scholarly journals Polyploidization and sexual dimorphism of floral traits in a subdioecious population of Dasiphora glabra

2020 ◽  
Author(s):  
Lin-Lin Wang ◽  
Na-Cai Yang ◽  
Min-Yu Chen ◽  
Yong-Ping Yang ◽  
Yuan-Wen Duan
Keyword(s):  
Sexual Dimorphism ◽  
Genome Size ◽  
Seed Production ◽  
Flower Size ◽  
Floral Traits ◽  
Pollen Transfer ◽  
Pollinator Visitation ◽  
Dioecious Plants ◽  
Male And Female ◽  
Male Flowers

Abstract Aims Sexual dimorphism is a common trait in plants with sex separation, which could influence female and male functions differently. In a subdioecious population of Dasiphora glabra on the Qinghai-Tibet Plateau, we investigated sexual dimorphism of floral traits and their effects on pollinator visitation, pollen flow and seed production. We also examined differences in genome size of hermaphroditic and dioecious plants. Methods We examined sexual dimorphism in flower number, flower size, and pollen and ovule production in a subdioecious population of D. glabra. We compared pollinator visitation, pollen dispersal, and seed production between sexes. We also examined the genome size of three sex morphs using flow cytometry. Important findings The number of hermaphroditic plants was significantly more than that of male and female plants, and dioecious plants accounted for ca. 40% in the study population. Hermaphroditic plants produced significantly more flowers than male and female plants. Flower size of male flowers was significantly larger than that of female and hermaphroditic flowers. Male flowers did not produce more pollen grains than hermaphroditic flowers, but female flowers produced more ovules than hermaphroditic flowers. Flies were the most frequent flower visitors and preferred large flowers, but their movements between flowers did not show any preference to large flowers. Simulated pollen flows suggested that effective pollen transfer was generally low for both hermaphroditic and male flowers, corresponding to the low seed set of naturally pollinated flowers. DNA contents of male and female plants were ca. four times than those of hermaphroditic plants. These results suggest male and female individuals have undergone polyploidy events and thus are not compatible with hermaphroditic individuals. Sexual dimorphism in floral traits in relation to pollination of dioicous plants might show an advantage in female and male functions, but this advantage is masked largely by low effectiveness of pollen transfer.

scholarly journals Active pollination favours sexual dimorphism in floral scent

2013 ◽  
Vol 280 (1772) ◽  
pp. 20132280 ◽  
Author(s):  
Tomoko Okamoto ◽  
Atsushi Kawakita ◽  
Ryutaro Goto ◽  
Glenn P. Svensson ◽  
Makoto Kato
Keyword(s):  
Sexual Dimorphism ◽  
Floral Scent ◽  
Choice Test ◽  
Sexually Dimorphic ◽  
Pollen Transfer ◽  
Male And Female ◽  
Unisexual Flowers ◽  
Male Flowers ◽  
Species Specific ◽  
Female Flowers

Zoophilous flowers often transmit olfactory signals to attract pollinators. In plants with unisexual flowers, such signals are usually similar between the sexes because attraction of the same animal to both male and female flowers is essential for conspecific pollen transfer. Here, we present a remarkable example of sexual dimorphism in floral signal observed in reproductively highly specialized clades of the tribe Phyllantheae (Phyllanthaceae). These plants are pollinated by species-specific, seed-parasitic Epicephala moths (Gracillariidae) that actively collect pollen from male flowers and pollinate the female flowers in which they oviposit; by doing so, they ensure seeds for their offspring. We found that Epicephala -pollinated Phyllanthaceae plants consistently exhibit major qualitative differences in scent between male and female flowers, often involving compounds derived from different biosynthetic pathways. In a choice test, mated female Epicephala moths preferred the scent of male flowers over that of female flowers, suggesting that male floral scent elicits pollen-collecting behaviour. Epicephala pollination evolved multiple times in Phyllantheae, at least thrice accompanied by transition from sexual monomorphism to dimorphism in floral scent. This is the first example in which sexually dimorphic floral scent has evolved to signal an alternative reward provided by each sex, provoking the pollinator's legitimate altruistic behaviour.

