Thirty-one tobacco introductions that were reported to display either a local lesion or a symptomless reaction to infection with tobacco mosaic virus (TMV) were screened for reaction to the virus (Chaplin and Gooding, 1969). Ten tobacco introductions (TI), TI 203, TI 407, TI 438, TI 450, TI 692, TI 1203, TI 1459, TI 1462, TI 1467, and TI 1500 were randomly chosen for further study to characterize their resistance to tobacco mosaic virus (TMV). Each TI line was crossed with susceptible cultivar K 326 to determine the mode of inheritance of resistance to TMV. The F2 progeny of TIs 1459, 1462, and 1500 segregated in a 3 local lesion:1 mosaic ratio, indicating that the gene governing resistance in these three TI lines was a single, dominant trait. The F2 progeny of TIs 203, 407, 438, 450, 692, 1203, and 1467 failed to segregate, only mosaic plants were observed. This would indicate that the gene(s) controlling resistance to TMV in these lines would not provide resistance for plant breeders to incorporate into a breeding program. Each TI line was also crossed with local lesion cultivar NC 567, which contains the N gene, in order to determine if the gene(s) governing resistance in the TI lines was allelic to the N gene in NC 567. The F2 progeny of TIs 1459 and 1462 did not segregate. All progeny displayed the local lesion reaction to TMV indicating that the gene governing resistance in these two lines is allelic to the N gene. The F2 progeny of the cross between TI 1500 and NC 567 segregated in a 15 local lesion: 1 mosaic ratio, which indicates that the gene controlling resistance in TI 1500 is not allelic to the N gene. When crossed with NC 567, the F2 progeny of TIs 407, 438 and 1467, segregated in a 3 local lesion: 1 mosaic ratio. No symptomless plants were observed. There was also segregation in the F2 progeny of the crosses between NC 567 and TIs 203, 450, 692, and 1203. However, the segregation was in no discernible ratio. Once again the F2 progeny of the crosses either displayed a local lesion or mosaic reaction and no symptomless progeny were observed. This would again indicate that the symptomless TI lines do no provide heritable resistance to TMV and therefore are not acceptable as an alternative source of resistance to TMV for the plant breeder. Tobacco introduction 1500 should be investigated further because a single, dominant trait that is not allelic to the N gene governs resistance to TMV in this line. / Master of Science

Part of the natural progression of any romantic relationship is that, over time, individuals will meet and form connections with each other’s friends and family (Milardo, 1982). Interestingly, the examination of social network introductions has largely been neglected by researchers. We do not know when couple members introduce each other to their friends and parents. We also do not know what effect, if any, these network introductions have on future relationship outcomes. The present study addressed these gaps. Specifically, I examined when couple members typically met each other’s friends and parents for the first time, whether relationship quality influenced the likelihood of making these introductions, and whether these introductions predicted later relationship outcomes (i.e., relationship quality, likelihood of breakup, and post-breakup adjustment). In the present study, participants in new romantic relationships (less than 6 months duration) completed a survey every two weeks for nine months. In each survey, participants indicated whether friend and family introductions had occurred, their current relationship quality, and whether they had broken up with their partners since the previous survey. If individuals reported having broken up, they were asked about their reactions to the breakup. Results revealed that friends were typically introduced before parents, and that relationship quality predicted the likelihood of newly dating individuals introducing their parents (but not friends) to their romantic partners. Largely, network introductions failed to predict later perceptions of relationship quality but did influence the likelihood of relationship dissolution over the course of the study. Furthermore, introductions to participants’ mothers predicted worse emotional reactions to a breakup, and introductions to participants’ fathers and best friends were associated with greater relationship longing. The results of this study represent an important first step in understanding when individuals introduce their romantic partners to their friends and family and how these introductions influence relationship development. / text

