scholarly journals Selection for two different mating systems in Aquilegia canadensis

2021 ◽  
Author(s):  
Chloë Dean-Moore
Keyword(s):  
Display Size ◽  
Mating Systems ◽  
Floral Traits ◽  
Floral Display ◽  
Reproductive Assurance ◽  
Flower Number ◽  
Positive Direction ◽  
Correlational Selection ◽  
Self Pollination ◽  
Floral Displays

Because plants are sessile, they depend on biotic and/or abiotic vectors to transfer pollen from the male pollen-producing anthers to the female pollen-receiving stigmas. As a result, plant mating systems evolve through selection on the floral traits that influence how much pollen is transferred from anthers to stigmas within flowers (self-pollination) vs. between flowers on different individuals (outcrossing). Thus, mating systems are influenced by the traits that dictate the relative abundance of self-versus outcrossed pollen on stigmas. Spatial separation between anthers and stigmas within flowers (herkogamy) is expected to regulate self-pollination yet there are few estimates of how natural selectin acts on this trait.  Aquilegia canadensis (columbine, Ranunculaceae) is a short-lived herbaceous plant of rocky outcrops throughout eastern North America that makes seed through both self-fertilization which is influenced by herkogamy, and outcrossing, which is likely influenced by the plant’s floral display size (flower number and size). Selfing provides reproductive assurance in natural populations of columbine, whereas outcrossing appears to produce much fitter offspring, and there is a trade-off between thes two components of the mating system. We, therefore, predicted correlational selection between herkogamy and display size: selection would favour reduced herkogamy among individuals with small floral displays (to enhance reproductive assurance) and increased herkogamy among individuals with large floral displays (to reduce selfing when outcrossing is likely). We tested this prediction by using multivariate linear regression to estimate phenotypic selection through seeds/fruit and seeds/plant on floral traits and plant size for 1015 plants from nine populations of A. canadensis at the Queen’s University Biological Station. Although we detected positive direction selection on display size mostly through flower number, we did not detect selection on herkogamy or correlational selection between herkogamy and display size. As expected, large size is universally favoured yet selection of floral morphology is weak.    

scholarly journals Phenotypic Selection on Flower Color and Floral Display Size by Three Bee Species

2021 ◽  
Vol 11 ◽  
Author(s):  
Johanne Brunet ◽  
Andrew J. Flick ◽  
Austin A. Bauer
Keyword(s):  
Plant Species ◽  
Display Size ◽  
Flower Color ◽  
Phenotypic Selection ◽  
Floral Traits ◽  
Floral Display ◽  
Floral Trait ◽  
Correlational Selection ◽  
Floral Display Size ◽  
Plant Level

Plants exhibit a wide array of floral forms and pollinators can act as agent of selection on floral traits. Two trends have emerged from recent reviews of pollinator-mediated selection in plants. First, pollinator-mediated selection on plant-level attractants such as floral display size is stronger than on flower-level attractant such as flower color. Second, when comparing plant species, distinct pollinators can exert different selection patterns on floral traits. In addition, many plant species are visited by a diverse array of pollinators but very few studies have examined selection by distinct pollinators. In the current study, we examined phenotypic selection on flower color and floral display size by three distinct bee species, the European honey bee, Apis mellifera, the common eastern bumble bee, Bombus impatiens, and the alfalfa leafcutting bee, Megachile rotundata, foraging on Medicago sativa. To estimate phenotypic selection by each bee species and for all bees combined simultaneously and on the same group of plants, we introduce a new method that combines pollinator visitation data to seed set and floral trait measurements data typical of phenotypic selection study. When comparing floral traits, all bee species selected on the number of racemes per stem and the number of stems per plant, two components of floral display size. However, only leafcutting bees selected on hue or flower color and only bumble bees selected on chroma or darkness of flowers. Selection on chroma occurred via correlational selection between chroma and number of open flowers per raceme and we examine how correlational selection may facilitate the evolution of flower color in plant populations. When comparing bee species, the three bee species exerted similar selection pattern on some floral traits but different patterns on other floral traits and differences in selection patterns were observed between flower-level and plant-level attractants. The trends detected were consistent with previous studies and we advocate the approach introduced here for future studies examining the impact of distinct pollinators on floral trait evolution.

An experimental study of floral display size and reproductive success in Viburnum opulus: importance of grouping

1991 ◽  
Vol 69 (2) ◽  
pp. 394-399 ◽  
Author(s):  
Pam G. Krannitz ◽  
M. Anwar Maun
Keyword(s):  
Experimental Study ◽  
Reproductive Success ◽  
Key Words ◽  
Small Groups ◽  
Display Size ◽  
Significant Proportion ◽  
Floral Display ◽  
Flower Number ◽  
Viburnum Opulus ◽  
Floral Display Size

