292 results on '"Gynodioecy"'
Search Results
2. A leaky dimorphic sexual system and breeding system characterize a successful island colonist: the reproductive biology of Plocama pendula (Rubiaceae).
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Anderson, Gregory J, Paz, Julia Pérez De, Anderson, Mona, Bernardello, Gabriel, and Taylor, David W
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GENITALIA , *POLLINATION , *RUBIACEAE , *POLLINATORS , *BIOLOGY , *FLOWER shows , *ISLANDS - Abstract
Island plants provide special opportunities for the study of evolution and ecology. In field and greenhouse studies we characterized a model reproductive system for Plocama pendula , endemic to the Canary Islands. This species has a complicated and not immediately obvious reproductive system. Pollination is biotic, and all flowers are morphologically hermaphroditic, but half of the plants characteristically bear flowers with nectar, pistils with reflexed stigmatic lobes and pollen-less anthers (i.e. they are functionally female flowers). The other half bear nectar-less flowers with abundant pollen and full-sized pistils that mostly have un-reflexed stigmatic lobes (i.e. they are hermaphroditic flowers functioning mostly as males). However, experiments show these pollen-bearing flowers to be self-compatible. Thus, the functionally male flowers have a breeding system that allows selfing in limited circumstances, but the functionally male flowers produce far fewer fruits than do functionally female flowers. With morphologically gynodioecious, functionally largely dioecious flowers, sometimes capable of selfing, the reproductive system of this species could be labelled as 'leaky' in many respects. Thus, we propose that P. pendula has colonized new habitats and persists in substantial populations at least in part because it manifests a reproductive system that is a model for successfully balancing the often-conflicting evolutionary demands of colonization, establishment and persistence. [ABSTRACT FROM AUTHOR]
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- 2021
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3. Dimorphism, Polyploidy, and Genetic Diversity in the Australian Endemic Lycium australe (Solanaceae).
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Miller, Jill S., Greenberg, Kimberly, Schneider, Derek, and Levin, Rachel A.
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GENETIC variation , *DNA sequencing , *PLOIDY , *DIPLOIDY , *SINGLE nucleotide polymorphisms , *SOLANACEAE , *POLYPLOIDY - Abstract
Premise of research. Whole-genome duplication is often associated with the evolution of dimorphic sexual systems; however, the association is not universal, and the evolutionary pathway(s) underlying the association remain unresolved. The genus Lycium has been demonstrated as a useful system for investigating ploidy and sexual system variation. Here, we describe ploidy and floral variation in L. australe and document genetic diversity and dimorphism across its range. Methodology. Sexual system and size dimorphism were assessed using morphological measurements of 486 flowers. Flow cytometry was used to determine DNA content and ploidy level for 167 plants from across the species range. Using the plastid region trnH-psbA and restriction site–associated DNA sequencing (RADseq), we explored the genetic structure of the species, including an examination of associations of ploidy and sexual system with genetic structure. Pivotal results. We find correlated variation in ploidy level, sexual system, and genetic structure in L. australe. Both gynodioecy and dioecy are documented and are associated with diploidy and polyploidy, respectively. Floral size dimorphism is also found among morphs in both sexual systems. We find significant genetic structure associated with ploidy level and geography based on genome-wide single-nucleotide polymorphisms and plastid haplotypes. Conclusions. We show that L. australe has associated polymorphism in sexual system and ploidy, but the association is an exception to the pattern in the genus. Genetic and ploidy variation in the species suggests potential reproductive barriers and ecological differentiation between cytotypes of differing ploidies. The widespread parapatric distributions of diploid and polyploid L. australe make it an ideal system for studying questions related to reproductive compatibility, ecological differentiation, and polyploid speciation. [ABSTRACT FROM AUTHOR]
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- 2021
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4. Environmental stressors affect sex ratios in sexually dimorphic plant sexual systems.
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Varga, S. and Soulsbury, C. D.
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SEX ratio , *DIOECIOUS plants , *POSITIVE systems , *PLANT species , *TREE-rings , *RATIO analysis - Abstract
Revealing the environmental pressures determining the frequency of females amongst populations of sexually dimorphic plants is a key research question. Analyses of sex ratio variation have been mainly done in dioecious plants, which misses key plant sexual systems that might represent intermediate stages in the evolution of dioecy from hermaphroditism. • We investigated female frequency across populations of sexually dimorphic plant species in relation to environmental stressors (temperature, precipitation), totaling 342 species, 2011 populations, representing 40 orders and three different sexual systems (dioecy, gynodioecy and subdioecy). We also included the biome where the population was located to test how female frequency may vary more broadly with climate conditions. • After correcting for phylogeny, our results for gynodioecious systems showed a positive relationship between female frequency and increased environmental stress, with the main effects being temperature-related. Subdioecious systems also showed strong positive relationships with temperature, and positive and negative relationships related to precipitation, while no significant effects on sex ratio in dioecious plants were detected. • Combined, we show that female frequencies in an intermediate sexual system on the pathway from hermaphroditism to dioecy respond strongly to environmental stressors and have different selective agents driving female frequency. [ABSTRACT FROM AUTHOR]
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- 2020
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5. Trait Transitions in Explicit Ecological and Genomic Contexts: Plant Mating Systems as Case Studies
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Castric, Vincent, Billiard, Sylvain, Vekemans, Xavier, Landry, Christian R., editor, and Aubin-Horth, Nadia, editor
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- 2014
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6. Life‐history trade‐offs promote the evolution of dioecy.
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Dorken, Marcel E. and Van Drunen, Wendy E.
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LIFE history theory , *REPRODUCTION , *ANDRODIOECY , *SEX allocation , *DIOECIOUS plants - Abstract
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. [ABSTRACT FROM AUTHOR]
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- 2018
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7. Pollination context alters female advantage in gynodioecious Silene vulgaris.
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Stone, J. D. and Olson, M. S.
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SILENE vulgaris , *GENETIC polymorphisms in plants , *POLLINATION , *POLLINATORS , *PLANT physiology - Abstract
Gynodioecy, the co-occurrence of females and hermaphrodites, is arguably the most common angiosperm gender polymorphism in many florae. Females' ability to invade and persist among hermaphrodites depends, in part, on pollinators providing adequate pollination to females. We directly measured diurnal and nocturnal pollinators' contributions to female and hermaphrodite seed production in artificial populations of gynodioecious Silene vulgaris by experimentally restricting pollinator access. We found that female relative seed production in this system depended strongly on pollination context: females produced more than twice as many seeds as hermaphrodites in the context of abundant, nectar-collecting moths. Conversely, females showed no seed production advantage in the context of pollen-collecting syrphid flies and bees due to acutely hermaphrodite-biased visitation. We infer that variation in pollinator type, behaviour and abundance may be important for achieving the female relative fitness thresholds necessary for the maintenance of gynodioecy. Generally, our study illustrates how pollinator-mediated mechanisms may influence the evolution of breeding systems and associated suites of floral traits. Segments of a pollinator community may facilitate gynodioecy by selecting for plant characteristics that increase the attractiveness of both sexes to pollinators, such as nectar rewards. Conversely, discriminating visitors in search of pollen may restrict gynodioecy in associated plant lineages by reducing male steriles' fitness below threshold levels. [ABSTRACT FROM AUTHOR]
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- 2018
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8. Dimorphism, Polyploidy, and Genetic Diversity in the Australian Endemic Lycium australe (Solanaceae)
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Derek Schneider, Rachel A. Levin, Jill S. Miller, and Kimberly Greenberg
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Sexual dimorphism ,Genetic diversity ,biology ,Evolutionary biology ,Dioecy ,Gene duplication ,Botany ,Plant Science ,Gynodioecy ,Lycium ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Solanaceae - Abstract
Premise of research. Whole-genome duplication is often associated with the evolution of dimorphic sexual systems; however, the association is not universal, and the evolutionary pathway(s) underlyi...
- Published
- 2021
9. Floral size and shape evolution following the transition to gender dimorphism.
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Kamath, Ambika, Levin, Rachel A., and Miller, Jill S.
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DIMORPHISM in plants ,FLOWER size - Abstract
PREMISE OF THE STUDY:: Floral morphology is expected to evolve following the transition from cosexuality to gender dimorphism in plants, as selection through male and female function becomes dissociated. Specifically, male‐biased dimorphism in flower size can arise through selection for larger flowers through male function, selection for smaller flowers through female function, or both. The evolutionary pathway to floral dimorphism can be most effectively reconstructed in species with intraspecific variation in sexual system. We examined the evolution of flower size and shape in Lycium californicum, whose populations are either gender dimorphic with male and female plants, or cosexual with hermaphroditic plants. METHODS:: Floral morphology was characterized in populations spanning the species’ complete range. For a subset of the range where cosexual and dimorphic populations are in close proximity, we compared the size and shape of flowers from female and male plants in dimorphic populations to hermaphrodites in cosexual populations, accounting for variation associated with abiotic environmental conditions. KEY RESULTS:: The magnitude of flower size dimorphism varied across dimorphic populations. After controlling for environmental variation across cosexual and dimorphic populations, flowers on males were larger than flowers on females and hermaphrodites, whereas flower size did not differ between females and hermaphrodites. Flower shape differences were associated with mating type, sexual system, and environmental variation. CONCLUSIONS:: While abiotic environmental gradients shape both overall flower size and shape, male‐biased flower size dimorphism in L. californicum appears to arise through selection for larger flowers in males but not smaller flowers in females. [ABSTRACT FROM AUTHOR]
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- 2017
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10. Low seed fertility of hermaphrodites is maintained in a gynodioecious species throughout the distribution range in Japan
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Gaku Kudo, Akari Shibata, and Yoshiaki Kameyama
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education.field_of_study ,Range (biology) ,Seed dispersal ,media_common.quotation_subject ,Dioecy ,Population ,food and beverages ,Zoology ,Fertility ,Plant Science ,Gynodioecy ,Biology ,Mating system ,education ,Ecology, Evolution, Behavior and Systematics ,Sex ratio ,media_common - Abstract
Dioecy, the separation of sex at the individual level, evolved in angiosperms from hermaphroditic ancestors. One of the postulated evolutionary pathways is by way of the gynodioecious stage, i.e., the coexistence of female and hermaphroditic individuals. In a morphologically gynodioecious species, Daphne jezoensis., seed fertility in hermaphrodites is limited compared to that of females, indicating that its sexual system is close to dioecy. The aim of this study was to clarify whether the gynodioecy in this species is a stable sexual system or a transitional state leading to dioecy. We evaluated variations in the degree of pollen limitation, sexual and mating systems, floral morphology, sex ratio, and the genetic structure of 14 populations across the species’ distribution range in Japan. Sexual systems were similar among populations throughout the distribution range although the southernmost populations had unique genetic structures to some extent. Hermaphrodites were commonly self-compatible, but their fruiting capacity was low in every population. This suggests that gynodioecy composed of females and hermaphrodites having low seed fertility is a consistent sexual system in D. jezoensis. Low seed fertility in hermaphrodites throughout the distribution range suggests that this sexual system is not necessarily a transitional state from gynodioecy to dioecy if occasional seed production in hermaphrodites has any advantage. One possible ecological advantage for the maintenance of hermaphrodites is that seed production by autonomous self-pollination may be beneficial in the colonization process after long-distance seed dispersal.
