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Janet Simkin - One of the best experts on this subject based on the ideXlab platform.
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effects of sheep stocking on the plant community and agricultural characteristics of upland Anthoxanthum odoratum geranium sylvaticum meadow in northern england
Grass and Forage Science, 2017Co-Authors: R. S. Smith, Robert Shiel, D. Millward, Janet SimkinAbstract:In the UK, upland hay meadows (Anthoxanthum odoratum–Geranium sylvaticum grassland) with high plant biodiversity are rare and confined to submontane areas of northern England. We report results from a 5-year experiment to test suggestions that recent biodiversity declines were attributable to increased sheep-stocking density and a longer spring stocking period, thus delaying the shut up date for the growth of the hay crop. Longer stocking periods and higher stocking densities decreased the forage mass at 8 July, but they increased herbage N content and digestibility, reduced plant species diversity and reduced populations and seed production of Rhinanthus minor. Compared with unstocked swards, the similarity of the vegetation to Anthoxanthum odoratum–Geranium sylvaticum grassland was reduced by 16·9% when stocking with sheep continued until 27 May each year, and by 8·3% when sward heights were maintained at 3 cm compared with 5 cm. Increased mean sward height and height of R. minor were positively correlated with accumulated temperatures. Results support suggestions that recent reductions in the nature value of these grasslands might be a consequence of high stocking densities persisting until later in the spring, carried out during a 1-year period with warmer temperatures.
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Principal components analysis (PCA) illustrating the variation in the plant species (∆) dataset at Palace Leas.
2017Co-Authors: Jonathan Kidd, Janet Simkin, Peter Manning, Simon Peacock, Elizabeth StockdaleAbstract:Environmental variables including soil and plant variables (dotted arrow) and treatment plot number (●) are overlain. A. capi = Agrostis capillaris, A. prat = Alopecurus pratensis, A. odor = Anthoxanthum odoratum, A. sylv = Anthriscus sylvestris, B. pere = Bellis perennis, B. hord = Bromus hordeaceus, C. maju = Conopodium majus, C. cris = Cynosurus cristatus, F. rubr = Festuca rubra, F. vern = Ficaria verna, H. lana = Holcus lanatus, L. camp = Luzula campestris, P. triv = Poa trivialis, R. acri = Ranunculus acris, R.bulb = Ranunculus bulbosus, R. mino = Rhinanthus minor, S. medi = Stellaria media, T. offi = Taraxacum officinale, T. prat = Trifolium pratense, T. repe = Trifolium repens, T. flav = Trisetum flavescens, V. sati = Vicia sativa, V. sepi = Vicia sepium.
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Effects of sheep stocking on the plant community and agricultural characteristics of upland Anthoxanthum odoratum–Geranium sylvaticum meadow in northern England
Grass and Forage Science, 2016Co-Authors: R. S. Smith, Robert Shiel, D. Millward, Janet SimkinAbstract:In the UK, upland hay meadows (Anthoxanthum odoratum–Geranium sylvaticum grassland) with high plant biodiversity are rare and confined to submontane areas of northern England. We report results from a 5-year experiment to test suggestions that recent biodiversity declines were attributable to increased sheep-stocking density and a longer spring stocking period, thus delaying the shut up date for the growth of the hay crop. Longer stocking periods and higher stocking densities decreased the forage mass at 8 July, but they increased herbage N content and digestibility, reduced plant species diversity and reduced populations and seed production of Rhinanthus minor. Compared with unstocked swards, the similarity of the vegetation to Anthoxanthum odoratum–Geranium sylvaticum grassland was reduced by 16·9% when stocking with sheep continued until 27 May each year, and by 8·3% when sward heights were maintained at 3 cm compared with 5 cm. Increased mean sward height and height of R. minor were positively correlated with accumulated temperatures. Results support suggestions that recent reductions in the nature value of these grasslands might be a consequence of high stocking densities persisting until later in the spring, carried out during a 1-year period with warmer temperatures.
Steven E. Kelley - One of the best experts on this subject based on the ideXlab platform.
