1
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Cossard GG, Pannell JR. Enhanced leaky sex expression in response to pollen limitation in the dioecious plant Mercurialis annua. J Evol Biol 2020; 34:416-422. [PMID: 33098734 PMCID: PMC7984330 DOI: 10.1111/jeb.13720] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/23/2020] [Accepted: 09/25/2020] [Indexed: 02/02/2023]
Abstract
In dioecious plants, males and females frequently show ‘leaky’ sex expression, with individuals occasionally producing flowers of the opposite sex. This leaky sex expression may have enabled the colonization of oceanic islands by dioecious plant species, and it is likely to represent the sort of variation upon which selection acts to bring about evolutionary transitions from dioecy to hermaphroditism. Although leakiness is commonly reported for dioecious species, it is not known whether it has plastic component. The question is interesting because males or females with an ability to enhance their leakiness plastically in the absence of mates would have an advantage of being able to produce progeny by self‐fertilization. Here, we demonstrate that leaky sex expression in the wind‐pollinated dioecious herb Mercurialis annua is plastically responsive to its mating context. We compared experimental populations of females growing either with or without males. Females growing in the absence of males were leakier in their sex expression than controls growing with males, producing more than twice as many male flowers. Our results thus provide a striking instance of plasticity in the reproductive behaviour of plants that is likely adaptive. We consider how females might sense their mating environment as a function of pollen availability, and we discuss possible constraints on the evolution of plasticity in sex expression when the environmental signals that individuals receive are unreliable.
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Affiliation(s)
- Guillaume G Cossard
- Department of Ecology and Evolution, Biophore Building, University of Lausanne, Lausanne, Switzerland
| | - John R Pannell
- Department of Ecology and Evolution, Biophore Building, University of Lausanne, Lausanne, Switzerland
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2
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Anderson AG, Bubrig LT, Fierst JL. Environmental stress maintains trioecy in nematode worms. Evolution 2020; 74:518-527. [PMID: 31990047 DOI: 10.1111/evo.13932] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 01/18/2020] [Indexed: 01/16/2023]
Abstract
Sex is determined by chromosomes in mammals but it can be influenced by the environment in many worms, crustaceans, and vertebrates. Despite this, there is little understanding of the relationship between ecology and the evolution of sexual systems. The nematode Auanema freiburgensis has a unique sex determination system in which individuals carrying one X chromosome develop into males while XX individuals develop into females in stress-free environments and self-fertile hermaphrodites in stressful environments. Theory predicts that trioecious populations with coexisting males, females, and hermaphrodites should be unstable intermediates in evolutionary transitions between mating systems. In this article, we study a mathematical model of reproductive evolution based on the unique life history and sex determination of A. freiburgensis. We develop the model in two scenarios, one where the relative production of hermaphrodites and females is entirely dependent on the environment and one based on empirical measurements of a population that displays incomplete, "leaky" environmental dependence. In the first scenario environmental conditions can push the population along an evolutionary continuum and result in the stable maintenance of multiple reproductive systems. The second "leaky" scenario results in the maintenance of three sexes for all environmental conditions. Theoretical investigations of reproductive system transitions have focused on the evolutionary costs and benefits of sex. Here, we show that the flexible sex determination system of A. freiburgensis may contribute to population-level resilience in the microscopic nematode's patchy, ephemeral natural habitat. Our results demonstrate that life history, ecology, and environment may play defining roles in the evolution of sexual systems.