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- 2021
11. Multilocus Sex Determination Revealed in Two Populations of Gynodioecious Wild Strawberry, Fragaria vesca subsp. bracteata.
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Ashman, Tia-Lynn, Tennessen, Jacob A., Dalton, Rebecca M., Govindarajulu, Rajanikanth, Koski, Matthew H., and Liston, Aaron
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INTERSEXUALITY , *ANGIOSPERM genetics , *STRAWBERRY genetics - Abstract
Gynodioecy, the coexistence of females and hermaphrodites, occurs in 20% of angiosperm families and often enables transitions between hermaphroditism and dioecy. Clarifying mechanisms of sex determination in gynodioecious species can thus illuminate sexual system evolution. Genetic determination of gynodioecy, however, can be complex and is not fully characterized in any wild species. We used targeted sequence capture to genetically map a novel nuclear contributor to male sterility in a selfpollinated hermaphrodite of Fragaria vesca subsp. bracteata from the southern portion of its range. To understand its interaction with another identified locus and possibly additional loci, we performed crosses within and between two populations separated by 2000 km, phenotyped the progeny and sequenced candidate markers at both sex-determining loci. The newly mapped locus contains a high density of pentatricopeptide repeat genes, a class commonly involved in restoration of fertility caused by cytoplasmic male sterility. Examination of all crosses revealed three unlinked epistatically interacting loci that determine sexual phenotype and vary in frequency between populations. Fragaria vesca subsp. bracteata represents the first wild gynodioecious species with genomic evidence of both cytoplasmic and nuclear genes in sex determination. We propose a model for the interactions between these loci and new hypotheses for the evolution of sex determining chromosomes in the subdioecious and dioecious Fragaria. [ABSTRACT FROM AUTHOR]
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- 2015
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12. Colonization, Baker's law, and the evolution of gynodioecy in Hawaii: implications from a study of Lycium carolinianum
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Jill S. Miller, Caitlin Blank, and Rachel A. Levin
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0106 biological sciences ,Mainland China ,Pollination ,Dioecy ,Locus (genetics) ,Plant Science ,Gynodioecy ,Biology ,010603 evolutionary biology ,01 natural sciences ,Hawaii ,Genetics ,Inbreeding depression ,Colonization ,Ecology, Evolution, Behavior and Systematics ,Islands ,Plant Dispersal ,Reproduction ,social sciences ,Lycium ,Biological Evolution ,Law ,population characteristics ,Mainland ,Introduced Species ,geographic locations ,010606 plant biology & botany - Abstract
Premise As Baker's law suggests, the successful colonization of oceanic islands is often associated with uniparental reproduction (self-fertility), but the high incidence of dimorphism (dioecy, gynodioecy) on islands complicates this idea. Lycium carolinianum is widespread, occurring on the North American mainland and the Hawaiian Islands. We examined Baker's ideas for mainland and island populations of L. carolinianum and examined inbreeding depression as a possible contributor to the evolution of gynodioecy on Maui. Methods Controlled crosses were conducted in two mainland populations and two populations in Hawaii. Treatments included self and cross pollination, unmanipulated controls, and autogamy/agamospermy. Alleles from the self-incompatibility S-RNase gene were isolated and compared between mainland and island populations. Given self-compatibility in Hawaii, we germinated seeds from self- and cross- treatments and estimated inbreeding depression using seven traits and a measure of cumulative fitness. Results Mainland populations of Lycium carolinianum are predominately self-incompatible with some polymorphism for self-fertility, whereas Hawaiian populations are self-compatible. Concordantly, S-RNase allelic diversity is reduced in Hawaii compared to the mainland. Hawaiian populations also exhibit significant inbreeding depression. Conclusions Self-compatibility in Hawaii and individual variation in self-fertility in mainland populations suggests that a colonization filter promoting uniparental reproduction may be acting in this system. Comparison of S-RNase variation suggests a collapse of allelic diversity and heterozygosity at the S-RNase locus in Hawaii, which likely contributed to mate limitation upon arrival to the Pacific. Inbreeding depression coupled with autonomous self-fertilization may have led to the evolution of gynodioecy on Maui.
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- 2019
13. Female advantage? Investigating female frequency and establishment performance in high-Arctic Silene acaulis
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Anne K. Brysting, Mildrid Elvik Svoen, Ingvil Henden Kålås, Eike Müller, and Pernille Bronken Eidesen
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Silene acaulis ,Ecology ,Dioecy ,Selfing ,Outcrossing ,Plant Science ,Gynodioecy ,Biology ,biology.organism_classification ,Arctic ,Botany ,Arctic vegetation ,Inbreeding ,Ecology, Evolution, Behavior and Systematics - Abstract
Many Arctic plants overcome limited time budgets and energy budgets by selfing, increasing the risk of inbreeding. Gynodioecious breeding systems allows for selfing by hermaphrodites, whereas enforced outcrossing through females lowers risk of inbreeding. Females persist due to female advantage in the system. Using the gynodioecious species Silene acaulis (L.) Jacq., we compared establishment performance and female frequency in 17 populations in open, sparsely vegetated habitats versus closed, denser vegetated habitats, across a regional climate gradient in high-Arctic Svalbard. For two populations, genetics were performed using microsatellites to compare inbreeding levels between habitats. As S. acaulis is a pioneer species, we expected denser vegetation to represent more competitive environments, reducing establishment performance and increasing female frequency due to female advantage. We expected similar responses to harsher regional climate. Establishment performance was reduced in closed habitats and harsher climate, but female frequency was slightly lower in closed habitats and did not differ between regional climates. High inbreeding levels may indicate that female advantage is counteracted by pollen limitation. However, female frequency increased with latitude. Lower sun angle at higher latitudes reduce the heat-trap effect of the cushion growth form, and female advantage might be expressed as response to reduced microclimate amelioration.
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- 2019
14. The Diversity and Dynamics of Sex Determination in Dioecious Plants
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Niels A. Müller, Birgit Kersten, Ana Paula Leite Montalvão, and Matthias Fladung
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Gynoecium ,biology ,sex determination via one gene ,Range (biology) ,sex chromosomes ,Dioecy ,fungi ,food and beverages ,Review ,monoecy ,sex determination via two genes ,Gynodioecy ,Plant Science ,lcsh:Plant culture ,hermaphroditism ,biology.organism_classification ,dioecy ,sex-determining region ,Inflorescence ,Evolutionary biology ,lcsh:SB1-1110 ,Asparagus ,Plant reproductive morphology ,Gene - Abstract
The diversity of inflorescences among flowering plants is captivating. Such charm is not only due to the variety of sizes, shapes, colors, and flowers displayed, but also to the range of reproductive systems. For instance, hermaphrodites occur abundantly throughout the plant kingdom with both stamens and carpels within the same flower. Nevertheless, 10% of flowering plants have separate unisexual flowers, either in different locations of the same individual (monoecy) or on different individuals (dioecy). Despite their rarity, dioecious plants provide an excellent opportunity to investigate the mechanisms involved in sex expression and the evolution of sex-determining regions (SDRs) and sex chromosomes. The SDRs and the evolution of dioecy have been studied in many species ranging from Ginkgo to important fruit crops. Some of these studies, for example in asparagus or kiwifruit, identified two sex-determining genes within the non-recombining SDR and may thus be consistent with the classical model for the evolution of dioecy from hermaphroditism via gynodioecy, that predicts two successive mutations, the first one affecting male and the second one female function, becoming linked in a region of suppressed recombination. On the other hand, aided by genome sequencing and gene editing, single factor sex determination has emerged in other species, such as persimmon or poplar. Despite the diversity of sex-determining mechanisms, a tentative comparative analysis of the known sex-determining genes and candidates in different species suggests that similar genes and pathways may be employed repeatedly for the evolution of dioecy. The cytokinin signaling pathway appears important for sex determination in several species regardless of the underlying genetic system. Additionally, tapetum-related genes often seem to act as male-promoting factors when sex is determined via two genes. We present a unified model that synthesizes the genetic networks of sex determination in monoecious and dioecious plants and will support the generation of hypothesis regarding candidate sex determinants in future studies.
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- 2021
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15. THE RELATIVE AND ABSOLUTE FREQUENCIES OF ANGIOSPERM SEXUAL SYSTEMS: DIOECY, MONOECY, GYNODIOECY, AND AN UPDATED ONLINE DATABASE.
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Renner, Susanne S.
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ANGIOSPERMS , *PHANEROGAMS , *ARALIACEAE , *ONLINE databases , *POLYGAMY - Abstract
Premise of the study: Separating sexual function between different individuals carries risks, especially for sedentary organisms. Nevertheless, many land plants have unisexual gametophytes or sporophytes. This study brings together data and theoretical insights from research over the past 20 yr on the occurrence and frequency of plant sexual systems, focusing on the flowering plants. • Methods: A list of genera with dioecious species, along with other information, is made available (http://www.umsl.edu/~renners/). Frequencies of other sexual systems are tabulated, and data on the genetic regulation, ecological context, and theoretical benefits of dioecy reviewed. • Key results: There are 15 600 dioecious angiosperms in 987 genera and 175 families, or 5-6% of the total species (7% of genera, 43% of families), with somewhere between 871 to 5000 independent origins of dioecy. Some 43% of all dioecious angiosperms are in just 34 entirely dioecious clades, arguing against a consistent negative influence of dioecy on diversification. About 31.6% of the dioecious species are wind-pollinated, compared with 5.5-6.4% of nondioecious angiosperms. Also, 1.4% of all angiosperm genera contain dioecious and monoecious species, while 0.4% contain dioecious and gynodioecious species. All remaining angiosperm sexual systems are rare. Chromosomal sex determination is known from 40 species; environmentally modulated sex allocation is common. Few phylogenetic studies have focused on the evolution of dioecy. • Conclusions: The current focus is on the genetic mechanisms underlying unisexual flowers and individuals. Mixed strategies of sexual and vegetative dispersal, together with plants' sedentary life style, may often favor polygamous systems in which sexually inconstant individuals can persist. Nevertheless, there are huge entirely dioecious clades of tropical woody plants. [ABSTRACT FROM AUTHOR]
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- 2014
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16. An angiosperm-wide analysis of the gynodioecy–dioecy pathway.