Organizations increasingly engage in launching new products, but they show heterogeneous decision-making patterns in new product strategies. This dissertation attempts to study the source of organizational heterogeneity in new product introductions (NPIs) by applying behavioral perspectives. To this end, this dissertation examines how organizations respond to the conditions of themselves and others through various decisions on new product introductions. I propose that organizations learn directly from their own experience that is relative to their own historical experience and their peers’ experience (i.e., performance feedback) and respond to it by jointly combining different aspects of NPIs such as NPI exploration and speed. Highlighting the perspectives of external actors, I also postulate that when organizations learn vicariously from their peers’ experience is contingent on the characteristics of peers and industry that are sending different signals to observing entities, such as external actors. Through three essays, I examine these ideas in the U.S. movie industry where movie studios rely on performance feedback and the conditions of others to make subsequent movie decisions.At the heart of this dissertation is the notion that organizations learn from their experience or experience of others by collecting performance information, interpreting it, and changing their NPI activities. This dissertation responds to an important call of Gavetti, Greve, Levinthala, & Ocasio (2012) for research in the cognitive aspects in decision making and the dynamics of interacting behavioral entities—organizations and institutional environments (e.g., peer organizations and investors)—filling important gaps in the literature and hence advancing our understanding of why, when, and which NPI decisions are adopted. / Business Administration/Strategic Management

Les activités humaines sont à l’origine de profondes modifications de la distribution naturelle des espèces. Les introductions d’espèces sont en particulier à l’origine de contacts secondaires entre espèces non isolées reproductivement et ayant divergé en allopatrie. Cette situation est un cas d’étude particulièrement intéressant pour étudier des processus éco-évolutifs, tels que la coexistence d’espèces occupant de même niches écologiques ou les flux de gènes contemporains (i.e. hybridation et introgression) entre espèces indigènes et non-indigènes. Cette thèse s’est ainsi intéressée aux interactions écologiques et génomiques entre deux ascidies congénériques et interfertiles, Ciona robusta et Ciona intestinalis. Ces deux ascidies, abondantes dans les habitats portuaires, sont en sympatrie en Manche Occidentale suite à l’introduction récente de C. robusta (supposée originaire du Pacifique Nord-Ouest) dans l’aire de distribution naturelle de C. intestinalis. Par une étude de la distribution spatiale et temporelle (inter-saisonnière et inter- annuelle) des adultes des deux espèces et de la sédentarisation de leurs juvéniles, nous avons montré que les deux espèces coexistent de façon durable, au sein de communautés similaires, à l’échelle régionale. Elles vivent en syntopie dans la majorité des habitats portuaires étudiés, bien qu’il existe une importante dynamique saisonnière de leur abondance relative : C. robusta est surtout présente en fin d’été et en automne, et toujours en moindre abondance par rapport à sa congénère indigène. Cette syntopie, l’interfertilité des deux espèces et le synchronisme de leur maturité sexuelle indiquent un potentiel d’hybridation important entre les deux espèces. L’hybridation réalisée est pourtant faible, comme montré avec quatre marqueurs moléculaires diagnostiques des deux espèces, analysés sur plus de 3000 individus : seulement 4% des individus présentent des génotypes compatibles avec de l’hybridation ou de l’introgression. Ces résultats ont été complétés par une étude de génomique des populations (310 marqueurs SNPs et 450 individus collectés dans différents océans) : ils confirment que les flux de gènes interspécifiques sont très rares. Par ailleurs, les rares locus présentant du polymorphisme partagé montrent un taux d’introgression hétérogène, et l’introgression est également observée dans des localités où seule l’une des espèces existe (ex. côtes américaines et chiliennes). L’ensemble des résultats génétiques et génomiques