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Feral horses occupy 31.6 million acres throughout western North America. Feral horses share similar habitats with a wide range of animal species, including pronghorn. Since horses are larger and often more aggressive than other animals of this region, they are generally socially dominant over all other native ungulate species. Pronghorn share water sources with horses in areas where both occur. In situations where horses exclude pronghorn from water, pronghorn fitness may be impaired, especially during the hottest months of the year when water is limited. The purpose of this study was to investigate interference competition between pronghorn and feral horses at water sources. During spring and summer 2010-11, we placed motion-sensitive cameras at water sources across the Sheldon National Wildlife Refuge in northwest Nevada. Cameras were used to examine the overlap of water use by pronghorn and horses and to determine the occurrence of spatial or temporal partitioning of water between these species. Additionally, we made direct observations of horses and pronghorn at high-use water sources to record the occurrences and outcomes of pronghorn/horse interactions as well as differences in pronghorn behavior in the presence and absence of horses. Pronghorn spent more time on vigilance behavior and less time foraging or drinking in the presence of horses than in their absence. Nearly half of pronghorn/horse interactions at water resulted in pronghorn exclusion from water. Our data also suggest that temporal partitioning of water between horses and pronghorn on an hourly basis may be occurring.

Repeatedly retrieving information from memory can induce forgetting of related, un-retrieved information below baseline, an effect termed retrieval-induced forgetting (RIF; Anderson, Bjork & Bjork, 1994). The inhibitory account of RIF (e.g., Anderson, 2003) has received extensive support in the literature, especially through studies designed to empirically test inhibitory-based principles of RIF in adults. These principles include cue independence (RIF persists in the absence of the cue used during practice), interference/competition dependence (inhibition serves to resolve interference/competition between the cue and associated items during practice), strength independence (RIF is not strictly due to a target strengthening and competitor forgetting trade-off), retrieval-specificity (retrieval attempts are required to create the interference/ competition responsible for triggering inhibition), and output interference independence (RIF persists when output interference is controlled). However, competition-based explanations do not require an inhibitory component and can also account for many adult RIF findings. Very little RIF research has examined young children’s memory, whose immature memory systems might not be capable of demonstrating an inhibitory-driven effect. This dissertation filled this gap in the literature by thoroughly evaluating the inhibitory account of RIF in kindergartners (Ks). Two groups of Ks completed two RIF tasks that tested cue independence, competition/interference dependence, and strength independence in the first experiment, and retrieval-specificity, output interference independence, and strength-independence again in the second experiment. When a novel cue was used to test final memory (Experiment 1), and when a cue-free recognition test was used that controlled for output interference (Experiment 2), no RIF was found. These results, along with correlational evidence of strength dependence, favour a competition-based account of Ks’ RIF. Implications for inhibition theory and the potential development of RIF are discussed.

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

Compétition et diversité sont des phénomènes majeurs en microbiologie. Dans le secteur de l’agroalimentaire, la compétition est à la base de la biopréservation, un procédé dont l’objectif est d’inhiber des microorganismes indésirables par l’utilisation de microorganismes compétiteurs. La diversité microbienne est quant à elle à l’origine de la diversité de produits fermentés et en particulier de la typicité des fromages. Pourtant, l’écologie de la compétition microbienne dans les aliments et le lien avec la diversité microbienne sont très mal connus. L’objectif de ces travaux de thèse était d’une part d’étudier la diversité et d’autre part la compétition chez une bactérie représentative de l’écosystème fromager. Le modèle d’étude choisi est la bactérie lactique Carnobacterium maltaromaticum. Une analyse de diversité de 21 souches de C. maltaromaticum a été réalisée par MultiLocus Sequence Typing (MLST) et a permis de compléter la structure connue de la population de C. maltaromaticum. Cette étude a permis de révéler la présence de 56 génotypes au sein d’une