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Haghighatnia M, Machac A, Schmickl R, Lafon Placette C. Darwin's 'mystery of mysteries': the role of sexual selection in plant speciation. Biol Rev Camb Philos Soc 2023; 98:1928-1944. [PMID: 37337476 DOI: 10.1111/brv.12991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 06/02/2023] [Accepted: 06/07/2023] [Indexed: 06/21/2023]
Abstract
Sexual selection is considered one of the key processes that contribute to the emergence of new species. While the connection between sexual selection and speciation has been supported by comparative studies, the mechanisms that mediate this connection remain unresolved, especially in plants. Similarly, it is not clear how speciation processes within plant populations translate into large-scale speciation dynamics. Here, we review the mechanisms through which sexual selection, pollination, and mate choice unfold and interact, and how they may ultimately produce reproductive isolation in plants. We also overview reproductive strategies that might influence sexual selection in plants and illustrate how functional traits might connect speciation at the population level (population differentiation, evolution of reproductive barriers; i.e. microevolution) with evolution above the species level (macroevolution). We also identify outstanding questions in the field, and suitable data and tools for their resolution. Altogether, this effort motivates further research focused on plants, which might potentially broaden our general understanding of speciation by sexual selection, a major concept in evolutionary biology.
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Affiliation(s)
- Mohammadjavad Haghighatnia
- Department of Botany, Faculty of Science, Charles University, Benatska 2, Prague, CZ-128 01, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, Průhonice, 252 43, Czech Republic
| | - Antonin Machac
- Laboratory of Environmental Microbiology, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, Prague, 14220, Czech Republic
| | - Roswitha Schmickl
- Department of Botany, Faculty of Science, Charles University, Benatska 2, Prague, CZ-128 01, Czech Republic
- Institute of Botany, The Czech Academy of Sciences, Zámek 1, Průhonice, 252 43, Czech Republic
| | - Clément Lafon Placette
- Department of Botany, Faculty of Science, Charles University, Benatska 2, Prague, CZ-128 01, Czech Republic
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2
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Jarvis GC, White CR, Marshall DJ. Macroevolutionary patterns in marine hermaphroditism. Evolution 2022; 76:3014-3025. [PMID: 36199199 PMCID: PMC10091813 DOI: 10.1111/evo.14639] [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: 09/30/2021] [Revised: 08/08/2022] [Accepted: 08/23/2022] [Indexed: 01/22/2023]
Abstract
Most plants and many animals are hermaphroditic; whether the same forces are responsible for hermaphroditism in both groups is unclear. The well-established drivers of hermaphroditism in plants (e.g., seed dispersal potential, pollination mode) have analogues in animals (e.g., larval dispersal potential, fertilization mode), allowing us to test the generality of the proposed drivers of hermaphroditism across both groups. Here, we test these theories for 1153 species of marine invertebrates, from three phyla. Species with either internal fertilization, restricted offspring dispersal, or small body sizes are more likely to be hermaphroditic than species that are external fertilizers, planktonic developers, or larger. Plants and animals show different biogeographical patterns, however: animals are less likely to be hermaphroditic at higher latitudes-the opposite to the trend in plants. Overall, our results suggest that similar forces, namely, competition among offspring or gametes, shape the evolution of hermaphroditism across plants and three invertebrate phyla.
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Affiliation(s)
- George C Jarvis
- School of Biological Sciences/Centre for Geometric Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Craig R White
- School of Biological Sciences/Centre for Geometric Biology, Monash University, Melbourne, VIC 3800, Australia
| | - Dustin J Marshall
- School of Biological Sciences/Centre for Geometric Biology, Monash University, Melbourne, VIC 3800, Australia
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3
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Chen K, Pannell JR. Disruptive selection via pollinators and seed predators on the height of flowers on a wind-dispersed alpine herb. AMERICAN JOURNAL OF BOTANY 2022; 109:1717-1729. [PMID: 36194694 PMCID: PMC9828390 DOI: 10.1002/ajb2.16073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 06/28/2022] [Indexed: 05/25/2023]
Abstract
PREMISE Floral stalk height is known to affect seed dispersal of wind-dispersed grassland species, but it may also affect the attractiveness of flowers and fruits of animal-pollinated and animal-dispersed plants. Stalk height may thus be responsive to selection via interactions with both mutualist pollinators and seed dispersers, but also antagonist florivores and seed predators. In this study, we aimed to determine the effect of pollinators and seed predators on selection on floral stalk height in the insect-pollinated and wind-dispersed, alpine, andromonoecious herb Pulsatilla alpina, whose flowers also vary in their sex allocation and thus in the resources available to both mutualists and antagonists. METHODS We measured the resource status of individuals in terms of their size and the height of the vegetation surrounding plants of P. alpina at 11 sites. In one population, we recorded floral stalk height over an entire growing season and investigated its association with floral morphology and floral sex allocation (pistil and stamen number) and used leaf-removal manipulations to assess the effect of herbivory on floral stalk height. Finally, in four populations, we quantified phenotypic selection on floral stalk height in four female components of reproductive success before seed dispersal. RESULTS Stalk height was positively associated with female allocation of the respective flower, the resource status of the individual, and the height of the surrounding vegetation, and negatively affected by leaf removal. Our results point to disruptive selection on stalk height in terms of both selection differentials and selection gradients for fertilization, seed predation, and seed maturation rates and to positive selection on stalk height in terms of a selection differential for mature seed number. CONCLUSIONS Stalk height of P. alpina is a costly trait that affects female reproductive success via interactions with both mutualists and antagonists. We discuss the interplay between the resource status and selection imposed on female reproductive success and its likely role in the evolution of sex-allocation strategies, especially andromonoecy.
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Affiliation(s)
- Kai‐Hsiu Chen
- Department of Ecology and EvolutionUniversity of LausanneBiophore Building1015LausanneSwitzerland
| | - John R. Pannell
- Department of Ecology and EvolutionUniversity of LausanneBiophore Building1015LausanneSwitzerland
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4
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Tonnabel J, David P, Pannell JR. Rapid divergence in vegetative morphology of a wind-pollinated plant between populations at contrasting densities. Evolution 2022; 76:1737-1748. [PMID: 35713285 PMCID: PMC9544426 DOI: 10.1111/evo.14539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/20/2021] [Accepted: 01/05/2022] [Indexed: 01/22/2023]
Abstract
Plant sexual dimorphism is thought to evolve in response to sex-specific selection associated with competition for access to mates or resources, both of which may be density dependent. In wind-pollinated plants in particular, vegetative traits such as plant size and architecture may influence resource acquisition and both pollen dispersal and receipt, with potential conflict between these two components of fitness. We evaluated the role of plant density in shaping plant traits by measuring evolutionary responses in experimental populations of the sexually dimorphic wind-pollinated plant Mercurialis annua. After three generations of evolution, we observed divergence between high- and low-density populations in several vegetative traits, whereas there was no divergence for reproductive traits. A reversal in the direction of sexually dimorphic traits expressed in young plants evolved in both low- and high-density populations compared to the original population (stored as seeds). Compared to the source population, males at high density evolved to be taller when young, whereas at low density young females tended to become smaller. These results demonstrate that a simple change in plant density can induce age-dependent and sex-specific evolution in the ontogeny of vegetative organs, and illustrates the power of experimental evolution for investigating plant trait evolution.
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Affiliation(s)
- Jeanne Tonnabel
- Department of Ecology and EvolutionUniversity of LausanneLausanneCH‐1015Switzerland
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, FranceCNRSMontpellier34293France
| | - Patrice David
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, FranceCNRSMontpellier34293France
| | - John R. Pannell
- Department of Ecology and EvolutionUniversity of LausanneLausanneCH‐1015Switzerland
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5
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Gerchen JF, Veltsos P, Pannell JR. Recurrent allopolyploidization, Y-chromosome introgression and the evolution of sexual systems in the plant genus Mercurialis. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210224. [PMID: 35306889 PMCID: PMC8935306 DOI: 10.1098/rstb.2021.0224] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The plant genus Mercurialis includes dioecious, monoecious and androdioecious species (where males coexist with hermaphrodites). Its diversification involved reticulate evolution via hybridization and polyploidization. The Y chromosome of the diploid species Mercurialis annua shows only mild signs of degeneration. We used sequence variation at a Y-linked locus in several species and at multiple autosomal and pseudoautosomal loci to investigate the origin and evolution of the Y chromosome across the genus. Our study provides evidence for further cases of allopolyploid speciation. It also reveals that all lineages with separate sexes (with one possible exception) share the same ancestral Y chromosome. Surprisingly, males in androdioecious populations of hexaploid M. annua carry a Y chromosome that is not derived from either of its two putative progenitor lineages but from a more distantly related perennial dioecious lineage via introgression. These results throw new light on the evolution of sexual systems and polyploidy in Mercurialis and secure it as a promising model for further study of plant sex chromosomes. This article is part of the theme issue 'Sex determination and sex chromosome evolution in land plants'.
