Competition of five native prairie grasses with Bromus inermis under three moisture regimes

1997 ◽  
Vol 75 (12) ◽  
pp. 2140-2145 ◽  
Author(s):  
Dean Nernberg ◽  
Mark R. T. Dale
Keyword(s):  
Competitive Ability ◽  
Environmental Gradients ◽  
Bromus Inermis ◽  
Reciprocal Relationship ◽  
Shoot Biomass ◽  
Native Grasses ◽  
Native Prairie ◽  
Prairie Grasses ◽  
Moisture Regimes ◽  
Reduced Water

We examined the effect of moisture on the competitive ability of five native grasses (Agropyron and Stipa) in competition with the non-native grass Bromus inermis Leyss. The plants were grown in large pots in growth rooms, and the moisture treatment was imposed by the frequency of watering. The competitive ability of the five native grasses, as measured by shoot biomass ratio, increased with reduced water availability, but even under the driest conditions, they competed poorly with B. inermis. The order of competitive ability found in this experiment did not match the order predicted from field observations based on the hypothesis of a strict reciprocal relationship between stress tolerance and competitive ability. Stipa viridula Trin. was the best competitor of the five, and Stipa curtiseta (A.S. Hitchc.) Barkworth was consistently the least competitive. The order of competitive ability was more variable when measured by the effect on Bromus than when measured by the effect on the native grasses themselves. The results suggest that tolerance of abiotic stress is less important than competitive exclusion in determining species distributions on environmental gradients Key words: competitive hierarchy, competitive reversal, transitivity.

scholarly journals Dissecting the genetic architecture of shoot growth in carrot (Daucus carota L.) using a diallel mating design

2017 ◽  
Author(s):  
Sarah D. Turner ◽  
Paul L. Maurizio ◽  
William Valdar ◽  
Brian S. Yandell ◽  
Philipp W. Simon
Keyword(s):  
Weed Control ◽  
Genetic Architecture ◽  
Competitive Ability ◽  
Shoot Growth ◽  
Mixed Model ◽  
Shoot Biomass ◽  
Additive Effects ◽  
Mating Design ◽  
Diallel Mating Design ◽  
Diallel Mating

ABSTRACTCrop establishment in carrot (Daucus carota L.) is limited by slow seedling growth and delayed canopy closure, resulting in high management costs for weed control. Varieties with improved growth habit (i.e. larger canopy and increased shoot biomass) may help mitigate weed control, but the underlying genetics of these traits in carrot is unknown. This project used a diallel mating design coupled with recent Bayesian analytical methods to determine the genetic basis of carrot shoot growth. Six diverse carrot inbred lines with variable shoot size were crossed in WI in 2014. F1 hybrids, reciprocal crosses, and parental selfs were grown in a randomized complete block design (RCBD) with two blocks in CA (2015, 2016) and in WI (2015). Measurements included canopy height, canopy width, shoot biomass, and root biomass. General and specific combining abilities were estimated using Griffing’s Model I. In parallel, additive, inbreeding, epistatic, and maternal effects were estimated from a Bayesian linear mixed model, which is more robust to dealing with missing data, outliers, and theoretical constraints than traditional biometric methods. Both additive and non-additive effects significantly influenced shoot traits, with non-additive effects playing a larger role early in the growing season, when weed control is most critical. Results suggest that early season canopy growth and root size express hybrid vigor and can be improved through reciprocal recurrent selection.Article SummaryBreeding for improved competitive ability is a priority in carrot, which suffers yield losses under weed pressure. However, improvement and in-depth genetic studies for these traits relies on knowledge of the underlying genetic architecture. This study estimated heritable and non-heritable components of carrot shoot growth from a diallel mating design using a Bayesian mixed model. Results directly contribute to improvement efforts by providing estimates of combining ability, identifying a useful tester line, and characterizing the genetic and non-genetic influences on traits for improved competitive ability in carrot.