collection de 71 souches, montrant une grande diversité génétique au sein de cette espèce. La compétition par interférence a été étudiée par réalisation de tests de compétition à haut débit. Chaque test de compétition mettait en jeu deux souches de la collection, une souche en situation d’expédition et une souche en situation de réception. Au total 5776 tests ont été réalisés à partir de la collection de 76 souches. Les résultats ont révélé que 60% des souches inhibaient au moins une autre souche de la collection indiquant que la compétition intraspécifique est majeure au sein de l’espèce C. maltaromaticum. Par ailleurs, une grande variabilité de largeur de spectre d’inhibition et de spectre de sensibilité a été observée. Une approche d’analyse de réseau a révélé une architecture « nested » du réseau compétitif suggérant que l’inhibition dépend non seulement des caractéristiques antagonistes des souches inhibitrices mais également du niveau de sensibilité des souches réceptrices. Une analyse génomique de 26 souches de la collection a été réalisée en vue de prédire leur contenu en gènes codant la synthèse de substances antagonistes et a permis d’identifier des gènes codant potentiellement des bactériocines. En conclusion, ces travaux de thèse ont montré que l’espèce Carnobacterium maltaromaticum est d’une part caractérisée par une grande diversité génétique et que d’autre part la compétition par interférence est fréquente au sein de la population / Competition and diversity are major phenomena in microbiology. In the agri-food sector, competition is the very basis of biopreservation, a process which objective is to inhibit undesirable microorganisms through the use of microbial competitors. Microbial diversity lies at the origin of the diversity of fermented products and particularly of the typicality of cheeses. However, the ecology of microbial competition in food and the link with microbial diversity are poorly understood. The goal of this thesis was to study the diversity and the competition of a representative model bacterium of the cheese ecosystem. The study model chosen is the lactic acid bacterium Carnobacterium maltaromaticum. An analysis of the diversity of 21 strains of C. maltaromaticum was performed by MultiLocus Sequence Typing (MLST) and allowed to complete the scheme of C. maltaromaticum population structure. This study revealed the presence of 56 genotypes among a collection of 71 strains, showing a high genetic diversity within this species. Interference competition was studied by performing high-throughput competition assays. Each competition assay involved two strains, one in the position of the sender strain and the other in the position of the receiver. In total, 5776 tests were performed on a collection of 76 strains. The results revealed that 60% of strains inhibited at least one other strain of the collection, indicating that intraspecific competition is major in C. maltaromaticum. Moreover, a large variability in the width of inhibition and sensitivity spectra has been observed. A network analysis approach revealed a nested architecture of the competitive network, suggesting that inhibition depends not only on the antagonistic characteristics of the inhibitory strains but also on the level of sensitivity of the receiver strains. A genomic analysis of 26 strains from the collection was performed in order to predict their gene content encoding the synthesis of antagonistic substances, and it allowed the identification of genes potentially encoding bacteriocins. In conclusion, this thesis has shown that the species Carnobacterium maltaromaticum is characterized by a high genetic diversity and that interference competition is frequent in the population

Pecari tajacu (caititus) e Tayassu pecari (queixadas) são simpátricos na maior parte de suas distribuições históricas e exercem funções similares em um mesmo nível trófico. Em razão do seu maior tamanho corporal e bandos mais numerosos, os queixadas podem ser considerados como uma espécie dominante em uma possível competição por interferência com os caititus. Contudo, as relações competitivas entre estas duas espécies ainda não são claras e os efeitos das interações por interferência são quase desconhecidos. Este trabalho avaliou o efeito da estacionalidade climática e de atividades antrópicas nas relações de competição por interferência entre caititus e queixadas no nordeste do Pantanal brasileiro. O primeiro capítulo é uma revisão dos principais temas do trabalho: taiassuídeos, Pantanal e a introdução de porcos na região. O segundo capítulo avaliou os efeitos da estacionalidade climática, a partir de uma perspectiva térmica e de disponibilidade de água, nos padrões de atividade e uso de recursos de caititus e queixadas durante as estações seca e úmida na região. As altas temperaturas associadas com a baixa disponibilidade