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Affiliation(s)
- J F Gerchen
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - P Veltsos
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - J R Pannell
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
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6
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Molinier C, Boyer L, Villamil N. Digest: Evolution and maintenance of androdioecy in a haplodiploid insect. Evolution 2021; 75:3000-3001. [PMID: 34505287 DOI: 10.1111/evo.14346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 06/26/2021] [Accepted: 08/29/2021] [Indexed: 11/29/2022]
Abstract
The coexistence of hermaphrodites and males (androdioecy) is rare in both plants and animals and has hitherto remained unknown in insects. Mongue et al. report a new case of androdioecy in the invasive haplodiploid insect Icerya purchasi, in which hermaphrodites can only self-fertilize, but occasionally mate with males. Revealingly, I. purchasi shares several features with other androdioecious species such as the consequences of evolution from separate sexes, low outcrossing rates, and its colonizing habit.
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Affiliation(s)
- Cécile Molinier
- CEFE, Univ Montpellier, CNRS, Univ Paul Valéry Montpellier 3, EPHE, IRD, Montpellier, France
| | - Loreleï Boyer
- CEFE, Univ Montpellier, CNRS, Univ Paul Valéry Montpellier 3, EPHE, IRD, Montpellier, France
| | - Nora Villamil
- Department of Ecology and Evolution, Université de Lausanne, Switzerland
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7
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The rapid dissolution of dioecy by experimental evolution. Curr Biol 2021; 31:1277-1283.e5. [PMID: 33472050 DOI: 10.1016/j.cub.2020.12.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/10/2020] [Accepted: 12/18/2020] [Indexed: 11/20/2022]
Abstract
Evolutionary transitions from hermaphroditism to dioecy have been common in flowering plants,1,2 but recent analysis also points to frequent reversions from dioecy to hermaphroditism.2-4 Here, we use experimental evolution to expose a mechanism for such reversions, validating an explanation for the scattered phylogenetic distribution of dioecy. We removed males from dioecious populations of the wind-pollinated plant Mercurialis annua and allowed natural selection to act on the remaining females that occasionally produced male flowers; such "leaky" sex expression is common in both males and females of dioecious plants.5 Over the course of four generations, females evolved a 23-fold increase in average male flower production. This phenotypic masculinization of females coincided with the evolution of partial self-fertilization, high average seed set in the continued absence of males, and a capacity to sire progeny when males were re-introduced into their populations. Our study thus validates a mechanism for the rapid dissolution of dioecy and the evolution of functional hermaphroditism under conditions that may frequently occur during periods of low population density, repeated colonization, or range expansion.6,7 Our results illustrate the power of natural selection, acting in replicated experimental populations, to bring about transitions in the mating behavior of plants.
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8
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Tonnabel J, Klein EK, Ronce O, Oddou-Muratorio S, Rousset F, Olivieri I, Courtiol A, Mignot A. Sex-specific spatial variation in fitness in the highly dimorphic Leucadendron rubrum. Mol Ecol 2021; 30:1721-1735. [PMID: 33559274 DOI: 10.1111/mec.15833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 01/27/2021] [Accepted: 01/29/2021] [Indexed: 12/16/2022]
Abstract
Sexual dimorphism in plants may emerge as a result of sex-specific selection on traits enhancing access to nutritive resources and/or to sexual partners. Here we investigated sex-specific differences in selection of sexually dimorphic traits and in the spatial distribution of effective fecundity (our fitness proxy) in a highly dimorphic dioecious wind-pollinated shrub, Leucadendron rubrum. In particular, we tested for the effect of density on male and female effective fecundity. We used spatial and genotypic data of parent and offspring cohorts to jointly estimate individual male and female effective fecundity on the one hand and pollen and seed dispersal kernels on the other hand. This methodology was adapted to the case of dioecious species. Explicitly modelling dispersal avoids the confounding effects of heterogeneous spatial distribution of mates and sampled seedlings on the estimation of effective fecundity. We also estimated selection gradients on plant traits while modelling sex-specific spatial autocorrelation in fecundity. Males exhibited spatial autocorrelation in effective fecundity at a smaller scale than females. A higher local density of plants was associated with lower effective fecundity in males but was not related to female effective fecundity. These results suggest sex-specific sensitivities to environmental heterogeneity in L. rubrum. Despite these sexual differences, we found directional selection for wider canopies and smaller leaves in both sexes, and no sexually antagonistic selection on strongly dimorphic traits in L. rubrum. Many empirical studies in animals similarly failed to detect sexually antagonistic selection in species expressing strong sexual dimorphism, and we discuss reasons explaining this common pattern.
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Affiliation(s)
- Jeanne Tonnabel
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France.,Department of Ecology and Evolution, Le Biophore, UNIL-SORGE, University of Lausanne, Lausanne, Switzerland
| | | | - Ophélie Ronce
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France.,CNRS, Biodiversity Research Center, University of British Columbia, Vancouver, Canada
| | | | - François Rousset
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Isabelle Olivieri
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Alexandre Courtiol
- Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Agnès Mignot
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
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9
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Zhao P, Xin G, Yan F, Wang H, Ren X, Woeste K, Liu W. The de novo genome assembly of Tapiscia sinensis and the transcriptomic and developmental bases of androdioecy. HORTICULTURE RESEARCH 2020; 7:191. [PMID: 33328438 PMCID: PMC7705024 DOI: 10.1038/s41438-020-00414-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 07/14/2020] [Accepted: 08/11/2020] [Indexed: 05/05/2023]
Abstract
Tapiscia sinensis (Tapisciaceae) possesses an unusual androdioecious breeding system that has attracted considerable interest from evolutionary biologists. Key aspects of T. sinensis biology, including its biogeography, genomics, and sex-linked genes, are unknown. Here, we report the first de novo assembly of the genome of T. sinensis. The genome size was 410 Mb, with 22,251 predicted genes. Based on whole-genome resequencing of 55 trees from 10 locations, an analysis of population genetic structure indicated that T. sinensis has fragmented into five lineages, with low intrapopulation genetic diversity and little gene flow among populations. By comparing whole-genome scans of male versus hermaphroditic pools, we identified 303 candidate sex-linked genes, 79 of which (25.9%) were located on scaffold 25. A 24-kb region was absent in hermaphroditic individuals, and five genes in that region, TsF-box4, TsF-box10, TsF-box13, TsSUT1, and TsSUT4, showed expression differences between mature male and hermaphroditic flowers. The results of this study shed light on the breeding system evolution and conservation genetics of the Tapisciaceae.
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Affiliation(s)
- Peng Zhao
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Guiliang Xin
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Feng Yan
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Huan Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Xiaolong Ren
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Keith Woeste
- USDA Forest Service Hardwood Tree Improvement and Regeneration Center (HTIRC), Department of Forestry and Natural Resources, Purdue University, 715 West State Street, West Lafayette, IN, 47907, USA
| | - Wenzhe Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, 710069, China.
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10
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Encinas-Viso F, Young AG, Pannell JR. The loss of self-incompatibility in a range expansion. J Evol Biol 2020; 33:1235-1244. [PMID: 32557922 DOI: 10.1111/jeb.13665] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 06/09/2020] [Accepted: 06/10/2020] [Indexed: 11/27/2022]
Abstract
It is commonly observed that plant species' range margins are enriched for increased selfing rates and, in otherwise self-incompatible species, for self-compatibility (SC). This has often been attributed to a response to selection under mate and/or pollinator limitation. However, range expansion can also cause reduced inbreeding depression, and this could facilitate the evolution of selfing in the absence of mate or pollinator limitation. Here, we explore this idea using spatially explicit individual-based simulations of a range expansion, in which inbreeding depression, variation in self-incompatibility (SI), and mate availability evolve. Under a wide range of conditions, the simulated range expansion brought about the evolution of selfing after the loss of SI in range-marginal populations. Under conditions of high recombination between the self-incompatibility locus (S-locus) and viability loci, SC remained marginal in the expanded metapopulation and could not invade the range core, which remained self-incompatible. In contrast, under low recombination and migration rates, SC was frequently able to displace SI in the range core by maintaining its association with a genomic background with purged genetic load. We conclude that the evolution of inbreeding depression during a range expansion promotes the evolution of SC at range margins, especially under high rates of recombination..
