京都大学 / 新制・課程博士 / 博士(経済学) / 甲第24378号 / 経博第665号 / 新制||経||303(附属図書館) / 京都大学大学院経済学研究科経済学専攻 / (主査)教授 関口 格, 教授 原 千秋, 准教授 陳 珈惠 / 学位規則第4条第1項該当 / Doctor of Economics / Kyoto University / DFAM

Field experiments using small replicated enclosures focused on interactions between larval populations of Epitheca cynosura and Ladona deplanata (Odonata: Anisoptera) - two species that emerge in early spring. The presence of Epitheca reduced the total biomass of Ladona, but Ladona had no significant effect on Epitheca. These early-emerging species reduced the biomass of small instars of late-emerging Anisoptera which colonized enclosures during the experiments; and the late-emerging Anisoptera seem to have inhibited colonization by Zygoptera larvae. Results are consistent with the importance of predatory (cannibalism or mutual predation) interactions in this community.

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The competitive strategy used by a new firm may be the most important strategy it ever employs (Covin & Slevin, 1989; Ferrier, 2001). A well-chosen and executed firm strategy is essential for a firm to realize its potential competitive advantage (Porter, 1981). A firm‘s strategic intent and resulting competitive actions are especially important when firms are new and vulnerable as they strive to learn which strategic actions help them adapt to their rivals actions and to their environment (Stinchcombe, 1965). Further, the competitive actions that new firms choose to take with rival firms affects the overall competitive dynamics of their industry (Smith, Ferrier, and Ndofor, 2001). One way to explore how the competitive actions of new firms affect their future is to capture and examine their individual competitive moves and countermoves over time (Smith, Grimm, Gannon, & Chen, 1991). Red Queen competition is a particular form of competitive dynamics that is well-suited to explore these issues of new rival firms (Barnett, 2008). Barnett and Sorenson (2002) suggested that competition and learning reinforce one another as organizations develop, and this is what van Valen (1973) referred to as the ‗Red Queen.‘ This definition of the Red Queen led to the development of the concept of Red Queen competition and the Red Queen effect. The competitive strategies these new firms use to obtain resources as they adapt, in particular how these firms compete and or cooperate, are key competitive strategies that remain understudied to-date (Amit, Glosten, and Muller, 1990). I explore Red Queen competition, and the ensuing Red Queen Effect, in a complex environmental setting that represents a high technology ecosystem (Arned, 1996, 2010; Iansiti & Levien, 2004a, 2004b; Moore, 1993; Pierce, 2009). New firms in such an ecosystem represent a particularly salient combination of type of firm, firm lifecycle period, and firm environment to iii examine strategic actions since these firms comprise a significant portion of the high-growth and future of our global economy (Stangler, 2010). Further, due to their need to rapidly adapt in a complex ecosystem, these firms rely heavily on short-lived information resources for competitive advantage (Barney, 1991; Nelson and Winter, 1982; Omerzel, 2008). To place this research in context, I consider the moderating effects of key environmental ecosystem resource conditions (Dess & Beard, 1984; Miller & Friesen, 1983; Sharfman & Dean, 1991). Empirical studies to-date have yielded mixed results and left unanswered questions about the basic components and the effects of Red Queen competition. To address these issues I explore this literature in chapter one of the dissertation, and in chapter two I develop a theoretical model of Red Queen competition that draws on the available empirical and theoretical literature to-date. Due to the mixed finding from the empirical results, I develop a precise agent-based simulation model of Red Queen competition in chapter three to facilitate data collection. Using this data I test a series of hypotheses designed to explore the fundamentals of Red Queen competition, specifically how escalating competitive activity for resources among new firms impacts their survival and performance. In addition, the moderating effect of environmental changes on Red Queen competition is also tested to explore the affect of context on Red Queen competition. Chapter four explains the findings from these hypotheses, future research directions, implications and limitations from the research, and my concluding thoughts

Plant communities that occur on edaphically heterogeneous landscapes are ideal systems for exploring questions of niche and community assembly. Species with affinity for harsh substrates often have well-defined edaphic niches and are ideal models for testing ecological and evolutionary theory. While plants on substrates such as serpentine and gypsum have received much attention, those on other harsh substrates, including on vertic clay soils, have gone unstudied. Vertic clay soils are both chemically and physically challenging to plant establishment and productivity. Plant communities associated with vertic clay soils of the San Joaquin Desert appear to have a distinctive mosaic pattern of species distribution that reflect differences in soil properties across the landscape. I conducted fieldwork and a pot study with 12 native annual plant species with an affinity for vertic clay soils to determine whether the vertic clay soils at two sites in the San Joaquin Desert were heterogeneous, whether soil heterogeneity predicted the pattern of species distributions observed, and to examine the competition effects of an invasive annual grass (Bromus madritensis) on these species. I found that the vertic clay soils at both of my sites are internally heterogeneous, that soil heterogeneity does appear to shape the patchy distribution of species at both these sites, and that these species have different realized edaphic niches. I utilized treatment soils spanning a gradient of chemical stress present at both study sites in my pot study and found that competition from B. madritensis reduces biomass for all species, and that the effect of competition differed between soil types. Further, I found that species’ edaphic niche optima shift when competition is present, and that competitive ability differed across the gradient of edaphic stress in my treatment soils.