indiquent que le flux de gènes interspécifique observé résulte d’introgressions anciennes (probablement au Pléistocène) et non contemporaines. Une dernière étude menée à l’échelle mondiale avec des marqueurs mitochondriaux a par ailleurs permis de montrer que les processus d’introduction de C. robusta diffèrent selon les régions d’introduction et pose la question du statut réellement non-indigène des deux espèces dans certaines régions. Ainsi, cette thèse a montré la (quasi)-absence d’hybridation actuelle entre C. robusta et C. intestinalis, en situation de syntopie. Elle ouvre des perspectives quant à l’étude des mécanismes d’isolement reproductif entre ces deux espèces. La question du devenir à long terme des deux espèces, qui par leur coexistence étroite sont en compétition, est posée. Cette compétition pourrait être modulée par leurs préférences environnementales et les changements climatiques en cours dans l’Atlantique Nord. Enfin, cette thèse illustre comment des processus contemporains et anciens interagissent pour façonner la distribution et l’évolution des espèces, la structure génétique de leurs populations et l’architecture de leur génome. / Human activities severely alter species ranges that have been built on evolutionary time scales, and biological introductions promote secondary contacts between non-reproductively isolated species that were in allopatry. Such a situation is a very interesting case-study to examine eco-evolutionary processes, for instance coexistence between species sharing the same ecological niche or inter-specific gene flow (i.e. hybridization and introgression) between native and non-native species. This PhD thesis studied ecological and genomic interactions between two biologically similar, interfertile and congeneric tunicates, namely Ciona robusta and Ciona intestinalis. They are both abundant in harbours and marinas. They are sympatric in the Western English Channel because of the recent introduction of C. robusta (putatively native to Asia) in the natural range of C. intestinalis. Based on spatial and temporal (seasons and years) adult abundance data and examination of recruitment patterns of the two species, we showed that the two species are sustainably coexisting at a regional scale in Brittany, within similar communities. They live in syntopy in most of the study marinas. However, there are significant changes in their relative abundance through time: C. robusta is mostly present at the end of the summer and in the autumn, although always being less abundant than its native congener. Syntopy, interfertility between the two species and synchronous sexual maturity all indicated a high likelihood of hybridization between the two species. The realized hybridization is however very low, as shown by 4 species-diagnostic molecular markers genotyped over more than 3000 individuals: only 4% of the individuals displayed a genotype compatible with hybridization or introgression. This result has been confirmed with a population genomics study (310 SNPs; 450 individuals collected worldwide): inter-specific gene flow is very low. In addition, the few loci showing shared polymorphism displayed variable introgression rates and introgression was observed even in allopatric localities (where only one of the two species exists nowadays). Overall, the genetic and genomic results indicate that interspecific gene flow is most likely due to past introgression events (that may have occurred during the Pleistocene). Finally, a study carried out at a worldwide scale with two mitochondrial loci, showed that the introduction processes of C. robusta are different among the introduced regions. This study also questions the non-native status of the two Ciona species in some regions. This work showed the near absence of contemporary hybridization between C. robusta and C. intestinalis, even in syntopy, opening new research perspectives about the mechanisms preventing their reproduction in the wild. It also questions the fate of these two competing species; this competition may depend on the interaction between their specific environmental preferences and on on-going climatic changes in the North Atlantic. Altogether, this work illustrates the interplay between contemporary and past processes on species distribution and evolution, population genetic structure and genomic architecture.