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Affiliation(s)
- Francisco Encinas-Viso
- Centre for Australian National Biodiversity Research, CSIRO National Research Collections, Canberra, ACT, Australia
| | - Andrew G Young
- Centre for Australian National Biodiversity Research, CSIRO National Research Collections, Canberra, ACT, Australia.,Centre for Biodiversity Analysis, The Australian National University, Canberra, ACT, Australia
| | - John R Pannell
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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11
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Puixeu G, Pickup M, Field DL, Barrett SCH. Variation in sexual dimorphism in a wind-pollinated plant: the influence of geographical context and life-cycle dynamics. THE NEW PHYTOLOGIST 2019; 224:1108-1120. [PMID: 31291691 PMCID: PMC6851585 DOI: 10.1111/nph.16050] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/27/2019] [Indexed: 06/09/2023]
Abstract
Understanding the mechanisms causing phenotypic differences between females and males has long fascinated evolutionary biologists. An extensive literature exists on animal sexual dimorphism but less information is known about sex differences in plants, particularly the extent of geographical variation in sexual dimorphism and its life-cycle dynamics. Here, we investigated patterns of genetically based sexual dimorphism in vegetative and reproductive traits of a wind-pollinated dioecious plant, Rumex hastatulus, across three life-cycle stages using open-pollinated families from 30 populations spanning the geographic range and chromosomal variation (XY and XY1 Y2 ) of the species. The direction and degree of sexual dimorphism was highly variable among populations and life-cycle stages. Sex-specific differences in reproductive function explained a significant amount of temporal change in sexual dimorphism. For several traits, geographical variation in sexual dimorphism was associated with bioclimatic parameters, likely due to the differential responses of the sexes to climate. We found no systematic differences in sexual dimorphism between chromosome races. Sex-specific trait differences in dioecious plants largely result from a balance between sexual and natural selection on resource allocation. Our results indicate that abiotic factors associated with geographical context also play a role in modifying sexual dimorphism during the plant life-cycle.
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Affiliation(s)
- Gemma Puixeu
- Institute of Science and Technology AustriaAm Campus 1Klosterneuburg3400Austria
| | - Melinda Pickup
- Institute of Science and Technology AustriaAm Campus 1Klosterneuburg3400Austria
- Department of Ecology and Evolutionary BiologyUniversity of Toronto25 Willcocks St.TorontoONM5S 3B2Canada
| | - David L. Field
- Department of Ecology and Evolutionary BiologyUniversity of Toronto25 Willcocks St.TorontoONM5S 3B2Canada
- School of ScienceEdith Cowan University270 Joondalup DriveJoondalupWA6027Australia
| | - Spencer C. H. Barrett
- Department of Ecology and Evolutionary BiologyUniversity of Toronto25 Willcocks St.TorontoONM5S 3B2Canada
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12
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Tonnabel J, David P, Klein EK, Pannell JR. Sex‐specific selection on plant architecture through “budget” and “direct” effects in experimental populations of the wind‐pollinated herb,
Mercurialis annua. Evolution 2019; 73:897-912. [DOI: 10.1111/evo.13714] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 02/11/2019] [Indexed: 12/26/2022]
Affiliation(s)
- Jeanne Tonnabel
- Department of Ecology and EvolutionUniversity of Lausanne CH‐1015 Lausanne Switzerland
| | - Patrice David
- CEFE, CNRS, Univ MontpellierUniv Paul Valéry Montpellier 3, EPHE, IRD Montpellier France
| | | | - John R. Pannell
- Department of Ecology and EvolutionUniversity of Lausanne CH‐1015 Lausanne Switzerland
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13
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Cossard GG, Pannell JR. A functional decomposition of sex inconstancy in the dioecious, colonizing plant Mercurialis annua. AMERICAN JOURNAL OF BOTANY 2019; 106:722-732. [PMID: 31081926 DOI: 10.1002/ajb2.1277] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 01/31/2019] [Indexed: 06/09/2023]
Abstract
PREMISE Plants with separate sexes often show "inconstant" or "leaky" sex expression, with females or males producing a few flowers of the opposite sex. The frequency and degree of such inconstancy may reflect residual hermaphroditic sex allocation after an evolutionary transition from combined to separate sexes. Sex inconstancy also represents a possible first step in the breakdown of dioecy back to hermaphroditism. In the Mercurialis annua (Euphorbiaceae) species complex, monoecy and androdioecy have evolved from dioecy in polyploid populations. Here, we characterize patterns of sex inconstancy in dioecious M. annua and discuss how sex inconstancy may have contributed to the breakdown of separate sexes in the genus. METHODS We measured sex inconstancy in three common gardens of M. annua over 2 years using a modification of Lloyd's phenotypic gender in terms of frequency and degree, with the degree calibrating inconstancy against the sex allocation of constant males and constant females, yielding a measure of gender that does not depend on the distribution of gender in the population. RESULTS Unusually for dioecious plants, the frequency of sex inconstancy in M. annua was greater in females, but its degree was greater for males in the 2 years of study. We suggest that this pattern is consistent with the maintenance of inconstancy in dioecious M. annua by selection for reproductive assurance under mate limitation. CONCLUSIONS Our study illustrates the utility of decomposing measures of sex inconstancy into its frequency and its degree and throws new light on the origin of variation in sexual systems in Mercurialis.
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Affiliation(s)
- Guillaume G Cossard
- Department of Ecology and Evolution, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - John R Pannell
- Department of Ecology and Evolution, University of Lausanne, CH-1015, Lausanne, Switzerland
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14
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Santos Del Blanco L, Tudor E, Pannell JR. Low siring success of females with an acquired male function illustrates the legacy of sexual dimorphism in constraining the breakdown of dioecy. Ecol Lett 2019; 22:486-497. [PMID: 30618173 PMCID: PMC6850444 DOI: 10.1111/ele.13207] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/24/2018] [Accepted: 11/20/2018] [Indexed: 01/03/2023]
Abstract
Dioecy has often broken down in flowering plants, yielding functional hermaphroditism. We reasoned that evolutionary transitions from dioecy to functional hermaphroditism must overcome an inertia of sexual dimorphism, because modified males or females will express the opposite sexual function for which their phenotypes have been optimised. We tested this prediction by assessing the siring success of monoecious individuals of the plant Mercurialis annua with an acquired male function but that are phenotypically still female‐like. We found that pollen dispersed by female‐like monoecious individuals was ~ 1/3 poorer at siring outcrossed offspring than pollen from monoecious individuals with an alternative male‐like inflorescence. We conclude that whereas dioecy might evolve from functional hermaphroditism by conferring upon individuals certain benefits of sexual specialisation, reversion from a strategy of separate sexes to one of combined sexes must overcome constraints imposed by the advantages of sexual dimorphism. The breakdown of dioecy must therefore often be limited to situations in which outcrossing cannot be maintained and where selection favours a capacity for inbreeding by functional hermaphrodites.
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Affiliation(s)
- Luis Santos Del Blanco
- Department of Ecology and Evolution, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
| | - Eleri Tudor
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | - John R Pannell
- Department of Ecology and Evolution, Biophore Building, University of Lausanne, 1015, Lausanne, Switzerland
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15
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Dorken ME, Van Drunen WE. Life-history trade-offs promote the evolution of dioecy. J Evol Biol 2018; 31:1405-1412. [PMID: 29908091 DOI: 10.1111/jeb.13335] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 06/14/2018] [Indexed: 11/29/2022]
Abstract
Most dioecious plants are perennial and subject to trade-offs between sexual reproduction and vegetative performance. However, these broader life-history trade-offs have not usually been incorporated into theoretical analyses of the evolution of separate sexes. One such analysis has indicated that hermaphroditism is favoured over unisexuality when female and male sex functions involve the allocation of nonoverlapping types of resources to each sex function (e.g. allocations of carbon to female function vs. allocations of nitrogen to male function). However, some dioecious plants appear to conform to this pattern of resource allocation, with different resource types allocated to female vs. male sex functions. Using an evolutionarily stable strategy approach, we show that life-history trade-offs between sexual reproduction and vegetative performance enable the evolution of unisexual phenotypes even when there are no direct resource-based trade-offs between female and male sex functions. This result might help explain the preponderance of perennial life histories among dioecious plants and why many dioecious plants with annual life histories have indeterminate growth with ongoing trade-offs between sexual reproduction and vegetative growth.