The primary objective of this study was to explore the relationship among various market structure constructs (consisting of barriers to entry, competition, growth, and market share) and their potential impact on financial performance. By applying theoretical underpinnings from the disciplines of marketing, strategy and industrial organization economics, and adapting them to the unique characteristics of the U.S. lodging industry, the above constructs were linked to produce the Lodging Market Structure (LMS) Model. The study consisted of a cross-sectional analysis using a sample of 67 well-recognized hotel brands operating in the U.S. (representing 63 percent of the national guestroom inventory), covering a four-year period between 1996 and 1999. Correlation and multiple regression analysis were used to examine the hypothesized relationships within the LMS model. This study represented the first comprehensive investigation of the competitive market structure of the U.S. lodging industry. The key findings of the study indicate that the financial performance of hotel brands in the United States is strongly impacted by competitive market structure. Among the various market structure constructs studied, barriers to entry played the most dominant role in determining the level of financial performance of hotel brands. Based on a strong negative relationship, barriers to entry are very effective in reducing competition in the U.S. lodging industry. Also, of the constructs studied, barriers to entry had the greatest influence on enhancing the market share of incumbent hotel brands. The growth rate of those incumbent brands has a positive relationship with barriers to entry. As competition intensifies, the growth rate of hotel brands slows down. Increases in competition are negatively correlated with a brand's market share. Competition has a strong negative relationship with the financial performance of hotel brands. Market share improves as the growth rate of hotel brands increases. As the growth rate of brands increases, profitability also improves. Likewise, improvements in a hotel brand's market share are positively related to increases in profitability. Lastly, the U.S. lodging market is becoming more competitive, and the industry has reached the mature stage of its lifecycle. / Ph. D.

Technical Standards have become a new arena of competition in the race for technological leadership since securing their control and ownership provides considerable economic and political advantages. Particularly telecommunication standards, which underpin global networks, can produce substantial economic and strategic benefits for the country and industry that largely shape their process and outcome. In light of these implications, new aspiring standard setters, such as China and South Korea, have actively increased their participation in international standards settings, challenging the predominant position of traditional standard setters such as the United States and European countries. The rise of new aspiring standard setters has provoked shifts in the power structures of international standardization regimes that had mostly reflected the preferences of traditional standard setters in the last decade, implying a redistribution of gains and costs among countries and industries. Despite this, only a few studies have focused on explaining power shifts in international standardization, drawing on IR/IPE theories. In addition, studies have only partially inquired about the political and economic of conditions that might explain such shifts. Against this background, this study aims to contribute to the literature focusing on power shifts in standardization by assessing under what conditions countries turn into leading standard setters. This is evaluated empirically by analyzing the capacity of six technological powers in shaping the three latest generations of telecommunication standards, namely 3G, 4G, and 5G. It deploys a multimethod approach to perform the analysis, combining a Qualitative Comparative Analysis (QCA) with a process tracing (PT) analysis. The study found that the combination of conditions composed of a great innovator, a large economic power, and a highly complementary domestic system resulted in the most consistent sufficiency path, suggesting that when countries hold roughly the same technological and economic capabilities, a complementary system conducive to a strong government-industry partnership proves crucial to shaping standardization. This interpretation calls for further research on the role and influence of governments in securing technological leadership by providing competitive advantages to industries contributing to global standards.

<p>Sperm competition, the contest between sperm from rival males for fertilizations, is an important evolutionary force shaping sperm characteristics. Theory predicts that males experiencing elevated levels of sperm competition will invest more in sperm number, size and speed. While broad support exists for the idea that elevations in sperm competition lead to increased investment in sperm production, there is mixed support for the role of sperm competition in shaping sperm size and swimming speed. In this thesis, using a combination of within-species and comparative studies, I describe how sperm competition has influenced sperm traits in fishes and critically test a number of predictions from sperm competition theory. In the marine plainfin midshipman fish (Porichthys notatus) and the fresh-water shell brooding cichlid Telmatochromis vittatus, I show that the males who experience the highest level of sperm competition had faster but not longer sperm. Instead, selection appears to have acted on sperm energetics, increasing energy production to drive sperm movement in males who experience more intense levels of sperm competition. In a comparative study using Tanganyikan cichlids, I show that males in species experiencing high levels of sperm competition (i.e. promiscuous species) had both longer and faster sperm than males of closely related species unlikely to experience sperm competition (i.e. monogamous species). I also uncovered a predicted but previously inadequately tested relationship between sperm size and speed. This relationship holds across, but not within, species and I discuss possible explanations for differences between and within species. Finally, I used directional tests of trait evolution to assess how selection acts to increase sperm swimming speed and provide evidence that the evolution of fast swimming sperm preceded the evolution of long sperm across cichlid fishes. Together, the results of this thesis show that spenn competition promotes the evolution of faster swimming spenn in fishes and highlights the importance of sperm energetics in detennining the competitive success of ejaculates.</p> / Thesis / Doctor of Philosophy (PhD)