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Dufay, M., Champelovier, P., Käfer, J., Henry, J. P., Mousset, S., and Marais, G. A. B.
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ANGIOSPERMS , *DIOECIOUS plants , *PLANT species , *PLANT classification , *PLANT phylogeny , *PLANT reproduction - Abstract
Background and Aims About 6 % of an estimated total of 240 000 species of angiosperms are dioecious. The main precursors of this sexual system are thought to be monoecy and gynodioecy. A previous angiosperm-wide study revealed that many dioecious species have evolved through the monoecy pathway; some case studies and a large body of theoretical research also provide evidence in support of the gynodioecy pathway. If plants have evolved through the gynodioecy pathway, gynodioecious and dioecious species should co-occur in the same genera. However, to date, no large-scale analysis has been conducted to determine the prevalence of the gynodioecy pathway in angiosperms. In this study, this gap in knowledge was addressed by performing an angiosperm-wide survey in order to test for co-occurrence as evidence of the gynodioecy pathway. Methods Data from different sources were compiled to obtain (to our knowledge) the largest dataset on gynodioecy available, with 275 genera that include at least one gynodioecious species. This dataset was combined with a dioecy dataset from the literature, and a study was made of how often dioecious and gynodioecious species could be found in the same genera using a contingency table framework. Key Results It was found that, overall, angiosperm genera with both gynodioecious and dioecious species occur more frequently than expected, in agreement with the gynodioecy pathway. Importantly, this trend holds when studying different classes separately (or sub-classes, orders and families), suggesting that the gynodioecy pathway is not restricted to a few taxa but may instead be widespread in angiosperms. Conclusions This work complements that previously carried out on the monoecy pathway and suggests that gynodioecy is also a common pathway in angiosperms. The results also identify angiosperm families where some (or all) dioecious species may have evolved from gynodioecious precursors. These families could be the targets of future small-scale studies on transitions to dioecy taking phylogeny explicitly into account. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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17. Gynodioecy or leaky dioecy? The unusual sexual system of a coral dune-habitant Tournefortia argentea (Boraginaceae)
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Meihong Wen, Kai Zhang, Yuanqing Xu, Dianxiang Zhang, Mingsong Wu, and Xiangping Wang
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0106 biological sciences ,biology ,Pollination ,Dioecy ,fungi ,food and beverages ,Zoology ,Plant Science ,Gynodioecy ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Sexual dimorphism ,Hermaphrodite ,Pollinator ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany ,Tournefortia ,Hand-pollination - Abstract
The high occurrence of dioecy on oceanic islands has attracted much attention from plant evolutionary biologists. Tournefortia argentea (Boraginaceae), an Indo-Pacific strand plant, has an unusual sexual system which remains poorly understood. Here, we investigated the sexual system of T. argentea based on morphological and micromorphological studies, as well as manipulated pollination treatments. Two morphs of plants were found in the natural populations on Xisha Islands: hermaphrodite and female plants. Each sexual morph exhibited different floral traits, showing a modest form of sexual dimorphism. Flowers of hermaphrodites display significantly larger size in corolla and anther than those of females. Fruit sets under natural condition and hand pollination in hermaphroditic individuals were both far lower than that of female ones, which shows characteristics of both leaky dioecy and gynodioecy. We investigated how these differences in floral traits between females and hermaphrodites affect the choice of pollinators. Although females and hermaphroditic flowers in T. argentea attracted the same assemblage of pollinator species, including Apidae, Syrphidae and Utetheisa lotrix (Arctiidae), the reduction in allocation to pollinator-attracting structures (corolla) and rewarding products caused a significant reduction in Apidae visitation to female flowers. Accordingly, T. argentea is another example of a gynodioecious species of flowering plants in Boraginaceae with clear sexual dimorphism occurring in oceanic islands. The sexual system in T. argentea may imply a transitional stage in the evolution to dioecy and may have been favored during colonization to newly reclaimed habitats, where mating partners may be limited.
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- 2020
18. Environmental stressors affect sex ratios in sexually dimorphic plant sexual systems
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Carl D. Soulsbury and Sandra Varga
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0106 biological sciences ,Dioecy ,Biome ,Population ,Zoology ,Plant Science ,Gynodioecy ,Biology ,Environment ,Affect (psychology) ,010603 evolutionary biology ,01 natural sciences ,Stress, Physiological ,Sex Ratio ,education ,C200 Botany ,Ecology, Evolution, Behavior and Systematics ,Plant Physiological Phenomena ,education.field_of_study ,Sex Characteristics ,Reproduction ,Stressor ,General Medicine ,Plants ,Biological Evolution ,C142 Reproductive Biology ,Sexual dimorphism ,C180 Ecology ,Sex ratio ,010606 plant biology & botany - Abstract
• Revealing the environmental pressures determining the frequency of females amongst populations of sexually dimorphic plants is a key research question. Analyses of sex-ratio variation have been mainly done in dioecious plants, which misses key plant sexual systems that might represent intermediate stages in the evolution of dioecy from hermaphroditism. • We investigated female frequency across populations of sexually dimorphic plant species in relation to environmental stressors (temperature, precipitation), totaling 342 species, 2011 populations, representing 40 orders and 3 different sexual systems (dioecy, gynodioecy, and subdioecy). We also included the biome where the population was located to test how female frequency may vary more broadly with climatic conditions. • After correcting for phylogeny, our results for gynodioecious systems showed a positive relationship between female frequency and increased environmental stress, with the main effects being temperature-related. Subdioecious systems showed also strong positive relationships with temperature and positive and negative relationships related to precipitation, whilst no significant effects on sex ratio in dioecious plants were detected. • Combined, we show that female frequencies in intermediate sexual system on the pathway from hermaphroditism to dioecy respond strongly to environmental stressors and have different selective agents driving female frequency.
- Published
- 2020
19. Gynodioecy to dioecy: are we there yet?
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Spigler, Rachel B. and Ashman, Tia-Lynn
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INTERSEXUALITY , *SELF-fertilization of plants , *PLANT reproduction , *ANGIOSPERMS , *MALE reproductive organs , *FEMALE reproductive organs , *PLANTS - Abstract
Background The ‘gynodioecy–dioecy pathway’ is considered to be one of the most important evolutionary routes from hermaphroditism to separate sexes (dioecy). Despite a large accumulation of evidence for female seed fertility advantages in gynodioecious species (females and hermaphrodites coexist) in support of the first step in the gynodioecy–dioecy pathway, we still have very little evidence for the second step, i.e. the transition from gynodioecy to dioecy. Scope We review the literature to evaluate whether basic predictions by theory are supported. To establish whether females' seed fertility advantage and frequencies are sufficient to favour the invasion of males, we review these for species along the gynodioecy–dioecy pathway published in the last 5 years. We then review the empirical evidence for predictions deriving from the second step, i.e. hermaphrodites' male fertility increases with female frequency, selection favours greater male fertility in hermaphrodites in gynodioecious species, and, where males and hermaphrodites coexist with females (subdioecy), males have greater male fertility than hermaphrodites. We review how genetic control and certain ecological features (pollen limitation, selfing, plasticity in sex expression and antagonists) influence the trajectory of a population along the gynodioecy–dioecy pathway. Conclusions Females tend to have greater seed fertility advantages over hermaphrodites where the two coexist, and this advantage is positively correlated with female frequency across species, as predicted by theory. A limited number of studies in subdioecious species have demonstrated that males have an advantage over hermaphrodites, as also predicted by theory. However, less evidence exists for phenotypic selection to increase male traits of hermaphrodites or for increasing male function of hermaphrodites in populations with high female frequency. A few key case studies underline the importance of examining multiple components of male fertility and the roles of pollen limitation, selfing and plasticity, when evaluating advantages. We conclude that we do not yet have a full understanding of the transition from gynodioecy to dioecy. [ABSTRACT FROM AUTHOR]
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- 2012
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20. Gender plasticity and sexual system stability in Wurmbea.
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Vaughton, Glenda and Ramsey, Mike
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SEX in plants , *PHENOTYPIC plasticity , *BOTANY , *FLOWERS ,SEX differences (Biology) - Abstract
Background and aims Sexually dimorphic populations are often located in drier habitats than cosexual populations. Gender plasticity (GP), whereby hermaphrodites alter female and male functions depending on resources, and sex-differential plasticity (SDP) between hermaphrodites and unisexuals are predicted to affect sexual system stability. Here, GP and SDP are evaluated in cosexual and gynodioecious Wurmbea biglandulosa and sub-dioecious and dioecious W. dioica. Methods GP was evaluated under two resource conditions, compared among sexual systems and assessed as to whether (1) males produced perfect flowers and (2) hermaphrodites altered investment in perfect (female function) and total (male function) flowers. SDP was assessed within sexual systems as differences between sex functions of hermaphrodites vs. unisexuals. Males and hermaphrodites were compared to assess whether size thresholds for female function differed among sexual systems. Plasticity costs were evaluated using correlations between female function and male traits in hermaphrodites, and in W. dioica by comparing hermaphrodite and male regressions between plant size and pollen production. Key Results In dioecious W. dioica no males exhibited GP, whereas 100 % did in gynodioecious and cosexual W. biglandulosa. In sub-dioecious W. dioica, resources affected GP (high, 66 %; low, 42 %). Hermaphrodites in all sexual systems reduced perfect but not total flowers under low resources. Unisexuals were unaffected, demonstrating SDP for female function only. Thresholds for female function were greater in sub-dioecious W. dioica than in W. biglandulosa. Plasticity costs were detected only in sub-dioecious W. dioica. Conclusions SDP for female function could assist female establishment in cosexual populations and maintain females in gynodioecious and sub-dioecious populations. Although the absence of male SDP should stabilize sub-dioecy, plasticity costs would render sub-dioecy unstable, favouring canalized males over hermaphrodites. This study highlights the importance of interactions between environmental conditions and hermaphrodite sex expression for the stability of dimorphic sexual systems. [ABSTRACT FROM AUTHOR]
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- 2012
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21. Functional characterization of gynodioecy in Fragaria vesca ssp. bracteata (Rosaceae).
