Comparative Analyses of Sex-Ratio Variation in Dioecious Flowering Plants

Field, David L.; Pickup, Melinda; Barrett, Spencer C. H.

doi:10.1111/evo.12001

Cited by 128 publications

(146 citation statements)

References 60 publications

(98 reference statements)

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“…These effects could be especially important in clonal species in which cumulative episodes of sexual reproduction may result in sexual dimorphism in rates of clonal reproduction and the number of flowering ramets per clone (39,40). Interestingly, in the comparative analysis conducted by Field et al (37), the opposite pattern was found in both the species level and phylogenetically controlled analyses. Clonality was associated with female-biased rather than male-biased sex ratios, particularly in herbaceous species.…”

Section: Clonality In Plants With Sexual Polymorphismsmentioning

confidence: 96%

“…The widespread occurrence in dioecious species of both sexual and clonal reproduction provides an opportunity to investigate how these two reproductive modes interact to influence sex ratios and fitness in plant populations. The classical theoretical arguments of Düsing (34), and Fisher (35) predict 1:1 sex ratios in dioecious populations, but recent comparative studies of plant populations indicate considerable variation in sex ratios both within and among species (36,37). Determining the ecological, demographic, and genetic factors responsible for this variation is an important problem in evolutionary biology.…”

Section: Clonality In Plants With Sexual Polymorphismsmentioning

confidence: 99%

“…Thus, unlike many animal studies, flowering or "operational" sex ratios are reported in most studies, and there are very few estimates of primary sex ratios in plant populations. A comparative analysis of sex ratios in 243 angiosperm species representing 61 families revealed that male-biased sex ratios were twice as common as female-biased sex ratios, with male bias evident in 61% of the families surveyed (37). The common occurrence of male-biased sex ratios may be, in part, associated with differences in the costs of reproduction between the sexes.…”

Section: Clonality In Plants With Sexual Polymorphismsmentioning

confidence: 99%

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Influences of clonality on plant sexual reproduction

Barrett

2015

Proc. Natl. Acad. Sci. U.S.A.

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204

183

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Flowering plants possess an unrivaled diversity of mechanisms for achieving sexual and asexual reproduction, often simultaneously. The commonest type of asexual reproduction is clonal growth (vegetative propagation) in which parental genotypes (genets) produce vegetative modules (ramets) that are capable of independent growth, reproduction, and often dispersal. Clonal growth leads to an expansion in the size of genets and increased fitness because large floral displays increase fertility and opportunities for outcrossing. Moreover, the clonal dispersal of vegetative propagules can assist "mate finding," particularly in aquatic plants. However, there are ecological circumstances in which functional antagonism between sexual and asexual reproductive modes can negatively affect the fitness of clonal plants. Populations of heterostylous and dioecious species have a small number of mating groups (two or three), which should occur at equal frequency in equilibrium populations. Extensive clonal growth and vegetative dispersal can disrupt the functioning of these sexual polymorphisms, resulting in biased morph ratios and populations with a single mating group, with consequences for fertility and mating. In populations in which clonal propagation predominates, mutations reducing fertility may lead to sexual dysfunction and even the loss of sex. Recent evidence suggests that somatic mutations can play a significant role in influencing fitness in clonal plants and may also help explain the occurrence of genetic diversity in sterile clonal populations. Highly polymorphic genetic markers offer outstanding opportunities for gaining novel insights into functional interactions between sexual and clonal reproduction in flowering plants.clonal growth | dioecy | geitonogamy | heterostyly | somatic mutations

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Section: Clonality In Plants With Sexual Polymorphismsmentioning

confidence: 96%

Section: Clonality In Plants With Sexual Polymorphismsmentioning

confidence: 99%

Section: Clonality In Plants With Sexual Polymorphismsmentioning

confidence: 99%

See 1 more Smart Citation

Influences of clonality on plant sexual reproduction

Barrett

2015

Proc. Natl. Acad. Sci. U.S.A.

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204

183

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“…In reality, many dioecious plants exhibit deviations from the 1:1 sex ratios for a number of reasons. In a recent review, Field et al (2013) showed that male bias is strongly associated with longevity, biotic seed dispersal and production of fleshly fruits. On the contrary, female bias is associated with abiotic pollen dispersal and the presence of sex chromosomes.…”