Drosophila melanogaster is a valuable model for studying various aspects of human cancer, including proliferative capacity, invasiveness and metabolic adaptation typical of tumour cells to support cell growth. One of the major players in this process is Myc, which can promote tumorigenesis by triggering a metabolic reprogramming that allows cells to produce macromolecules, by modulating glycolytic flux, glutaminolysis, lipidogenesis, and autophagy. The process by which hyperproliferative cells undergo metabolic reprogramming to sustain growth can be recapitulated in the epithelial cells from Drosophila imaginal discs, where different levels of Myc induce cell competition. This process is a mechanism for selection of cells expressing higher level of Myc that acquire a super-competitor condition, with the ability to non-autonomously kill the neighbouring slow-growing cells. The direct connection between Myc, glutamine metabolism and autophagy and their role in competitive events between cancerous cells and wild type cells have not been clearly explained; therefore, the main purpose of this project is to determine a plausible link between Myc and autophagy, by examining the dependency of Myc-induced autophagy on glutaminase and major regulators of autophagy, such as TOR, Atg1, Atg5 and ammonia, a by-product of glutamine catabolism, by dissecting these mechanisms both in normal epithelial clones and hyperproliferating RasV12 -expressing cells. Our results show that Myc promotes the transcription of glutamine-related genes and the production of ammonia, and that glutaminase is necessary for Myc-induced autophagy in epithelial cells of clones of the wing imaginal discs, with a mechanism independent from TOR and Atg1. Conversely, the effect of Myc on autophagy induction is mediated by Atg5. We then investigated the contribute of Myc in autophagy in RasV12-transformed cells, that upregulate Myc to sustain growth and hyperproliferation. Intriguingly, our data report that autophagy is increased non-autonomously in neighbouring wild type cells, and that this non-autonomous RasV12-driven autophagic flux depends on Myc activity. Moreover, downregulation of glutaminase in RasV12-expressing cells significantly reduces non-autonomous autophagy. Collectively, our results give new insights on how glutamine metabolism can contribute to Myc-induced autophagy and how this enhances cancerous cell fitness.

As coral reefs decline globally, there is an urgent need to understand recovery pathways and trajectories to both assess reef status and intervene with reef restoration efforts. However, the ecological role of various coral taxa on reef successional pathways is poorly understood. Building on terrestrial successional frameworks, it seems logical that weedy coral species may be placeholder species that quickly colonize cleared areas after a disturbance, but that are later replaced by more competitive, slower-growing species, leading to overall more biodiverse reefs. To test the competitive ability of a common pioneer species on Pacific reefs, Montipora aequituberculata, we tracked about 600 colonies across six equatorial islands through two time points (50 colonies per site per island), examining whether this species was more typically overgrown by other species over time, or whether M. aequituberculata was a more dominant competitor capable of overgrowing other reef taxa. Using photogrammetric data, we set out to answer questions about the fates of focal colonies and their place in the competitive hierarchy. Trajectories of area change of the focal colonies varied across islands, though they did not follow geographic patterns. Many of the changes in these post-disturbance reefs sometimes differed by site, even on the same island, and were not consistent within an archipelago. At an island scale, Howland (Phoenix Islands) and Flint (Line Islands) showed the greatest growth of focal colonies, while Enderbury (Phoenix) and Millennium (Line) lost the most coral coverage of focal colonies. Interactions between the focal colony and other coral species were more consistent across islands, with the most common interactions being with other colonies of M. aequituberculata as well as common species of Porites and Pocillopora. There was a consistent trend of focal colonies mostly being overgrown by other colonies of M. aequituberculata: this conspecific replacement suggests that this species is capable of self-perpetuating as a primary space holder in lieu of other coral interactions. In contrast, most other coral species were commonly overgrown by the focal M. aequituberculata, suggesting that M. aequituberculata is a strong competitor when vying for groundcover. Indeed, M. aequituberculata may be able to dominate reefs post-disturbance until stress-tolerant species take over. Surprisingly however, we did not see a consistent pattern of species interaction, meaning that there was not a single coral taxon that universally overgrew M. aequituberculata, suggesting that M. aequituberculata is a generalist competitor and is not a specialized facilitator of any one competitively dominant taxa. Islands with similar species interaction patterns are not the same islands with similar growth or loss patterns, suggesting that site-level ecological complexity overrules any general patterns of geography or species interactions. This study is among the first to provide detailed species interactions in a successional framework, paving the way for future studies to do the same in the hopes that we can predict the trajectory of reefs based on the community composition.