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Affiliation(s)
- Ashlyn G Anderson
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL, 35487-0344.,Current Address: Department of Biostatistics, University of Florida, Gainesville, FL, 32611-7450
| | - Louis T Bubrig
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL, 35487-0344
| | - Janna L Fierst
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL, 35487-0344
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3
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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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4
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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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5
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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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6
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Theologidis I, Chelo IM, Goy C, Teotónio H. Reproductive assurance drives transitions to self-fertilization in experimental Caenorhabditis elegans. BMC Biol 2014; 12:93. [PMID: 25369737 PMCID: PMC4234830 DOI: 10.1186/s12915-014-0093-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/23/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Evolutionary transitions from outcrossing between individuals to selfing are partly responsible for the great diversity of animal and plant reproduction systems. The hypothesis of 'reproductive assurance' suggests that transitions to selfing occur because selfers that are able to reproduce on their own ensure the persistence of populations in environments where mates or pollination agents are unavailable. Here we test this hypothesis by performing experimental evolution in Caenorhabditis elegans. RESULTS We show that self-compatible hermaphrodites provide reproductive assurance to a male-female population facing a novel environment where outcrossing is limiting. Invasions of hermaphrodites in male-female populations, and subsequent experimental evolution in the novel environment, led to successful transitions to selfing and adaptation. Adaptation was not due to the loss of males during transitions, as shown by evolution experiments in exclusively hermaphroditic populations and in male-hermaphrodite populations. Instead, adaptation was due to the displacement of females by hermaphrodites. Genotyping of single-nucleotide polymorphisms further indicated that the observed evolution of selfing rates was not due to selection of standing genetic diversity. Finally, numerical modelling and evolution experiments in male-female populations demonstrate that the improvement of male fitness components may diminish the opportunity for reproductive assurance. CONCLUSIONS Our findings support the hypothesis that reproductive assurance can drive the transition from outcrossing to selfing, and further suggest that the success of transitions to selfing hinges on adaptation of obligate outcrossing populations to the environment where outcrossing was once a limiting factor.
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7
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Weeks SC, Benvenuto C, Reed SK, Duff RJ, Duan ZH, David P. A field test of a model for the stability of androdioecy in the freshwater shrimp, Eulimnadia texana. J Evol Biol 2014; 27:2080-95. [PMID: 25145977 DOI: 10.1111/jeb.12459] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 07/04/2014] [Indexed: 12/01/2022]
Abstract
The evolution of hermaphroditism from dioecy is a poorly studied transition. Androdioecy (the coexistence of males and hermaphrodites) has been suggested as an intermediate step in this evolutionary transition or could be a stable reproductive mode. Freshwater crustaceans in the genus Eulimnadia have reproduced via androdioecy for 24+ million years and thus are excellent organisms to test models of the stability of androdioecy. Two related models that allow for the stable maintenance of males and hermaphrodites rely on the counterbalancing of three life history parameters. We tested these models in the field over three field seasons and compared the results to previous laboratory estimates of these three parameters. Male and hermaphroditic ratios within years were not well predicted using either the simpler original model or a version of this model updated to account for differences between hermaphroditic types ('monogenic' and 'amphigenic' hermaphrodites). Using parameter estimates of the previous year to predict the next year's sex ratios revealed a much better fit to the original relative to the updated version of the model. Therefore, counter to expectations, accounting for differences between the two hermaphroditic types did not improve the fit of these models. At the moment, we lack strong evidence that the long-term maintenance of androdioecy in these crustaceans is the result of a balancing of life history parameters; other factors, such as metapopulation dynamics or evolutionary constraints, may better explain the 24+ million year maintenance of androdioecy in clam shrimp.
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Affiliation(s)
- S C Weeks
- Integrated Bioscience Program, Department of Biology, The University of Akron, Akron, OH, USA
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8
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Leonard JL. Williams' paradox and the role of phenotypic plasticity in sexual systems. Integr Comp Biol 2013; 53:671-88. [PMID: 23970358 DOI: 10.1093/icb/ict088] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
As George Williams pointed out in 1975, although evolutionary explanations, based on selection acting on individuals, have been developed for the advantages of simultaneous hermaphroditism, sequential hermaphroditism and gonochorism, none of these evolutionary explanations adequately explains the current distribution of these sexual systems within the Metazoa (Williams' Paradox). As Williams further pointed out, the current distribution of sexual systems is explained largely by phylogeny. Since 1975, we have made a great deal of empirical and theoretical progress in understanding sexual systems. However, we still lack a theory that explains the current distribution of sexual systems in animals and we do not understand the evolutionary transitions between hermaphroditism and gonochorism. Empirical data, collected over the past 40 years, demonstrate that gender may have more phenotypic plasticity than was previously realized. We know that not only sequential hermaphrodites, but also simultaneous hermaphrodites have phenotypic plasticity that alters sex allocation in response to social and environmental conditions. A focus on phenotypic plasticity suggests that one sees a continuum in animals between genetically determined gonochorism on the one hand and simultaneous hermaphroditism on the other, with various types of sequential hermaphroditism and environmental sex determination as points along the spectrum. Here I suggest that perhaps the reason we have been unable to resolve Williams' Paradox is because the problem was not correctly framed. First, because, for example, simultaneous hermaphroditism provides reproductive assurance or dioecy ensures outcrossing does not mean that there are no other evolutionary paths that can provide adaptive responses to those selective pressures. Second, perhaps the question we need to ask is: What selective forces favor increased versus reduced phenotypic plasticity in gender expression? It is time to begin to look at the question of sexual system as one of understanding the timing and degree of phenotypic plasticity in gender expression in the life history in terms of selection acting on a continuum, rather than on a set of discrete sexual systems.