Abiotic constraints on the competitive ability of exotic and native grasses in a Pacific Northwest prairie

Oecologia ◽  
2007 ◽  
Vol 155 (2) ◽  
pp. 357-366 ◽  
Author(s):  
Laurel Pfeifer-Meister ◽  
Esther M. Cole ◽  
Bitty A. Roy ◽  
Scott D. Bridgham
Keyword(s):  
Pacific Northwest ◽  
Competitive Ability ◽  
Native Grasses ◽  
Abiotic Constraints

scholarly journals The evolution of competitive ability for essential resources

2019 ◽  
Author(s):  
Joey R. Bernhardt ◽  
Pavel Kratina ◽  
Aaron Pereira ◽  
Manu Tamminen ◽  
Mridul K. Thomas ◽  
...  
Keyword(s):  
Competitive Ability ◽  
Community Dynamics ◽  
Species Coexistence ◽  
Resource Competition ◽  
Environmental Gradients ◽  
Light Limitation ◽  
Major Question ◽  
Trade Offs ◽  
Resource Requirements ◽  
Competitive Abilities

AbstractCompetition for limiting resources is among the most fundamental ecological interactions and has long been considered a key driver of species coexistence and biodiversity. Species’ minimum resource requirements, their R*s, are key traits that link individual physiological demands to the outcome of competition. However, a major question remains unanswered - to what extent are species’ competitive traits able to evolve in response to resource limitation? To address this knowledge gap, we performed an evolution experiment in which we exposed Chlamydomonas reinhardtii for approximately 285 generations to seven environments in chemostats which differed in resource supply ratios (including nitrogen, phosphorus and light limitation) and salt stress. We then grew the ancestors and descendants in common garden and quantified their competitive abilities for essential resources. We investigated constraints on trait evolution by testing whether changes in resource requirements for different resources were correlated. Competitive abilities for phosphorus improved in all populations, while competitive abilities for nitrogen and light increased in some populations and decreased in others. In contrast to the common assumption that there are trade-offs between competitive abilities for different resources, we found that improvements in competitive ability for a resource came at no detectable cost. Instead, improvements in competitive ability for multiple resources were either positively correlated or not significantly correlated. Using resource competition theory, we then demonstrated that rapid adaptation in competitive traits altered the predicted outcomes of competition. These results highlight the need to incorporate contemporary evolutionary change into predictions of competitive community dynamics over environmental gradients.

scholarly journals Mixotrophy in nanoflagellates across environmental gradients in the ocean

2019 ◽  
Vol 116 (13) ◽  
pp. 6211-6220 ◽  
Author(s):  
Kyle F. Edwards
Keyword(s):  
Competitive Ability ◽  
Resource Competition ◽  
Environmental Gradients ◽  
Light Availability ◽  
Field Studies ◽  
Heterotrophic Nanoflagellates ◽  
Coastal Environments ◽  
Unicellular Eukaryotes ◽  
Theoretical Predictions ◽  
Trophic Strategy

Mixotrophy, the combination of autotrophic and heterotrophic nutrition, is a common trophic strategy among unicellular eukaryotes in the ocean. There are a number of hypotheses about the conditions that select for mixotrophy, and field studies have documented the prevalence of mixotrophy in a range of environments. However, there is currently little evidence for how mixotrophy varies across environmental gradients, and whether empirical patterns support theoretical predictions. Here I synthesize experiments that have quantified the abundance of phototrophic, mixotrophic, and heterotrophic nanoflagellates, to ask whether there are broad patterns in the prevalence of mixotrophy (relative to pure autotrophy and heterotrophy), and to ask whether observed patterns are consistent with a trait-based model of trophic strategies. The data suggest that mixotrophs increase in abundance at lower latitudes, while autotrophs and heterotrophs do not, and that this may be driven by increased light availability. Both mixotrophs and autotrophs increase greatly in productive coastal environments, while heterotrophs increase only slightly. These patterns are consistent with a model of resource competition in which nutrients and carbon can both limit growth and mixotrophs experience a trade-off in allocating biomass to phagotrophy vs. autotrophic functions. Importantly, mixotrophy is selected for under a range of conditions even when mixotrophs experience a penalty for using a generalist trophic strategy, due to the synergy between photosynthetically derived carbon and prey-derived nutrients. For this reason mixotrophy is favored relative to specialist strategies by increased irradiance, while at the same time increased nutrient supply increases the competitive ability of mixotrophs against heterotrophs.

