Effects of sexual dimorphism on pollinator behaviour in a dioecious species

Studies published on the reproductive success of dioecious species concentrate on the role of sex ratios and pollinator behaviour. In the case of Rubus chamaemorus L., a circumboreal dioecious species, we hypothesized that flower survival and biomass allocation to reproductive tissues, which are climate dependent, also influence fruit production. Only 0.05% of total biomass is allocated to reproduction, whereas 94% goes to underground organs responsible for vegetative propagation. Many male (28 – 51%) and female flower buds (35 – 54%) and young fruits (24–51%) die prematurely mainly because of the climate; fruit production then becomes independent from initial female flower density. The scarcity of female flowers at most sites (except near open water) limits fruit production. The limited sexual reproduction would allow cloudberry to maintain somatic resources, thereby increasing the longevity of individuals and their chance of encountering the climatic conditions required for reproductive success. Such a strategy is adaptive in a variable climate like that of the subarctic. Furthermore, the reduced importance of sexual reproduction would diminish the need to optimize sex ratios. Other selective pressures (e.g., competition) would then favour male clones in most sites, in spite of the unproductive pollen excess.

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Temporal dynamics of sexual dimorphism in a dioecious species

Annals of Botany ◽

10.1093/aob/mcaa088 ◽

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.

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Effects of sexual dimorphism on pollinator behaviour in a dioecious species

10.1101/2021.04.15.440026 ◽

2021 ◽

Author(s):

Laura Moquet ◽

Anne-Laure Jacquemart ◽

Mathilde Dufay ◽

Isabelle De Cauwer

Keyword(s):

Sexual Dimorphism ◽

Bombus Terrestris ◽

Male Flower ◽

Pollen Grains ◽

Flower Size ◽

Pollination Efficiency ◽

Flower Number ◽

Pollinator Behaviour ◽

Number Of Visits ◽

Female Flowers

Floral traits often display sexual dimorphism in insect-pollinated dioecious plant species, with male individuals typically being showier than females. While this strategy is theorized to be optimal when pollinators are abundant, it might represent a risk when they become scarce, because the disproportionately high number of visits on the most attractive sex, males, might preclude efficient pollen transfer from males to females. Here, the effect of sexual dimorphism on pollination efficiency was assessed in experimental arrays of dioecious Silene dioica that were exposed to one frequent visitor of the species, Bombus terrestris, and that differed in the magnitude of sexual dimorphism for either flower number or flower size. While flower size dimorphism did not impact pollination efficiency, we found that flower number dimorphism negatively affected the number of visits on female plants, on female flowers and on the number of female flowers visited after a male flower. However, flower number dimorphism had no effect on the number of pollen grains deposited per stigma, presumably because the decrease in the number of visits to female flowers was compensated by a higher number of pollen grains deposited per visit.

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Rheotaxis Response Based on Sexual Dimorphism in the Green Swordtail Fish, Xiphophorus hellerii

Biota ◽

10.20414/jb.v13i2.298 ◽

2020 ◽

Vol 13 (2) ◽

pp. 128-139

Author(s):

Muhammad Irsyad Abiyusfi Ghafari ◽

Vita Fitrianti

Keyword(s):

Sexual Dimorphism ◽

Gravid Female ◽

Adult Males ◽

Dioecious Species ◽

Swordtail Fish ◽

Xiphophorus Hellerii ◽

Males And Females ◽

Morphological Differences ◽

Gravid Females ◽

The Individual

Morphological distinctions between males and females of a species are referred to by sexual dimorphism. It may result from various selection pressures affecting either sex or both and may occur in any dioecious species, including Green Swordtail fish, which are sexually reproductive. This study examined the different rheotaxis responses of Xiphophorus hellerii based on different sexes and morphological features. We analyzed ten adult males, ten gravid females, and ten non-gravid females of Xiphophorus helleri collected down the river and transferred into the column. We counted the number of the individual that performed positive rheotaxis (+), negative rheotaxis (-), and indifference response (0). The result showed different rheotaxis responses shown by male, non-gravid female, and gravid female X. hellerii. The highest percentage of positive rheotaxis response (movement against the current) was shown by non-gravid female X. hellerii, reaching up to 89%. Morphological differences between male, non-gravid female, and gravid female X. hellerii appear to affect the orientation and ability of X. hellerii in giving response against current and certainly has an impact on their survival in nature.