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Affiliation(s)
- Janet L Leonard
- Joseph M. Long Marine Laboratory, University of California-Santa Cruz, Santa Cruz, CA 95060, USA
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9
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De Vos S, Bossier P, Van Stappen G, Vercauteren I, Sorgeloos P, Vuylsteke M. A first AFLP-based genetic linkage map for brine shrimp Artemia franciscana and its application in mapping the sex locus. PLoS One 2013; 8:e57585. [PMID: 23469207 PMCID: PMC3587612 DOI: 10.1371/journal.pone.0057585] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/22/2013] [Indexed: 12/26/2022] Open
Abstract
We report on the construction of sex-specific linkage maps, the identification of sex-linked markers and the genome size estimation for the brine shrimp Artemia franciscana. Overall, from the analysis of 433 AFLP markers segregating in a 112 full-sib family we identified 21 male and 22 female linkage groups (2n = 42), covering 1,041 and 1,313 cM respectively. Fifteen putatively homologous linkage groups, including the sex linkage groups, were identified between the female and male linkage map. Eight sex-linked AFLP marker alleles were inherited from the female parent, supporting the hypothesis of a WZ-ZZ sex-determining system. The haploid Artemia genome size was estimated to 0.93 Gb by flow cytometry. The produced Artemia linkage maps provide the basis for further fine mapping and exploring of the sex-determining region and are a possible marker resource for mapping genomic loci underlying phenotypic differences among Artemia species.
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Affiliation(s)
- Stephanie De Vos
- Laboratory of Aquaculture, Artemia Reference Center (ARC), Department of Animal Production, Ghent University, Gent, Belgium
- Department of Plant Systems Biology, VIB, Gent, Belgium
- Department of Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
| | - Peter Bossier
- Laboratory of Aquaculture, Artemia Reference Center (ARC), Department of Animal Production, Ghent University, Gent, Belgium
| | - Gilbert Van Stappen
- Laboratory of Aquaculture, Artemia Reference Center (ARC), Department of Animal Production, Ghent University, Gent, Belgium
| | - Ilse Vercauteren
- Department of Plant Systems Biology, VIB, Gent, Belgium
- Department of Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
| | - Patrick Sorgeloos
- Laboratory of Aquaculture, Artemia Reference Center (ARC), Department of Animal Production, Ghent University, Gent, Belgium
| | - Marnik Vuylsteke
- Department of Plant Systems Biology, VIB, Gent, Belgium
- Department of Biotechnology and Bioinformatics, Ghent University, Gent, Belgium
- * E-mail:
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10
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Mathers TC, Hammond RL, Jenner RA, Zierold T, Hänfling B, Gómez A. High lability of sexual system over 250 million years of evolution in morphologically conservative tadpole shrimps. BMC Evol Biol 2013; 13:30. [PMID: 23384124 PMCID: PMC3585860 DOI: 10.1186/1471-2148-13-30] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 01/25/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sexual system is a key factor affecting the genetic diversity, population structure, genome structure and the evolutionary potential of species. The sexual system androdioecy - where males and hermaphrodites coexist in populations - is extremely rare, yet is found in three crustacean groups, barnacles, a genus of clam shrimps Eulimnadia, and in the order Notostraca, the tadpole shrimps. In the ancient crustacean order Notostraca, high morphological conservatism contrasts with a wide diversity of sexual systems, including androdioecy. An understanding of the evolution of sexual systems in this group has been hampered by poor phylogenetic resolution and confounded by the widespread occurrence of cryptic species. Here we use a multigene supermatrix for 30 taxa to produce a comprehensive phylogenetic reconstruction of Notostraca. Based on this phylogenetic reconstruction we use character mapping techniques to investigate the evolution of sexual systems. We also tested the hypothesis that reproductive assurance has driven the evolution of androdioecy in Notostraca. RESULTS Character mapping analysis showed that sexual system is an extremely flexible trait within Notostraca, with repeated shifts between gonochorism and androdioecy, the latter having evolved a minimum of five times. In agreement with the reproductive assurance hypothesis androdioecious notostracans are found at significantly higher latitudes than gonochoric ones indicating that post glacial re-colonisation may have selected for the higher colonisation ability conferred by androdioecy. CONCLUSIONS In contrast to their conserved morphology, sexual system in Notostraca is highly labile and the rare reproductive mode androdioecy has evolved repeatedly within the order. Furthermore, we conclude that this lability of sexual system has been maintained for at least 250 million years and may have contributed to the long term evolutionary persistence of Notostraca. Our results further our understanding of the evolution of androdioecy and indicate that reproductive assurance is a recurrent theme involved in the evolution of this sexual system.