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Affiliation(s)
- Marcel E Dorken
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - Wendy E Van Drunen
- Department of Integrative Biology, University of Guelph, Guelph, ON, Canada
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16
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Nakahara T, Fukano Y, Hirota SK, Yahara T. Size advantage for male function and size-dependent sex allocation in Ambrosia artemisiifolia, a wind-pollinated plant. Ecol Evol 2017; 8:1159-1170. [PMID: 29375787 PMCID: PMC5773293 DOI: 10.1002/ece3.3722] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 11/19/2017] [Accepted: 11/20/2017] [Indexed: 11/10/2022] Open
Abstract
In wind‐pollinated plants, male‐biased sex allocation is often positively associated with plant size and height. However, effects of size (biomass or reproductive investment) and height were not separated in most previous studies. Here, using experimental populations of monoecious plants, Ambrosia altemisiifolia, we examined (1) how male and female reproductive investments (MRI and FRI) change with biomass and height, (2) how MRI and height affect male reproductive success (MRS) and pollen dispersal, and (3) how height affects seed production. Pollen dispersal kernel and selection gradients on MRS were estimated by 2,102 seeds using six microsatellite markers. First, MRI increased with height, but FRI did not, suggesting that sex allocation is more male‐biased with increasing plant height. On the other hand, both MRI and FRI increased with biomass but often more greatly for FRI, and consequently, sex allocation was often female‐biased with biomass. Second, MRS increased with both height and MRI, the latter having the same or larger effect on MRS. Estimated pollen dispersal kernel was fat‐tailed, with the maximum distance between mates tending to increase with MRI but not with height. Third, the number of seeds did not increase with height. Those findings showed that the male‐biased sex allocation in taller plants of A. artemisiifolia is explained by a direct effect of height on MRS.
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Affiliation(s)
- Toru Nakahara
- Graduate School of Systems Life Sciences Kyushu University Fukuoka Japan
| | - Yuya Fukano
- Graduate School of Agricultural and Life Sciences The University of Tokyo Tokyo Japan
| | - Shun K Hirota
- Institute of Decision Science for a Sustainable Society Kyushu University Fukuoka Japan.,Present address: Kawatabi Field Science Center Graduate School of Agricultural Science Tohoku University Miyagi Japan
| | - Tetsukazu Yahara
- Department of Biology Faculty of Science Kyushu University Fukuoka Japan
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17
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Tonnabel J, David P, Pannell JR. Sex-specific strategies of resource allocation in response to competition for light in a dioecious plant. Oecologia 2017; 185:675-686. [PMID: 29043498 PMCID: PMC5681607 DOI: 10.1007/s00442-017-3966-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 09/25/2017] [Indexed: 11/06/2022]
Abstract
The differential plasticity hypothesis suggests that sexual dimorphism in dioecious plants could evolve in response to sex-specific resource requirements for reproduction (i.e., high carbon requirements for ovules and high nitrogen demands for pollen). When resources become limiting during growth, males and females should, therefore, adjust their allocation to resource-harvesting organs differently. To investigate the potential for plants to respond to resource limitation late in life and to test the differential plasticity hypothesis, we grew male and female individuals of the annual wind-pollinated plant Mercurialis annua in a common garden. Late in the growth season, we simulated a change in competition by decreasing plant density in half of the replicates. We measured both allocation to vegetative and reproductive traits and analyzed the relative allocation to reproduction vs. growth. Males and females differentially adjusted their resource allocation in response to varying plant densities, despite the fact that they were reproductively mature. Males maintained the same relative allocation of resource to reproductive vs. vegetative tissues at both densities. In contrast, females reduced vegetative growth proportionally less than seed production at the higher density. Our results highlight the dynamic nature of allocation decisions taken by plants, which respond quickly and in a sexually dimorphic way to changes in their competitive circumstances. The existence of resource 'currencies' limiting male and female functions differently have potentially led to the evolution of sex-specific strategies of resource acquisition and deployment, with females conserving resources for vegetative organs to ensure their future carbon-rich reproduction.
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Affiliation(s)
- Jeanne Tonnabel
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland.
| | - Patrice David
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS, Université de Montpellier, Université Paul Valéry Montpellier, EPHE, 1919 route de Mende, 34293, Montpellier Cedex 5, France
| | - John R Pannell
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland
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18
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Detwiler JT, Caballero IC, Criscione CD. Role of parasite transmission in promoting inbreeding: I. Infection intensities drive individual parasite selfing rates. Mol Ecol 2017. [DOI: 10.1111/mec.14211] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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19
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Käfer J, Marais GAB, Pannell JR. On the rarity of dioecy in flowering plants. Mol Ecol 2017; 26:1225-1241. [PMID: 28101895 DOI: 10.1111/mec.14020] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 12/27/2016] [Accepted: 12/28/2016] [Indexed: 01/21/2023]
Abstract
Dioecy, the coexistence of separate male and female individuals in a population, is a rare but phylogenetically widespread sexual system in flowering plants. While research has concentrated on why and how dioecy evolves from hermaphroditism, the question of why dioecy is rare, despite repeated transitions to it, has received much less attention. Previous phylogenetic and theoretical studies have suggested that dioecy might be an evolutionary dead end. However, recent research indicates that the phylogenetic support for this hypothesis is attributable to a methodological bias and that there is no evidence for reduced diversification in dioecious angiosperms. The relative rarity of dioecy thus remains a puzzle. Here, we review evidence for the hypothesis that dioecy might be rare not because it is an evolutionary dead end, but rather because it easily reverts to hermaphroditism. We review what is known about transitions between hermaphroditism and dioecy, and conclude that there is an important need to consider more widely the possibility of transitions away from dioecy, both from an empirical and a theoretical point of view, and by combining tools from molecular evolution and insights from ecology.
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Affiliation(s)
- Jos Käfer
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Lyon 1, Bât. Grégor Mendel 43, bd du 11 novembre 1918, 69622, Villeurbanne cedex, France
| | - Gabriel A B Marais
- Laboratoire de Biométrie et Biologie Evolutive, CNRS, UMR 5558, Université Lyon 1, Bât. Grégor Mendel 43, bd du 11 novembre 1918, 69622, Villeurbanne cedex, France
| | - John R Pannell
- Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
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20
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A test of the size-constraint hypothesis for a limit to sexual dimorphism in plants. Oecologia 2016; 181:873-84. [PMID: 27037560 DOI: 10.1007/s00442-016-3616-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 03/16/2016] [Indexed: 10/22/2022]
Abstract
In flowering plants, many dioecious species display a certain degree of sexual dimorphism in non-reproductive traits, but this dimorphism tends to be much less striking than that found in animals. Sexual size dimorphism in plants may be limited because competition for light in crowded environments so strongly penalises small plants. The idea that competition for light constrains the evolution of strong sexual size dimorphism in plants (the size-constraint hypothesis) implies a strong dependency of the expression of sexual size dimorphism on the neighbouring density as a result of the capacity of plants to adjust their reproductive effort and investment in growth in response to their local environment. Here, we tested this hypothesis by experimentally altering the context of competition for light among male-female pairs of the light-demanding dioecious annual plant Mercurialis annua. We found that males were smaller than females across all treatments, but sexual size dimorphism was diminished for pairs grown at higher densities. This result is consistent with the size-constraint hypothesis. We discuss our results in terms of the tension between selection on size acting in opposite directions on males and females, which have different optima under sexual selection, and stabilizing selection for similar sizes in males and females, which have similar optima under viability selection for plasticity in size expression under different density conditions.
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21
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Ewers‐Saucedo C, Hope NB, Wares JP. The unexpected mating system of the androdioecious barnacle
Chelonibia testudinaria
(Linnaeus 1758). Mol Ecol 2016; 25:2081-92. [DOI: 10.1111/mec.13593] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 02/06/2016] [Accepted: 02/17/2016] [Indexed: 02/04/2023]
Affiliation(s)
| | - Neva B. Hope
- Department of Genetics University of Georgia Athens GA 30602 USA
| | - John P. Wares
- Department of Genetics University of Georgia Athens GA 30602 USA
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22
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Pannell JR, Auld JR, Brandvain Y, Burd M, Busch JW, Cheptou PO, Conner JK, Goldberg EE, Grant AG, Grossenbacher DL, Hovick SM, Igic B, Kalisz S, Petanidou T, Randle AM, de Casas RR, Pauw A, Vamosi JC, Winn AA. The scope of Baker's law. THE NEW PHYTOLOGIST 2015; 208:656-67. [PMID: 26192018 DOI: 10.1111/nph.13539] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/27/2015] [Indexed: 05/13/2023]
Abstract
Baker's law refers to the tendency for species that establish on islands by long-distance dispersal to show an increased capacity for self-fertilization because of the advantage of self-compatibility when colonizing new habitat. Despite its intuitive appeal and broad empirical support, it has received substantial criticism over the years since it was proclaimed in the 1950s, not least because it seemed to be contradicted by the high frequency of dioecy on islands. Recent theoretical work has again questioned the generality and scope of Baker's law. Here, we attempt to discern where the idea is useful to apply and where it is not. We conclude that several of the perceived problems with Baker's law fall away when a narrower perspective is adopted on how it should be circumscribed. We emphasize that Baker's law should be read in terms of an enrichment of a capacity for uniparental reproduction in colonizing situations, rather than of high selfing rates. We suggest that Baker's law might be tested in four different contexts, which set the breadth of its scope: the colonization of oceanic islands, metapopulation dynamics with recurrent colonization, range expansions with recurrent colonization, and colonization through species invasions.