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Somatic and genetic factors in sun and shade population differentiation in Plantago lanceolata and Anthoxanthum odoratum
New Phytologist, 1998Co-Authors: Daniel A. Sims, Steven E. KelleyAbstract:Differences between individuals collected from sun and shade populations could result from either somatic or genetic differences, particularly in populations of perennial plants. Our objective in this study was to separate somatic from genetic differences. We collected Anthoxanthum odoratum and Plantago lanceolata from sun and shade populations and made measurements on both vegetatively propagated clones and seed progeny from each clone. The parental populations differed in a wide range of physiological and morphological traits. However, only photosynthetic capacity was significantly different between both the original sun and shade populations and their seed progeny. In both species, plants from the sun population had higher photosynthetic capacities than those from the shade population when grown in a common environment. This demonstrates that there was genetic differentiation between the sun and shade populations. Photosynthetic capacity of parents and offspring also differed, suggesting a somatic effect. Since many of the original clones were virus-infected, but all but one of the offspring were virus-free, this might have been a result of virus infection. However, in spite of the fact that the parents and offspring clones were propagated vegetatively so that the plants were at the same developmental stage at the time of measurement, we cannot rule out the possibility that differences in age of cell lines could also have been a factor.
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Viral Pathogens and the Advantage of Sex in the Perennial Grass Anthoxanthum odoratum
1997Co-Authors: Steven E. KelleyAbstract:The ubiquity of sexual reproduction among plants and animals remains one of the major unresolved paradoxes of modern evolutionary biology. In order for sex to be maintained in populations, sex must confer immediate and substantial fitness benefits. Theoreticians have proposed numerous mechanisms to explain how such advantages arise, but experimental data are few. In one well-studied population of the perennial grass Anthoxanthum odoratum in a mown North Carolina field, sexual offspring have been found to have significantly higher fitness than asexual offspring. More recent field experiments show that an aphid-transmitted virus, barley yellow dwarf (BYDV)-strain SGV, specifically transmitted by Schizaphus graminum, frequently infects Anthoxanthum progeny soon after transplantation into the field, BYDV infection is asymptomatic in Anthoxanthum, but BYDV-inoculated clones planted directly in the field had significantly lower fitness than healthy controls.
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Viral Pathogens and the Advantage of Sex in the Perennial Grass Anthoxanthum odoratum [and Discussion]
Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 1994Co-Authors: Steven E. Kelley, J. ShykoffAbstract:The ubiquity of sexual reproduction among plants and animals remains one of the major unresolved paradoxes of modern evolutionary biology. In order for sex to be maintained in populations, sex must confer immediate and substantial fitness benefits. Theoreticians have proposed numerous mechanisms to explain how such advantages arise, but experimental data are few. In one well-studied population of the perennial grass Anthoxanthum odoratum in a mown North Carolina field, sexual offspring have been found to have significantly higher fitness than asexual offspring. More recent field experiments show that an aphid-transmitted virus, barley yellow dwarf (BYDV)-strain SGV, specifically transmitted by Schizaphus graminum, frequently infects Anthoxanthum progeny soon after transplantation into the field. BYDV infection is asymptomatic in Anthoxanthum, but BYDV-inoculated clones planted directly in the field had significantly lower fitness than healthy controls. Sexual females have been hypothesized to gain a fitness advantage for their offspring in the presence of pathogens either by providing `an escape in time' from pathogens preadapted to the parental genotype or through the production of rare genotypes, which escape frequency-dependent infection. When parental clones and seed-derived sexual offspring were planted in identical but separate arrays in sites near where the parent was collected, parental clones were twice as frequently infected as sexual offspring. Factors other than genetic variation may have contributed to differences in levels of infection between sexual and asexual progeny: in this experiment, clonally derived asexual offspring tillers were slightly larger than seed-derived sexual tillers; in field experiments, larger plants were more frequently infected than smaller plants. When different families were planted into a common site, there was evidence that genotypes were less frequently infected when locally rare than when common. Taken together, the data suggest that BYDV infection generates advantages for rare or sexually produced genotypes in Anthoxanthum. The pattern of infection is likely to result from a complex interaction between vector, host, and viral genetics and population structure, vector behaviour, and host and vector dispersal patterns. Sexually produced genotypes appear to benefit because they are both novel and rare, but the observed minority advantage was weak. Other viral, bacterial, and fungal pathogens in this Anthoxanthum population may act as frequency-dependent selective forces in different places in the field, collectively generating the substantial and observed overall fitness advantage of rare genotypes. Further study is needed to elucidate their role. Nevertheless, the data do show that viral pathogens, which are often asymptomatic, play a significant evolutionary role in plant populations.