Two components of the floral display of Viburnum opulus L. were manipulated to determine their effect on fruit initiation and maturation. We altered the size of the floral display by planting individual shrubs in groups of 1, 5, or 10 in 1985 and in groups of 2 or 6 in 1986. In addition, we changed inflorescence size by altering the number of sterile accessory flowers per inflorescence: 0, 4, or untreated in 1985 and 0 or untreated in 1986. The sterile-flower treatment did not explain a significant proportion of the variation in fruit initiation or maturation. In contrast, the plant-grouping treatment was significant in 1985 but not in 1986. The number and proportion of fruits initiated were higher in larger groups of plants than in small groups in 1985 (P < 0.0001 for analyses performed at group and plant levels). The proportion of fruits initiated in group sizes 1, 5, and 10 was 6.9, 15.0, and 22.7% per plant, respectively, and 4.3, 9.1, and 19.4% per inflorescence, respectively. The larger groups did not initiate or mature proportionally more fruits in 1986. Twice as much rain fell in 1986 as in 1985, and shrubs produced more fruits overall (32.2% fruit initiation versus 11% in 1985), but it is not clear why group size differences did not have an effect on fruit initiation and maturation in 1986. Within the plant-grouping treatment fruit initiation and maturation were always significantly correlated with flower number (P < 0.0001) in both 1985 and 1986, but the increase in the number of fruits initiated was not proportional to the increase in flower number. Key words: floral display size, fruit initiation, plant grouping, pollination, Viburum opulus.

scholarly journals Floral traits and environmental factors regulate insects visits to flowering plants at night

2021 ◽  
Author(s):  
Lichao Feng ◽  
Zhiqi Du ◽  
David Kulhavy ◽  
Sina Adl ◽  
Qingfan Meng
Keyword(s):  
Relative Humidity ◽  
Environmental Factors ◽  
Ambient Temperature ◽  
Display Size ◽  
Flowering Plants ◽  
Insect Species ◽  
Floral Traits ◽  
Floral Display ◽  
Late Night ◽  
Flower Visiting

Flower-visiting insects have co-evolved with flowering-plants. While it has been shown that floral traits and environmental factors influence insects visitations during the day, it is yet unclear how these factors influence insects visitations at night. We sampled a montane meadow located near Jilin in northeastern China in July and August in 2019, 4 nights each month, and two time periods each night. We sampled 94 flower-visiting insect species in total and documented the floral traits and ambient factors. First, focusing on the insects functions, we allocated all insects into three functional groups (pollination, predation, and feeding). We found that most nocturnal insects exhibited predation behavior, and they had the highest species turnover rate. Second, focusing on the environmental factors, we found that ambient temperature and relative humidity strongly influence the diversity of flower-visiting insects. Variation partitioning analysis further suggested that ambient temperature has a stronger effect on the flowering-visiting insects at early night, while the relative humidity has a stronger effect on the flowering-visiting insects at late night. Third, focusing on floral traits, we found that most insects have a preference for flowers with moderately-sized corolla diameters (20 to 30 mm). Furthermore, display size had a strong linear correlation with flowering-visiting insect species richness and frequency of presence. In sum, our findings suggest that ambient temperature, relative humidity, and floral display size strongly regulate nocturnal flower-visiting insects.

scholarly journals Plant reproductive strategies are not correlated with morphological or genetic diversity in specialized pollination interactions

2020 ◽  
Author(s):  
Maureen Murua ◽  
Anahí Espíndola ◽  
Fernanda Pérez
Keyword(s):  
Genetic Diversity ◽  
Reproductive Strategies ◽  
Floral Biology ◽  
Floral Traits ◽  
Floral Display ◽  
Reproductive Assurance ◽  
Evolutionary Transitions ◽  
Self Fertilization ◽  
Self Compatibility ◽  
Selfing Species

Abstract Bachground: One of the most common evolutionary transitions in angiosperms is the reproductive change from outcrossing to self-fertilization, which has occurred independently in many lineages. This transition has been associated with changes in floral biology, ecology and genetics, with selfing species experiencing reduced floral display and herkogamy, rapid plant growth, and increased inbreeding depression. Here, we aim to test whether self-compatibility was associated with a reduction in floral traits important to the attraction and interaction with pollinators, and a reduction in genetic diversity and inbreeding. Results: Our self-incompatibility tests indicated that 50% of the species studied here are self-incompatible. In relation to floral traits, we found that self-incompatible species do not show a reduction in the size of their floral traits, but rather we found larger corolla, elaiophore area, and herkogamy in self-compatible ones. The microsatellite analysis did not identify any significant decrease in the genetic diversity or increase in inbreeding levels in the self-compatible Calceolaria species. Conclusions: Despite our results go against our expectations, in the case of Calceolaria , their high dependence on only two genera of oil-bees put the species in a vulnerable position, probably facilitating the evolution of mechanisms of reproductive assurance in the absence of pollinators. As a result, the plants maintain their attraction traits while evolving an ability to self. In addition, we also did not detect a significant change in genetic diversity or inbreeding when different reproductive strategies are used. This suggests that selfing could be delayed, facilitating -when possible- the exchange of genes by cross-pollination first, and buffering the negative genetic effects of self-pollination.

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.

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