scholarly journals Temporal dynamics of sexual dimorphism in a dioecious species

2020 ◽  
Vol 126 (3) ◽  
pp. 471-480
Author(s):  
L Moquet ◽  
L Lateur ◽  
A-L Jacquemart ◽  
I De Cauwer ◽  
M Dufay
Keyword(s):  
Sexual Dimorphism ◽  
Plant Species ◽  
Temporal Dynamics ◽  
Flower Size ◽  
Flowering Plant ◽  
Floral Traits ◽  
Flower Number ◽  
Pollinator Behaviour ◽  
Flower Production ◽  
Flowering Season

Abstract Background and Aims Sexual dimorphism for floral traits is common in dioecious plant species. Beyond its significance for understanding how selection acts on plant traits through male vs. female reproductive function, sexual dimorphism has also been proposed as a possible risky characteristic for insect-pollinated plants, as it could drive pollinators to forage mostly on male plants. However, even though most flowering plant species spread their flowering across several weeks or months, the temporal variation of floral phenotypes and sexual dimorphism have rarely been investigated. Methods We performed a survey of male and female plants from the dioecious generalist-pollinated Silene dioica (Caryophyllaceae) in a common garden experiment, over two consecutive flowering seasons. Flower number and floral size were measured each week, as well as pollen quantity and viability in male plants. Key Results Sexual dimorphism was found for all investigated floral traits, with males showing an overall higher investment in flower production and flower size. Males and females showed a similar temporal decline in flower size. The temporal dynamics of daily flower number differed between sexes, with males showing a peak in the middle of their flowering season, whereas flower production by females was quite stable over time. At the scale of the experimental population, both individual and floral sex ratios appeared to vary across the flowering season. Moreover, because the onset of flowering varied among plants, the magnitude of sexual dimorphism in floral size also fluctuated strongly through time. Conclusions Capturing male/female differences with only one temporal measurement per population may not be informative. This opens stimulating questions about how pollinator behaviour and resulting pollination efficiency may vary across the flowering season.

scholarly journals Reproductive biology of Amasonia obovata Gleason (Laminaceae)

2014 ◽  
Vol 44 (4) ◽  
pp. 427-434 ◽  
Author(s):  
Thays de Assis Schvinn ◽  
Anderson Fernandes de Miranda ◽  
Celice Alexandre Silva
Keyword(s):  
Reproductive Success ◽  
Seed Production ◽  
Reproductive Biology ◽  
High Frequency ◽  
Rainy Season ◽  
Mating Strategies ◽  
Floral Traits ◽  
Mato Grosso ◽  
Male And Female ◽  
Self Fertilization

Floral mechanisms that ensure seed production via autogamy are more likely to occur in species growing in environments where pollination is scarce. Amasonia obovata was studied in the State of Mato Grosso-Brazil, from 2009 to 2012, to analyze the morphological and reproductive characteristics, aside from investigating the association of the reproductive success with the pollinator frequency and identity. The flowering and fruiting of A. obovata was concentrated in a period of five months during the rainy season. The dichogamy in flowers of A. obovata is not clearly defined, since the sexual functions were overlapped in the male and female phases. The species is self-compatible and not apomictic. The fruiting percentage obtained by hand self-pollination did not differ from cross-breeding (F = 0.74, P =0.39). In the observations from 2010 to 2012, a hummingbird (Thalurania furcata) legitimate visited 20-100% of the flowers in the male and female phases on different A. obovata plants. Due to the high frequency, this hummingbird was considered the single potential pollinator of the species. These findings show that a limited availability of pollinators may select for floral traits and plant mating strategies that lead to a system of self-fertilization.