Companies that advertise during the Super Bowl can reach 40 million U.S. households with a 30-second commercial spot, but the cost can exceed $2 million. This research examines Nielsen television ratings and expenses for related commercial spots and suggests that the Super Bowl is not always the best site for introducing new companies or products to the marketplace. ANOVA test results indicate that younger companies may better affect purchase decisions by advertising more frequently during less expensive programming slots.

When purchasing durable goods, consumers not only pay for current but also future consumption; consequently, forward looking behavior is an important consideration in durable goods markets. For example, anticipating that prices will go down in the future, consumers may delay the purchase today; such behavior has a significant impact on the firm’s marketing strategies. This dissertation investigates the impact of durability on two marketing strategies: new product introductions and supply chain design. The first part of this dissertation (Chapter 3) examines a durable goods manufacturer’s new product introduction strategy under different market environments where network effects and product compatibility are important. More specifically, this part explores the incentives of a firm to use either a replacement strategy or a skipping strategy—in the former, the firm commercializes the existing technology, while in the latter, it does not; in either case, an improved technology will be available in the future and the firm will introduce a new product at that time. Using a two-period analytical model with network effects, the analysis shows how the level of improvement in the new product, along with the type of compatibility between the products, interacts with network strength to determine the manufacturer’s optimal strategy. Under gradual new product improvement, there is a strict preference for replacement. In contrast, under rapid new product improvement, that preference only holds in markets with relatively high levels of the network strength; at lower levels of the network strength, skipping is preferred; interestingly, for moderate values of the network strength, the level of product improvement affects the manufacturer’s optimal choice differently under varying types of compatibility. The second part of this dissertation (Chapters 4 and 5) focuses on the supply chain design decisions of a durable goods manufacturer who is a sole supplier of an essential proprietary component for making the end product. Three different supply chain structures iii are considered. In the first, the manufacturer operates as a “component supplier” and sells the component to a downstream firm who then makes the end product. In the second structure, the manufacturer produces the end product using its component but does not make that component available to any other firms; here, the manufacturer operates as a “sole entrant”. Finally, the manufacturer can operate as a “dual distributor” who not only makes the end product using its own component, but sells the component to a downstream firm who then competes against the manufacturer in the end product market. The extant literature on the optimal choice among the above supply chain structures has focused mainly on static settings in a framework of price competition. By contrast, researchers predominantly use quantity competition to examine durable goods markets in dynamic (i.e., multiple time period) settings. Moreover, the literature notes diversity in optimal firm behavior under the two types of (i.e., price and quantity) competition. Therefore, to transition from supply chain design in a static setting to a more dynamic one where consumers are forward-looking, this part utilizes Chapter 4 to analyze the manufacturer’s choice using quantity competition in a static setting. This analysis (in Chapter 4) identifies precisely the shift in the manufacturer’s choice of supply chain structure when moving from price competition to a quantity competition framework. With that analysis as a benchmark, the next chapter focuses on the manufacturer’s choice in a dynamic setting. More specifically, Chapter 5 investigates the impact of durability on the optimality of the supply chain structures identified above. Using a two period setting, the analysis explores how the manufacturer’s preference for different supply chain structures is modified. The findings reveal that, e.g., when durability is taken into account, the manufacturer’s preference for the sole entrant role goes up, while the preference for the component supplier role goes down. Further, under certain conditions, the manufacturer may opt to be a dual distributor in the first period and then choose to become only a component supplier in the second period. The underlying rationale for such shifts in preference iv is directly linked to durability, which creates future competition and substantially reduces the manufacturer’s profitability in the long run. Interestingly, this negative impact varies across different supply chain structures. Overall, this dissertation contributes to the current literature on durable goods and enhances our understanding of the impact of durability on the optimality of distinct marketing strategies, and provides insights that are valuable to both academics and managers.

No description available.

Cette thèse s’inscrit dans le contexte de la biologie de l’invasion de la chrysomèle des racines du maïs, Diabrotica virgifera virgifera (Dvv), en Europe. Les introductions multiples de cette peste sur le vieux continent à partir des années 1990 et en provenance des États-Unis ont conduit à la formation de plusieurs foyers envahissants dont deux principaux, différenciés génétiquement et situés en Italie du Nord-Ouest (Italie NO) et en Europe Centrale et du Sud-Est (Europe CSE). Ces deux foyers sont entrés en contact en 2008, en Italie du Nord, dans la région de la Vénétie. L’objectif principal de ces trois années de recherche était de détecter, d’étudier et de documenter un cas précis d’hybridation au cours d’une invasion biologique. Dans un premier temps, j'ai montré que la zone de contact détectée en Vénétie résultait bien en une zone hybride. Pour cela plusieurs types d’analyses de génétique des populations ont été réalisés à l’aide de marqueurs micro-satellites. Dans un second temps, j'ai exploité cette zone hybride et utilisé la théorie des clines neutres et le déséquilibre de liaison pour estimer la dispersion (σ) de Dvv en Italie du Nord aux alentours de 20 km.génération−1/2. Enfin j'ai montré l’absence d'impact de l’hybridation au cours de l’invasion européenne de Dvv in natura, en mesurant sur des génotypes hybrides et parentaux, de nombreux traits phénotypiques positivement liés à la fitness des individus. Ainsi, une sélection ou contre sélection des hybrides est à exclure dans ce cas précis d’hybridation et la dynamique de l’invasion de cette peste en Europe ne devrait être affectée en aucune façon. / This thesis deals with the invasion biology of the western corn rootworm, (WCR) in Europe. Multiple introductions of this pest in Europe from the United States and the 90’s, led to the formation of two main invasive outbreaks, genetically differentiated and located in Northwest Italy (NW Italy) and in Central and South-Eastern Europe (CSE Europe). Both outbreaks converged towards each other and came into contact in 2008, in the region of Veneto (Northern Italy). The main objective of these three years of research was to detect study and document a precise case of hybridization during a biological invasion. First of all, I showed that the contact zone detected in Veneto results in a hybrid zone. For that, several types of population genetics analyses were performed using microsatellite markers. In a second time, I exploited this hybrid zone and used the theory of neutral clines and the linkage disequilibrium to estimate dispersal (σ) of WCR in Northern Italy around 20 km.generation-1/2. Finally I showed the absence of impact of hybridization in the european invasion of WCR in natura, by measuring on hybrid and parental genotypes, numerous phenotypic traits positively associated to the fitness of individuals. Thus, a selection or a selection against hybrids is excluded in this particular case of hybridization and the invasion dynamics of WCR in Europe should not be affected in any way.

