Competition for pollination: effects of pollen of an invasive plant on seed set of a native congener

Oecologia ◽  
2001 ◽  
Vol 129 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Beverly J. Brown ◽  
Randall J. Mitchell
Botany ◽  
2009 ◽  
Vol 87 (3) ◽  
pp. 283-292 ◽  
Author(s):  
B. R. Montgomery

Introduced plants may compete for pollination with native plants, resulting in reduced fruit or seed set. In this study, I use several techniques to assess whether the invasive plant Euphorbia esula  L. (leafy spurge, Euphorbiaceae) reduces the pollination success of chasmogamous flowers of the native plant Viola pedatifida G. Don (prairie violet, Violaceae), which has chasmogamous and cleistogamous flowers. Euphorbia pollen was found on most Viola stigmas, suggesting the potential for competition. Additionally, application of Euphorbia pollen to Viola stigmas prior to conspecific pollen reduced seed set. However, natural receipt of Euphorbia and other heterospecific pollen was not associated with decreased fruit or seed set. In the field, fruit set was higher for Viola in sites with Euphorbia despite increased Euphorbia pollen receipt, and seed set did not vary with the presence of Euphorbia. However, there was no significant interaction between the presence of Euphorbia and flower type (cleistogamous or chasmogamous), suggesting that increased fruit set near Euphorbia is unrelated to pollination. This study suggests that Viola and Euphorbia interact through shared pollinators, but there is no evidence that competition for pollination with Euphorbia reduces Viola’s fecundity or results in increased reliance on cleistogamous flowers.


Web Ecology ◽  
2018 ◽  
Vol 18 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Manuela Giovanetti ◽  
Margarida Ramos ◽  
Cristina Máguas

Abstract. Acacia longifolia, a native legume from Australia, has been introduced in many European countries and elsewhere, thus becoming one of the most important global invasive species. In Europe, its flowering occurs in a period unsuitable for insect activity: nonetheless it is considered entomophilous. Floral traits of this species are puzzling: brightly coloured and scented as liked by insects, but with abundant staminate small-sized flowers and relatively small pollen grains, as it is common in anemophilous species. Invasion processes are especially favoured when reshaping local ecological networks, thus the interest in understanding pollination syndromes associated with invasive plant species that may facilitate invasiveness. Moreover, a striking difference exists between its massive flowering and relatively poor seed set. We introduced a novel approach: first, we consider the possibility that a part of the pollination success is carried on by wind and, second, we weighted the ethological perspective of the main pollinator. During the flowering season of A. longifolia (February–April 2016), we carried on exclusion experiments to detect the relative contribution of insects and wind. While the exclusion experiments corroborated the need for pollen vectors, we actually recorded a low abundance of insects. The honeybee, known pollinator of acacias, was relatively rare and not always productive in terms of successful visits. While wind contributed to seed set, focal observations confirmed that honeybees transfer pollen when visiting both the inflorescences to collect pollen and the extrafloral nectaries to collect nectar. The mixed pollination strategy of A. longifolia may then be the basis of its success in invading Portugal's windy coasts.


2021 ◽  
Author(s):  
◽  
Justyna Giejsztowt

<p>Drivers of global change have direct impacts on the structure of communities and functioning of ecosystems, and interactions between drivers may buffer or exacerbate these direct effects. Interactions among drivers can lead to complex non-linear outcomes for ecosystems, communities and species, but are infrequently quantified. Through a combination of experimental, observational and modelling approaches, I address critical gaps in our understanding of the interactive effects of climate change and plant invasion, using Tongariro National Park (TNP; New Zealand) as a model. TNP is an alpine ecosystem of cultural significance which hosts a unique flora with high rates of endemism. TNP is invaded by the perennial shrub Calluna vulgaris (L.) Hull. My objectives were to: 1) determine whether species-specific phenological shifts have the potential to alter the reproductive capacity of native plants in landscapes affected by invasion; 2) determine whether the effect of invasion intensity on the Species Area Relationship (SAR) of native alpine plant species is influenced by environmental stress; 3) develop a novel modelling framework that would account for density-dependent competitive interactions between native species and C. vulgaris and implement it to determine the combined risk of climate change and plant invasion on the distribution of native plant species; and 4) explore the possible mechanisms leading to a discrepancy in C. vulgaris invasion success on the North and South Islands of New Zealand. I show that species-specific phenological responses to climate warming increase the flowering overlap between a native and an invasive plant. I then show that competition for pollination with the invader decreases the sexual reproduction of the native in some landscapes. I therefore illustrate a previously undescribed interaction between climate warming and plant invasion where the effects of competition for pollination with an invader on the sexual reproduction of the native may be exacerbated by climate warming. Furthermore, I describe a previously unknown pattern of changing invasive plant impact on SAR along an environmental stress gradient. Namely, I demonstrate that interactions between an invasive plant and local native plant species richness become increasingly facilitative along elevational gradients and that the strength of plant interactions is dependent on invader biomass. I then show that the consequences of changing plant interactions at a local scale for the slope of SAR is dependent on the pervasion of the invader. Next, I demonstrate that the inclusion of invasive species density data in distribution models for a native plant leads to greater reductions in predicted native plant distribution and density under future climate change scenarios relative to models based on climate suitability alone. Finally, I find no evidence for large-scale climatic, edaphic, and vegetative limitations to invasion by C. vulgaris on either the North and South Islands of New Zealand. Instead, my results suggest that discrepancies in invasive spread between islands may be driven by human activity: C. vulgaris is associated with the same levels of human disturbance on both islands despite differences in the presence of these conditions between then islands. Altogether, these results show that interactive effects between drivers on biodiversity and ecosystem dynamics are frequently not additive or linear. Therefore, accurate predictions of global change impacts on community structure and ecosystems function require experiments and models which include of interactions among drivers such as climate change and species invasion. These results are pertinent to effective conservation management as most landscapes are concurrently affected by multiple drivers of global environmental change.</p>