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Li, Junmin, Koski, Matthew H., and Ashman, Tia-Lynn
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PLANT phylogeny , *ROSACEAE , *PLANT reproduction , *PLANT diversity , *GREENHOUSES , *GENETIC sex determination - Abstract
Background and Aims Gynodioecy is a phylogenetically widespread and important sexual system where females coexist with hermaphrodites. Because dioecy can arise from gynodioecy, characterization of gynodioecy in close relatives of dioecious and sub-dioecious species can provide insight into this transition. Thus, we sought to determine whether Fragaria vesca ssp. bracteata, a close relative to F. chiloensis and F. virginiana, exhibits the functional and population genetic hallmarks of a gynodioecious species. Methods We compared reproductive allocation of females and hermaphrodites grown in the greenhouse and estimated genetic diversity (allelic diversity, heterozygosity) and inbreeding coefficients for field-collected adults of both sexes using simple sequence repeat (SSR) markers. We estimated mating system and early seed fitness from open-pollinated families of both sex morphs. Key Results Under greenhouse conditions, females and hermaphrodites allocated similarly to all reproductive traits except flower number, and, as a consequence, females produced 30 % fewer seeds per plant than hermaphrodites. Under natural conditions, hermaphrodites produce seeds by self-fertilization approx. 75 % of the time, and females produced outcrossed seeds with very little biparental inbreeding. Consistent with inbreeding depression, seeds from open-pollinated hermaphrodites were less likely to germinate than those from females, and family-level estimates of hermaphrodite selfing rates were negatively correlated with germination success and speed. Furthermore, estimates of inbreeding depression based on genetic markers and population genetic theory indicate that inbreeding depression in the field could be high. Conclusions The joint consideration of allocation and mating system suggests that compensation may be sufficient to maintain females given the current understanding of sex determination. Fragaria vesca ssp. bracteata exhibited similar sex morph-dependent patterns of mating system and genetic diversity, but less reproductive trait dimorphism, than its sub-dioecious and dioecious congeners. [ABSTRACT FROM AUTHOR]
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- 2012
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22. Reproductive biology of woody species in Caatinga, a dry forest of northeastern Brazil
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Virgínia de Lima Leite, Ana and Machado, Isabel Cristina
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CAATINGA plants , *PLANT species , *TROPICAL dry forests , *FLOWERING of plants , *SAPOTACEAE , *ARID regions , *OVULES , *BIOTIC communities , *POLLINATION - Abstract
Abstract: Studies concerning reproductive biology at the community level have not yet been reported for Caatinga. In this study, we analyzed the flowering phenology, floral longevity, and breeding system of 15 typical woody species in this ecosystem. Flowering occurred mostly during the dry season for ten species. Among dioecious plants, male individuals predominate for two out of three species analyzed. In Maytenus rigida, a gynodioecious species, female individuals predominate in the population; the number of flowers per inflorescence is the same between hermaphrodite (14.0 ± 4.4) and female (14.8 ± 4.6) individuals, but significant differences are found with respect to fruit set by hermaphrodite (1.9 ± 0.9) and pistillate flowers (4.0 ± 2.4). Self-compatibility occurs in 26.7% of the studied species, whereas 73.3% present obligatory xenogamy. Among self-incompatible species, two have a stylar site of rejection, while self-pollen tubes reach the ovules in five. Late-acting self-incompatibility in Sideroxylon obtusifolium constitutes the first record of this mechanism in Sapotaceae. The majority of the species studied have a lower fruit/flower than seed/ovule ratio. Reproduction of woody plants in this arid ecosystem depends upon biotic vectors that can promote cross-pollination and gene flow. [Copyright &y& Elsevier]
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- 2010
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23. Sex-allocation plasticity in hermaphrodites of sexually dimorphic Fragaria virginiana (Rosaceae).
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Bishop, Eric J., Spigler, Rachel B., and Ashman, Tia-Lynn
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- *
BIOLOGICAL variation , *DEFORMATIONS (Mechanics) , *MATERIAL plasticity , *POLLINATION , *PLANT reproduction , *ALLOMETRY - Abstract
Sex-allocation plasticity is thought to play an important role in the evolution of separate sexes in plants. Accordingly, much attention has been paid to environmentally induced variation in fruit and seed production in sexually dimorphic species, but we know little about whether this variation arises as a direct response to environmental variation or is instead an indirect consequence of changes in plant size. In this study, we characterize sex-allocation plasticity across a resource gradient for several reproductive traits in hermaphrodites of gyno(sub)dioecious Fragaria virginiana Duch. We find significant plasticity, on average, for flower number, proportion fruit set, ovule number, proportion seed set, and runner number in response to resource variation. Plasticity of most traits examined tended to be at least partially independent of variation in plant size, suggesting that it is not simply an indirect consequence of plant allometry. Moreover, we find genetic variation for plasticity of key reproductive traits. Comparisons of relative plasticities among traits reveal that F. virginiana hermaphrodites are more likely to adjust female investment via changes in fruit and seed set than ovule number, and most likely to adjust male investment via flower number rather than anther number or pollen per anther, although there is genotypic variation for plasticity in pollen per anther. Evidence of within-population variation can logically be extended to suggest that variation in hermaphrodite sex-expression seen among natural populations of F. virginiana may be due, at least in part, to sex-allocation plasticity. [ABSTRACT FROM AUTHOR]
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- 2010
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24. Sniffing out patterns of sexual dimorphism in floral scent.
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Ashman, Tia-Lynn
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SEXUAL dimorphism , *FRAGRANCE of flowers , *ANGIOSPERMS , *INTERSEXUALITY , *PLANT reproduction , *PLANTS - Abstract
1. A major transition in flowering plants has been the evolution of separate sexes (dioecy) from combined sexes (hermaphroditism). This transition is often, but not always, accompanied by the evolution of sexual dimorphism in attractive traits, and floral scent is no exception. 2. In this review I aim to improve our understanding of variation in sexual dimorphism in floral scent characteristics by first explicating the relevant hypotheses, and then deriving explicit predictions for the pattern of floral scent from each. 3. Next, I synthesize and qualitatively review published data on floral volatile emission rate and composition in 33 gender dimorphic species to identify emerging patterns, and evaluate these in light of predictions derived from the hypotheses. 4. Although conclusions must be viewed as preliminary, a handful of strong patterns were revealed: (1) in the majority of the species studied males emit more volatiles per flower than females, (2) in over half of the species studied the sexes differed in at least one aspect of scent composition, (3) sexual dimorphism in scent composition was less common in species with rewardless females and/or brood site pollination than those that offered nectar and/or pollen, (4) a one-to-one correspondence between sex differences in overall scent composition and male organ-specific scent production is largely not found. 5. This review has highlighted gaps in our understanding of the genesis of patterns of sexual dimorphism in floral scent, and makes clear that to move the field forward we need to shift our focus from pattern to process, and this will be best achieved by simultaneously testing alternative hypotheses at the same level of analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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25. Genetic mapping of sex determination in a wild strawberry, Fragaria virginiana, reveals earliest form of sex chromosome.
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Spigler, R. B., Lewers, K. S., Main, D. S., and Ashman, T.-L.
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- *
GENETIC sex determination , *STRAWBERRIES , *INTERSEXUALITY , *SEX chromosome variations , *GENETIC polymorphisms , *GENETICS - Abstract
The evolution of separate sexes (dioecy) from hermaphroditism is one of the major evolutionary transitions in plants, and this transition can be accompanied by the development of sex chromosomes. Studies in species with intermediate sexual systems are providing unprecedented insight into the initial stages of sex chromosome evolution. Here, we describe the genetic mechanism of sex determination in the octoploid, subdioecious wild strawberry, Fragaria virginiana Mill., based on a whole-genome simple sequence repeat (SSR)-based genetic map and on mapping sex determination as two qualitative traits, male and female function. The resultant total map length is 2373 cM and includes 212 markers on 42 linkage groups (mean marker spacing: 14 cM). We estimated that approximately 70 and 90% of the total F. virginiana genetic map resides within 10 and 20 cM of a marker on this map, respectively. Both sex expression traits mapped to the same linkage group, separated by approximately 6 cM, along with two SSR markers. Together, our phenotypic and genetic mapping results support a model of gender determination in subdioecious F. virginiana with at least two linked loci (or gene regions) with major effects. Reconstruction of parental genotypes at these loci reveals that both female and hermaphrodite heterogamety exist in this species. Evidence of recombination between the sex-determining loci, an important hallmark of incipient sex chromosomes, suggest that F. virginiana is an example of the youngest sex chromosome in plants and thus a novel model system for the study of sex chromosome evolution.Heredity (2008) 101, 507–517; doi:10.1038/hdy.2008.100; published online 17 September 2008 [ABSTRACT FROM AUTHOR]
- Published
- 2008
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26. PHENOTYPIC PLASTICITY OF HERMAPHRODITE SEX ALLOCATION PROMOTES THE EVOLUTION OF SEPARATE SEXES: AN EXPERIMENTAL TEST OF THE SEX-DIFFERENTIAL PLASTICITY HYPOTHESIS USING SAGITTARIA LATIFOLIA (ALISMATACEAE).
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Dorken, Marcel E. and Mitchard, Edward T. A.
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- *
INTERSEXUALITY in animals , *PHENOTYPIC plasticity , *SEX allocation , *SEX differentiation (Embryology) , *SAGITTARIA latifolia , *HUMAN sexuality - Abstract
Separate sexes can evolve under nuclear inheritance when unisexuals have more than twice the reproductive fitness of hermaphrodites through one sex function (e.g., when females have more than twice the seed fertility of hermaphrodites). Because separate sexes are thought to evolve most commonly via a gynodioecious intermediate (i.e., populations in which females and hermaphrodites cooccur), the conditions under which females can become established in populations of hermaphrodites are of considerable interest. It has been proposed that resource-poor conditions could promote the establishment of females if hermaphrodites are plastic in their sex allocation and allocate fewer resources to seed production under these conditions. If this occurs, the seed fertility of females could exceed the doubling required for the evolution of unisexuality under low-, but not high-resource conditions (the sex-differential plasticity hypothesis). We tested this hypothesis using replicate experimental arrays of the aquatic herb Sagittaria latifolia grown under two fertilizer treatments. The results supported the sex-differential plasticity hypothesis, with females having more than twice the seed fertility of hermaphrodites under low-, but not high-fertilizer conditions. Our findings are consistent with the idea that separate sexes are more likely to evolve under unfavorable conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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27. GENDER VARIATION AND TRANSITIONS BETWEEN SEXUAL SYSTEMS IN MERCURIALIS ANNUA (EUPHORBIACEAE).
