Pollen Biology and Dispersal Dynamics in Waterhemp (Amaranthustuberculatus)

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 416-422 ◽  
Author(s):  
Jianyang Liu ◽  
Adam S. Davis ◽  
Patrick J. Tranel
Keyword(s):  
Gene Flow ◽  
Herbicide Resistance ◽  
Pollen Dispersal ◽  
Rapid Evolution ◽  
Pollen Competition ◽  
Long Distance ◽  
Pollination Success ◽  
Evolution Of Resistance ◽  
Pollen Longevity ◽  
Pollen Density

Waterhemp is a major weed of field crops in the Midwestern United States. Its prevalence is at least partly due to its rapid evolution of resistance to many groups of herbicides over the last two decades. In light of its dioecy and anemophily, pollen movement in waterhemp is considered to be an important factor in the spread of herbicide resistance genes. Thus, the biology and dispersal profile of waterhemp pollen are critical determinants for understanding and predicting the spatial population dynamics of herbicide resistance in this species. In this study, pollen longevity was investigated with greenhouse experiments, and pollen dispersal and the effect of pollen competition were investigated in field plots. Pollen dispersal was determined by measuring the frequency of seeds produced on receptor plants positioned at various distances from a pollen source, which flowered in synchrony with the receptor plants. Results indicated that waterhemp pollen can remain viable up to 120 h, implying a low limitation of pollen dispersal by its longevity. Effective pollen dispersal declined exponentially with distance, with most pollen fertilizing recipient plants within 50 m of the pollen source. However, long distance pollen dispersal (800 m) was also observed. We also saw evidence for pollen swamping in this species. Under conditions of pollen competition among distinct genotypes, pollination success was inversely related to distance between pollen donors and receptors. However, relative pollen density may also play an important role in determining the rate of long distance gene flow. This study confirmed the potential of waterhemp pollen to effect long distance gene flow and provides supporting data for quantitative spatial modeling of waterhemp resistance dynamics.

scholarly journals Camelina (Camelina sativa L. Crantz) Crop Performance, Insect Pollinators, and Pollen Dispersal in the Northeastern US

2019 ◽  
Author(s):  
Richard Rizzitello ◽  
Chuan-Jie Zhang ◽  
Carol Auer
Keyword(s):  
Gene Flow ◽  
Honey Bees ◽  
Pollen Dispersal ◽  
Camelina Sativa ◽  
Genetically Engineered ◽  
Oilseed Crop ◽  
Crop Failure ◽  
Long Distance ◽  
Insect Visitation ◽  
Pollinating Insects

AbstractCamelina sativa (camelina) is an oilseed crop in the Brassicaceae that has been genetically engineered for the production of biofuels, dietary supplements, and other industrial compounds. Cultivation in North America is both recent and limited, so there are gaps in knowledge regarding yield, weed competition, and pollen-mediated gene flow. For these experiments, camelina ‘SO-40’ was grown for three years without weed control. Spring-sown camelina was harvested at 80-88 days with ∼1200 growing degree days (GDD) with yields of 425-508 kg/hectare. Camelina yields were the same with or without weeds, showing competitive ability in low-management conditions. Crop failure in 2015 was associated with delayed rainfall and above-average temperatures after seeding. Camelina flowers attracted pollinating insects from the Hymenoptera, Diptera, Lepidoptera, and Coleoptera. Hymenoptera included honey bees (Apis melifera), mining bees (Andrenidae), sweat bees (Halictidae), bumble bees (Bombus spp.) and leaf cutter bees (Megachilidae). Insect visitation on camelina flowers was associated with modest increases in seed yield. Honey bees comprised 28-33% of all pollinators and were shown to carry camelina pollen on their legs. Air sampling showed that wind-blown pollen was present at low concentrations at 9 m beyond the edges of the field. These experiments demonstrated for the first time that camelina pollen dispersal could occur through honey bees or wind, although bee activity would likely be more significant for long-distance gene flow.

scholarly journals Adding landscape genetics and individual traits to the ecosystem function paradigm reveals the importance of species functional breadth