de água na estação seca acentuaram a sobreposição temporal entre as espécies pela redução da atividade diurna. Contudo, neste período foi registrada uma sobreposição de habitat mais baixa do que no período úmido quando taiassuídeos evitaram as áreas intensamente alagadas. Os resultados mostram um aumento de sobreposição de nicho em um gradiente ambiental como resultado da estacionalidade climática podendo ser parcialmente compensado pela redução em outra dimensão. Neste caso, a partição temporal parece ser um mecanismo viável para redução da competição entre espécies potencialmente competidoras. O terceiro capítulo avaliou a influência da pecuária (principal forma de uso da terra na região) somado à presença de porcos ferais (Sus scrofa) nas relações de competição por interferência entre taiassuídeos. Foram comparados os padrões de atividade e as coocorrências dos taiassuídeos em uma unidade de conservação (livre de porcos) adjacente a uma fazenda de pecuária tradicional (com alta densidade de porcos). As duas espécies parecem adotar diferentes estratégias que permitem a sobrevivência nas fazendas de gado com presença de porcos. Os padrões observados nos caititus sugerem uma utilização mais restrita do espaço e uma tendência em reduzir a sobreposição temporal com seus potenciais competidores. Por outro lado, queixadas expandiram sua ocorrência na fazenda, embora também tenham modificado significativamente seu padrão de atividade permanecendo ativos durante maior parte do dia quando em simpatria com porcos. Contudo, as mudanças observadas na área da fazenda não levaram a um aumento direto da competição entre caititus e queixadas. Adicionalmente, a comparação entre porcos ferais nas duas áreas permite especular sobre a forte dependência desta espécie às mudanças ambientais resultantes da pecuária praticada na região. Por fim, o último capítulo discute os principais resultados e apresenta as conclusões finais. / Pecari tajacu and Tayassu pecari are sympatric over most of their historical range and perform similar functions in the same trophic level. Because of its greater body size and more numerous herds, the white-lipped peccary can be considered the dominant species in a possible interference competition with the collared peccary. However, the competitive relationships between these species are not yet clear and effects of interactions by interference are almost unknown. This study evaluated the effect of climatic seasonality and anthropogenic activities in the relations of interference competition between collared and white-lipped peccaries in the northeastern Brazilian Pantanal. The first chapter is an extensive review of the main themes: peccaries, Pantanal and the introduction of pigs in the region. The second chapter evaluated the effects of climate seasonality from a thermal perspective and water availability on the activity patterns and resource use of collared peccary and white-lipped peccary during wet and dry seasons. The high temperatures associated with water shortage in dry season accentuated the temporal overlap between the species due to the reduction of daytime activity. However, in this period there was a habitat overlap reduction compared to wet period where peccaries avoided the flooded areas. The results show that an increase in niche overlap on the environmental gradient as a result of climatic seasonality may be partially compensated by a reduction in other niche dimensions. In this case, temporal partitioning appears to be a viable mechanism to reduce competition by potentially competing species. The third chapter evaluated the potential influence of livestock (the main form of land use in region) added to the presence of feral hogs in the relations of interference competition between peccaries. It was compared the patterns of activity and co-occurrence of peccaries in a conservation area (free of pigs) adjacent to another area with a traditional cattle ranch (with high density of pigs). Both species seem adopt different strategies that enable their survival in cattle ranches with presence of pigs. The collared peccary patterns suggest a constrained use of space and a trend to reduce the temporal overlap with competitors. On the other hand, white-lipped peccaries increased the occurrence rate and also modified its pattern of activity remaining active during most of the day resulting in a high rate of co-occurrence with feral hogs. However, these changes observed in the cattle ranch area did not result in a direct increase of interference competition between peccaries. Additionally, the comparison between feral hogs in the two areas allows us to speculate about a strong dependence of this species on environmental changes resulting from livestock activities in the region. Finally, the last chapter discusses the main results found and presents the general conclusions.