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Affiliation(s)
- John R Pannell
- Department of Ecology and Evolution, University of Lausanne, 1015, Lausanne, Switzerland
| | - Josh R Auld
- Department of Biology, West Chester University, West Chester, PA, 19383, USA
| | - Yaniv Brandvain
- Department of Plant Biology, University of Minnesota, St Paul, MN, 55108, USA
| | - Martin Burd
- School of Biological Sciences, Monash University, Melbourne, VIC, 3800, Australia
| | - Jeremiah W Busch
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Pierre-Olivier Cheptou
- CEFE UMR 5175, CNRS, Universite de Montpellier, Université Paul-Valery Montpellier, EPHE, CEFE 34293, Montpellier Cedex 05, France
| | - Jeffrey K Conner
- Kellogg Biological Station and Department of Plant Biology, Michigan State University, Hickory Corners, MI, 49060, USA
| | - Emma E Goldberg
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN, 55108, USA
| | | | | | - Stephen M Hovick
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH, 43210, USA
| | - Boris Igic
- Department of Biological Sciences, University of Illinois at Chicago, 840 W Taylor St, M/C 067, Chicago, IL, 60607, USA
| | - Susan Kalisz
- Department of Biology, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Theodora Petanidou
- Laboratory of Biogeography and Ecology, Department of Geography, University of the Aegean, 81100 Mytilene, Lesvos, Greece
| | - April M Randle
- Department of Environmental Science, University of San Francisco, San Francisco, CA, 94117-1049, USA
| | - Rafael Rubio de Casas
- CEFE UMR 5175, CNRS, Universite de Montpellier, Université Paul-Valery Montpellier, EPHE, CEFE 34293, Montpellier Cedex 05, France
- Departmento Ecología, Facultad de Ciencias, Universidad de Granada, UGR, 18071, Granada, Spain
- Estación Experimental de Zonas Áridas, EEZA-CSIC, Carretera de Sacramento s/n, La Cañada de San Urbano, EEZA 04120, Almeria, Spain
| | - Anton Pauw
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, 7602, South Africa
| | - Jana C Vamosi
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N1N4, Canada
| | - Alice A Winn
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
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23
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Abstract
Dioecy (separate male and female individuals) ensures outcrossing and is more prevalent in animals than in plants. Although it is common in bryophytes and gymnosperms, only 5% of angiosperms are dioecious. In dioecious higher plants, flowers borne on male and female individuals are, respectively deficient in functional gynoecium and androecium. Dioecy is inherited via three sex chromosome systems: XX/XY, XX/X0 and WZ/ZZ, such that XX or WZ is female and XY, X0 or ZZ are males. The XX/XY system generates the rarer XX/X0 and WZ/ZZ systems. An autosome pair begets XY chromosomes. A recessive loss-of-androecium mutation (ana) creates X chromosome and a dominant gynoecium-suppressing (GYS) mutation creates Y chromosome. The ana/ANA and gys/GYS loci are in the sex-determining region (SDR) of the XY pair. Accumulation of inversions, deleterious mutations and repeat elements, especially transposons, in the SDR of Y suppresses recombination between X and Y in SDR, making Y labile and increasingly degenerate and heteromorphic from X. Continued recombination between X and Y in their pseudoautosomal region located at the ends of chromosomal arms allows survival of the degenerated Y and of the species. Dioecy is presumably a component of the evolutionary cycle for the origin of new species. Inbred hermaphrodite species assume dioecy. Later they suffer degenerate-Y-led population regression. Cross-hybridization between such extinguishing species and heterologous species, followed by genome duplication of segregants from hybrids, give rise to new species.
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24
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Tedder A, Helling M, Pannell JR, Shimizu-Inatsugi R, Kawagoe T, van Campen J, Sese J, Shimizu KK. Female sterility associated with increased clonal propagation suggests a unique combination of androdioecy and asexual reproduction in populations of Cardamine amara (Brassicaceae). ANNALS OF BOTANY 2015; 115:763-76. [PMID: 25776435 PMCID: PMC4373288 DOI: 10.1093/aob/mcv006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 09/29/2014] [Accepted: 12/23/2014] [Indexed: 05/03/2023]
Abstract
BACKGROUND AND AIMS The coexistence of hermaphrodites and female-sterile individuals, or androdioecy, has been documented in only a handful of plants and animals. This study reports its existence in the plant species Cardamine amara (Brassicaceae), in which female-sterile individuals have shorter pistils than seed-producing hermaphrodites. METHODS Morphological analysis, in situ manual pollination, microsatellite genotyping and differential gene expression analysis using Arabidopsis microarrays were used to delimit variation between female-sterile individuals and hermaphrodites. KEY RESULTS Female sterility in C. amara appears to be caused by disrupted ovule development. It was associated with a 2.4- to 2.9-fold increase in clonal propagation. This made the pollen number of female-sterile genets more than double that of hermaphrodite genets, which fulfils a condition of co-existence predicted by simple androdioecy theories. When female-sterile individuals were observed in wild androdioecious populations, their ramet frequencies ranged from 5 to 54 %; however, their genet frequencies ranged from 11 to 29 %, which is consistent with the theoretically predicted upper limit of 50 %. CONCLUSIONS The results suggest that a combination of sexual reproduction and increased asexual proliferation by female-sterile individuals probably explains the invasion and maintenance of female sterility in otherwise hermaphroditic populations. To our knowledge, this is the first report of the coexistence of female sterility and hermaphrodites in the Brassicaceae.
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Affiliation(s)
- Andrew Tedder
- Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan
| | - Matthias Helling
- Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan
| | - John R Pannell
- Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan
| | - Rie Shimizu-Inatsugi
- Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan
| | - Tetsuhiro Kawagoe
- Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan
| | - Julia van Campen
- Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan
| | - Jun Sese
- Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan
| | - Kentaro K Shimizu
- Institute of Evolutionary Biology and Environmental Studies and Institute of Plant Biology, University of Zurich, Winterthurerstrasse 190, CH-8057, Switzerland, Department of Ecology and Evolution, University of Lausanne, Lausanne CH-1015, Switzerland, Center for Ecological Research (CER), Kyoto University, 2-509-3, Hirano, Otsu, Shiga 520-2113, Japan and Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST) Koto-ku, Tokyo, 135-0064, Japan
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25
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Pannell JR. Evolution of the mating system in colonizing plants. Mol Ecol 2015; 24:2018-37. [DOI: 10.1111/mec.13087] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/12/2015] [Accepted: 01/15/2015] [Indexed: 12/16/2022]
Affiliation(s)
- John R. Pannell
- Department of Ecology and Evolution; University of Lausanne; Biophore Building 1015 Lausanne Switzerland
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26
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Wind pollination, clonality, and the evolutionary maintenance of spatial segregation of the sexes. Evol Ecol 2014. [DOI: 10.1007/s10682-014-9733-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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27
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Sánchez Vilas J, Pannell JR. Plasticity in sex allocation in the plant Mercurialis annua
is greater for hermaphrodites sampled from dimorphic than from monomorphic populations. J Evol Biol 2014; 27:1939-47. [DOI: 10.1111/jeb.12447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 06/17/2014] [Accepted: 06/18/2014] [Indexed: 11/30/2022]
Affiliation(s)
- J. Sánchez Vilas
- Organisms and Environment Division; Cardiff School of Biosciences; Cardiff University; Cardiff UK
| | - J. R. Pannell
- Department of Ecology and Evolution; University of Lausanne; Lausanne Switzerland
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28
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Pannell JR, Eppley SM, Dorken ME, Berjano R. Regional variation in sex ratios and sex allocation in androdioecious Mercurialis annua. J Evol Biol 2014; 27:1467-77. [PMID: 24618014 DOI: 10.1111/jeb.12352] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 02/03/2014] [Accepted: 02/03/2014] [Indexed: 11/29/2022]
Abstract
In androdioecious metapopulations, where males co-occur with hermaphrodites, the absence of males from certain populations or regions may be explained by locally high selfing rates, high hermaphrodite outcross siring success (e.g. due to high pollen production by hermaphrodites), or to stochastic processes (e.g. the failure of males to invade populations or regions following colonization or range expansion by hermaphrodites). In the Iberian Peninsula and Morocco, the presence of males with hermaphrodites in the wind-pollinated androdioecious plant Mercurialis annua (Euphorbiaceae) varies both among populations within relatively small regions and among regions, with some regions lacking males from all populations. The species is known to have expanded its range into the Iberian Peninsula from a southern refugium. To account for variation in male presence in M. annua, we test the following hypotheses: (1) that males are absent in areas where plant densities are lower, because selfing rates should be correspondingly higher; (2) that males are absent in areas where hermaphrodites produce more pollen; and (3) that males are absent in areas where there is an elevated proportion of populations in which plant density and hermaphrodite pollen production disfavour their invasion. We found support for predictions two and three in Morocco (the putative Pleistocene refugium for M. annua) but no support for any hypothesis in Iberia (the expanded range). Our results are partially consistent with a hypothesis of sex-allocation equilibrium for populations in Morocco; in Iberia, the absence of males from large geographical regions is more consistent with a model of sex-ratio evolution in a metapopulation with recurrent population turnover. Our study points to the role of both frequency-dependent selection and contingencies imposed by colonization during range expansions and in metapopulations.