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Pannell, John R., Dorken, Marcel E., Pujol, Benoit, and Berjano, Regina
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- *
PLANT variation , *EUPHORBIA , *PLANT species , *PLANT fertilization , *PLANT physiology , *PLANT reproduction , *STERILITY in plants , *SPECIES hybridization , *POPULATION biology - Abstract
Evolutionary transitions between hermaphroditism and dioecy have occurred numerous times in the land plants. We briefly review the factors thought to be responsible for these transitions, and we provide a synthesis of what has been learned from recent studies of the annual herb Mercurialis annua, in which dioecy (males and females), monoecy (functional hermaphrodites), and androdioecy (males and hermaphrodites) occur in different parts of its geographic range. Previous research on M. annua has revealed the importance of genome duplication and hybridization in the origin of much of the observed variation. Here we show, however, that spatial transitions in the sexual system also occur within the same ploidy level. In particular, we present an analysis, using flow cytometry data, of ploidy variation across a previously unstudied transition between hermaphroditism and androdioecy, in which we find that the sexual-system transition is uncoupled from the shift in ploidy levels. We review recent research that shows that such transitions between sexual systems in M. annua are consistent with differential selection at the regional level for reproductive assurance during colonization. We also present new experimental data that highlight both the importance of the resource status of plants and that of their local mating context in regulating gender strategies and sex ratios. The studies reviewed and the new results presented emphasize the role that shifts in the ecological and genetic context of plant populations may play in causing transitions between sexual systems. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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28. A PHYLOGENETIC STUDY OF EVOLUTIONARY TRANSITIONS IN SEXUAL SYSTEMS IN AUSTRALASIAN WURMBEA (COLCHICACEAE).
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Case, Andrea L., Graham, Sean W., Macfarlane, Terry D., and Barrett, Spencer C. H.
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PLANT evolution , *PLANT species , *PLANT genetics , *GENETIC transformation , *MONOCOTYLEDONS , *ANGIOSPERMS , *PLASTIDS , *PLANT cells & tissues , *PLANT pigments - Abstract
Using phylogenies to make sound inferences about character evolution depends on a variety of factors, including tree uncertainty, taxon sampling, and the degree of evolutionary lability in the character of interest. We explore the effect of these and other sources of ambiguity for maximum likelihood (ML)-based inferences of sexual-system evolution in Wurmbea, a small genus of geophytic monocots from the Southern Hemisphere. We reconstructed Wurmbea phylogeny using four noncontiguous regions (ca. 5.5 kb) of the plastid genome across a broad sampling of taxa, and we confirm that the genus is divided into two well-supported clades, each defined by its geography (Africa vs. Australasia) and variation in sexual system (i.e., uniformly monomorphic vs. sexually variable, respectively). We demonstrate that the predominantly Australian clade includes the sexually monomorphic species Iphigenia novae-zelandiae. We observe treewide uncertainty in the state of all ancestral nodes, and therefore all state transitions, when all taxa in Wurmbea are considered. We demonstrate that this is primarily a consequence of interspersion of terminals with gender dimorphism vs. monomorphism throughout the Australasian clade, rather than tree uncertainty or the presence of very short internal branches. We accounted for tree uncertainty by randomly sampling alternative resolutions of branches that are poorly supported by ML bootstrap analysis, effectively interpreting these as soft polytomies. Under the assumption that well-supported aspects of our gene tree accurately depict organismal phylogeny, there is a marked evolutionary lability in the sexual systems of Australasian Wurmbea. A more problematic issue is that our results contradict the monophyly of two sexually polymorphic Australian species, Wurmbea dioica and Wurmbea biglandulosa. If this reflects paraphyly at the species level, lateral gene transfer, or failed coalescence, then the interpretations of character transitions will need to be adjusted. Our analysis provides an example of the impediments to linking macroevolutionary pattern with microevolutionary processes for evolutionarily labile traits in recently evolved plant groups that possess a high degree of variation in sexual characters. [ABSTRACT FROM AUTHOR]
- Published
- 2008
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29. AN EXPERIMENTAL TEST OF THE EFFECTS OF RESOURCES AND SEX RATIO ON MATERNAL FITNESS AND PHENOTYPIC SELECTION IN GYNODIOECIOUS FRAGARIA VIRGINIANA.
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Case, Andrea L. and Ashman, Tia-Lynn
- Subjects
- *
SEX ratio , *PLANT species , *SEXUAL dimorphism , *STRAWBERRIES , *NATURAL selection , *ROSACEAE , *PLANTS - Abstract
Resources, sex ratio, and seed production by hermaphrodites covary among natural populations of many gynodioecious plant species, such that they are functionally "more dioecious" as resources become more limiting. Strong correlations among these three factors confound our understanding of their relative roles in maintaining polymorphic sexual systems. We manipulated resource availability and sex ratio and measured their effects on relative fertility and phenotypic selection through the maternal fitness of females and hermaphrodites of Fragaria virginiana. Two results were particularly surprising. First, hermaphrodites showed little variability in fecundity across resource treatments and showed strong positive and context-dependent selection for fruit set. This suggests that variation in hermaphrodite seed production along resource gradients in nature may result from adaptation rather than plasticity. Second, although females increased their fecundity with higher resources, their fertility was unaffected by sex ratio, which is predicted to mediate pollen limitation of females in natural populations where they are common. Selection on petal size of females was also weak. indicating a minimal effect of pollinator attraction on variation in the fertility of female plants. Hence, we found no mechanistic explanation for the complete absence of high-resource high female populations in nature. Despite strong selection for increased fruit set of hermaphrodites, both the strength of selection and its contribution to the maintenance of gynodioecy are severely reduced under conditions where females have high relative fecundity (i.e., low resources and high-female sex ratios). High relative fertility plus high female frequency means that the evolution of phenotypic traits in hermaphrodites (i.e., response to selection via seed function) should be manifested through females because most hermaphrodites will have female mothers. Fruit set was never under strong selection in females; hence, selection to increase fruit set hermaphrodites will he less effective in maintaining their fruiting ability in natural populations with low resources and high female frequency. In sum, both sex ratio and resource availability influence trait evolution indirectly--through their effects on relative fertility of the sexes and patterns of selection. Sex ratio did not impose strong pollen limitation on females but did directly moderate the outcome of natural selection by biasing the maternal sex of the next generation. This direct effect of sex ratio on the manifestation of natural selection is expected to have far greater impact on the evolution of traits, such as seed-producing ability in hermaphrodites and the maintenance of sexual polymorphisms in nature, compared to indirect effects of sex ratio on relative fertility of the sexes. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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30. LEAF DAMAGE AND GENDER BUT NOT FLOWER DAMAGE AFFECT FEMALE FITNESS IN NEMOPHILA MENZIESH (HYDROPHYLLACEAE).
- Author
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Mccall, Andrew C.
- Subjects
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PLANT reproduction , *SEX in plants , *PLANT evolution , *HYDROPHYLLACEAE , *FLOWERS - Abstract
Researchers can answer questions about the evolution or maintenance of separate sexes using dioecious plant systems. Because females in these species typically put more resources into reproductive effort than male plants, researchers have hypothesized that females may be less tolerant of the stresses found in marginal habitats. Herbivory can act as a biotic stressor that reduces resources in plants much like a marginal habitat can. Females may be limited by resources, and may thus be less tolerant to herbivory than males. Here, I explore the relationships between florivory, leaf herbivory, and gender in a gynodioecious, annual plant, Neniophila rnenziesii (Hydrophyllaceae, senso lato). I performed a crossed design experiment examining the main effects and interactions of plant gender, artificial leaf damage, and artificial flower damage on components of female plant fitness. Leaf damage decreased fruit set and females made significantly more fruit than hermaphrodites. However, contrary to theory, I found little evidence for a gender by damage interaction for either type of artificial herbivory. Based on these results, I propose more work exploring the effects of both source and sink damage in dioecious species to help elucidate where and when different sexual morphs are favored by natural selection. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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31. Disparity in floral traits and breeding systems in the iconic columnar cactus Pachycereus pringlei (Cactaceae)
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José Luis León de la Luz, Carina Gutiérrez-Flores, J. Hugo Cota-Sánchez, and Francisco León
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0106 biological sciences ,Gynoecium ,Ecology ,biology ,Dioecy ,Plant Science ,Gynodioecy ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Sexual dimorphism ,Pachycereus pringlei ,Hermaphrodite ,Cactus ,Ovule ,Ecology, Evolution, Behavior and Systematics ,010606 plant biology & botany - Abstract
Studies on breeding systems and flower morphology are valuable to infer how environmental factors impose evolutionary change in plants. This study focused on the characterization of floral morphs and reproductive systems in Pachycereus pringlei and how this iconic columnar cactus might be a useful genus to understand the evolution of these highly variable structures. We determined breeding systems, characterized floral morphs in five genetic populations, and used pollen:ovule ratios and stamen-stigma distance to verify the sexual system in bisexual flowers. Our inquiries provide insights into the factors driving intra-specific disparity in flower attributes and the reproductive versatility in P. pringlei . Foremost, the lability of breeding systems is expressed primarily as gynodioecy in the North, trioecy in the South, mainly dioecy in CBS, and hermaphroditic in Catalana and Cerralvo Islands. A latitudinal trend in ovule production, dimensions in gynoecium, androecium, and floral display characters is consistent with a northward increase in vegetative traits suggesting physiological responses to the environmental variation characterizing the Baja California Peninsula (BCP). Also, nectary size decreases northwards in staminate flower, but these flowers are larger in the CBS and South populations suggesting sex-specific selection, e.g., pollinator-driven, acting in different magnitudes on sexual attributes of floral morphs and populations. The presence of rudimentary structures of the dysfunctional sex support the hypothesis of the evolution of unisexuality from an early bisexual ancestor. In conclusion, this investigation provides insights into the factors driving intra-specific disparity in flower attributes and the reproductive versatility in P. pringlei to replace ancestral conditions, specifically the substitution of the hermaphrodite phase with dioecious, gynodioecious, and trioecious breeding systems throughout mainland BCP and Sonora. We posit that the biogeographic patterns of breeding systems and floral traits of this emblematic cactus resulted from the interaction of past factors (northwards range expansion) and contemporary biotic and abiotic factors.