Pecari tajacu (caititus) e Tayassu pecari (queixadas) são simpátricos na maior parte de suas distribuições históricas e exercem funções similares em um mesmo nível trófico. Em razão do seu maior tamanho corporal e bandos mais numerosos, os queixadas podem ser considerados como uma espécie dominante em uma possível competição por interferência com os caititus. Contudo, as relações competitivas entre estas duas espécies ainda não são claras e os efeitos das interações por interferência são quase desconhecidos. Este trabalho avaliou o efeito da estacionalidade climática e de atividades antrópicas nas relações de competição por interferência entre caititus e queixadas no nordeste do Pantanal brasileiro. O primeiro capítulo é uma revisão dos principais temas do trabalho: taiassuídeos, Pantanal e a introdução de porcos na região. O segundo capítulo avaliou os efeitos da estacionalidade climática, a partir de uma perspectiva térmica e de disponibilidade de água, nos padrões de atividade e uso de recursos de caititus e queixadas durante as estações seca e úmida na região. As altas temperaturas associadas com a baixa disponibilidade de água na estação seca acentuaram a sobreposição temporal entre as espécies pela redução da atividade diurna. Contudo, neste período foi registrada uma sobreposição de habitat mais baixa do que no período úmido quando taiassuídeos evitaram as áreas intensamente alagadas. Os resultados mostram um aumento de sobreposição de nicho em um gradiente ambiental como resultado da estacionalidade climática podendo ser parcialmente compensado pela redução em outra dimensão. Neste caso, a partição temporal parece ser um mecanismo viável para redução da competição entre espécies potencialmente competidoras. O terceiro capítulo avaliou a influência da pecuária (principal forma de uso da terra na região) somado à presença de porcos ferais (Sus scrofa) nas relações de competição por interferência entre taiassuídeos. Foram comparados os padrões de atividade e as coocorrências dos taiassuídeos em uma unidade de conservação (livre de porcos) adjacente a uma fazenda de pecuária tradicional (com alta densidade de porcos). As duas espécies parecem adotar diferentes estratégias que permitem a sobrevivência nas fazendas de gado com presença de porcos. Os padrões observados nos caititus sugerem uma utilização mais restrita do espaço e uma tendência em reduzir a sobreposição temporal com seus potenciais competidores. Por outro lado, queixadas expandiram sua ocorrência na fazenda, embora também tenham modificado significativamente seu padrão de atividade permanecendo ativos durante maior parte do dia quando em simpatria com porcos. Contudo, as mudanças observadas na área da fazenda não levaram a um aumento direto da competição entre caititus e queixadas. Adicionalmente, a comparação entre porcos ferais nas duas áreas permite especular sobre a forte dependência desta espécie às mudanças ambientais resultantes da pecuária praticada na região. Por fim, o último capítulo discute os principais resultados e apresenta as conclusões finais. / Pecari tajacu and Tayassu pecari are sympatric over most of their historical range and perform similar functions in the same trophic level. Because of its greater body size and more numerous herds, the white-lipped peccary can be considered the dominant species in a possible interference competition with the collared peccary. However, the competitive relationships between these species are not yet clear and effects of interactions by interference are almost unknown. This study evaluated the effect of climatic seasonality and anthropogenic activities in the relations of interference competition between collared and white-lipped peccaries in the northeastern Brazilian Pantanal. The first chapter is an extensive review of the main themes: peccaries, Pantanal and the introduction of pigs in the region. The second chapter evaluated the effects of climate seasonality from a thermal perspective and water availability on the activity patterns and resource use of collared peccary and white-lipped peccary during wet and dry seasons. The high temperatures associated with water shortage in dry season accentuated the temporal overlap between the species due to the reduction of daytime activity. However, in this period there was a habitat overlap reduction compared to wet period where peccaries avoided the flooded areas. The results show that an increase in niche overlap on the environmental gradient as a result of climatic seasonality may be partially compensated by a reduction in other niche dimensions. In this case, temporal partitioning appears to be a viable mechanism to reduce competition by potentially competing species. The third chapter evaluated the potential influence of livestock (the main form of land use in region) added to the presence of feral hogs in the relations of interference competition between peccaries. It was compared the patterns of activity and co-occurrence of peccaries in a conservation area (free of pigs) adjacent to another area with a traditional cattle ranch (with high density of pigs). Both species seem adopt different strategies that enable their survival in cattle ranches with presence of pigs. The collared peccary patterns suggest a constrained use of space and a trend to reduce the temporal overlap with competitors. On the other hand, white-lipped peccaries increased the occurrence rate and also modified its pattern of activity remaining active during most of the day resulting in a high rate of co-occurrence with feral hogs. However, these changes observed in the cattle ranch area did not result in a direct increase of interference competition between peccaries. Additionally, the comparison between feral hogs in the two areas allows us to speculate about a strong dependence of this species on environmental changes resulting from livestock activities in the region. Finally, the last chapter discusses the main results found and presents the general conclusions.

