Pollen-mediated gene flow between paraquat-resistant and susceptible hare barley (Hordeum leporinum)

Weed Science ◽  
2006 ◽  
Vol 54 (4) ◽  
pp. 685-689 ◽  
Author(s):  
Imam Hidayat ◽  
Jeanine Baker ◽  
Christopher Preston
Keyword(s):  
Gene Flow ◽  
The Self ◽  
Weed Species ◽  
Resistance Evolution ◽  
Rapid Accumulation ◽  
Hordeum Leporinum ◽  
Flow Through ◽  
Low Levels ◽  
Susceptible Populations ◽  
Pollen Movement

Pollen movement between individuals can increase the rate of herbicide resistance evolution by spreading resistance alleles within or between populations and by facilitating the rapid accumulation of resistance alleles within individuals. This study investigated the level of pollen-mediated gene flow between paraquat-resistant and paraquat-susceptible populations of the self-pollinated weed species hare barley. The experiment was conducted in both directions, from resistant to susceptible and susceptible to resistant, across 2 yr. To maximize the potential for pollen flow, individual plants were grown in a single pot. The level of gene flow was similar across years and between genotypes. The level of pollen-mediated gene flow ranged from 0.06 to 0.15%. Gene flow from resistant to susceptible plants was confirmed by demonstrating segregation for resistance in the progeny of suspected crosses. This study suggests that pollen-mediated gene flow will occur in this species at frequencies less than 0.16% and could assist the accumulation of resistance alleles within a population. These low levels of gene flow through pollen movement suggest that cross-pollination over larger distances would be unlikely and pollen movement probably does not contribute to gene flow between populations.

Glyphosate-Resistant Rigid Ryegrass (Lolium rigidum) Populations in the Western Australian Grain Belt

2010 ◽  
Vol 24 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Mechelle J. Owen ◽  
Stephen B. Powles
Keyword(s):  
Cropping Systems ◽  
Acetolactate Synthase ◽  
Glyphosate Resistance ◽  
Weed Species ◽  
Resistance Evolution ◽  
Crop Field ◽  
Intensive Cropping ◽  
Low Levels ◽  
Rigid Ryegrass ◽  
Acetyl Coenzyme A Carboxylase

Glyphosate-resistance evolution in weeds is evident globally, especially in areas where transgenic glyphosate-resistant crops dominate. Resistance to glyphosate is currently known in 16 weed species, including rigid ryegrass in Australia. Following the first report of glyphosate resistance in 1998, there are now 78 documented glyphosate-resistant populations of rigid ryegrass in grain-growing regions of southern Australia. In some regions where glyphosate-resistance evolution has already occurred in rigid ryegrass, transgenic glyphosate-resistant canola was introduced in 2008, further highlighting the need to monitor glyphosate-resistance evolution in weeds. A rigid ryegrass population (WALR70) was collected in 2005 from a crop field in Esperance, Western Australia, after it had survived applications of glyphosate. Dose–response experiments confirmed resistance in the population, with the glyphosate rate resulting in 50% mortality (LD50) for WALR70 being 11 times greater than that for a susceptible biotype. The WALR70 population also had low levels of resistance to some acetyl coenzyme A carboxylase (ACCase)- and acetolactate synthase (ALS)-inhibiting herbicides (diclofop, fluazifop, clodinafop, tralkoxydim, chlorsulfuron, and imazethapyr), but was susceptible to other herbicide modes of action, such as atrazine, trifluralin, and paraquat. Two other rigid ryegrass populations assessed in this study were also confirmed to be resistant to glyphosate. The increasing number of glyphosate-resistant rigid ryegrass populations in Australia is of concern to growers because of the importance of glyphosate in intensive cropping systems and the introduction of glyphosate-resistant canola to this region.

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.

NEUROTIC SYMPTOMATICS RELATED TO PERSONAL CHARACTERISTICS IN YOUTH

2019 ◽  
pp. 2014-2019
Author(s):  
Milen Dimov
Keyword(s):  
Personal Characteristics ◽  
The Self ◽  
The Other ◽  
Social Responsiveness ◽  
Training Process ◽  
Self Assessment ◽  
School Year ◽  
Real Behavior ◽  
Low Levels ◽  
The Ideal

The present study traces the dynamics of personal characteristics in youth and the manifested neurotic symptoms in the training process. These facts are the reason for the low levels of school results in the context of the existing theoretical statements of the problem and the empirical research conducted among the trained teenagers. We suggest that the indicators of neurotic symptomatology in youth – aggression, anxiety, and neuroticism, are the most demonstrated, compared to the other studied indicators of neurotic symptomatology. Studies have proved that there is a difference in the act of neurotic symptoms when tested in different situations, both in terms of expression and content. At the beginning of the school year, neurotic symptoms, more demonstrated in some aspects of aggressiveness, while at the end of school year, psychotism is more demonstrated. The presented summarized results indicate that at the beginning of the school year, neurotic symptoms are strongly associated with aggression. There is a tendency towards a lower level of social responsiveness, both in the self-assessment of real behavior and in the ideal “I”-image of students in the last year of their studies. The neurotic symptomatology, more demonstrated due to specific conditions in the life of young people and in relation to the characteristics of age.