- Published
- 2017
32. Restricted female function of hermaphrodites in a gynodioecious shrub, Daphne jezoensis (Thymelaeaceae)
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Yoshiaki Kameyama, Gaku Kudo, and Akari Shibata
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0106 biological sciences ,Dioecy ,Population ,Germination ,Plant Science ,Gynodioecy ,Biology ,010603 evolutionary biology ,01 natural sciences ,Japan ,Hermaphrodite ,Botany ,Inbreeding depression ,Hermaphroditic Organisms ,education ,Sex allocation ,education.field_of_study ,food and beverages ,Selfing ,Fertility ,Phenotype ,Seeds ,Daphne ,Genetic Fitness ,010606 plant biology & botany ,Hand-pollination - Abstract
Gynodioecy is the coexistence of hermaphrodites and females in a population. It is supposed to be an intermediate stage in the evolutionary pathway from hermaphroditism to dioecy in angiosperm. Hermaphrodites gain fitness through both seed and pollen production whereas females gain fitness only through seed production. As females spread in a gynodioecious population, sexual selection prompts hermaphrodites to invest in male function and male-biased hermaphrodites prevail. In the gynodioecious shrub Daphne jezoensis (Thymelaeaceae), female frequency is stably around 50% in most populations, and fruit-set rate of hermaphrodites is commonly low. Therefore, D. jezoensis is likely at a later stage in the evolutionary pathway. Female function of hermaphrodites (fruit-set rate, selfing rate, seed size, and germination rate) was assessed in three populations under natural conditions. In order to evaluate the potential seed fertility and inbreeding depression by selfing in hermaphrodites, hand pollination treatments were also performed. Over a 2-year period under natural conditions, 18-29% of hermaphrodites and 69-81% of females set fruit. Across all three populations, the mean fruit-set rate ranged 9.5-49.2% in females and only 3.9-10.2% in hermaphrodites. Even with artificial outcross-pollination, 59-91% of hermaphrodites failed to set any fruit. When self-pollination was performed in hermaphrodites, both of fruit-set and germination rates were decreased, indicating early-acting inbreeding depression. In addition, more than half of the hermaphrodite seeds were produced by selfing under natural pollination, but pollinator service was still required. Totally, hermaphrodites performed poorly as seed producers because of the intrinsically-low fruiting ability and a combination of autogamous selfing and strong inbreeding depression, indicating the absence of reproductive assurance. These results indicate that the mating system of D. jezoensis is functionally close to dioecy.
- Published
- 2017
33. Does inbreeding avoidance maintain gender dimorphism in Wurmbea dioica (Colchicaceae)?
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Ramsey, M., Vaughton, G., and Peakall, R.
- Subjects
- *
INBREEDING , *DIMORPHISM in plants , *MATERIAL plasticity , *REPRODUCTION , *FRUIT development , *INTERSEXUALITY - Abstract
The maintenance of females in gender dimorphic populations requires that they have a fitness advantage to compensate for their loss of male reproductive function. We assess whether inbreeding avoidance provides this advantage in two subdioecious Wurmbea dioica populations by estimating seed production, outcrossing rates and inbreeding depression. Fruiting males produced less than half as many seeds as females, owing to low outcrossing rates and early acting inbreeding depression. Inbreeding coefficients of fruiting males demonstrated that progeny were more inbred than their parents, implying that few selfed progeny reach maturity, as confirmed by inbreeding depression estimates that exceeded 0.85. In a glasshouse experiment, open-pollinated females exhibited a fitness advantage of 3.7 relative to fruiting males, but when we increased fruiting male outcrossing rate, female advantage was only 1.4. This reduced advantage is insufficient to maintain females if nuclear genes control sex. Thus, inbreeding avoidance could maintain females at high frequencies, although this is contingent upon high frequencies of fruiting males, which can be altered by environmentally determined gender plasticity. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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34. Floral size and shape evolution following the transition to gender dimorphism
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Ambika Kamath, Jill S. Miller, and Rachel A. Levin
- Subjects
0106 biological sciences ,Mating type ,Plant Infertility ,Range (biology) ,Dioecy ,Lycium californicum ,Zoology ,Flowers ,Plant Science ,Gynodioecy ,Environment ,010603 evolutionary biology ,01 natural sciences ,Intraspecific competition ,Species Specificity ,Genetics ,Ecology, Evolution, Behavior and Systematics ,Abiotic component ,Sex Characteristics ,Geography ,biology ,Reproduction ,fungi ,food and beverages ,Lycium ,biology.organism_classification ,Biological Evolution ,Sexual dimorphism ,010606 plant biology & botany - Abstract
Premise of the study Floral morphology is expected to evolve following the transition from cosexuality to gender dimorphism in plants, as selection through male and female function becomes dissociated. Specifically, male-biased dimorphism in flower size can arise through selection for larger flowers through male function, selection for smaller flowers through female function, or both. The evolutionary pathway to floral dimorphism can be most effectively reconstructed in species with intraspecific variation in sexual system. We examined the evolution of flower size and shape in Lycium californicum, whose populations are either gender dimorphic with male and female plants, or cosexual with hermaphroditic plants. Methods Floral morphology was characterized in populations spanning the species' complete range. For a subset of the range where cosexual and dimorphic populations are in close proximity, we compared the size and shape of flowers from female and male plants in dimorphic populations to hermaphrodites in cosexual populations, accounting for variation associated with abiotic environmental conditions. Key results The magnitude of flower size dimorphism varied across dimorphic populations. After controlling for environmental variation across cosexual and dimorphic populations, flowers on males were larger than flowers on females and hermaphrodites, whereas flower size did not differ between females and hermaphrodites. Flower shape differences were associated with mating type, sexual system, and environmental variation. Conclusions While abiotic environmental gradients shape both overall flower size and shape, male-biased flower size dimorphism in L. californicum appears to arise through selection for larger flowers in males but not smaller flowers in females.
- Published
- 2017
35. The geometry of gender: hyper-diversification of sexual systems inUrticaL. (Urticaceae)
- Author
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Bernadette Grosse-Veldmann and Maximilian Weigend
- Subjects
0106 biological sciences ,0301 basic medicine ,food.ingredient ,Dioecy ,Urtica ,Geometry ,Gynodioecy ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Urticaceae ,03 medical and health sciences ,030104 developmental biology ,food ,Taxon ,Genus ,Plant reproductive morphology ,Clade ,Ecology, Evolution, Behavior and Systematics - Abstract
Urtica L. (Urticaceae) is generally reported as a genus of monoecious and dioecious taxa. However, the gender information found in the literature does not at all reflect the actual diversity of gender patterns in Urtica. Dioecy appears to be truly absent from Urtica, but otherwise there has been a major diversification in the geometry of gender and no comparable patterns exist in other plant groups. Thus, we here define technical terms for all unique architectural types of monoecy found in Urtica and closely related genera and reconstruct the ancestral gender states in a Bayesian framework. Our studies are based on a near-comprehensive sampling, including 61 of the 63 Urtica species recognized. We report polygamy, two types of gynodioecy and five different architectural types of monoecy. A total of 15 switches appear to have taken place within the genus. Although gender characteristics have diversified strongly, they are relatively conserved within clades. Monoecy is the predominant sexual system within Urtica and specifically basiandrous monoecy (i.e. basal inflorescence branches of each individual male only, apical branches female) is the most widespread type, reported for 11 different clades. In particular, it characterizes the basally branching pilulifera-clade and the sister genus Zhengyia, and may thus represent the plesiomorphic condition for Urtica. Gender distribution and gross morphology appear to evolve largely independently from each other and gender distribution is largely independent of growth habit. However, polygamous taxa are most common amongst rhizomatous perennials (one-third of the taxa).
- Published
- 2017
36. SEXES SHOW DIFFERENTIAL TOLERANCE TO SPITTLEBUG DAMAGE AND CONSEQUENCES OF DAMAGE FOR MULTI-SPECIES INTERACTIONS.
- Author
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Cole, Denise H. and Ashman, Tia-Lynn
- Subjects
- *
CERCOPIDAE , *ANIMAL-plant relationships , *STRAWBERRIES , *SEX in plants , *PLANT evolution , *POLLINATORS - Abstract
Antagonists can play a role in sexual system evolution if tolerance or resistance is sex-dependent. Our understanding of this role will be enhanced by consideration of the effects of antagonists on other plant-animal interactions. This study determined whether the sex morphs of a gynodioecious Fragaria virginiana differ in their susceptibility and response to damage by spittlebugs and whether damage altered pollinator attraction traits or interactions with other antagonists. Tolerance, but not resistance, to spittlebugs differed between the sexes. Generally, spittlebugs were more damaging to hermaphrodites than females, a finding in accord with the hypothesis that the pollen-beating morph is less tolerant of source-damage than the pollen-sterile morph when damage is incurred during flowering. In both sex morphs, spittlebugs reduced inflorescence height, increased petal size, but did not affect the number of open flowers per day, suggesting that the net effect of damage may be to increase pollinator attraction. Spittlebug infestation modified interactions with other antagonists in a sex-dependent manner: spittlebugs reduced attack by bud-clipping weevils in hermaphrodites but increased infection by leaf fungi in females. The complex interactions between plant sex, antagonists, and pollinator attraction documented here emphasize the importance of considering sex-differential multi-species interactions in plant sexual evolution. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
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37. WIND POLLINATION, SEXUAL DIMORPHISM, AND CHANGES IN FLORAL TRAITS OF SCHIEDEA (CARYOPHYLLACEAE).
- Author
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Golonka, Annette M., Sakai, Ann K., and Weller, Stephen G.
- Subjects
- *
CARYOPHYLLACEAE , *POLLINATION , *PLANT fertilization , *CARYOPHYLLALES , *PHANEROGAMS , *PLANT morphology - Abstract
Both changes in sex allocation and pollination mode may promote the separation of sexes in plant populations. Simultaneous evolution of wind pollination and dimorphism has occurred in Schiedea, where species with different female frequencies provide an opportunity to observe the effect of wind pollination on sex allocation and floral morphology. Differences among species in the ratio of anther to ovary volume were not the result of sex allocation trade-offs, but instead resulted from production of vestigial stamens in females; there were no changes in ovary volume in males and hermaphrodites (MH) of dimorphic species. Relative to hermaphroditic species, dimorphic species had more condensed inflorescences, a pattern often associated with wind pollination. Within dimorphic species, MH had longer filament lengths than females, and females had longer stigmas than MHs. These traits are characteristic of wind pollination, but there was no relationship between the degree of sexual dimorphism and female frequency. Ovary volume and ovule number and size had positive phenotypic correlations between females and MH of dimorphic species, making sex specialization more difficult. In dimorphic Schiedea species, selection for wind pollination may have a greater effect on floral traits than trade-offs in allocation between male and female function. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
38. THE SCENT OF A MALE: THE ROLE OF FLORAL VOLATILES IN POLLINATION OF A GENDER DIMORPHIC PLANT.
- Author
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Ashman, Tia-Lynn, Bradburn, Megan, Cole, Denise H., Blaney, Bernard H., and Raguso, Robert A.