Pecari tajacu (caititus) e Tayassu pecari (queixadas) são simpátricos na maior parte de suas distribuições históricas e exercem funções similares em um mesmo nível trófico. Em razão do seu maior tamanho corporal e bandos mais numerosos, os queixadas podem ser considerados como uma espécie dominante em uma possível competição por interferência com os caititus. Contudo, as relações competitivas entre estas duas espécies ainda não são claras e os efeitos das interações por interferência são quase desconhecidos. Este trabalho avaliou o efeito da estacionalidade climática e de atividades antrópicas nas relações de competição por interferência entre caititus e queixadas no nordeste do Pantanal brasileiro. O primeiro capítulo é uma revisão dos principais temas do trabalho: taiassuídeos, Pantanal e a introdução de porcos na região. O segundo capítulo avaliou os efeitos da estacionalidade climática, a partir de uma perspectiva térmica e de disponibilidade de água, nos padrões de atividade e uso de recursos de caititus e queixadas durante as estações seca e úmida na região. As altas temperaturas associadas com a baixa disponibilidade de água na estação seca acentuaram a sobreposição temporal entre as espécies pela redução da atividade diurna. Contudo, neste período foi registrada uma sobreposição de habitat mais baixa do que no período úmido quando taiassuídeos evitaram as áreas intensamente alagadas. Os resultados mostram um aumento de sobreposição de nicho em um gradiente ambiental como resultado da estacionalidade climática podendo ser parcialmente compensado pela redução em outra dimensão. Neste caso, a partição temporal parece ser um mecanismo viável para redução da competição entre espécies potencialmente competidoras. O terceiro capítulo avaliou a influência da pecuária (principal forma de uso da terra na região) somado à presença de porcos ferais (Sus scrofa) nas relações de competição por interferência entre taiassuídeos. Foram comparados os padrões de atividade e as coocorrências dos taiassuídeos em uma unidade de conservação (livre de porcos) adjacente a uma fazenda de pecuária tradicional (com alta densidade de porcos). As duas espécies parecem adotar diferentes estratégias que permitem a sobrevivência nas fazendas de gado com presença de porcos. Os padrões observados nos caititus sugerem uma utilização mais restrita do espaço e uma tendência em reduzir a sobreposição temporal com seus potenciais competidores. Por outro lado, queixadas expandiram sua ocorrência na fazenda, embora também tenham modificado significativamente seu padrão de atividade permanecendo ativos durante maior parte do dia quando em simpatria com porcos. Contudo, as mudanças observadas na área da fazenda não levaram a um aumento direto da competição entre caititus e queixadas. Adicionalmente, a comparação entre porcos ferais nas duas áreas permite especular sobre a forte dependência desta espécie às mudanças ambientais resultantes da pecuária praticada na região. Por fim, o último capítulo discute os principais resultados e apresenta as conclusões finais. / Pecari tajacu and Tayassu pecari are sympatric over most of their historical range and perform similar functions in the same trophic level. Because of its greater body size and more numerous herds, the white-lipped peccary can be considered the dominant species in a possible interference competition with the collared peccary. However, the competitive relationships between these species are not yet clear and effects of interactions by interference are almost unknown. This study evaluated the effect of climatic seasonality and anthropogenic activities in the relations of interference competition between collared and white-lipped peccaries in the northeastern Brazilian Pantanal. The first chapter is an extensive review of the main themes: peccaries, Pantanal and the introduction of pigs in the region. The second chapter evaluated the effects of climate seasonality from a thermal perspective and water availability on the activity patterns and resource use of collared peccary and white-lipped peccary during wet and dry seasons. The high temperatures associated with water shortage in dry season accentuated the temporal overlap between the species due to the reduction of daytime activity. However, in this period there was a habitat overlap reduction compared to wet period where peccaries avoided the flooded areas. The results show that an increase in niche overlap on the environmental gradient as a result of climatic seasonality may be partially compensated by a reduction in other niche dimensions. In this case, temporal partitioning appears to be a viable mechanism to reduce competition by potentially competing species. The third chapter evaluated the potential influence of livestock (the main form of land use in region) added to the presence of feral hogs in the relations of interference competition between peccaries. It was compared the patterns of activity and co-occurrence of peccaries in a conservation area (free of pigs) adjacent to another area with a traditional cattle ranch (with high density of pigs). Both species seem adopt different strategies that enable their survival in cattle ranches with presence of pigs. The collared peccary patterns suggest a constrained use of space and a trend to reduce the temporal overlap with competitors. On the other hand, white-lipped peccaries increased the occurrence rate and also modified its pattern of activity remaining active during most of the day resulting in a high rate of co-occurrence with feral hogs. However, these changes observed in the cattle ranch area did not result in a direct increase of interference competition between peccaries. Additionally, the comparison between feral hogs in the two areas allows us to speculate about a strong dependence of this species on environmental changes resulting from livestock activities in the region. Finally, the last chapter discusses the main results found and presents the general conclusions.

No description available.

No description available.