Pollinator visitation, pollen limitation, and selection on flower size through female function in contrasting habitats within a population of Campanula persicifolia

2006 ◽  
Vol 84 (3) ◽  
pp. 412-420 ◽  
Author(s):  
Vivi-Irèn Hansen ◽  
Ørjan Totland
Keyword(s):  
Seed Production ◽  
Structural Equation ◽  
Pollen Limitation ◽  
Phenotypic Selection ◽  
Flower Size ◽  
Pollinator Visitation ◽  
Pollinator Attraction ◽  
Female Function ◽  
Flower Visitation ◽  
Visitation Rates

We looked at whether flower visitation rates, pollen limitation on seed production, and phenotypic selection on flower size through female function varied across a sharp gradient in light intensity (open meadow vs. forest) within a population of the perennial plant Campanula persicifolia L. (Campanulaceae). Flower visitation rates of putative pollinators were similar in both habitats. Seed number per fruit was strongly pollen limited, with no difference in the magnitude of pollen limitation between the two habitats. This strong pollen limitation set the basis for significant phenotypic selection, through female function, on a trait that probably is important for pollinator attraction: flower size. This was revealed by path analysis and structural equation modelling. The lack of difference in pollen limitation on seed production in the two habitats may be explained by the similarity in flower visitation rates in the two habitats. Moreover, the similarity in pollen limitation in the two habitats probably resulted in a similar magnitude and direction of selection on flower size through female function. Our results suggest that pollen limitation and selection through female function may vary little across space within a popualtion despite large variation in the environmental conditions experienced by plants.

scholarly journals Sex-biased genes and metabolites explain morphologically sexual dimorphism and reproductive costs in Salix paraplesia catkins

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Zeyu Cai ◽  
Congcong Yang ◽  
Jun Liao ◽  
Haifeng Song ◽  
Sheng Zhang
Keyword(s):  
Gene Expression ◽  
Energy Consumption ◽  
Sexual Dimorphism ◽  
Molecular Mechanisms ◽  
Temporal Dynamics ◽  
Biomass Accumulation ◽  
Reproductive Costs ◽  
Male And Female ◽  
Unisexual Flowers ◽  
Male Flowers

AbstractDioecious species evolved from species with monomorphic sex systems in order to achieve overall fitness gains by separating male and female functions. As reproductive organs, unisexual flowers have different reproductive roles and exhibit conspicuous sexual dimorphism. To date, little is known about the temporal variations in and molecular mechanisms underlying the morphology and reproductive costs of dioecious flowers. We investigated male and female flowers of Salix paraplesia in three flowering stages before pollination (the early, blooming and late stages) via transcriptional sequencing as well as metabolite content and phenotypic analysis. We found that a large number of sex-biased genes, rather than sex-limited genes, were responsible for sexual dimorphism in S. paraplesia flowers and that the variation in gene expression in male flowers intensified this situation throughout flower development. The temporal dynamics of sex-biased genes derived from changes in reproductive function during the different flowering stages. Sexually differentiated metabolites related to respiration and flavonoid biosynthesis exhibited the same bias directions as the sex-biased genes. These sex-biased genes were involved mainly in signal transduction, photosynthesis, respiration, cell proliferation, phytochrome biosynthesis, and phenol metabolism; therefore, they resulted in more biomass accumulation and higher energy consumption in male catkins. Our results indicated that sex-biased gene expression in S. paraplesia flowers is associated with different reproductive investments in unisexual flowers; male flowers require a greater reproductive investment to meet their higher biomass accumulation and energy consumption needs.

Sexual dimorphism in floral traits of gynodioecious Lobelia siphilitica (Lobeliaceae) is consistent across populations

Botany ◽  
2012 ◽  
Vol 90 (12) ◽  
pp. 1245-1251 ◽  
Author(s):  
Christina M. Caruso
Keyword(s):  
Sexual Dimorphism ◽  
Genetic Correlations ◽  
Species Range ◽  
Flower Size ◽  
Floral Traits ◽  
Flower Number ◽  
Gender Dimorphism

