. [PMID: 21897440 DOI: 10.1038/hdy.2011.76] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Quantifying the effect of pollen dispersal and flowering traits on mating success is essential for understanding evolutionary responses to changing environments and establishing strategies for forest tree breeding. This study examined, quantitatively, the effects of male fecundity, interindividual distance and anisotropic pollen dispersal on the mating success of Scots pine (Pinus sylvestris), utilizing a well-mapped Scots pine seed orchard. Paternity analysis of 1021 seeds sampled from 87 trees representing 28 clones showed that 53% of the seeds had at least one potential pollen parent within the orchard. Pronounced variation in paternal contribution was observed among clones. Variations in pollen production explained up to 78% of the variation in mating success, which was 11.2 times greater for clones producing the largest amount of pollen than for clones producing the least pollen. Mating success also varied with intertree distance and direction, which explained up to 28% of the variance. Fertilization between neighboring trees 2.3 m apart was 2.4 times more frequent than between trees 4.6 m apart, and up to 12.4 times higher for trees downwind of the presumed prevailing wind direction than for upwind trees. The effective number of pollen donors recorded in the seed orchard (12.2) was smaller than the theoretical expectation (19.7). Based on the empirical observations, a mating model that best describes the gene dispersal pattern in clonal seed orchards was constructed.
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Frascaria-Lacoste N, Henry A, Gérard PR, Bertolino P, Collin E, Fernández-Manjarrés J. Should Forest Restoration with Natural Hybrids Be Allowed? Restor Ecol 2011. [DOI: 10.1111/j.1526-100x.2011.00804.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Austerlitz F, Gleiser G, Teixeira S, Bernasconi G. The effects of inbreeding, genetic dissimilarity and phenotype on male reproductive success in a dioecious plant. Proc Biol Sci 2011; 279:91-100. [PMID: 21561968 DOI: 10.1098/rspb.2011.0652] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pollen fate can strongly affect the genetic structure of populations with restricted gene flow and significant inbreeding risk. We established an experimental population of inbred and outbred Silene latifolia plants to evaluate the effects of (i) inbreeding depression, (ii) phenotypic variation and (iii) relatedness between mates on male fitness under natural pollination. Paternity analysis revealed that outbred males sired significantly more offspring than inbred males. Independently of the effects of inbreeding, male fitness depended on several male traits, including a sexually dimorphic (flower number) and a gametophytic trait (in vitro pollen germination rate). In addition, full-sib matings were less frequent than randomly expected. Thus, inbreeding, phenotype and genetic dissimilarity simultaneously affect male fitness in this animal-pollinated plant. While inbreeding depression might threaten population persistence, the deficiency of effective matings between sibs and the higher fitness of outbred males will reduce its occurrence and counter genetic erosion.
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Affiliation(s)
- Frédéric Austerlitz
- Laboratoire Ecologie, Systématique et Evolution, UMR CNRS 8079, Université, Paris-Sud, 91405 Orsay Cedex, France
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26
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Field DL, Ayre DJ, Whelan RJ, Young AG. The importance of pre-mating barriers and the local demographic context for contemporary mating patterns in hybrid zones of Eucalyptus aggregata and Eucalyptus rubida. Mol Ecol 2011; 20:2367-79. [PMID: 21375638 DOI: 10.1111/j.1365-294x.2011.05054.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The frequency of hybridization in plants is context dependent and can be influenced by the local mating environment. We used progeny arrays and admixture and pollen dispersal analyses to assess the relative importance of pre-mating reproductive barriers and the local demographic environment as explanations of variation in hybrid frequency in three mapped hybrid zones of Eucalyptus aggregata and E. rubida. A total of 731 open-pollinated progeny from 36 E. aggregata maternal parents were genotyped using six microsatellite markers. Admixture analysis identified substantial variation in hybrid frequency among progeny arrays (0-76.9%). In one hybrid zone, hybrid frequency was related to pre-mating barriers (degree of flowering synchrony) and demographic components of the local mating environment (decreasing population size, closer proximity to E. rubida and hybrid trees). At this site, average pollen dispersal distance was less and almost half (46%) of the hybrid progeny were sired by local E. rubida and hybrid trees. In contrast, at the other two sites, pre-mating and demographic factors were not related to hybrid frequency. Compared to the first hybrid zone where most of the E. rubida (76%) and all hybrids flowered, in the remaining sites fewer E. rubida (22-41%) and hybrid trees (0-50%) flowered and their reproductive success was lower (sired 0-23% of hybrids). As a result, most hybrids were sired by external E. rubida/hybrids located at least 2-3 km away. These results indicate that although pre-mating barriers and local demography can influence patterns of hybridization, their importance can depend upon the scale of pollen dispersal.