Botany ◽  
2013 ◽  
Vol 91 (11) ◽  
pp. 745-751 ◽  
Author(s):  
Erica Wassink ◽  
Christina M. Caruso

Although interspecific competition for pollination is hypothesized to result in divergence in floral traits (i.e., character displacement), few studies have tested whether selection on these traits differs in the presence and absence of a competitor for pollination. We measured phenotypic selection on floral traits of Lobelia siphilitica L. growing in the presence and absence of Mimulus ringens L., a potential competitor for pollination. Because L. siphilitica is gynodioecious, we estimated selection separately for female and hermaphrodite plants. The presence of M. ringens did not decrease seed set of L. siphilitica. However, the presence of M. ringens did affect selection on daily display size of female L. siphilitica; there was significant selection for smaller daily displays in the absence of M. ringens, but nonsignificant selection for larger displays in the presence of M. ringens. In addition, selection on flower colour did not differ in the presence and absence of M. ringens, but did differ between female and hermaphrodite L. siphilitica. Consequently, our results suggest that the evolution of floral traits in L. siphilitica, but not the evolution of sexual dimorphism in these traits, can be affected by interactions for pollination with M. ringens.


2018 ◽  
Vol 285 (1884) ◽  
pp. 20181072 ◽  
Author(s):  
Shiyun Qiu ◽  
Xiao Xu ◽  
Shuangshuang Liu ◽  
Wenwen Liu ◽  
Jing Liu ◽  
...  

Flowering synchrony can play an important role in plants' reproductive success, which is essential for the successful establishment and spread of invasive plants. Although flowering synchrony has been found to be closely related to climatic factors, the effects of variation in such factors along latitudinal gradient on flowering synchrony and the role of flowering synchrony in the reproductive success of invading populations remain largely unexplored. In a 2-year field study, we examined the latitudinal variation of flowering phenology, especially flowering synchrony, in an invasive plant, Spartina alterniflora , along coastal China, and its relationship with population seed set across three climatic zones. We found that first flowering date was delayed, and flowering synchrony increased with increasing latitude. Flowering synchrony was negatively related to temperature during flowering season but not to soil properties or precipitation, suggesting that climate has shaped the latitudinal pattern of flowering synchrony. Moreover, a positive correlation between flowering synchrony and seed set across latitudes indicates the possible role of flowering synchrony in the latitudinal pattern of sexual reproduction in S. alterniflora . These results suggest that, in addition to the effects of climate on the growth of invasive species, climatic factors can play an important role in the invasion success of alien plants by regulating the flowering synchrony and thus the reproductive success of invasive plants.


Botany ◽  
2011 ◽  
Vol 89 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Elizabeth M. Da Silva ◽  
Risa D. Sargent

Relatively little attention has been paid to pollinator-mediated interactions among invasive and native plants in spite of the fact that pollen transfer between species in invaded communities has been shown to occur. In this study, we investigated the impact of pollen deposition from the invasive plant species Lythrum salicaria on seed set in a native species that is a member of the same family, Decodon verticillatus. Whole plants were subjected to hand pollination by conspecific (D. verticillatus only) or mixed (a 1:1 mixture of D. verticillatus and L. salicaria) pollen to determine if the addition of a mixed pollen load interferes with the ability of D. verticillatus pollen to set seed. We found the mixed pollen treatment reduced D. verticillatus seed set by 33.3% relative to the conspecific pollen treatment. Our study demonstrates that invasive plants have the potential to negatively impact the reproductive success of a native species through pollinator-mediated interactions. We discuss the potential implications of our findings to the evolution and persistence of native plant populations in invaded communities.