Section: Introductionmentioning

confidence: 99%

Relative strength of fine-scale spatial genetic structure in paternally vs biparentally inherited DNA in a dioecious plant depends on both sex proportions and pollen-to-seed dispersal ratio

et al. 2016

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In plants, the spatial genetic structure (SGS) is shaped mainly by gene dispersal and effective population density. Among additional factors, the mode of DNA inheritance and dioecy influence SGS. However, their joint impact on SGS remains unclear, especially in the case of paternally inherited DNA. Using theoretical approximations and computer simulations, here we showed that the relative intensity of SGS measured in paternally and biparentally inherited DNA in a dioecious plant population depends on both the proportion of males and the pollen-to-seed dispersal ratio. As long as males do not prevail in a population, SGS is more intense in paternally than biparentally inherited DNA. When males prevail, the intensity of SGS in paternally vs biparentally inherited DNA depends on the compound effect of sex proportions and the pollen-to-seed dispersal ratio. To empirically validate our predictions, we used the case of Taxus baccata, a dioecious European tree. First, we showed that mitochondrial DNA (mtDNA) in T. baccata is predominantly (98%) paternally inherited. Subsequently, using nuclear DNA (nuDNA) and mitochondrial microsatellite data, we compared the fine-scale SGS intensity at both marker types in two natural populations. The population with equal sex proportions showed stronger SGS in mtDNA than in nuDNA. On the other hand, we found lower SGS intensity in mtDNA than in nuDNA in the population with 67% males. Thus, the empirical results provided good support for the theoretical predictions, suggesting that knowledge about SGS in paternally vs biparentally inherited DNA may provide insight into effective sex proportions within dioecious populations.

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“…The preponderance of archegoniate gametophytes in dioecious bryophytes contrasts with a preponderance of staminate sporophytes in dioecious angiosperms (with interesting exceptions) [44,45]. A factor that may contribute to female biases being more common in bryophytes than in angiosperms is that pollen can be transferred to ovules over much greater distances than sperm can be transferred to archegonia.…”

Section: (A) Female Advantagementioning

confidence: 98%

Living together and living apart: the sexual lives of bryophytes

Haig¹

2016

Phil. Trans. R. Soc. B

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One contribution of 15 to a theme issue 'Weird sex: the underappreciated diversity of sexual reproduction'. Haploid gametophytes of bryophytes spread by clonal growth but mate locally, within an area defined by the range of sperm movement. Rarity of establishment from spores or vegetative competition can result in unisexual populations unable to reproduce sexually. Females typically outcompete males, probably because females expend fewer resources than males on the production of gametes. Extreme sexual dimorphism-tiny males growing as epiphytes on much larger females-has evolved many times. Haploid selfing is common in bryophytes with bisexual gametophytes, and results in completely homozygous sporophytes. Spores from these sporophytes recapitulate the genotype of their single haploid parent. This process can be considered analogous to 'asexual' reproduction with 'sexual' reproduction occurring after rare outcrossing between haploid parents. Ferns also produce bisexual haploid gametophytes but, unlike bryophytes, haploid outcrossing predominates over haploid selfing. This difference is probably related to clonal growth and vegetative competition occurring in the haploid but not the diploid phase in bryophytes, but the reverse in ferns. Ferns are thereby subject to stronger inbreeding depression than bryophytes.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'. Sexual lives of bryophytesAnimal life histories are characterized by multicellular diploid individuals that produce haploid gametes by meiosis. Gametes are the only haploid cells of such life cycles. The life histories of bryophytes (mosses, liverworts and hornworts) are fundamentally different. Multicellular haploid gametophytes (gameteproducing plants) produce gametes by mitosis. The fertilization of an ovum by a sperm produces a zygote that develops into a short-lived multicellular diploid sporophyte (spore-producing plant) that grows attached to the maternal gametophyte on which it depends for nutrients. Sporophytes produce haploid spores by meiosis that germinate to produce new gametophytes (figure 1). Mating is restricted to the distance over which sperm can find ova, usually in the millimetre to centimetre range [1]. Clonal expansion occurs via vegetative spread of gametophytes into neighbouring space and production of gemmae (asexual propagules) that disperse gametophytic clones to new sites [2].Gametophytes of dioecious bryophytes are unisexual, producing either eggs or sperm, but not both. Males and females compete for space but require close proximity for sexual reproduction. By contrast, gametophytes of monoecious bryophytes are bisexual, able to produce both eggs and sperm. A bisexual gametophyte that fertilizes its own eggs engenders homozygous sporophytes all of whose spores are genetically identical (excepting meiotic errors and postzygotic mutations). Roughly 70% of liverworts, 60% of mosses and 40% of hornworts are dioecious [3]. Bryophyte life cycles are not only fascinating in th...

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Comparative Analyses of Sex-Ratio Variation in Dioecious Flowering Plants

Abstract: Dioecy (separate female and male individuals) is a relatively uncommon sexual system in angiosperms (∼6% of species), but has evolved independently from hermaphroditism at least 100

Cited by 128 publications

References 60 publications

Influences of clonality on plant sexual reproduction

Influences of clonality on plant sexual reproduction

Relative strength of fine-scale spatial genetic structure in paternally vs biparentally inherited DNA in a dioecious plant depends on both sex proportions and pollen-to-seed dispersal ratio

Living together and living apart: the sexual lives of bryophytes

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