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Affiliation(s)
- David L Field
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S3B2, Canada.
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Robson PRH, Kelly R, Jensen EF, Giddings GD, Leitch M, Davey C, Gay AP, Jenkins G, Thomas H, Donnison IS. A flexible quantitative methodology for the analysis of gene-flow between conventionally bred maize populations using microsatellite markers. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2011; 122:819-29. [PMID: 21109994 DOI: 10.1007/s00122-010-1489-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 11/04/2010] [Indexed: 05/30/2023]
Abstract
Previous studies of gene-flow in agriculture have used a range of physical and biochemical markers, including transgenes. However, physical and biochemical markers are not available for all commercial varieties, and transgenes are difficult to use when trying to estimate gene flow in the field where the use of transgenes is often restricted. Here, we demonstrate the use of simple sequence repeat microsatellite markers (SSRs) to study gene flow in maize. Developing the first quantitative analysis of pooled SSR samples resulted in a high sampling efficiency which minimised the use of resources and greatly enhanced the possibility of hybrid detection. We were able to quantitatively distinguish hybrids in pools of ten samples from non-hybrid parental lines in all of the 24 pair-wise combinations of commercial varieties tested. The technique was used to determine gene flow in field studies, from which a simple model describing gene flow in maize was developed.
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Klein EK, Carpentier FH, Oddou-Muratorio S. Estimating the variance of male fecundity from genotypes of progeny arrays: evaluation of the Bayesian forward approach. Methods Ecol Evol 2011. [DOI: 10.1111/j.2041-210x.2010.00085.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Lepais O, Gerber S. Reproductive patterns shape introgression dynamics and species succession within the European white oak species complex. Evolution 2010; 65:156-70. [PMID: 20722727 DOI: 10.1111/j.1558-5646.2010.01101.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reproductive system of hybrids is an important factor shaping introgression dynamics within species complexes. We combined paternity and parentage analyses with previous species characterization by genetic assignment, to directly identify reproductive events that occurred within a stand comprising four European white oak species. Comparing species status of parent pairs provided a precise quantification of hybridization rate, backcrosses, and intraspecific matings in two life stages. The detailed mating system analysis revealed new findings on the dynamics of interspecific gene flow. First, hybrids acted successfully as both male and female during reproduction. They produced acorns and seedlings that were as viable as those sired by purebreds. Second, species maintenance could be due to a relatively low level of interspecific mating contrasting with a large proportion of intraspecific crosses and backcrosses. Despite a high proportion of hybrids and extensive interspecific gene flow, partial species integrity is maintained by genetically controlled pollen discrimination, ensuring preferential matings within purebreds and high parental species fidelity in hybrid reproduction, which impedes complete collapse into a continuous hybrid swarm. Finally, we showed that pollen from the different species had unequal contributions to reproduction suggesting that introgression processes could ultimately lead to extirpation or expansion of some species.
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Affiliation(s)
- Olivier Lepais
- INRA, UMR 1202 BIOGECO, 69 route d'Arcachon, F-33612 Cestas, France.