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Affiliation(s)
- J R Pannell
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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29
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Harder LD, Prusinkiewicz P. The interplay between inflorescence development and function as the crucible of architectural diversity. ANNALS OF BOTANY 2013; 112:1477-93. [PMID: 23243190 PMCID: PMC3828939 DOI: 10.1093/aob/mcs252] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
BACKGROUND Most angiosperms present flowers in inflorescences, which play roles in reproduction, primarily related to pollination, beyond those served by individual flowers alone. An inflorescence's overall reproductive contribution depends primarily on the three-dimensional arrangement of the floral canopy and its dynamics during its flowering period. These features depend in turn on characteristics of the underlying branching structure (scaffold) that supports and supplies water and nutrients to the floral canopy. This scaffold is produced by developmental algorithms that are genetically specified and hormonally mediated. Thus, the extensive inflorescence diversity evident among angiosperms evolves through changes in the developmental programmes that specify scaffold characteristics, which in turn modify canopy features that promote reproductive performance in a particular pollination and mating environment. Nevertheless, developmental and ecological aspects of inflorescences have typically been studied independently, limiting comprehensive understanding of the relations between inflorescence form, reproductive function, and evolution. SCOPE This review fosters an integrated perspective on inflorescences by summarizing aspects of their development and pollination function that enable and guide inflorescence evolution and diversification. CONCLUSIONS The architecture of flowering inflorescences comprises three related components: topology (branching patterns, flower number), geometry (phyllotaxis, internode and pedicel lengths, three-dimensional flower arrangement) and phenology (flower opening rate and longevity, dichogamy). Genetic and developmental evidence reveals that these components are largely subject to quantitative control. Consequently, inflorescence evolution proceeds along a multidimensional continuum. Nevertheless, some combinations of topology, geometry and phenology are represented more commonly than others, because they serve reproductive function particularly effectively. For wind-pollinated species, these combinations often represent compromise solutions to the conflicting physical influences on pollen removal, transport and deposition. For animal-pollinated species, dominant selective influences include the conflicting benefits of large displays for attracting pollinators and of small displays for limiting among-flower self-pollination. The variety of architectural components that comprise inflorescences enable diverse resolutions of these conflicts.
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Affiliation(s)
- Lawrence D. Harder
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
- For correspondence. Email
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Johansson ML, Raimondi PT, Reed DC, Coelho NC, Serrão EA, Alberto FA. Looking into the black box: simulating the role of self-fertilization and mortality in the genetic structure of Macrocystis pyrifera. Mol Ecol 2013; 22:4842-54. [PMID: 23962179 DOI: 10.1111/mec.12444] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 07/03/2013] [Indexed: 01/10/2024]
Abstract
Patterns of spatial genetic structure (SGS), typically estimated by genotyping adults, integrate migration over multiple generations and measure the effective gene flow of populations. SGS results can be compared with direct ecological studies of dispersal or mating system to gain additional insights. When mismatches occur, simulations can be used to illuminate the causes of these mismatches. Here, we report a SGS and simulation-based study of self-fertilization in Macrocystis pyrifera, the giant kelp. We found that SGS is weaker than expected in M. pyrifera and used computer simulations to identify selfing and early mortality rates for which the individual heterozygosity distribution fits that of the observed data. Only one (of three) population showed both elevated kinship in the smallest distance class and a significant negative slope between kinship and geographical distance. All simulations had poor fit to the observed data unless mortality due to inbreeding depression was imposed. This mortality could only be imposed for selfing, as these were the only simulations to show an excess of homozygous individuals relative to the observed data. Thus, the expected data consistently achieved nonsignificant differences from the observed data only under models of selfing with mortality, with best fits between 32% and 42% selfing. Inbreeding depression ranged from 0.70 to 0.73. The results suggest that density-dependent mortality of early life stages is a significant force in structuring Macrocystis populations, with few highly homozygous individuals surviving. The success of these results should help to validate simulation approaches even in data-poor systems, as a means to estimate otherwise difficult-to-measure life cycle parameters.
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Affiliation(s)
- Mattias L Johansson
- Department of Biological Sciences, University of Wisconsin - Milwaukee, PO Box 413, Milwaukee, WI, 53201, USA
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Addis A, Fabiano F, Delogu V, Carcupino M. Reproductive system morphology of Lightiella magdalenina(Crustacea, Cephalocarida): functional and adaptive implications. INVERTEBR REPROD DEV 2013. [DOI: 10.1080/07924259.2012.704408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Lorenzi MC, Sella G. In Between Breeding Systems: Neither Dioecy Nor Androdioecy Explains Sexual Polymorphism in Functionally Dioecious Worms. Integr Comp Biol 2013; 53:689-700. [DOI: 10.1093/icb/ict043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Krueger-Hadfield SA, Roze D, Mauger S, Valero M. Intergametophytic selfing and microgeographic genetic structure shape populations of the intertidal red seaweedChondrus crispus. Mol Ecol 2013; 22:3242-60. [DOI: 10.1111/mec.12191] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 11/27/2012] [Accepted: 11/29/2012] [Indexed: 12/28/2022]
Affiliation(s)
- S. A. Krueger-Hadfield
- UPMC Univ Paris 06; UMR7144; Adaptation et Diversité en Milieu Marin; Station Biologique de Roscoff; Place Georges Teissier 29682 Roscoff France
- CNRS; UMR7144; Adaptation et Diversité en Milieu Marin; Station Biologique de Roscoff; Place Georges Teissier 29682 Roscoff France
- Departamento de Ecología; Facultad de Ciencias Biológicas; Center for Advanced Studies in Ecology and Biodiversity; Pontificia Universidad Católica de Chile; 6513677 Santiago Chile
| | - D. Roze
- UPMC Univ Paris 06; UMR7144; Adaptation et Diversité en Milieu Marin; Station Biologique de Roscoff; Place Georges Teissier 29682 Roscoff France
- CNRS; UMR7144; Adaptation et Diversité en Milieu Marin; Station Biologique de Roscoff; Place Georges Teissier 29682 Roscoff France
| | - S. Mauger
- UPMC Univ Paris 06; UMR7144; Adaptation et Diversité en Milieu Marin; Station Biologique de Roscoff; Place Georges Teissier 29682 Roscoff France
- CNRS; UMR7144; Adaptation et Diversité en Milieu Marin; Station Biologique de Roscoff; Place Georges Teissier 29682 Roscoff France
| | - M. Valero
- UPMC Univ Paris 06; UMR7144; Adaptation et Diversité en Milieu Marin; Station Biologique de Roscoff; Place Georges Teissier 29682 Roscoff France
- CNRS; UMR7144; Adaptation et Diversité en Milieu Marin; Station Biologique de Roscoff; Place Georges Teissier 29682 Roscoff France
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Vilas JS, Pannell JR. Do plants adjust their sex allocation and secondary sexual morphology in response to their neighbours? ANNALS OF BOTANY 2012; 110:1471-1478. [PMID: 22899829 PMCID: PMC3489149 DOI: 10.1093/aob/mcs182] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 06/21/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND AND AIMS Changes in the sex allocation (i.e. in pollen versus seed production) of hermaphroditic plants often occur in response to the environment. In some homosporous ferns, gametophytes choose their gender in response to chemical cues sent by neighbours, such that spores develop as male gametophytes if they perceive a female or hermaphrodite nearby. Here it is considered whether a similar process might occur in the androdioecious angiosperm species Mercurialis annua, in which males co-occur with hermaphrodites; previous work on a Spanish population of M. annua found that individuals were more likely to develop as males at high density. METHODS Using a novel approach to treat plants with leachate from pots containing males or hermaphrodites of M. annua, the hypothesis that individuals assess their mating opportunities, and adjust their sex expression accordingly, was tested through an exchange of chemical cues through the soil. KEY RESULTS For the population under study, from Morocco, no evidence was found for soil-signal-dependent sex expression: neither sex ratios nor sex allocation differed among experimental treatments. CONCLUSIONS The results imply either that the Moroccan population under study behaves differently from that previously studied in Spain (pointing to potential geographical variation in plasticity for sex expression), or that our method failed to capture the signals used by M. annua for adjustment of sex expression.