Wheat Crops and Native Prairie in Relation to the Nutritional Ecology of Camnula pellucida (Scudder) (Orthoptera: Acrididae) in Saskatchewan

1963 ◽  
Vol 95 (7) ◽  
pp. 764-770 ◽  
Author(s):  
R. Pickford
Keyword(s):  
Dominant Role ◽  
Nutritional Ecology ◽  
Bouteloua Gracilis ◽  
Field Cage ◽  
Agropyron Smithii ◽  
Native Prairie ◽  
Prairie Grasses ◽  
Complete Life Cycle ◽  
Stipa Comata ◽  
Mixed Prairie

AbstractField cage experiments conducted through the complete life cycle of Camnula pellucida (Scudder) demonstrated that wheat, the major cereal crop grown in Saskatchewan, played the dominant role in the nutritional ecology of this grasshopper. A native sod mixture, comprising Stipa comata, Bouteloua gracilis, Agropyron smithii, and Carex eleocharis, four of the dominant species of the mixed prairie association, was consistently unfavourable during all stages of grasshopper growth and development. Grasshoppers reared on wheat survived better, were considerably larger and laid up to 20 times more eggs than those reared on the native prairie grasses. The presence of the native sod with wheat contributed nothing nutritionally to the food combination. The unfavourable qualities of the native grasses, although resulting in small adults, low fecundity and small pods, did not affect the hatchability of eggs laid or the development and survival of nymphs that hatched from them.

Native prairie grasses and microbial community responses to reclamation of taconite iron ore tailing

1995 ◽  
Vol 73 (10) ◽  
pp. 1645-1654 ◽  
Author(s):  
Robert K. Noyd ◽  
F. L. Pfleger ◽  
Michael R. Norland ◽  
Michael J. Sadowsky
Keyword(s):  
Microbial Biomass ◽  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Soil Microbial Biomass ◽  
Plant Cover ◽  
Arbuscular Mycorrhizal ◽  
Yard Waste ◽  
Soil Microbial ◽  
Native Prairie ◽  
Prairie Grasses

The effect of reclamation treatments on seeded native grass cover and species composition, soil microbial biomass carbon, and populations of actinomycetes, fungi, free-living N2-fixing bacteria, and aerobic heterotrophic bacteria was compared in field plots in coarse taconite tailing. Reclamation treatments consisted of all possible combinations of three rates of composed yard waste, three rates of fertilizer, and inoculation with arbuscular mycorrhizal fungi. Composted yard waste increased plant cover, soil microbial biomass, and populations of all groups of microorganisms compared with unamended, non-inoculated control plots. Microbial populations and biomass in tailing plots were low compared with natural soils and were correlated with plant cover and available P. Mycorrhizal inoculation resulted in a 6% increase in plant cover, although this was not significant, and significantly enhanced N2-fixer populations in June but did not affect other groups of microorganisms. There were no differences between moderate and high rates of composted yard waste. We conclude that incorporation of a moderate rate of organic matter can ameliorate the stressful conditions of coarse taconite tailing and can enhance the initiation of a functional soil ecosystem able to support the establishment of seeded native prairie grasses and may provide a long-term solution to reclamation of taconite tailing. Key words: arbuscular mycorrhizal fungi, mine reclamation, soil microorganisms, composted yard waste.

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