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Affiliation(s)
- Thomas C Mathers
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull, HU6 7RX, UK
| | - Robert L Hammond
- Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - Ronald A Jenner
- Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom
| | - Thorid Zierold
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull, HU6 7RX, UK
- Museum für Naturkunde Chemnitz, Moritzstrasse 20, D-09111, Chemnitz, Germany
| | - Bernd Hänfling
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull, HU6 7RX, UK
| | - Africa Gómez
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull, HU6 7RX, UK
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11
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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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12
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Weeks SC, Sanderson TF, Wallace BF, Bagatto B. Behavioral Cost of Reproduction in a Freshwater Crustacean (Eulimnadia texana). Ethology 2011. [DOI: 10.1111/j.1439-0310.2011.01942.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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13
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Escobar JS, Auld JR, Correa AC, Alonso JM, Bony YK, Coutellec M, Koene JM, Pointier J, Jarne P, David P. PATTERNS OF MATING‐SYSTEM EVOLUTION IN HERMAPHRODITIC ANIMALS: CORRELATIONS AMONG SELFING RATE, INBREEDING DEPRESSION, AND THE TIMING OF REPRODUCTION. Evolution 2011; 65:1233-53. [DOI: 10.1111/j.1558-5646.2011.01218.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Juan S. Escobar
- Centre d’Ecologie Fonctionnelle et Evolutive UMR 5175, 1919 Route de Mende, Campus CNRS, 34293 Montpellier Cedex 5, France
- E‐mail:
| | - Josh R. Auld
- University of Pittsburgh, Department of Biological Sciences, 101 Clapp Hall, 4249 Fifth Avenue, Pittsburgh, Pennsylvania 15260
| | - Ana C. Correa
- Institut de Recherche pour le Développement, GEMI UMR 2724 CNRS‐IRD, 911 Avenue Agropolis, 34394 Montpellier, France
- Programa de Estudio y Control de Enfermedades Tropicales, Universidad de Antioquia, Calle 62 N° 52–59, Sede de Investigación Universitaria, Medellin, Colombia
| | - Juan M. Alonso
- USR 3278 CNRS‐EPHE CRIOBE, Université de Perpignan, 68860 Perpignan cedex, France
| | - Yves K. Bony
- USR 3278 CNRS‐EPHE CRIOBE, Université de Perpignan, 68860 Perpignan cedex, France
- Department of Biological Sciences, Laboratoire d’Environnement et de Biologie Aquatique (LEBA), URES de Daloa (University of Abobo‐Adjamé), 28 BP 465, Abidjan 28, Ivory Coast
| | - Marie‐Agnès Coutellec
- Institut National de Recherche Agronomique, UMR0985 Ecologie et Santé des Ecosystèmes, 65 rue de Saint‐Brieuc, CS 84215, F‐35042 Rennes Cedex, France
| | - Joris M. Koene
- Animal Ecology, Faculty of Earth and Life Sciences, VU University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Jean‐Pierre Pointier
- USR 3278 CNRS‐EPHE CRIOBE, Université de Perpignan, 68860 Perpignan cedex, France
| | - Philippe Jarne
- Centre d’Ecologie Fonctionnelle et Evolutive UMR 5175, 1919 Route de Mende, Campus CNRS, 34293 Montpellier Cedex 5, France
| | - Patrice David
- Centre d’Ecologie Fonctionnelle et Evolutive UMR 5175, 1919 Route de Mende, Campus CNRS, 34293 Montpellier Cedex 5, France
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14
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Chasnov JR. The evolution from females to hermaphrodites results in a sexual conflict over mating in androdioecious nematode worms and clam shrimp. J Evol Biol 2010; 23:539-56. [PMID: 20074309 DOI: 10.1111/j.1420-9101.2009.01919.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The nematode worm Caenorhabditis elegans and the clam shrimp Eulimnadia texana are two well-studied androdioecious species consisting mostly of self-fertilizing hermaphrodites and few males. To understand how androdioecy can evolve, a simple two-step mathematical model of the evolutionary pathway from a male-female species to a selfing-hermaphrodite species is constructed. First, the frequency of mutant females capable of facultative self-fertilization increases if the benefits of reproductive assurance exceed the cost. Second, hermaphrodites become obligate self-fertilizers if the fitness of selfed offspring exceeds one-half the fitness of outcrossed offspring. Genetic considerations specific to C. elegans and E. texana show that males may endure as descendants of the ancestral male-female species. These models combined with an extensive literature review suggest a sexual conflict over mating in these androdioecious species: selection favours hermaphrodites that self and males that outcross. The strength of selection on hermaphrodites and males differs, however. Males that fail to outcross suffer a genetic death. Hermaphrodites may never encounter a rare male, and those that do and outcross only bear less fecund offspring. This asymmetric sexual conflict results in an evolutionary stand-off: rare, but persistent males occasionally fertilize common, but reluctant hermaphrodites. A consequence of this stand-off may be an increase in the longevity of the androdioecious mating system.