In angiosperms, the evolution of gender dimorphism is often correlated with the evolution of sexual dimorphism in floral traits. The magnitude of sexual dimorphism will reflect both sex-specific selection and constraints on evolution in response to this selection. If the evolution of sexual dimorphism is constrained by genetic correlations, then trait means are predicted to evolve more quickly than the magnitude of sexual dimorphism in the same traits. To test whether mean floral traits evolve more quickly than sexual dimorphism in these traits, I measured flower size and flower number of gynodioecious Lobelia siphilitica L. from 10–14 populations across the species’ range. Females produced more flowers than hermaphrodites, but neither mean flower number nor the magnitude of dimorphism in flower number varied among populations. Pistillate flowers were smaller than perfect flowers, and mean flower size varied among populations. However, the magnitude of dimorphism in flower size did not vary. My results suggest that the evolution of sexual dimorphism in flower size, but not necessarily flower number, could be constrained by within- or between-sex genetic correlations in L. siphilitica.

scholarly journals Sexual dimorphism in floral scents of the neotropical orchid Catasetum arietinum and its possible ecological and evolutionary significance

AoB Plants ◽  
2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Katharina Brandt ◽  
Isabel Cristina Machado ◽  
Daniela Maria do Amaral Ferraz Navarro ◽  
Stefan Dötterl ◽  
Manfred Ayasse ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Chemical Composition ◽  
Floral Scent ◽  
Evolutionary Significance ◽  
Male And Female ◽  
Floral Scents ◽  
First Case ◽  
Male Flowers ◽  
Euglossine Bee ◽  
Female Flowers

Abstract Dioecy in angiosperms is often associated with sexual dimorphism in floral traits other than the sexual organs. Species of the neotropical orchid genus Catasetum produce unisexual flowers characterized by a remarkable morphological sexual dimorphism. Catasetum species emit strong floral perfumes that act as both signal and reward for male euglossine bee pollinators. Although the role of floral perfumes of Catasetum in attracting euglossine pollinators is well investigated, little is known about whether perfumes differ between floral sexes and, if they do, whether this chemical dimorphism influences the pollination ecology of the plants. Taking Catasetum arietinum as a model species, our aim was to observe the behaviour of pollinators on male and female flowers and to compare scent properties (i.e. chemical composition, total amount and temporal fluctuation) of male and female flowers. Floral scent samples were collected by using dynamic headspace methods and were analysed via gas chromatography coupled with mass spectroscopy (GC-MS). Catasetum arietinum is pollinated by males of two Euglossa species (i.e. E. nanomelanotricha and E. securigera). Bees approached male and female inflorescences of C. arietinum in similar proportions but landed significantly more often and spent more time on female flowers, which emitted more scent than male flowers. Furthermore, the amount of scent emitted varied across the different times of sampling, corresponding to the pattern of the diel foraging activity of pollinating bees on male and female flowers. The chemical composition of scents differed significantly between sexes. The two major compounds (Z)-methyl-p-methoxycinnamate and (E)-geranyl geraniol contributed most to this difference. This is the first case of sexual dimorphism reported in orchid floral perfumes. We discuss the influence of sex-specific floral scents on the behaviour of euglossine pollinators and offer new insights into the ecological and evolutionary significance of divergence in floral scents among dioecious plants.

scholarly journals Comparative Analysis of Volatile Compounds in Flowers of Different Actinidia Species

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1675
Author(s):  
Agnieszka Stasiak ◽  
Piotr Latocha
Keyword(s):  
Volatile Compounds ◽  
Female Flower ◽  
Dioecious Plants ◽  
Male And Female ◽  
Flower Volatiles ◽  
Or Groups ◽  
Pollinating Insects ◽  
Male Flowers ◽  
Actinidia Spp ◽  
Female Flowers

Among the actinidia genus (Actinidia spp.) native to China, few species are grown commercially for their edible and healthy fruits. As they are dioecious plants, a lot of interest is paid to effective pollination and to insects as the most efficient pollinators. In this study we have concentrated on the composition of volatile compounds in male flowers of four different actinidia species (A. chinensis var. deliciosa, A. arguta, A. kolomikta and A. polygama) and on the diversity between male and female flower volatiles for the two most winter-hardy species (A. arguta and A. kolomikta) with growing commercial value. Analyses were provided using gas chromatography with mass spectrometry (GC-MS). In total, 120 compounds were found in 15 actinidia genotypes. However, the number of identified compounds varied between species. Different main compounds or groups of volatile compounds characterised flowers of every species. Smaller differences were observed between male and female flowers of the same species. Our results suggest that actinidia flowers could be attractive to pollinating insects.

