Global ETD Search

1	Internal analysis of asymmetric competitive market strucuture using supermarket aggregate data Wu, Fang Unknown Date No description available. internal analysis market structure aggregate date Bayesian technique asymmetric competition
2	Size-structured competition and predation in red-eyed treefrog tadpoles Asquith, Christopher 25 March 2010 (has links) Body size is important in determining the outcome of competition and predator-prey interactions. Size structure of a population (i.e. relative proportion of large and small conspecifics) may be particularly important in organisms with prolonged breeding periods and rapid growth where populations may have multiple cohorts at different stages of development competing for one resource. Both the consumptive and nonconsumptive effects of predators can also be size-dependent and can alter competitive interactions. Here we study the importance of size structure in the Neotropical leaf-breeding tree frog, Agalychnis callidryas. This species is a prolonged breeder such that multiple overlapping cohorts of differing sizes are common. Specifically, we examine size-specific intraspecific competition between A. callidryas tadpoles and then explore how predation affects these interactions. To determine the strength of inter-cohort competition, we manipulated the density and relative proportion of large and hatchling tadpoles in a response surface design and quantified growth. We then observed the effect of a dragonfly larvae predator (Anax amazili) on tadpole growth and survival at different size-structured treatments. Large tadpoles were greater per individual competitors while hatchlings were greater per gram competitors. When predators were added, dragonflies reduced survival and growth of hatchlings substantially, but had no effect on large tadpoles. Further, dragonflies reduced hatchling growth more when other hatchlings were present. The predator effect on hatchling growth was 23% larger than the effect of competition with large tadpoles, such that the importance of size structure for A. callidryas may be mediated more through predation than intercohort competition. Population size structure asymmetric competition nonconsumptive predator effects leaf-breeding treefrogs Smithsonian Tropical Research Institute Biology Life Sciences
3	Intraspecific competition among early life stages and the optimal spawning strategy of red drum (Sciaenops ocellatus) Nakayama, Shinnosuke, 1978- 24 January 2011 (has links) This collection of studies was designed to understand the mechanisms and consequences of competition among early life stages of red drum (Sciaenops ocellatus), with a special attention to asymmetric competition and multiple-breeding strategy of parents. The overall hypotheses were that (1) red drum larvae show behavioral interactions, and the magnitude of these interactions is explained by the sizes of the competing individuals, (2) red drum larvae compete for food and habitat use, and the competition is asymmetric as determined by size and behavioral interactions, and (3) the parents can reduce negative effects of competition among larvae and increase larval survival by altering their multiple-spawning traits. The laboratory experiments showed the existence of sociality in red drum larvae. The magnitudes of aggressive behavior, vigilant behavior and shoaling behavior were explained by a combination of absolute and relative phenotypes of competing individuals, such as body lengths and body condition. A new method of combining the laboratory experiments and the foraging theory disentangled interference competition for food from exploitative competition, revealing that both absolute and relative body lengths of competing individuals influence feeding efficiencies. In addition, vigilant behavior decreased feeding efficiency regardless of body sizes. The competitor size and behavioral interactions between individuals had different effects on competition for habitat use: the existence of larger individuals prevented the newly settled larvae from entering preferred habitats, whereas the aggressive behavior from the occupants of preferred habitats moved newly settled larvae to the unpreferred habitats. Finally, computer simulations using an individual-based model revealed that as interference competition among larvae increased, the number of spawning events and the spawning interval of the parents increased to lessen competition and maximize total survival of offspring. / text Red drum Sciaenops ocellatus Intraspecific competition Red drum larvae Spawning Multiple-breeding strategy Asymmetric competition Behavioral interactions Interference competition
4	Intra- and interspecific variation of functional traits, growth performance and belowground competition in <i>Populus</i> species Hajek, Peter 27 March 2014 (has links) No description available. 333 577 Populus tremula Populus tremuloides Fine root morphology Genetic variation Intraspecific variation Relative growth rate Root tissue density Specific root area Asymmetric competition Pioneer roots Root age Fine root morphology Root order Genetic variability Vulnerability to cavitation P50 Hydraulic conductivity High conductivity roots Coarse root anatomy Branch xylem anatomy Vessel diameter Relative growth rate Poplar Ökologie {Biologie} (PPN619463619)
5	Impact of climate change-induced drought on tree root hydraulic properties and competition belowground / Einfluss von Bodentrockenheit auf die hydraulischen Eigenschaften und das Konkurrenzverhalten von Baumwurzeln Rewald, Boris 30 April 2008 (has links) No description available. 580 Pflanzen (Botanik) WNA 250 WVC 400 WVE 420 WVR 200 Mathematics and Natural Science Winterlinde Hainbuche Altbäume asymetrische Konkurrenz Buche Boden-Trockenheit Dach-Experiment Embolierate Feinwurzel Grobwurzel Klimawandel Olive Salzstress spezifische Leitfähigkeit Traubeneiche unterirdische Konkurrenz Xylemmorphologie Tilia cordata Carpinus betulus asymmetric competition belowground competition climate change coarse root drought stress embolism Fagus sylvatica fine root salt stress specific conductivity mature trees NaCl Olea europaea Quercus petraea roof experiment xylem morphology 42.40 42.58 42.97 43.47 43.61

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