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Affiliation(s)
- Julia Sánchez Vilas
- Department of Ecology and Evolution, Le Biophore, UNIL-SORGE, University of Lausanne, Switzerland.
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Variability of individual genetic load: consequences for the detection of inbreeding depression. Genetica 2012; 140:39-51. [PMID: 22638826 DOI: 10.1007/s10709-012-9656-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Accepted: 05/02/2012] [Indexed: 10/28/2022]
Abstract
Inbreeding depression is a key factor affecting the persistence of natural populations, particularly when they are fragmented. In species with mixed mating systems, inbreeding depression can be estimated at the population level by regressing the average progeny fitness by the selfing rate of their mothers. We applied this method using simulated populations to investigate how population genetic parameters can affect the detection power of inbreeding depression. We simulated individual selfing rates and genetic loads from which we computed fitness values. The regression method yielded high statistical power, inbreeding depression being detected as significant (5 % level) in 92 % of the simulations. High individual variation in selfing rate and high mean genetic load led to better detection of inbreeding depression while high among-individual variation in genetic load made it more difficult to detect inbreeding depression. For a constant sampling effort, increasing the number of progenies while decreasing the number of individuals per progeny enhanced the detection power of inbreeding depression. We discuss the implication of among-mother variability of genetic load and selfing rate on inbreeding depression studies.
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Perry LE, Pannell JR, Dorken ME. Two's company, three's a crowd: experimental evaluation of the evolutionary maintenance of trioecy in Mercurialis annua (Euphorbiaceae). PLoS One 2012; 7:e35597. [PMID: 22532862 PMCID: PMC3330815 DOI: 10.1371/journal.pone.0035597] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 03/19/2012] [Indexed: 11/25/2022] Open
Abstract
Trioecy is an uncommon sexual system in which males, females, and hermaphrodites co-occur as three clearly different gender classes. The evolutionary stability of trioecy is unclear, but would depend on factors such as hermaphroditic sex allocation and rates of outcrossing vs. selfing. Here, trioecious populations of Mercurialis annua are described for the first time. We examined the frequencies of females, males and hermaphrodites across ten natural populations and evaluated the association between the frequency of females and plant densities. Previous studies have shown that selfing rates in this species are density-dependent and are reduced in the presence of males, which produce substantially more pollen than hermaphrodites. Accordingly, we examined the evolutionary stability of trioecy using an experiment in which we (a) indirectly manipulated selfing rates by altering plant densities and the frequency of males in a fully factorial manner across 20 experimental plots and (b) examined the effect of these manipulations on the frequency of the three sex phenotypes in the next generation of plants. In the parental generation, we measured the seed and pollen allocations of hermaphrodites and compared them with allocations by unisexual plants. In natural populations, females occurred at higher frequencies in denser patches, a finding consistent with our expectations. Under our experimental conditions, however, no combination of plant densities and male frequencies was associated with increased frequencies of females. Our results suggest that the factors that regulate female frequencies in trioecious populations of M. annua are independent of those regulating male frequencies (density), and that the stable co-existence of all three sex phenotypes within populations is unlikely.
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Affiliation(s)
- Laura E. Perry
- Department of Biology, Trent University, Peterborough, Ontario, Canada
| | - John R. Pannell
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Marcel E. Dorken
- Department of Biology, Trent University, Peterborough, Ontario, Canada
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Korbecka G, Hamilton A, Pannell JR. Mixed mating in androdioecious Mercurialis annua inferred using progeny arrays and diploid-acting microsatellite loci in a hexaploid background. ANNALS OF BOTANY 2011; 107:1057-61. [PMID: 21320876 PMCID: PMC3080618 DOI: 10.1093/aob/mcr028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS The frequency at which males can be maintained with hermaphrodites in androdioecious populations is predicted to depend on the selfing rate, because self-fertilization by hermaphrodites reduces prospective siring opportunities for males. In particular, high selfing rates by hermaphrodites are expected to exclude males from a population. Here, the first estimates are provided of the mating system from two wild hexaploid populations of the androdioecious European wind-pollinated plant M. annua with contrasting male frequencies. METHODS Four diploid microsatellite loci were used to genotype 19-20 progeny arrays from two populations of M. annua, one with males and one without. Mating-system parameters were estimated using the program MLTR. KEY RESULTS Both populations had similar, intermediate outcrossing rates (t(m) = 0·64 and 0·52 for the population with and without males, respectively). The population without males showed a lower level of correlated paternity and biparental inbreeding and higher allelic richness and gene diversity than the population with males. CONCLUSIONS The results demonstrate the utility of new diploid microsatellite loci for mating system analysis in a hexaploid plant. It would appear that androdioecious M. annua has a mixed-mating system in the wild, an uncommon finding for wind-pollinated species. This study sets a foundation for future research to assess the relative importance of the sexual system, plant-density variation and stochastic processes for the regulation of male frequencies in M. annua over space and time.
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Affiliation(s)
- Grażyna Korbecka
- Department of Plant Sciences, Oxford University, South Parks Road, Oxford OX1 3RB, UK
- Department of Plant Breeding and Biotechnology, Institute of Soil Science and Plant Cultivation, ul. Czartoryskich 8, 24-100 Puławy, Poland
- For correspondence. E-mail
| | - Alastair Hamilton
- Department of Plant Sciences, Oxford University, South Parks Road, Oxford OX1 3RB, UK
| | - John R. Pannell
- Department of Plant Sciences, Oxford University, South Parks Road, Oxford OX1 3RB, UK
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Hesse E, Pannell JR. Sexual dimorphism in a dioecious population of the wind-pollinated herb Mercurialis annua: the interactive effects of resource availability and competition. ANNALS OF BOTANY 2011; 107:1039-45. [PMID: 21385775 PMCID: PMC3080628 DOI: 10.1093/aob/mcr046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 05/11/2009] [Accepted: 01/26/2011] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS Male-biased sex allocation commonly occurs in wind-pollinated hermaphroditic plants, and is often positively associated with size, notably in terms of height. Currently, it is not well established whether a corresponding pattern holds for dioecious plants: do males of wind-pollinated species exhibit greater reproductive allocation than females? Here, sexual dimorphism is investigated in terms of life history trade-offs in a dioecious population of the wind-pollinated ruderal herb Mercurialis annua. METHODS The allocation strategies of males and females grown under different soil nutrient availability and competitive (i.e. no, male or female competitor) regimes were compared. KEY RESULTS Male reproductive allocation increased disproportionately with biomass, and was greater than that of females when grown in rich soils. Sexual morphs differentially adjusted their reproductive allocation in response to local environmental conditions. In particular, males reduced their reproductive allocation in poor soils, whereas females increased theirs, especially when competing with another female rather than growing alone. Finally, males displayed smaller above-ground vegetative sizes than females, but neither nutrient availability nor competition had a strong independent effect on relative size disparities between the sexes. CONCLUSIONS Selection appears to favour plasticity in reproductive allocation in dioecious M. annua, thereby maintaining a relatively constant size hierarchy between sexual morphs. In common with other dioecious species, there seems to be little divergence in the niches occupied by males and females of M. annua.
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Affiliation(s)
- Elze Hesse
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, UK.
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Johnson SL, Yund PO. EFFECTS OF FERTILIZATION DISTANCE ON MALE GAIN CURVES IN A FREE-SPAWNING MARINE INVERTEBRATE: A COMBINED EMPIRICAL AND THEORETICAL APPROACH. Evolution 2009; 63:3114-23. [DOI: 10.1111/j.1558-5646.2009.00784.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Pujol B, Zhou SR, Sanchez Vilas J, Pannell JR. Reduced inbreeding depression after species range expansion. Proc Natl Acad Sci U S A 2009; 106:15379-83. [PMID: 19717421 PMCID: PMC2741259 DOI: 10.1073/pnas.0902257106] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Indexed: 11/18/2022] Open
Abstract
Many species expanded their geographic ranges from core "refugium" populations when the global climate warmed after the Pleistocene. The bottlenecks that occur during such range expansions diminish genetic variation in marginal populations, rendering them less responsive to selection. Here, we show that range expansion also strongly depletes inbreeding depression. We compared inbreeding depression among 20 populations across the expanded range of a common European plant, and found that marginal populations had greatly reduced inbreeding depression. Similar patterns were also revealed by multilocus computer simulations. Low inbreeding depression is predicted to ease conditions for the evolution of self-fertilization, and selfing is known to be particularly frequent in marginal populations. Therefore, our findings expose a remarkable aspect of evolution at range margins, where a history of expansion can reverse the direction of selection on the mating system, providing a parsimonious explanation for the high incidence of selfing in marginal populations.