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CHYBICKI IJ, BURCZYK J. Realized gene flow within mixed stands of Quercus robur L. and Q. petraea (Matt.) L. revealed at the stage of naturally established seedling. Mol Ecol 2010; 19:2137-51. [DOI: 10.1111/j.1365-294x.2010.04632.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gomez C, Batti A, Le Pierrès D, Campa C, Hamon S, de Kochko A, Hamon P, Huynh F, Despinoy M, Poncet V. Favourable habitats forCoffeainter-specific hybridization in central New Caledonia: combined genetic and spatial analyses. J Appl Ecol 2010. [DOI: 10.1111/j.1365-2664.2009.01762.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Marshall DL, Avritt JJ, Maliakal-Witt S, Medeiros JS, Shaner MGM. The impact of plant and flower age on mating patterns. ANNALS OF BOTANY 2010; 105:7-22. [PMID: 19875519 PMCID: PMC2794063 DOI: 10.1093/aob/mcp260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/18/2009] [Accepted: 09/18/2009] [Indexed: 05/06/2023]
Abstract
BACKGROUND Over a season, plant condition, amount of ongoing reproduction and biotic and abiotic environmental factors vary. As flowers age, flower condition and amount of pollen donated and received also vary. These internal and external changes are significant for fitness if they result in changes in reproduction and mating. SCOPE Literature from several fields was reviewed to provide a picture of the changes that occur in plants and flowers that can affect mating over a season. As flowers age, both the entire flower and individual floral whorls show changes in appearance and function. Over a season, changes in mating often appear as alteration in seed production vs. pollen donation. In several species, older, unpollinated flowers are more likely to self. If flowers are receiving pollen, staying open longer may increase the number of mates. In wild radish, for which there is considerable information on seed paternity, older flowers produce fewer seeds and appear to discriminate less among pollen donors. Pollen donor performance can also be linked to maternal plant age. Different pollinators and mates are available across the season. Also in wild radish, maternal plants appear to exert the most control over paternity when they are of intermediate age. CONCLUSIONS Although much is known about the characters of plants and flowers that can change over a season, there is less information on the effects of age on mating. Several studies document changes in self-pollination over time, but very few, other than those on wild radish, consider more subtle aspects of differential success of pollen donors over time.
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Affiliation(s)
- Diane L Marshall
- Department of Biology, University of New Mexico, MSC03 2020, Albuquerque, NM 87131, USA.
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Gene flow and mating patterns in individuals of wych elm (Ulmus glabra) in forest and open land after the influence of Dutch elm disease. CONSERV GENET 2009. [DOI: 10.1007/s10592-009-0028-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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De-Lucas AI, González-Martínez SC, Vendramin GG, Hidalgo E, Heuertz M. Spatial genetic structure in continuous and fragmented populations of Pinus pinaster Aiton. Mol Ecol 2009; 18:4564-76. [PMID: 19793351 DOI: 10.1111/j.1365-294x.2009.04372.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Habitat fragmentation, i.e., the reduction of populations into small isolated remnants, is expected to increase spatial genetic structure (SGS) in plant populations through nonrandom mating, lower population densities and potential aggregation of reproductive individuals. We investigated the effects of population size reduction and genetic isolation on SGS in maritime pine (Pinus pinaster Aiton) using a combined experimental and simulation approach. Maritime pine is a wind-pollinated conifer which has a scattered distribution in the Iberian Peninsula as a result of forest fires and habitat fragmentation. Five highly polymorphic nuclear microsatellites were genotyped in a total of 394 individuals from two population pairs from the Iberian Peninsula, formed by one continuous and one fragmented population each. In agreement with predictions, SGS was significant and stronger in fragments (Sp = 0.020 and Sp = 0.026) than in continuous populations, where significant SGS was detected for one population only (Sp = 0.010). Simulations suggested that under fat-tailed dispersal, small population size is a stronger determinant of SGS than genetic isolation, while under normal dispersal, genetic isolation has a stronger effect. SGS was always stronger in real populations than in simulations, except if unrealistically narrow dispersal and/or high variance of reproductive success were modelled (even when accounting for potential overestimation of SGS in real populations as a result of short-distance sampling). This suggests that factors such as nonrandom mating or selection not considered in the simulations were additionally operating on SGS in Iberian maritime pine populations.