2017 ◽  
Vol 114 (48) ◽  
pp. 12761-12766 ◽  
Author(s):  
Antonio R. Castilla ◽  
Nathaniel S. Pope ◽  
Megan O’Connell ◽  
María F. Rodriguez ◽  
Laurel Treviño ◽  
...  
Keyword(s):  
Gene Flow ◽  
Seed Production ◽  
Critical Role ◽  
Pollen Dispersal ◽  
Plant Size ◽  
Dispersal Ability ◽  
Floral Display ◽  
Long Distance ◽  
Pollinator Community ◽  
Local Plant

Animal pollination mediates both reproduction and gene flow for the majority of plant species across the globe. However, past functional studies have focused largely on seed production; although useful, this focus on seed set does not provide information regarding species-specific contributions to pollen-mediated gene flow. Here we quantify pollen dispersal for individual pollinator species across more than 690 ha of tropical forest. Specifically, we examine visitation, seed production, and pollen-dispersal ability for the entire pollinator community of a common tropical tree using a series of individual-based pollinator-exclusion experiments followed by molecular-based fractional paternity analyses. We investigate the effects of pollinator body size, plant size (as a proxy of floral display), local plant density, and local plant kinship on seed production and pollen-dispersal distance. Our results show that while large-bodied pollinators set more seeds per visit, small-bodied bees visited flowers more frequently and were responsible for more than 49% of all long-distance (beyond 1 km) pollen-dispersal events. Thus, despite their size, small-bodied bees play a critical role in facilitating long-distance pollen-mediated gene flow. We also found that both plant size and local plant kinship negatively impact pollen dispersal and seed production. By incorporating genetic and trait-based data into the quantification of pollination services, we highlight the diversity in ecological function mediated by pollinators, the influential role that plant and population attributes play in driving service provision, and the unexpected importance of small-bodied pollinators in the recruitment of plant genetic diversity.

scholarly journals Hawkmoth Pollination Facilitates Long-distance Pollen Dispersal and Reduces Isolation Across a Gradient of Land-use Change

2019 ◽  
Vol 104 (3) ◽  
pp. 495-511 ◽  
Author(s):  
Krissa A. Skogen ◽  
Rick P. Overson ◽  
Evan T. Hilpman ◽  
Jeremie B. Fant
Keyword(s):  
Land Use ◽  
Gene Flow ◽  
Habitat Fragmentation ◽  
Land Use Change ◽  
Pollen Dispersal ◽  
Suitable Habitat ◽  
Long Distance Dispersal ◽  
Effective Population ◽  
Long Distance ◽  
Genetic Diversity And Structure

Land-use change is among the top drivers of global biodiversity loss, which impacts the arrangement and distribution of suitable habitat for species. Population-level effects include increased isolation, decreased population size, and changes to mutualistic and antagonistic interactions. However, the extent to which species are impacted is determined by life history characteristics including dispersal. In plants, mating dynamics can be changed in ways that can negatively impact population persistence if dispersal of pollen and/or seed is disrupted. Long-distance dispersal has the potential to buffer species from the negative impacts of land-use change. Biotic vectors of long-distance dispersal have been less frequently studied, though specific taxa are known to travel great distances. Here, we describe population genetic diversity and structure in a sphingophilous species that is experiencing habitat fragmentation through land-use change, Oenothera harringtonii W. L. Wagner, Stockh. & W. M. Klein (Onagraceae). We use 12 nuclear and four plastid microsatellite markers and show that pollen dispersal by hawkmoths drives high gene flow and low population differentiation despite a range-wide gradient of land-use change and habitat fragmentation. By separating the contributions of pollen and seed dispersal to gene flow, we show that most of the genetic parameters are driven by hawkmoth-facilitated long-distance pollen dispersal, but populations with small, effective population sizes experience higher levels of relatedness and inbreeding. We discuss considerations for conservation efforts for this and other species that are pollinated by long-distance dispersers.

scholarly journals Rapid evolution of weedy traits during sunflower de-domestication: the importance of hybridization and standing genetic variation