- Subjects
- *
PLANT reproduction , *POLLINATORS , *FLORAL products , *PLANT fertilization , *STRAWBERRIES , *INTERSEXUALITY - Abstract
Most flowering plants rely on animal pollinators to transfer male gametes between individuals, and thus a significant problem for gender dimorphic plants is that pollinators often avoid female flowers. Here we show for the first time that one important reason pollinators shun female flowers is because they do not smell like males. We compared emission rates and floral scent composition in a gynodioecious wild strawberry (Fragaria virginiana) where females receive half as many visits by generalist pollinators as conspecific hermaphrodites. We used floral extracts to determine the source of sexually dimorphic odor and pollinator responses. Specifically, we used extracts of whole flowers and specific floral parts in choice tests to determine that pollinators preferred the scent of hermaphrodite flowers over those of females and that this discrimination was due primarily to the scent of hermaphrodite anthers. These data conclusively show that scent can be a major driver of pollinator behavior in gender dimorphic plants. Our results also indicate that scent is an important modulator of pollinator behavior even in a small flowered, weakly scented species visited by generalist pollinators, and not just peculiar to intensely scented, deceptive, or specialized pollination systems. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
39. Evolutionary consequences of gender plasticity in genetically dimorphic breeding systems.
- Author
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Delph, Lynda F. and Wolf, Diana E.
- Subjects
- *
HUMAN genetic variation , *BREEDING , *GENETICS , *ONAGRACEAE , *CARYOPHYLLACEAE - Abstract
A functional view of gender helps evolutionary biologists evaluate the mechanisms underlying breeding-system evolution. Evolutionary pathways from hermaphroditism to dioecy include the intermediate breeding systems of gynodioecy and androdioecy. These pathways start with the invasion of unisexual mutants, females or males, respectively, followed by alteration of the hermaphrodites to allocate more to the sexual function that the unisexuals lack. Eventually, hermaphrodites become unisexual and dioecy has evolved. Some species evolving along these pathways stop short of completing this second step, or even revert back from dioecy. We evaluate the hypothesis that gender plasticity is involved in these transitions to and from dioecy. Evidence from studies of subdioecious species that have evolved along the gynodioecy pathway suggests that gender plasticity occurs and stabilizes subdioecy by lowering the cost of producing seed. Factors influencing species evolving toward androdioecy, or reverting to androdioecy from dioecy, appear to be more varied and include reproductive assurance, herbivory and gender plasticity. In general, gender specialization appears to be favored in resource-poor environments regardless of which pathway is taken to dioecy.New Phytologist(2005)doi: 10.1111/j.1469-8137.2005.01339.x© New Phytologist(2005) [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
40. Pollination by fungus gnats in four species of the genus Mitella (Saxifragaceae).
- Author
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Okuyama, Yudai, Kato, Makoto, and Murakami, Noriaki
- Subjects
- *
MYCETOPHILIDAE , *PLANT fertilization , *PHANEROGAMS , *ROSALES , *POLLINARIA , *FRUIT development - Abstract
The first example of pollination by fungus gnats in the eudicots is reported. The genus Mitella (Saxifragales) is characteristically produces minute, inconspicuous, mostly dull-coloured flowers with linear, sometimes pinnately branched, petals. To understand the function of these characteristic flowers, we studied the pollination biology of four Mitella species with different floral traits and different sexual expression: dioecious M. acerina, gynodioecious M. furusei var. subramosa, and hermaphroditic M. stylosa var. makinoi and M. integripetala. Flower-bagging experiments showed that wind pollination did not occur in the dioecious and gynodioecious species. Two years of observations of flower visitors at six study sites in Japan revealed that the principal pollinators of all four Mitella were specific species of fungus gnats (Mycetophilidae), which landed on the flowers with their long spiny legs settling on the petals. Characteristically, numerous pollen grains were attached to the fungus gnats in specific locations on the body. Although, on average, 1.3–2.6 fungus gnats visited each inflorescence per day, the fruit set of both bisexual and female flowers exceeded 63%. These results suggest that fungus gnats are highly efficient pollinators of Mitella spp., and that Mitella flowers are morphologically adapted to pollination by fungus gnats. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society, 2004, 144, 449–460. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
41. Patterns of fruit production in the subdioecious plant Astilbe biternata (Saxifragaceae).
- Author
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Olson, Matthew S.
- Subjects
- *
FRUIT , *ASTILBE , *PLANT ecology - Abstract
Summary1 Patterns of fruit production in the subdioecious plant Astilbe biternata were used to test whether sex ratio is correlated with relative fruit production by females and males; whether males that produce large inflorescences also produce proportionally more fruit; whether male fruit production is correlated with habitat type; and whether pollen limitation could affect fruiting. 2 Inflorescence length, a good predictor for flower production, was surveyed along with percentage fruit production and sex ratio in 22 populations from throughout the species range, including eight populations where plants were growing in both roadside and understorey habitats. In one population, the percentage fruit production of males and females was assessed in relation to the distance from to the nearest pollen source. 3 There was significant variation in sex ratios among populations, but this was not correlated with relative (female:male) total fruit production. Fruiting males produced smaller inflorescences than either females or non-fruiting males, and within fruiting males, individuals with large inflorescences produced proportionally fewer fruits than those with small inflorescences. The proportion of males that produced fruit was higher in roadside than understorey habitats whereas all females produced fruit in both habitats. Female, but not male, percentage fruit production decreased with distance from the nearest potential pollen source. 4 Allocation patterns to fruiting differed between males and females. Percentage fruit production declined as inflorescence size increased for both males and females. Astilbe biternata males with a genetic propensity to produce fruit might produce smaller inflorescences, or fruit production might be determined by resource availability within the inflorescence after the inflorescence is produced. [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
42. Determinants of sex allocation in a gynodioecious wild strawberry: implications for the evolution of dioecy and sexual dimorphism.
- Author
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Ashman and Ashman, Tia-Lynn
- Subjects
- *
STRAWBERRIES , *INTERSEXUALITY , *SEXUAL dimorphism , *SEX in plants , *PLANTS - Abstract
One evolutionary pathway from plants with combined male and female functions (hermaphroditism) to those with separate sexes (dioecy) involves females coexisting with hermaphrodites (gynodioecy). The research presented here explores sex allocation in Fragaria virginiana (a gynodioecious wild strawberry), within the context of theory on the gynodioecy–dioecy transition. By growing clonally replicated plants in the greenhouse and surveying six populations in situ, I evaluated the effects of plant size, genotype, sexual identity, population of origin and female frequency on sex allocation. I found significant positive effects of plant size on most sex allocation traits studied. In addition to strong sex-specific allocation patterns, I found significant broad-sense heritabilities for all traits, suggesting that plants could respond to selection. Moreover, there was a negative genetic correlation between pollen production and fruit set per flower within hermaphrodites, lending support to a basic assumption of sex allocation theory. On the other hand, several sex allocation traits, namely pollen and ovules per flower in hermaphrodites, were positively genetically correlated, suggesting that they may act to constrain the evolution of sexual dimorphism. Populations differed in the frequency of females, and females were more prevalent on sites with lower soil moisture and where hermaphrodites were least likely to produce fruit, suggesting that females’ seed fitness relative to that of hermaphrodites may be strongly environment-dependent in this species. [ABSTRACT FROM AUTHOR]
- Published
- 1999
- Full Text
- View/download PDF
43. Floral biology and reproductive ecology of Clusia nemorosa ( Clusiaceae) in northeastern Brazil.
- Author
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Lopes, Ariadna and Machado, Isabel
- Abstract
Between March 1993 and May 1995 the floral biology and the phenology of Clusia nemorosa G. Mey. ( Clusiaceae) were studied in two dioecious populations in Pernambuco State, and some observations were made in gynodioecious populations, that were encountered only in Bahia State. The species flowers from June to January/February. The flowers are bowl shaped, and last only one day. The floral reward is resin which is produced by staminodia in all types of flowers. The sex ratio was 1:1 for the studied populations. The pollen viability was approximately 98%. Apomixis was not observed. The rate of fruit set, in hermaphrodite individuals, under natural conditions and the sex ratio of the gynodioecious populations studied suggest that the hermaphrodite individuals may behave as males. Clusia nemorosa is melittophilous and was visited by 16 species of bees. The main pollinators were Euplusia mussitans, E. iopyhrra, Eulaema cingulata, E. nigrita, Euglossa cordata and Euglossa sp. [ABSTRACT FROM AUTHOR]