2021 ◽  
Author(s):  
◽  
Justyna Giejsztowt

<p>Drivers of global change have direct impacts on the structure of communities and functioning of ecosystems, and interactions between drivers may buffer or exacerbate these direct effects. Interactions among drivers can lead to complex non-linear outcomes for ecosystems, communities and species, but are infrequently quantified. Through a combination of experimental, observational and modelling approaches, I address critical gaps in our understanding of the interactive effects of climate change and plant invasion, using Tongariro National Park (TNP; New Zealand) as a model. TNP is an alpine ecosystem of cultural significance which hosts a unique flora with high rates of endemism. TNP is invaded by the perennial shrub Calluna vulgaris (L.) Hull. My objectives were to: 1) determine whether species-specific phenological shifts have the potential to alter the reproductive capacity of native plants in landscapes affected by invasion; 2) determine whether the effect of invasion intensity on the Species Area Relationship (SAR) of native alpine plant species is influenced by environmental stress; 3) develop a novel modelling framework that would account for density-dependent competitive interactions between native species and C. vulgaris and implement it to determine the combined risk of climate change and plant invasion on the distribution of native plant species; and 4) explore the possible mechanisms leading to a discrepancy in C. vulgaris invasion success on the North and South Islands of New Zealand. I show that species-specific phenological responses to climate warming increase the flowering overlap between a native and an invasive plant. I then show that competition for pollination with the invader decreases the sexual reproduction of the native in some landscapes. I therefore illustrate a previously undescribed interaction between climate warming and plant invasion where the effects of competition for pollination with an invader on the sexual reproduction of the native may be exacerbated by climate warming. Furthermore, I describe a previously unknown pattern of changing invasive plant impact on SAR along an environmental stress gradient. Namely, I demonstrate that interactions between an invasive plant and local native plant species richness become increasingly facilitative along elevational gradients and that the strength of plant interactions is dependent on invader biomass. I then show that the consequences of changing plant interactions at a local scale for the slope of SAR is dependent on the pervasion of the invader. Next, I demonstrate that the inclusion of invasive species density data in distribution models for a native plant leads to greater reductions in predicted native plant distribution and density under future climate change scenarios relative to models based on climate suitability alone. Finally, I find no evidence for large-scale climatic, edaphic, and vegetative limitations to invasion by C. vulgaris on either the North and South Islands of New Zealand. Instead, my results suggest that discrepancies in invasive spread between islands may be driven by human activity: C. vulgaris is associated with the same levels of human disturbance on both islands despite differences in the presence of these conditions between then islands. Altogether, these results show that interactive effects between drivers on biodiversity and ecosystem dynamics are frequently not additive or linear. Therefore, accurate predictions of global change impacts on community structure and ecosystems function require experiments and models which include of interactions among drivers such as climate change and species invasion. These results are pertinent to effective conservation management as most landscapes are concurrently affected by multiple drivers of global environmental change.</p>


2009 ◽  
Vol 134 (5) ◽  
pp. 560-566 ◽  
Author(s):  
David M. Czarnecki ◽  
Zhanao Deng

Lantana camara, a member of the verbena family, is a popular ornamental yet highly invasive plant. It can escape from cultivation through seed dispersal and can contaminate native lantana species (Lantana depressa) through cross-pollination. Ploidy manipulation is being used as a genetic approach to produce sterile, noninvasive lantana cultivars. Polyploids have been observed in lantana (Lantana), but little information is available about the mechanisms for lantana polyploidization and the possible effects of natural polyploidization on the sterility (or fertility) of lantana triploids. In this study, we analyzed the ploidy level of more than 1500 lantana progeny from self, open, and/or controlled pollinations of 10 commercial cultivars and seven breeding lines. Our results confirmed the occurrence of unreduced gametes, specifically, unreduced female gametes (UFGs), in lantana. The frequency of UFG formation varied among commercial cultivars, and cultivars/breeding lines could be categorized into two groups: UFG producers and nonproducers. Tetraploid cultivars Gold, Pink Caprice, and Radiation fall into the UFG-producing group, while diploid cultivars Cream, Denholm White and Lola and tetraploid cultivars Carlos, Dallas Red and Irene belong to the nonproducer group. The frequency of UFG formation observed in nine UFG producers was 5.5% to 100%, varying with cultivar, growing condition, and/or pollination scheme. Progeny of the cross between ‘Carlos’ (seed parent) and ‘Gold’ (pollen parent) also showed the ability to produce UFGs, indicating that the trait (UFG formation) could be transmitted from ‘Gold’ to its progeny and is likely to be controlled by nuclear gene(s). Lantana triploids with or without the UFG-forming ability in its genetic background showed a significant difference in seed set: the former produced abundant seed when pollinated, while the latter produced little or no seed. The results stress the need to avoid using lantana with UFG-forming ability as parents in crosses designed to produce sterile triploids for invasiveness control. Additionally, the results from this study suggest multiple pathways for emergence and evolution of polyploids in cultivated and naturalized lantana populations.


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