High gene flow through pollen partially compensates spatial limited gene flow by seeds for a Neotropical tree in forest conservation and restoration areas

2021 ◽  
Author(s):  
Patricia Sanae Sujii ◽  
Evandro Vagner Tambarussi ◽  
Carolina Grando ◽  
Ellida de Aguiar Silvestre ◽  
João Paulo Gomes Viana ◽  
...  
Keyword(s):  
Gene Flow ◽  
Forest Conservation ◽  
Neotropical Tree ◽  
High Gene Flow ◽  
High Gene ◽  
Limited Gene Flow ◽  
Flow Through

Internal vs External Control and Magnitude of Aggression toward Self and Others

1971 ◽  
Vol 29 (2) ◽  
pp. 403-411 ◽  
Author(s):  
George H. Davis ◽  
David R. Mettee
Keyword(s):  
Locus Of Control ◽  
The Self ◽  
External Control ◽  
Outcome Information ◽  
Low Levels ◽  
Perceived Locus Of Control

Ss measuring high or low on the Rotter (1966) I-E Scale were given or denied information about outcome and then asked to aggress against themselves or another unknown S. It was reasoned that the Self for internals and Others for externals (i.e., the perceived locus of control) would be regarded as appropriate aggression targets. Results indicated that internals treated themselves much as externals treated Others (appropriate targets). When the target was inappropriate, internals and externals again reacted similarly but in a very different manner from their reactions to appropriate targets. If success or failure information was provided, aggression against appropriate targets was low and apparently inhibited since these Ss reported high levels of anger following the opportunity to aggress. In the absence of outcome information, appropriate targets received high levels of aggression which apparently drained off some hostility since these Ss reported low levels of anger following aggression. In the case of inappropriate targets, both manifest aggression and reported anger fell between the above extremes irrespective of the information provided Ss.

scholarly journals RADseq data reveal a lack of admixture in a mouse lemur contact zone contrary to previous microsatellite results

2021 ◽  
Author(s):  
Jelmer Wijtze Poelstra ◽  
B. Karina Montero ◽  
Jan Lüdemann ◽  
Ziheng Yang ◽  
S. Jacques Rakotondranary ◽  
...  
Keyword(s):  
Gene Flow ◽  
Contact Zone ◽  
Mouse Lemur ◽  
Biological Processes ◽  
Microsatellite Data ◽  
Ancestral Gene ◽  
Mouse Lemurs ◽  
Low Levels ◽  
Future Work ◽  
Lemur Species

Despite being one of the most fundamental biological processes, the process of speciation remains poorly understood in many groups of organisms. Mouse lemurs are a species-rich genus of small primates endemic to Madagascar, whose diversity has only recently been uncovered using genetic data and is primarily found among morphologically cryptic, allopatric populations. To assess to what extent described species represent reproductively isolated entities, studies are needed in areas where mouse lemur taxa come into contact. Hybridization has previously been reported in a contact zone between two closely related mouse lemur species (Microcebus murinus and M. griseorufus) based on microsatellite data. Here, we revisit this system using RADseq data for populations in, near, and far from the contact zone, including many of the individuals that had previously been identified as hybrids. Surprisingly, we find no evidence for admixed nuclear ancestry in any of the individuals. Re-analyses of microsatellite data and simulations suggest that previously inferred hybrids were false positives and that the program NewHybrids can be particularly sensitive to erroneously inferring hybrid ancestry. Using coalescent-bases analyses, we also show an overall lack of recent gene flow between the two species, and low levels of ancestral gene flow. Combined with evidence for local syntopic occurrence, these data indicate that M. murinus and M. griseorufus are reproductively isolated. Finally, we estimate that they diverged less than a million years ago, suggesting that completion of speciation is relatively rapid in mouse lemurs. Future work should focus on the underpinnings of reproductive isolation in this cryptic primate radiation, which are mostly unknown. Our study also provides a cautionary tale for the inference of hybridization with microsatellite data.

Population genetic structure in duckweed (Lemna minor, Lemnaceae)

1996 ◽  
Vol 74 (2) ◽  
pp. 222-230 ◽  
Author(s):  
Christopher T. Cole ◽  
Martin I. Voskuil
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Population Genetic ◽  
Lemna Minor ◽  
Vegetative Reproduction ◽  
Low Frequency ◽  
Morphological Differentiation ◽  
Genotypic Diversity ◽  
Allozyme Variation ◽  
Low Levels

Allozyme variation in 11 Minnesota populations of Lemna minor L. was studied, using 11 enzyme systems, resolving 16 putative loci from 285 plants. Significant deviations from Hardy–Weinberg frequencies occurred in several populations that had excesses of heterozygotes at several loci. While genotypic diversity and evenness measures are similar to other vegetatively reproducing plants (D = 0.541, E = 0.607), very few multilocus genotypes per population were found (mean = 4.0). Substantial population structure was evident (FST = 0.407), apparently reflecting low levels of gene flow (Nm = 0.30) despite the capacity of this species for dispersal of plantlets. This low level of gene flow and apparent low frequency of sexual reproduction has produced substantial levels of genetic divergence among populations, despite an absence of morphological differentiation. Keywords: allozymes, genetic structure, hydrophily, Lemna, vegetative dispersal, vegetative reproduction.