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Affiliation(s)
- J R Chasnov
- Department of Mathematics, Hong Kong University of Science and Technology, Kowloon, Hong Kong.
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WEEKS SC, CHAPMAN EG, ROGERS DC, SENYO DM, HOEH WR. Evolutionary transitions among dioecy, androdioecy and hermaphroditism in limnadiid clam shrimp (Branchiopoda: Spinicaudata). J Evol Biol 2009; 22:1781-99. [DOI: 10.1111/j.1420-9101.2009.01813.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Darwin devoted much of his working life to the study of plant reproductive systems. He recognized that many of the intricacies of floral morphology had been shaped by natural selection in favour of outcrossing, and he clearly established the deleterious effects of self-fertilization on progeny. Although Darwin hypothesized the adaptive significance of self-fertilization under conditions of low mate availability, he held that a strategy of pure selfing would be strongly disadvantageous in the long term. Here, I briefly review these contributions to our understanding of plant reproduction. I then suggest that investigating two very different sexual systems, one in plants and the other in animals, would throw further light on the long-term implications of a commitment to reproduction exclusively by selfing.
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Affiliation(s)
- John R Pannell
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
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Skew distribution of founder-specific inbreeding depression effects on the longevity of Landrace sows. Genet Res (Camb) 2009; 90:499-508. [DOI: 10.1017/s0016672308009907] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
SummaryInbreeding is a biological phenomenon of special relevance in domestic species in which its influence has been typically associated with reductions in animal fitness. Nevertheless, recent research suggests substantial founder-specific variability in terms of inbreeding depression on some productive traits, although this centred on a very reduced number of founders. This research focuses on the modelling of founder-specific inbreeding depression (FSID) effects from a more general point of view, characterizing the expected distribution of FSID effects on sow longevity. Under a change-point Weibull proportional hazards model solved through Bayesian inference, a skew-normala prioridistribution for the FSID effects of 19 founders was assumed. In terms of the deviance information criterion, this model was clearly preferred to other prior distributions for FSID effects as well as to a standard analysis of the overall inbreeding depression effect, although all models were consistent with an overall negative genetic effect of inbreeding on sow longevity. The joint posterior distribution of FSID effects showed a skewed pattern with substantial right-tail overexpression, in which the mean (0·036), mode (0·034), S.D. (0·032) and asymmetry parameter (0·045) reported a higher incidence of positive estimates (85·2%) with an unfavourable effect on sow longevity. The founder with the worst inbreeding depression effect reduced sow longevity by 32 days for 1% or 167 days for 10% partial inbreeding. As a whole, our analyses highlighted substantial variability in FSID effects, with unfavourable, neutral and even favourable influences on sow longevity. This heterogeneity could be related to an uneven distribution of the recessive deleterious genetic load among founder genomes, and also with the different selection pressures applied to each founder line. The implementation of skew-normal priors also proved an appealing way to bypass the strict scenario imposed by the standard symmetric-Gaussian distribution, allowing right- and left-tail overexpression as well as non-zero modal estimates.
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