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Sexual dimorphism and sex ratios of two Australian dioecious species of alpine pineapple grass, Astelia alpina var. novaehollandiae and Astelia psychrocharis (Asteliaceae)

Nordic Journal of Botany ◽

10.1111/j.1756-1051.2003.tb00385.x ◽

2003 ◽

Vol 23 (2) ◽

pp. 225-236 ◽

Cited By ~ 3

Author(s):

Catherine Marina Pickering ◽

Mark Jordan ◽

Wendy Hill

Keyword(s):

Sexual Dimorphism ◽

Sex Ratios ◽

Dioecious Species

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Life-history studies–a new approach to the taxonomy of ligulate species of Desmarestia (Phaeophyceae) from the Pacific coast of Canada

Canadian Journal of Botany ◽

10.1139/b86-291 ◽

1986 ◽

Vol 64 (10) ◽

pp. 2192-2196 ◽

Cited By ~ 9

Author(s):

Akira F. Peters ◽

Dieter G. Müller

Keyword(s):

Life History ◽

Sexual Dimorphism ◽

North America ◽

Life Histories ◽

Pacific Coast ◽

Culture Conditions ◽

Growth Forms ◽

Dioecious Species ◽

New Approach ◽

The Pacific

Life histories of two ligulate forms of Desmarestia with different phylloid width from one site on the Canadian Pacific coast were studied in culture. Meiospores from a form with narrow phylloids germinated into monoecious gametophytes. Meiospores from a form with broad phylloids developed into dioecious gametophytes, showing sexual dimorphism characteristic for dioecious species of Desmarestia. The two growth forms also differed in culture conditions required for gametogenesis. We conclude that at least two different species of ligulate Desmarestia occur on the Pacific coast of North America.

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Sexual Dimorphism and between-Year Variation in Flowering, Fruit Set and Pollinator Behaviour in a Boreal Willow

Oikos ◽

10.2307/3565663 ◽

1988 ◽

Vol 53 (1) ◽

pp. 58 ◽

Cited By ~ 30

Author(s):

Thomas Elmqvist ◽

Jon Ågren ◽

Anders Tunlid ◽

Jon Agren

Keyword(s):

Sexual Dimorphism ◽

Fruit Set ◽

Pollinator Behaviour

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Sexual dimorphism in the electric knifefish, Gymnorhamphichthys rondoni (Rhamphichthyidae: Gymnotiformes)

Acta Amazonica ◽

10.1590/1809-4392201804392 ◽

2019 ◽

Vol 49 (3) ◽

pp. 213-220

Author(s):

Elisa Queiroz GARCIA ◽

Jansen ZUANON

Keyword(s):

Sexual Dimorphism ◽

Body Height ◽

Principal Component ◽

The Body ◽

Vertical Line ◽

Head Length ◽

Genital Papilla ◽

Adult Males ◽

Dioecious Species ◽

Males And Females

ABSTRACT Sexual dimorfism refers to morphological differences between males and females of a species. It may be a result of different selection pressures acting on either or both sexes and may occur in any sexually-reproducing dioecious species, including fishes. We analyzed 63 females and 63 adult males of Gymnorhamphichthys rondoni (Gymnotiformes) collected by us or deposited in museum collections. Sex was identified through abdominal dissection. We measured length from snout to posterior end of anal-fin, anal-fin length, distance from anus to anal-fin origin, distance from genital papilla to anal-fin origin, body width at beginning of anal-fin, and head length. Morphometric data submitted to a Principal Component Analysis (PCA) grouped males and females according to variables related to body size (along the first component) and to head length and body height along the second and third components. Females were larger than males, whereas males had proportionally larger heads and higher bodies than females. The urogenital papilla of males and females showed differences in shape, size and relative position on the body. The female papilla was elongated horizontally, larger than that of males, and was located on a vertical line below the eye, while the papilla of the males was vertically elongated and located on a vertical line below the operculum. To our knowledge, this is the first recorded case of sexual dimorphism in a species of Rhamphichthyidae, a condition that is now known in all the currently recognized families of Gymnotiformes.

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Hydraulic constraints of reproduction do not explain sexual dimorphism in the genus Leucadendron (Proteaceae)

10.1101/209460 ◽

2017 ◽

Author(s):

Adam B. Roddy ◽

Justin van Blerk ◽

Jeremy J. Midgley ◽

Adam G. West

Keyword(s):

Sexual Dimorphism ◽

Fire Frequency ◽

Sexually Dimorphic ◽

Hydraulic Efficiency ◽

Costs Of Reproduction ◽

Dioecious Species ◽

Shoot Architecture ◽

Males And Females ◽

And Function ◽

In Fire

AbstractBecause of the importance of reproduction in plant life history, the physiological costs of reproduction often influence vegetative structure and function. In dioecious species, these effects can be quite obvious, as different costs of male and female reproductive functions are entirely separated among different individuals in a population. In fire-prone ecosystems, in which recruitment is driven by fire frequency, many plants will maintain their seeds in the canopy, only to be released after a fire. The dioecious genus Leucadendron is a notable case of this, as females can maintain their seed cones for years, and, even more interestingly, species in the genus differ substantially in the degree to which males and females are sexually dimorphic. A recent study (Harris and Pannell 2010) argued that the hydraulic costs of maintaining seed cones for many years would effect the degree of sexual dimorphism among species. However, this assumed that shoot hydraulic architecture would be related to traits exhibiting sexual dimorphism. Here we explicitly test this hypothesis on two Leucadendron species. We found (1) that metrics of branch ramification used in the previous study to characterize dimorphism do not conform to known scaling relationships and (2) that sexual dimorphism in shoot architecture has no effect on hydraulic efficiency. Both of these results seriously question the pattern described by Harris and Pannell (2010) and suggest that the hydraulic costs of prolonged seed retention in Leucadendron do not significantly affect branch architecture.

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