scholarly journals Going to great lengths: selection for long corolla tubes in an extremely specialized bat–flower mutualism

2009 ◽  
Vol 276 (1665) ◽  
pp. 2147-2152 ◽  
Author(s):  
Nathan Muchhala ◽  
James D. Thomson
Keyword(s):  
Pollen Grains ◽  
Pollen Transfer ◽  
Male And Female ◽  
Selective Pressures ◽  
Flight Cage ◽  
Visit Duration ◽  
Selection For ◽  
Male Flowers ◽  
Tongue Length ◽  
Female Flowers

In a hypothesis that has remained controversial since its inception, Darwin suggested that long-tubed flowers and long-tongued pollinators evolved together in a coevolutionary race, with each selecting for increasing length in the other. Although the selective pressures that flowers impose on tongue length are relatively straightforward, in that longer tongues allow access to more nectar, selective pressures that pollinators impose on flower length are less clear. Here, we test for such selective pressures in the highly specialized mutualism between the nectar bat Anoura fistulata , which can extend its tongue twice as far as other nectar bats, and Centropogon nigricans , which has flowers of a similar length (8–9 cm). We used flight cage experiments to examine the effects of artificially manipulated flower lengths on (i) bat behaviour and (ii) pollen transfer. Increased length produced longer visits, but did not affect the force bats applied during visits. In the second experiment, flower length increased both the male and female components of flower function: long male flowers delivered more pollen grains and long female flowers received more pollen grains. However, pollen transfer was not correlated with visit duration, so the mechanism behind differences in pollen transfer remains unclear. By demonstrating that bats select for increasing flower length, these results are consistent with the hypothesis that A. fistulata evolved its remarkable tongue in a coevolutionary race with long-tubed flowers similar to that envisioned by Darwin.

Reproductive ecology and the effect of altitude on sex ratios in the dioecious herb Aciphylla simplicifolia (Apiaceae)

2002 ◽  
Vol 50 (3) ◽  
pp. 289 ◽  
Author(s):  
Catherine Marina Pickering ◽  
Wendy Hill
Keyword(s):  
Sexual Dimorphism ◽  
Sex Ratios ◽  
Reproductive Ecology ◽  
Flowering Phenology ◽  
Specific Pattern ◽  
Floral Display ◽  
Vegetation Zone ◽  
Dioecious Plants ◽  
Male And Female ◽  
Floral Displays

The reproductive ecology of the dioecious herb Aciphylla simplicifolia (F.Muell.) Benth. (Apiaceae, Mountain Aciphylla) was examined in Kosciuszko National Park. Differences in floral display and flowering phenology between male and female plants were consistent with predictions based on theories concerning sexual dimorphism in dioecious plants. For example, male plants had larger floral displays than females at the alpine sites sampled. Male inflorescences had four times as many flowers as females and more than three times the area of floral display. In addition to differences in floral display, there was a sex-specific pattern in flowering phenology at six alpine sites. At these sites, there were more male inflorescences with buds and flowers and more female inflorescences finished flowering than would be expected if gender did not affect flowering phenology. To determine whether increasingly severe conditions associated with higher-altitude sites were associated with male-biased sex ratios, the number of male and female plants were compared for 20 sites over a 600-m altitudinal range from montane to alpine (total 4274 plants). As altitude increased and as the vegetation zone changed from subalpine to alpine, the sex ratio became increasingly male-biased, with sites in the alpine ranging from 1.45 males per female to 8.53 males per female. Sexual dimorphism in floral display, flowering phenology and sex ratios was consistent with what would be predicted for plants with sex-specific differences in resource allocation.

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