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Affiliation(s)
- Benoit Pujol
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom; and
| | - Shu-Rong Zhou
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom; and
- Laboratory of Arid and Grassland Ecology under the Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu, People's Republic of China
| | - Julia Sanchez Vilas
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom; and
| | - John R. Pannell
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom; and
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Vandepitte K, Roldán-Ruiz I, Honnay O. Reproductive consequences of mate quantity versus mate diversity in a wind-pollinated plant. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2009. [DOI: 10.1016/j.actao.2009.04.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Inbreeding depression in dioecious populations of the plant Mercurialis annua: comparisons between outcrossed progeny and the progeny of self-fertilized feminized males. Heredity (Edinb) 2009; 102:600-8. [PMID: 19293836 DOI: 10.1038/hdy.2009.21] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Inbreeding depression is a key factor in the maintenance of separate sexes in plants through selection for the avoidance of self-fertilization. However, very little is known about the levels of inbreeding depression in dioecious species, obviously because it is difficult to self-fertilize males or females. We overcame this problem by clonally propagating males from lineages in a dioecious metapopulation of the European annual plant Mercurialis annua, feminizing some of them and crossing the feminized with the unfeminized clones. Using this method, we compared the fitness of selfed vs outcrossed progeny under field conditions in Spain, where this species grows naturally. Multiplicative inbreeding depression (based on seed germination, early and late survival, seed mass and pollen viability) ranged from -0.69 to 0.82, with a mean close to zero. We consider possible explanations for both the low mean and high variance in inbreeding depression in M. annua, and we discuss the implications of our results for the maintenance of dioecy over hermaphroditism.
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Dorken ME, Pannell JR. Hermaphroditic Sex Allocation Evolves When Mating Opportunities Change. Curr Biol 2009; 19:514-7. [DOI: 10.1016/j.cub.2009.01.067] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 01/30/2009] [Accepted: 01/30/2009] [Indexed: 10/21/2022]
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Miyake K, Olson MS. Experimental evidence for frequency dependent self-fertilization in the gynodioecious plant, Silene vulgaris. Evolution 2009; 63:1644-52. [PMID: 19187245 DOI: 10.1111/j.1558-5646.2009.00646.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
After over a half century of empirical and theoretical research regarding the evolution and maintenance of gynodioecy in plants, unexplored factors influencing the relative fitnesses of females and hermaphrodites remain. Theoretical studies suggest that hermaphrodite self-fertilization (selfing) rate influences the maintenance of gynodioecy and we hypothesized that population sex ratio may influence hermaphrodite selfing rate. An experimental test for frequency-dependent self-fertilization was conducted using replicated populations constructed with different sex ratios of the gynodioecious plant Silene vulgaris. We found that hermaphrodite selfing increased with decreased hermaphrodite frequency, whereas evidence for increased inbreeding depression was equivocal. We argue that incorporation of context dependent inbreeding into future models of the evolution of gynodioecy is likely to yield novel insights into sex ratio evolution.
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Affiliation(s)
- Keiko Miyake
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska 99775, USA
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Friedman J, Barrett SCH. The consequences of monoecy and protogyny for mating in wind-pollinated Carex. THE NEW PHYTOLOGIST 2009; 181:489-497. [PMID: 19121043 DOI: 10.1111/j.1469-8137.2008.02664.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Monoecy and protogyny are widespread in wind-pollinated plants and have been interpreted as outcrossing mechanisms, though few studies have investigated their function. Carex, a large genus of anemophilous herbs, is predominantly monoecious and many species are protogynous. We investigated whether monoecy and protogyny limit self-pollination in seven Carex species. We conducted field experiments comparing stigmatic pollen loads and seed set between intact and emasculated stems. We tested for self-compatibility and evaluated pollen limitation of seed set by supplemental pollination. Finally, we measured outcrossing rates in open-pollinated and emasculated stems using allozyme markers. Emasculated stems captured significantly less pollen than open-pollinated stems and set less seed. Pollen deposition during the female-only phase for intact stems was only 12% of the total captured. Outcrossing rates for three species indicated high selfing (range t = 0.03-0.39). Allozyme loci in the remaining species were monomorphic also suggesting high selfing. These results demonstrate that neither monoecy nor protogyny is particularly effective at limiting self-fertilization. Selection for the avoidance of selfing is unlikely to maintain monoecy in many Carex species although protogyny may provide limited opportunities for outcrossing. We propose that geitonogamy in self-compatible wind-pollinated species with unisexual flowers may be widespread and provides reproductive assurance.
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Affiliation(s)
- Jannice Friedman
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
| | - Spencer C H Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
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Dorken ME, Pannell JR. Density-dependent regulation of the sex ratio in an annual plant. Am Nat 2008; 171:824-30. [PMID: 18429672 DOI: 10.1086/587524] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Sex ratios are subject to strong frequency-dependent selection regulated by the mating system and the relative male versus female investment. In androdioecious plant populations, where males co-occur with hermaphrodites, the sex ratio depends on the rate of self-fertilization by hermaphrodites and on the relative pollen production of males versus hermaphrodites. Here, we report evolutionary changes in the sex ratio from experimental mating arrays of the androdioecious plant Mercurialis annua. We found that the progeny sex ratio depended strongly on density, with fewer males in the progeny of plants grown under low density. This occurred in part because of a plastic adjustment in pollen production by hermaphrodites, which produced more pollen when grown at low density than at high density. Our results provide support for the prediction that environmental conditions govern sex ratios through their effects on the relative fertility of unisexual versus hermaphrodite individuals.
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Affiliation(s)
- Marcel E Dorken
- Department of Plant Sciences, South Parks Road, University of Oxford, Oxford OX1 3RB, United Kingdom.
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Friedman J, Barrett SCH. High outcrossing in the annual colonizing species Ambrosia artemisiifolia (Asteraceae). ANNALS OF BOTANY 2008; 101:1303-9. [PMID: 18387973 PMCID: PMC2710250 DOI: 10.1093/aob/mcn039] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
BACKGROUND AND AIMS Variation in mating patterns may be particularly evident in colonizing species because they commonly experience wide variation in plant density. Here, the role of density for the mating system of Ambrosia artemisiifolia (common ragweed), a wind-pollinated annual colonizing species previously reported as self-compatible, is explored. METHODS The effect of population density on the proportion of self- and cross-fertilized seeds was examined using allozyme markers and experimental arrays conducted over two seasons in the field. Also the reproductive success of isolated plants located in diverse habitats was measured. The potential occurrence of a physiological mechanism preventing self-fertilization, i.e. self-incompatibility, following controlled self- and cross-pollinations in the glasshouse was examined. KEY RESULTS Outcrossing rates estimated using allozyme markers were uniformly high, regardless of the spacing between plants. However, when single plants were isolated from congeners they set few seeds. Observations of pollen-tube growth and seed set following controlled pollinations demonstrated that plants of A. artemisiifolia possess a strong self-incompatibility mechanism, contrary to earlier reports and assumptions. CONCLUSIONS The maintenance of high outcrossing rates in colonizing populations of A. artemisiifolia is likely to be facilitated by the prodigious production of wind-borne pollen, high seed production and extended seed dormancy.
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Affiliation(s)
- Jannice Friedman
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St, Toronto, Ontario, Canada.
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EPPLEY SM, JESSON LK. Moving to mate: the evolution of separate and combined sexes in multicellular organisms. J Evol Biol 2008; 21:727-36. [DOI: 10.1111/j.1420-9101.2008.01524.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Jacquemyn H, Brys R. Density-dependent mating and reproductive assurance in the temperate forest herb Paris quadrifolia (Trilliaceae). AMERICAN JOURNAL OF BOTANY 2008; 95:294-298. [PMID: 21632354 DOI: 10.3732/ajb.95.3.294] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In animal-pollinated plants, autonomous selfing provides reproductive assurance under conditions of infrequent pollinator visits or a lack of mates, but few data are available for wind-pollinated species or species with combined insect and wind-pollination, for which it is often assumed that pollen availability does not limit reproduction. In this study, the capacity of autonomous selfing was investigated in the temperate forest herb Paris quadrifolia, and an emasculation experiment was performed under natural field conditions to investigate the contribution of autonomous selfing to total seed set across a continuous gradient of densities of flowering conspecifics. In the absence of wind or pollinators, autonomous selfing was observed through anthers approaching stigmas at the end of flowering and the capacity for autonomous pollination was about 0.34. Under natural conditions, considerable outcross pollination was observed, but the proportion of ovules successfully fertilized significantly decreased with decreasing density of conspecifics when flowers were emasculated, but not when flowers were left intact. These results indicate that autonomous selfing resulted in reproductive assurance (RA = 0.16) and thus support the hypothesis that autonomous selfing can also provide reproductive assurance in wind-pollinated species.
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Affiliation(s)
- Hans Jacquemyn
- Division Plant Ecology and Systematics, University of Leuven, Arenbergpark 31, B-3001 Heverlee, Belgium
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