2021 ◽  
Author(s):  
Fernando Hernandez ◽  
Roman Boris Vercellino ◽  
Claudio Pandolfo ◽  
Jennifer R. Mandel ◽  
Alejandro Presotto
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Seed Dormancy ◽  
Herbicide Resistance ◽  
Competitive Ability ◽  
Management Strategies ◽  
Rapid Evolution ◽  
High Genetic Diversity ◽  
Herbicide Resistant ◽  
Evolution Of Resistance

Hybridization between crops and their wild relatives may promote the evolution of de-domesticated (feral) weeds. Wild sunflower is typically found in ruderal environments, but crop-wild hybridization may facilitate the evolution of weedy biotypes. Using one crop-specific mitochondrial marker (CMS-PET1) and 14 nuclear SSR markers, we studied the origin and genetic diversity of BRW, a recently discovered weedy biotype. Then, using a resurrection approach, we tested for rapid evolution of weedy traits (seed dormancy, herbicide resistance, and competitive ability) by sampling weedy and wild biotypes 10 years apart (2007 and 2017). All the weedy plants present the CMS-PET1 cytotype, confirming their feral origin. At the nuclear markers, BRW showed higher genetic diversity than the cultivated lines, as high genetic diversity as the most diverse wild biotypes, and low differentiation with one wild biotype, suggesting that wild hybridization increased the genetic diversity of the feral BRW. Regarding weedy trait evolution, we found support for rapid evolution towards higher seed dormancy, but not for higher competitive ability or herbicide resistance. Standing genetic variation probably facilitated the evolution of seed dormancy and limited the evolution of herbicide resistance, as no resistant alleles were found in the ancestral biotype. Our results demonstrate that natural crop-wild hybrids can evolve quickly in farmers' fields, leading to the establishment of weedy biotypes of cultivated origin. Although herbicide resistance did not evolve in BRW, management strategies aimed at preventing the evolution of resistance should be a priority in order to avoid the emergence and spread of herbicide resistant biotypes in Argentina.

scholarly journals Using empirical data to model transgene dispersal

2003 ◽  
Vol 358 (1434) ◽  
pp. 1157-1162 ◽  
Author(s):  
T. R. Meagher ◽  
F. C. Belanger ◽  
P. R. Day
Keyword(s):  
Gene Flow ◽  
Transgenic Plants ◽  
Herbicide Resistance ◽  
Pollen Dispersal ◽  
Genetically Modified Crops ◽  
Creeping Bentgrass ◽  
Published Data ◽  
Local Conditions ◽  
Ecological Performance ◽  
Resistance Trait

One element of the current public debate about genetically modified crops is that gene flow from transgenic cultivars into surrounding weed populations will lead to more problematic weeds, particularly for traits such as herbicide resistance. Evolutionary biologists can inform this debate by providing accurate estimates of gene flow potential and subsequent ecological performance of resulting hybrids. We develop a model for gene flow incorporating exponential distance and directional effects to be applied to windpollinated species. This model is applied to previously published data on gene flow in experimental plots of Agrostis stolonifera L. (creeping bentgrass), which assessed gene flow from transgenic plants resistant to the herbicide glufosinate to surrounding non–transgenic plants. Our results show that although pollen dispersal can be limited in some sites, it may be extensive in others, depending on local conditions such as exposure to wind. Thus, hybridization under field conditions is likely to occur. Given the nature of the herbicide resistance trait, we regard this trait as unlikely to persist in the absence of herbicide, and suggest that the ecological consequences of such gene flow are likely to be minimal.

Future Outlook for Herbicide-Resistance Research

1990 ◽  
Vol 4 (1) ◽  
pp. 208-214 ◽  
Author(s):  
Mary Lynn Roush ◽  
Steven R. Radosevich ◽  
Bruce D. Maxwell
Keyword(s):  
Gene Flow ◽  
Herbicide Resistance ◽  
Interdisciplinary Research ◽  
Research Agenda ◽  
Life History Traits ◽  
Biological Processes ◽  
Ecological Research ◽  
Management Tools ◽  
Interdisciplinary Approaches ◽  
Evolution Of Resistance