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Viruses and the Advantage of Sex in Anthoxanthum odoratum: A Review
Plant Species Biology, 1993Co-Authors: Steven E. KelleyAbstract:The nature of the selective forces responsible for the maintenance of sexual reproduction in populations remains controversial. Theoreticians have proposed a variety of mechanisms to explain how sex is adaptive, including varying environments, sib competition, mutational damage, and pathogens. In a well-studied population of the short-lived, perennial grass Anthoxanthum odoratum in a mown North Carolina field, significant fitness advantages for sexual vs. asexual offspring have been shown. Evidence from two recent experiments implicates barley yellow dwarf luteovirus (BYDV), a single-stranded RNA virus, as a cause of the short-term advantage for sex in this population. When planted in sites close to parents, asexual offspring were twice as frequently infected as sexual offspring. In other sites, infection was more frequent among common than rare genotypes. Viruses possess a unique combination of features which make them plausible candidates to favor sexual reproduction in plants. Viruses are pervasive, have subtle but significant fitness effects, have the potential for rapid mutation and evolution, and are spread by vectors whose behaviors are host frequency dependent. The ecological and evolutionary consequences of viruses in plant populations deserve further study.
R. S. Smith - One of the best experts on this subject based on the ideXlab platform.
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effects of sheep stocking on the plant community and agricultural characteristics of upland Anthoxanthum odoratum geranium sylvaticum meadow in northern england
Grass and Forage Science, 2017Co-Authors: R. S. Smith, Robert Shiel, D. Millward, Janet SimkinAbstract:In the UK, upland hay meadows (Anthoxanthum odoratum–Geranium sylvaticum grassland) with high plant biodiversity are rare and confined to submontane areas of northern England. We report results from a 5-year experiment to test suggestions that recent biodiversity declines were attributable to increased sheep-stocking density and a longer spring stocking period, thus delaying the shut up date for the growth of the hay crop. Longer stocking periods and higher stocking densities decreased the forage mass at 8 July, but they increased herbage N content and digestibility, reduced plant species diversity and reduced populations and seed production of Rhinanthus minor. Compared with unstocked swards, the similarity of the vegetation to Anthoxanthum odoratum–Geranium sylvaticum grassland was reduced by 16·9% when stocking with sheep continued until 27 May each year, and by 8·3% when sward heights were maintained at 3 cm compared with 5 cm. Increased mean sward height and height of R. minor were positively correlated with accumulated temperatures. Results support suggestions that recent reductions in the nature value of these grasslands might be a consequence of high stocking densities persisting until later in the spring, carried out during a 1-year period with warmer temperatures.
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Effects of sheep stocking on the plant community and agricultural characteristics of upland Anthoxanthum odoratum–Geranium sylvaticum meadow in northern England
Grass and Forage Science, 2016Co-Authors: R. S. Smith, Robert Shiel, D. Millward, Janet SimkinAbstract:In the UK, upland hay meadows (Anthoxanthum odoratum–Geranium sylvaticum grassland) with high plant biodiversity are rare and confined to submontane areas of northern England. We report results from a 5-year experiment to test suggestions that recent biodiversity declines were attributable to increased sheep-stocking density and a longer spring stocking period, thus delaying the shut up date for the growth of the hay crop. Longer stocking periods and higher stocking densities decreased the forage mass at 8 July, but they increased herbage N content and digestibility, reduced plant species diversity and reduced populations and seed production of Rhinanthus minor. Compared with unstocked swards, the similarity of the vegetation to Anthoxanthum odoratum–Geranium sylvaticum grassland was reduced by 16·9% when stocking with sheep continued until 27 May each year, and by 8·3% when sward heights were maintained at 3 cm compared with 5 cm. Increased mean sward height and height of R. minor were positively correlated with accumulated temperatures. Results support suggestions that recent reductions in the nature value of these grasslands might be a consequence of high stocking densities persisting until later in the spring, carried out during a 1-year period with warmer temperatures.
Yoshito Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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Movement of allelopathic compound coumarin from plant residue of sweet vernalgrass (Anthoxanthum odoratum L.) to soil
Grassland Science, 2009Co-Authors: Yoshito YamamotoAbstract:This study investigated the movement of coumarin, an allelopathic compound, from the plant residue of sweet vernalgrass (Anthoxanthum odoratum L.) to soil, as well as the dynamics of coumarin in soil. The level of coumarin dissolved from sweet vernalgrass plant residue in both Andosols and Cambisols, which were watered every day, peaked on the fifth day after the beginning of watering, and fell gradually thereafter. Specifically, the coumarin content in Cambisols on the fifth day was 14.2 p.p.m., which is four times the coumarin level found in Andosols. The recovery percentage of coumarin extracted with MeOH from the soil-treated coumarin water solution was approximately 70% in Cambisols and 35% in Andosols. As the days continued, the recovery rate of coumarin tended to decrease, but not in the disinfected soils. The recovery rate of coumarin in Andosols at temperatures of 25°C and 15°C rapidly decreased on the sixth and 10th days, respectively. These results indicate that the coumarin of sweet vernalgrass plant residue will move into soil easily after rainfall, and that both soil type and the presence of microorganisms are related to the disappearance of coumarin in soil.