Transfer of resistance alleles from herbicide-resistant to susceptible grass weeds via pollen-mediated gene flow

2021 ◽  
pp. 1-51
Author(s):  
Amit J. Jhala ◽  
Hugh J. Beckie ◽  
Carol Mallory-Smith ◽  
Marie Jasieniuk ◽  
Roberto Busi ◽  
...  
Keyword(s):  
Gene Flow ◽  
Herbicide Resistance ◽  
Creeping Bentgrass ◽  
Agricultural Landscapes ◽  
Italian Ryegrass ◽  
Weed Species ◽  
Herbicide Resistant ◽  
Wild Oats ◽  
Rigid Ryegrass ◽  
Grass Weed

Abstract The objective of this paper was to review the reproductive biology, herbicide-resistant (HR) biotypes, pollen-mediated gene flow (PMGF), and potential for transfer of alleles from HR to susceptible grass weeds including barnyardgrass, creeping bentgrass, Italian ryegrass, johnsongrass, rigid (annual) ryegrass, and wild oats. The widespread occurrence of HR grass weeds is at least partly due to PMGF, particularly in obligate outcrossing species such as rigid ryegrass. Creeping bentgrass, a wind-pollinated turfgrass species, can efficiently disseminate herbicide resistance alleles via PMGF and movement of seeds and stolons. The genus Agrostis contains about 200 species, many of which are sexually compatible and produce naturally occurring hybrids as well as producing hybrids with species in the genus Polypogon. The self-incompatibility, extremely high outcrossing rate, and wind pollination in Italian ryegrass clearly point to PMGF as a major mechanism by which herbicide resistance alleles can spread across agricultural landscapes, resulting in abundant genetic variation within populations and low genetic differentiation among populations. Italian ryegrass can readily hybridize with perennial ryegrass and rigid ryegrass due to their similarity in chromosome numbers (2n=14), resulting in interspecific gene exchange. Johnsongrass, barnyardgrass, and wild oats are self-pollinated species, so the potential for PMGF is relatively low and limited to short distances; however, seeds can easily shatter upon maturity before crop harvest, leading to wider dispersal. The occurrence of PMGF in reviewed grass weed species, even at a low rate is greater than that of spontaneous mutations conferring herbicide resistance in weeds and thus can contribute to the spread of herbicide resistance alleles. This review indicates that the transfer of herbicide resistance alleles occurs under field conditions at varying levels depending on the grass weed species.

Comparative study of selfsteem and social skills in addicts inpatients in a Therapeutic Community / Estudio comparativo de autoestima y habilidades sociales en pacientes adictos de una comunidad terapéutica

2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Alejandra Cattan
Keyword(s):  
Social Skills ◽  
Descriptive Study ◽  
Self Esteem ◽  
The Self ◽  
Community Center ◽  
Drug Addicts ◽  
The Social ◽  
Low Levels ◽  
Admission Group ◽  
Selection Of

La presente investigación tiene como objetivo describir, analizar y comparar la autoestima y las habilidades sociales de un grupo de jóvenes, entre 17 y 24 años de edad, consumidores de drogas que se encuentran realizando tratamiento en la comunidad terapéutica Aylén (Argentina). Es una investigación de tipo descriptiva comparativa, con un diseño de diferencias entre grupos (G1, grupo de admisión) y (G2, grupo de reinserción social). La muestra estuvo conformada por 54 sujetos (25 para grupo de admisión y 29 para el grupo de reinserción social). Los instrumentos utilizados fueron el inventario de Autoestima de Barksdale y la Escala de Habilidades sociales de Goldstein, las cuales fueron adaptadas y validadas para ser aplicadas a la población de estudio. Asimismo, a partir de los procedimientos de validación de estos instrumentos se propusieron para cada uno, nuevos agrupamientos de factores. Los resultados mostraron, bajos niveles de autoestima para ambos grupos y entre niveles bajos y normales de habilidades sociales en cada una de las categorías componentes y el total. Finalmente, no se confirmaron las hipótesis de diferencias significativas en los niveles de autoestima y los niveles de habilidades sociales entre los jóvenes en etapa de admisión y los jóvenes en etapa de reinserción social. AbstractThe objective of the present investigation is to analyze and compare the socials skills and the self-esteem of a group of juveniles between the ages of 17 and 24 years, drug addicts, both under medical treatment in a Community center in Argentina. This is a comparative-descriptive study, with the design of two groups: G1 for admission group and G2 for the reinsertion group. The sample was made of a group of 56 people, 25 for the admission group and 29 for the social reinsertion group. The instruments used were the Goldstein Social Skills Scale and the Self-Esteem Inventory from Barksdale, that were adapted for the use in such case. Also for the use of such instruments, new validation measures were implemented in the selection of the variables. The results showed low levels of self esteem for both groups and between low and normal levels of social skills in each category. Finally, no important differences were founded in the levels of self esteem between the admission group and the social reinsertion period for the juveniles.

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