Management of herbicide resistance will require interdisciplinary research to understand the mechanisms and dynamics of resistance. We believe that models are valuable tools. Models propose hypotheses about biological processes that influence the evolution of resistance and management tools that may reduce resistance in weed populations. Hypotheses help to direct research. For example, our model proposes that fitness and gene flow dramatically influence the evolution of and recovery from resistance in weed populations. Therefore, our research agenda should include ecological investigations of the life-history traits involved in fitness and gene flow. The model suggests thresholds of susceptible weed abundance to reduce selection pressure and to delay resistance. These thresholds will be related closely to economic weed thresholds. While the resistance issue emphasizes the need for basic biological and ecological research, resistance is only a part of the broader research agenda, which calls for holistic and interdisciplinary approaches to understanding and managing crop systems.

scholarly journals Populations genetics and the evolution of herbicide resistance in weeds

2005 ◽  
Vol 75 (4) ◽  
pp. 25-35 ◽  
Author(s):  
M. Jasieniuk ◽  
B.D. Maxwell
Keyword(s):  
Gene Flow ◽  
Herbicide Resistance ◽  
Random Mating ◽  
Large Population ◽  
Rapid Evolution ◽  
Geographic Region ◽  
Resistance Mutations ◽  
Weed Species ◽  
Susceptible Population ◽  
Resistance Evolution

Numerous factors, including mutation, selection, inheritance, mating System, and gene flow are important in the evolution of herbicide resistance in weeds. Spontaneous gene mutation is believed to be the main source of genetic variation for resistance evolution in a geographic region in which resistance has not been detected previously. Despite mutation frequencies that are probably very low, the probability of occurrence of at least a single resistant mutant in a susceptible population may be high for weed species with high fecundities and large population sizes. Subsequent repeated treatments with herbicides having the same mode of action could lead to the rapid evolution of predominantly resistant populations. Rare dominantly inherited resistance mutations spread significantly more rapidly than recessive mutations in random mating populations, but at roughly the same rate in highly self-fertilizing species. Gene flow, through the movement of pollen or seed from resistant weed populations, may provide a source of resistance alleles to adjacent or nearby susceptible fields. Mathematical models indicate that the strength of selection imposed by a herbicide and the initial frequency of the resistant phenotype most strongly influence the rate of resistance evolution. The models predict that the most effective strategies to manage resistance are to reduce the intensity of selection by herbicide and to limit the migration of herbicide-resistant seed.

Long distance pollen-mediated gene flow at a landscape level: the weed beet as a case study

2007 ◽  
Vol 16 (18) ◽  
pp. 3801-3813 ◽  
Author(s):  
STÉPHANE FÉNART ◽  
FRÉDÉRIC AUSTERLITZ ◽  
JOËL CUGUEN ◽  
JEAN-FRANÇOIS ARNAUD
Keyword(s):  
Gene Flow ◽  
Long Distance ◽  
Landscape Level

Spatial genetic substructure within natural populations of jack pine (Pinus banksiana)

1991 ◽  
Vol 69 (3) ◽  
pp. 547-551 ◽  
Author(s):  
Chang Yi Xie ◽  
Peggy Knowles
Keyword(s):  
Spatial Autocorrelation ◽  
Pinus Banksiana ◽  
Pollen Dispersal ◽  
Natural Populations ◽  
Jack Pine ◽  
Spatial Autocorrelation Analysis ◽  
Autocorrelation Analysis ◽  
Long Distance ◽  
Genetic Substructure ◽  
Good Agreement

Spatial autocorrelation analysis was used to investigate the geographic distribution of allozyme genotypes within three natural populations of jack pine (Pinus banksiana Lamb.). Results indicate that genetic substructuring within these populations is very weak and the extent differs among populations. These results are in good agreement with those inferred from mating-system studies. Factors such as the species' predominantly outbreeding system, high mortality of selfs and inbreds prior to reproduction, long-distance pollen dispersal, and the absence of strong microhabitat selection may be responsible for the observed weak genetic substructuring. Key words: jack pine, Pinus banksiana, genetic substructure, allozyme, spatial autocorrelation analysis.

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