- Published
- 1998
- Full Text
- View/download PDF
44. Evolution of male sterility mechanisms in gynodioecious and dioecious species of Cirsium ( Cynareae, Compositae).
- Author
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Delannay, Xavier
- Abstract
The genus Cirsium comprises both gynodioecious and dioecious species. The observation of microsporogenesis in female plants of C. montanum, C. oleraceum, C. palustre and C. spinosissimum shows that the male sterility is due to a degeneration of the tapetum. This degeneration occurs more or less early according to the species and, in the light of these results, a scheme of evolution in the male sterility mechanism is proposed. Furthermore, the male sterility mechanism in C. montanum is very similar to that previously found in female plants of the dioecious species C. arvense. This fact enhances the possibility of evolution of the dioecy of C. arvense from the gynodioecy found in other species. According to these results, a general scheme of evolution of sexes in the genus Cirsium is proposed. [ABSTRACT FROM AUTHOR]
- Published
- 1979
- Full Text
- View/download PDF
45. The role of infectious disease in the evolution of females: Evidence from anther-smut disease on a gynodioecious alpine carnation
- Author
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Valentina Carasso, Ian F. Miller, Janis Antonovics, Michael E. Hood, and Emily Bruns
- Subjects
0106 biological sciences ,0301 basic medicine ,Dioecy ,Frequency-dependent selection ,Population ,Zoology ,Gynodioecy ,Flowers ,Biology ,010603 evolutionary biology ,01 natural sciences ,Article ,03 medical and health sciences ,Dianthus ,Genetics ,education ,Pollination ,Ecology, Evolution, Behavior and Systematics ,Plant Diseases ,education.field_of_study ,Basidiomycota ,Mating system ,biology.organism_classification ,Fecundity ,Biological Evolution ,030104 developmental biology ,Fertility ,General Agricultural and Biological Sciences ,Microbotryum ,Sex ratio - Abstract
In flowering plants, the evolution of females is widely hypothesized to be the first step in the evolutionary pathway to separate male and female sexes, or dioecy. Natural enemies have the potential to drive this evolution if they preferentially attack hermaphrodites over females. We studied sex-based differences in exposure to anther-smut (Microbotryum), a sterilizing pollinator-transmitted disease, in Dianthus pavonius, a gynodioecious perennial herb. We found that within a heavily diseased population, females consistently had lower levels of Microbotryum spore deposition relative to hermaphrodites and that this difference was driven by rapid floral closing in females following successful pollination. We further show that this protective closing behavior is frequency-dependent; females close faster when they are rare. These results indicate that anther-smut disease is an important source of selection for females, especially since we found in a common garden experiment no evidence that females have any inherent fecundity advantages over hermaphrodites. Finally, we show that among populations, those where anther-smut is present have a significantly higher frequency of females than those where the disease is absent. Taken together our results indicate that anther-smut disease is likely an important biotic factor driving the evolution and maintenance of females in this gynodioecious species.
- Published
- 2018
46. Life-history trade-offs promote the evolution of dioecy
- Author
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Marcel E. Dorken and Wendy E. Van Drunen
- Subjects
0106 biological sciences ,Resource (biology) ,Models, Genetic ,Dioecy ,Reproduction ,Androdioecy ,Gynodioecy ,Biology ,Plants ,Indeterminate growth ,010603 evolutionary biology ,01 natural sciences ,Biological Evolution ,Sexual reproduction ,Evolutionarily stable strategy ,Phenotype ,Evolutionary biology ,Genetic Fitness ,Life History Traits ,Ecology, Evolution, Behavior and Systematics ,Sex allocation ,Plant Physiological Phenomena ,010606 plant biology & botany - 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.
- Published
- 2018
47. The Evolution of Sexual Systems in Animals
- Author
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Janet L. Leonard
- Subjects
Phenotypic plasticity ,Sequential hermaphroditism ,Evolutionary biology ,Dioecy ,Androdioecy ,Environmental sex determination ,Gynodioecy ,Biology ,biology.organism_classification ,Sex allocation ,Sexual reproduction - Abstract
A sexual system is the pattern of gender allocation that characterizes a species. In both plants and animals, simultaneous hermaphroditism and dioecy are the most common and stable sexual systems. Other sexual systems, sequential hermaphroditism, environmental sex determination, gynodioecy, androdioecy, and trioecy, are less stable and less widely distributed. The boundaries between these sexual systems are not always clear, largely because phenotypic plasticity is an important and prevalent component of sexual reproduction. One can view sexual systems in the Metazoa as lying on a gradient of phenotypic plasticity from simultaneous hermaphroditism at the high end through sequential hermaphroditism and environmental sex determination to genetically determined dioecy, which has a minimum of phenotypic plasticity in sex allocation. The distribution of sexual systems across the Metazoa gave rise to Williams’ Paradox, which states that the pattern is best explained by phylogeny rather than sex allocation theory. Today, sex allocation theory seems to explain transitions in sexual system in those taxa with labile sexual systems adequately. However, the stability of either dioecy or simultaneous hermaphroditism in many major taxa, such as phyla and classes, remains inexplicable. While in angiosperms the evolutionary pathways between dioecy and simultaneous hermaphroditism are fairly well understood, a plausible evolutionary sequence for transitions between dioecy and simultaneous hermaphroditism in animals has been lacking. Here, the proposal is made that it is useful to view transitions from simultaneous hermaphroditism to dioecy as the result of selection for decreasing phenotypic plasticity and vice versa. A scenario for evolutionary transitions between simultaneous hermaphroditism and dioecy, in animals, through intermediate stages of sequential hermaphroditism and environmental sex determination is proposed.
- Published
- 2018
48. Estimating divergence times and ancestral breeding systems in Ficus and Moraceae
- Author
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Qian Zhang, Stefan A. Little, Renske E. Onstein, and Hervé Sauquet
- Subjects
0106 biological sciences ,0301 basic medicine ,biology ,Phylogenetic tree ,Dioecy ,Reproduction ,Androdioecy ,Ficus ,Plant Science ,Gynodioecy ,Original Articles ,Macroevolution ,Crown group ,Moraceae ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Biological Evolution ,Evolution, Molecular ,03 medical and health sciences ,030104 developmental biology ,Evolutionary biology - Abstract
Background and aims Although dioecy, which characterizes only 6 % of angiosperm species, has been considered an evolutionary dead end, recent studies have demonstrated that this is not necessarily the case. Moraceae (40 genera, 1100 spp., including Ficus, 750 spp.) are particularly diverse in breeding systems (including monoecy, gynodioecy, androdioecy and dioecy) and thus represent a model clade to study macroevolution of dioecy. Methods Ancestral breeding systems of Ficus and Moraceae were inferred. To do so, a new dated phylogenetic tree of Ficus and Moraceae was first reconstructed by combining a revised 12-fossil calibration set and a densely sampled molecular data set of eight markers and 320 species. Breeding system evolution was then reconstructed using both parsimony and model-based (maximum likelihood and Bayesian) approaches with this new time scale. Key results The crown group ages of Ficus and Moraceae were estimated in the Eocene (40.6-55.9 Ma) and Late Cretaceous (73.2-84.7 Ma), respectively. Strong support was found for ancestral dioecy in Moraceae. Although the ancestral state of Ficus remained particularly sensitive to model selection, the results show that monoecy and gynodioecy evolved from dioecy in Moraceae, and suggest that gynodioecy probably evolved from monoecy in Ficus. Conclusions Dioecy was found not to be an evolutionary dead end in Moraceae. This study provides a new time scale for the phylogeny and a new framework of breeding system evolution in Ficus and Moraceae.
- Published
- 2017
49. Sexual allocation in the gynodioecious species Cyananthus macrocalyx (Campanulaceae) at high elevations in the Sino-Himalaya Mountains
- Author
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Hang Sun, Yang Niu, Jianguo Chen, and Yang Yang
- Subjects
0106 biological sciences ,education.field_of_study ,Biomass (ecology) ,Gynoecium ,Ecology ,Dioecy ,Population ,food and beverages ,Plant Science ,Gynodioecy ,Biology ,medicine.disease_cause ,010603 evolutionary biology ,01 natural sciences ,Pollinator ,Pollen ,medicine ,education ,Ecology, Evolution, Behavior and Systematics ,Sex allocation ,010606 plant biology & botany ,Demography - Abstract
Sexual allocation pattern is considered highly relevant for the maintenance of females in the process of evolution from hermaphrodites to dioecy. Theoretical and empirical studies predict that gynodioecious plants should invest more resources in male function under harsher environments and/or when female frequency is higher; and that there are trade-offs between male and female function. We studied sexual allocation pattern in the gynodioecious species Cyananthus macrocalyx in two populations in SW China. The results showed that although the total flower mass in hermaphrodites was significantly higher than that in females, females and hermaphrodites allocated similar biomass to female function (pistil biomass). As a consequence, females allocated relatively more resource to female function, while hermaphrodites allocated relatively more resource to pollinator attractiveness. There was no difference in total flower mass, pistil mass, and pollen production in hermaphrodites between the two populations. These results suggest that the females compensate for the disadvantage of lacking male function by allocating relatively more resource to female function, while hermaphrodites gain fitness through both male and female functions. This study supports the idea that if females are to be maintained in a gynodioecious population, they must allocate more resource to female functions than is necessary for hermaphrodites. However, our results were in contrast to those of previous studies, in that trade-offs between male and female functions and male-biased allocation under high female frequency were not observed. This study adds to the body of research on plant sexual allocation, and for that it is, at least at some aspects, contrary to previous statements, it could be helpful for advancing the theoretical predictions in the future.
- Published
- 2015
50. Intraspecific variation in gender strategies in Lycium (Solanaceae): Associations with ploidy and changes in floral form following the evolution of gender dimorphism
- Author
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Caitlin M. Blank, Rachel A. Levin, and Jill S. Miller
- Subjects
Ecology ,Reproduction ,Dioecy ,Genetic Variation ,Flowers ,Plant Science ,Gynodioecy ,Lycium ,Biology ,biology.organism_classification ,Mating system ,Biological Evolution ,Hawaii ,Intraspecific competition ,Polyploidy ,Sexual dimorphism ,Phylogeography ,Evolutionary biology ,Genetics ,Ploidy ,Mexico ,Ecology, Evolution, Behavior and Systematics - Abstract
Premise of the study: An association between polyploidy and gender dimorphism has been noted in several plant lineages. Whereas the majority of Lycium species are diploid and have hermaphroditic fl owers in cosexual populations, gender dimorphism (gynodioecy, dioecy) has been shown to be uniformly associated with polyploidy in previous studies. Preliminary fi eld observations suggested that some populations of Lycium carolinianum were dimorphic, providing a test of this association. Methods: We assessed sexual systems and cytotype variation (to infer ploidy) across 17 populations of L. carolinianum . Comparison of fl owers in cosexual and dimorphic populations were used to infer changes in reproductive morphology associated with the evolution of gynodioecy. Key results: The majority of populations were cosexual in gender expression, but dimorphism was present in the Yucat a�n and in some populations in Hawaii. Populations varied in ploidy and were either diploid or tetraploid. Floral sexual dimorphism was present in all gynodioecious populations, though the magnitude differed and was cryptic in some cases. Our results are consistent with the hypothesis that following the evolution of gynodioecy, fl owers on hermaphrodites increased in size. Conclusions: Dimorphic sexual systems have likely evolved convergently in L. carolinianum . In contrast to previous studies, dimorphism is not perfectly associated with polyploidy. Although our sample from the Yucat a�n was both tetraploid and dimorphic, all populations in Hawaii were diploid regardless of sexual system. Ongoing phylogeographic and mating system studies will contribute to our understanding of reproductive evolution in this widespread, polymorphic species.
- Published
- 2014
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