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Affiliation(s)
- A I De-Lucas
- Departamento de Producción Vegetal y Recursos Forestales, E.T.S. Ingenierías Agrarias, Universidad de Valladolid, Avenida de Madrid 44, E-34004 Palencia, Spain.
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SLAVOV GT, LEONARDI S, BURCZYK J, ADAMS WT, STRAUSS SH, DIFAZIO SP. Extensive pollen flow in two ecologically contrasting populations ofPopulus trichocarpa. Mol Ecol 2009; 18:357-73. [DOI: 10.1111/j.1365-294x.2008.04016.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bacles CFE, Ennos RA. Paternity analysis of pollen-mediated gene flow for Fraxinus excelsior L. in a chronically fragmented landscape. Heredity (Edinb) 2008; 101:368-80. [DOI: 10.1038/hdy.2008.66] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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KLEIN EK, DESASSIS N, ODDOU-MURATORIO S. Pollen flow in the wildservice tree,Sorbus torminalis(L.) Crantz. IV. Whole interindividual variance of male fecundity estimated jointly with the dispersal kernel. Mol Ecol 2008; 17:3323-36. [DOI: 10.1111/j.1365-294x.2008.03809.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Fortuna MA, García C, Guimarães PR, Bascompte J. Spatial mating networks in insect-pollinated plants. Ecol Lett 2008; 11:490-8. [PMID: 18318718 DOI: 10.1111/j.1461-0248.2008.01167.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gene flow in plant populations is largely determined by landscape heterogeneity. Both the shape of the pollination kernel and the spatial distribution of trees affect the distribution of pollen grains and the genotypes they harbour, but little is known about the relative contribution of each of these two factors. Using genetic markers we build a spatial network of pollination events between any two trees in a population of Prunus mahaleb, an insect-pollinated plant. Then, we apply tools from the science of complex networks to characterize the structure of such a mating network. Although the distribution of the number of pollen donors per tree is quite homogeneous, the identity of donors is distributed heterogeneously across the population. This results in a population structured in well-defined modules or compartments, formed by a group of mother trees and their shared pollen donors. Long-distance pollination events decrease the modular structure by favouring mating among all available mates. This increases gene flow across the entire population, reducing its genetic structure, and potentially decreasing the role of genetic drift.
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Affiliation(s)
- Miguel A Fortuna
- Integrative Ecology Group, Estación Biológica de Doñana, CSIC, Apdo. 1056, E-41080 Sevilla, Spain.
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Elzinga JA, Atlan A, Biere A, Gigord L, Weis AE, Bernasconi G. Time after time: flowering phenology and biotic interactions. Trends Ecol Evol 2007; 22:432-9. [PMID: 17573151 DOI: 10.1016/j.tree.2007.05.006] [Citation(s) in RCA: 310] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/30/2007] [Accepted: 05/31/2007] [Indexed: 11/23/2022]
Abstract
The role of biotic interactions in shaping plant flowering phenology has long been controversial; plastic responses to the abiotic environment, limited precision of biological clocks and inconsistency of selection pressures have generally been emphasized to explain phenological variation. However, part of this variation is heritable and selection analyses show that biotic interactions can modulate selection on flowering phenology. Our review of the literature indicates that pollinators tend to favour peak or earlier flowering, whereas pre-dispersal seed predators tend to favour off-peak or later flowering. However, effects strongly vary among study systems. To understand such variation, future studies should address the impact of mutualist and antagonist dispersal ability, ecological specialization, and habitat and plant population characteristics. Here, we outline future directions to study how such interactions shape flowering phenology.
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Affiliation(s)
- Jelmer A Elzinga
- Department of Ecology and Evolution, University of Lausanne, CH 1015 Lausanne, Switzerland
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