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Allelopathic potential of Anthoxanthum odoratum for invading Zoysia -grassland in Japan
Journal of chemical ecology, 1995Co-Authors: Yoshito YamamotoAbstract:The growth ofZoysia japonica surroundingAnthoxanthum odoratum onZoysia-grassland in Japan was investigated in June 1994. The stem density ofZ. japonica tended to decrease with short distances between twoA. odoratum plants. This showed that the growth ofZ. japonica surroundingA. odoratum was reduced. Basic, neutral, and acidic fractions extracted fromA. odoratum plants inhibited the seedling growth of lettuce. In particular the neutral fraction showed the strongest activity among the three fractions. The main inhibitory compound obtained atR f 0.6–0.7, on the thin-layer chromatogram of the neutral fraction, was isolated and identified as coumarin by means of GC-MS. Coumarin solution inhibited seedling growth ofZ. japonica in low concentrations but, conversely, promoted seedling growth ofA. odoratum. Coumarin was contained in all parts ofA. odoratum and its concentration varied with the season and from one individual plant to another. In particular, coumarin was highly concentrated in the leaves, accounting for more than 2.5% of dry leaf weight in June. The inhibitory effect of these aqueous extracts was correlated to the amount of coumarin inA. odoratum leaves and cournarin was considered to be the main inhibitory compound.
Monica A. Geber - One of the best experts on this subject based on the ideXlab platform.
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Lack of adaptation from standing genetic variation despite the presence of putatively adaptive alleles in introduced sweet vernal grass (Anthoxanthum odoratum)
Journal of evolutionary biology, 2015Co-Authors: Billie A. Gould, Monica A. GeberAbstract:Population genetic theory predicts that the availability of appropriate standing genetic variation should facilitate rapid evolution when species are introduced to new environments. However, few tests of rapid evolution have been paired with empirical surveys for the presence of previously identified adaptive genetic variants in natural populations. In this study, we examined local adaptation to soil Al toxicity in the introduced range of sweet vernal grass (Anthoxanthum odoratum), and we genotyped populations for the presence of Al tolerance alleles previously identified at the long-term ecological Park Grass Experiment (PGE, Harpenden, UK) in the species native range. We found that markers associated with Al tolerance at the PGE were present at appreciable frequency in introduced populations. Despite this, there was no strong evidence of local adaptation to soil Al toxicity among populations. Populations demonstrated significantly different intrinsic root growth rates in the absence of Al. This suggests that selection on correlated root growth traits may constrain the ability of populations to evolve significantly different root growth responses to Al. Our results demonstrate that genotype-phenotype associations may differ substantially between the native and introduced parts of a species range and that adaptive alleles from a native species range may not necessarily promote phenotypic differentiation in the introduced range.
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De Novo Transcriptome Assembly and Identification of Gene Candidates for Rapid Evolution of Soil Al Tolerance in Anthoxanthum odoratum at the Long-Term Park Grass Experiment.
PloS one, 2015Co-Authors: Billie A. Gould, Susan R. Mccouch, Monica A. GeberAbstract:Studies of adaptation in the wild grass Anthoxanthum odoratum at the Park Grass Experiment (PGE) provided one of the earliest examples of rapid evolution in plants. Anthoxanthum has become locally adapted to differences in soil Al toxicity, which have developed there due to soil acidification from long-term experimental fertilizer treatments. In this study, we used transcriptome sequencing to identify Al stress responsive genes in Anthoxanhum and identify candidates among them for further molecular study of rapid Al tolerance evolution at the PGE. We examined the Al content of Anthoxanthum tissues and conducted RNA-sequencing of root tips, the primary site of Al induced damage. We found that despite its high tolerance Anthoxanthum is not an Al accumulating species. Genes similar to those involved in organic acid exudation (TaALMT1, ZmMATE), cell wall modification (OsSTAR1), and internal Al detoxification (OsNRAT1) in cultivated grasses were responsive to Al exposure. Expression of a large suite of novel loci was also triggered by early exposure to Al stress in roots. Three-hundred forty five transcripts were significantly more up- or down-regulated in tolerant vs. sensitive Anthoxanthum genotypes, providing important targets for future study of rapid evolution at the PGE.