Depuis les années 1990, on observe une accélération de la vitesse de propagation après établissementd’une grande partie des insectes introduits accidentellement en Europe. L’invasion fulgurante de lapyrale du buis, Cydalima perspectalis, est un exemple de ce phénomène. Observée pour la premièrefois en 2007 en Allemagne, elle s’est ensuite propagée jusqu’au Caucase en une décennie. Il a étérapidement supposé que le commerce de buis d’ornement entre les pays européens et la Chine auraitpermis son introduction tandis que l‘intensification des échanges commerciaux entre pays européensaurait facilité sa propagation à travers le continent. Cependant, certains traits biologiques de l’insecteont également pu favoriser son invasion. Pour mieux comprendre les facteurs impliqués dans soninvasion fulgurante, une approche pluridisciplinaire a été utilisée au cours de cette thèse. Tout d’abord,les routes d’invasion ont été appréhendées avec deux types de marqueurs génétiques. Puis, deux traitsbiologiques ayant pu favoriser son établissement et son expansion ont été étudiés : ses capacités devol et la diapause. Les résultats génétiques ont permis de cibler la partie côtière de la Chine commezone source probable, et suggèrent au moins deux introductions indépendantes depuis la Chine suivipar un phénomène tête de pont probablement lié au commerce d’ornement. Les capacités de volestimées sont élevées et expliqueraient la dispersion de l’insecte à l’échelle locale. De plus, la sortie dediapause influencée par la température a pu permettre l’adaptation du nombre de générations enfonction du climat annuel. Ces deux traits biologiques ont par conséquent dû favoriser son invasion àl’échelle locale mais il apparaît que les activités humaines, en particulier le commerce des plantesornementales, ont joué un rôle majeur dans son invasion fulgurante à large échelle en Europe et auCaucase. / Since 1990, recently established non-native insect species appear to be spreading across Europesignificantly faster than before. The box tree moth, Cydalima perspectalis, is a representative of such arapid spread. First observed in 2007, it spread across Europe to Asia Minor in a decade, damaging onBuxus plants in urban areas as well as in forests. The trade of ornamental box plants between Europeand China has been hypothesized as the invasion pathway of the insect while the trade betweenEuropean countries could explain its fast expansion. The biological traits of the moth may also havefavored its spread. To understand the factors involved in both its invasion and fast expansion, we useda multidisciplinary approach. First, the invasion routes were tentatively assessed using two geneticmarkers. Then, two biological traits, flight capacities and diapause, were studied because they may havepromote its spread. The genetic analyses clearly suggest an origin from Eastern China origin but alsocomplex invasion pathways. Two independent introduction events probably happened directly fromChina followed by bridgehead effects due to ornamental plant trade. The moth flight capacities areimportant but can only explain dispersal at local scale. Moreover, diapause termination was influencedby temperature, which may lead to an adapted number of generation depending on local climate. Thesebiological traits may have favored local invasions. However, our study suggests that human-mediateddispersal played a key role in the fast expansion of C. perspectalis across Europe and Asia Minor.

Les effets des introductions d'espèces non natives sur le milieu restent mal connus et les poissons top-prédateurs, au sommet du réseau trophique (intégrateurs), sont des modèles d'étude intéressants pour observer ces impacts. Des changements de fonctionnement de communautés animales, en liaison avec ces introductions, ont été mis en évidence par les analyses des isotopes stables au sein des réseaux trophiques lentiques et lotiques, grâce à l'évaluation des positions trophiques et des régimes alimentaires des top-prédateurs. De plus, la chimie des otolithes a permis de reconstituer l'histoire de vie de poissons introduits (translocation). Ainsi, de nouvelles informations sur l'écologie trophique des poissons top-prédateurs ont été acquises et permettront la mise en place de plans de gestion.