• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 32
  • 14
  • 10
  • 5
  • 2
  • Tagged with
  • 72
  • 72
  • 18
  • 14
  • 12
  • 11
  • 10
  • 9
  • 9
  • 8
  • 8
  • 8
  • 7
  • 7
  • 7
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Genetic Consequences of Dispersal and Social Behavior in Lions, Panthera leo

Spong, Goran January 2001 (has links)
This thesis combines behavioral observations of African lions (Panthera leo) with genetic analyses, in an attempt to clarify causes and consequences of lion group living. The numerous complex cooperative behaviors of lions present an excellent opportunity to investigate the evolution and maintenance of group living. This thesis focuses on female group living and male dispersal patterns. Lion sociality is found to be more complex than previously thought. Short dispersal distances result in strong kinship ties among prides, creating the potential for kin selection to operate among prides. Simultaneously, some prides contained unrelated females, depriving females in such prides of inclusive fitness benefits from group living. Concurrent with short dispersal distances in both males and females, significant genetic differentiation could be detected over relatively short distances in analyses of males. Extensive behavioral observations showed that territorial behaviors were unaffected by kinship ties to intruders. Instead, favorable odds and several environmental conditions were important factors. Space use analyses showed large overlap among prides. Again, kinship did not affect degree of overlap. Conclusively, these results show that the ultimate causes of lion sociality remain elusive, but that kin selection may be less important than generally thought. Lion sociality seems to be explicable mainly in terms of direct fitness benefits, which therefore should be given more attention.
42

Developing Behavioral Indices of Population Viability: A Case Study of California Sea Lions in the Gulf of California, Mexico

January 2012 (has links)
abstract: Despite years of effort, the field of conservation biology still struggles to incorporate theories of animal behavior. I introduce in Chapter I the issues surrounding the disconnect between behavioral ecology and conservation biology, and propose the use of behavioral knowledge in population viability analysis. In Chapter II, I develop a framework that uses three strategies for incorporating behavior into demographic models, outline the costs of each strategy through decision analysis, and build on previous work in behavioral ecology and demography. First, relevant behavioral mechanisms should be included in demographic models used for conservation decision-making. Second, I propose rapid behavioral assessment as a useful tool to approximate demographic rates through regression of demographic phenomena on observations of related behaviors. This technique provides behaviorally estimated parameters that may be applied to population viability analysis for use in management. Finally, behavioral indices can be used as warning signs of population decline. The proposed framework combines each strategy through decision analysis to provide quantitative rules that determine when incorporating aspects of conservation behavior may be beneficial to management. Chapter III applies this technique to estimate birthrate in a colony of California sea lions in the Gulf of California, Mexico. This study includes a cost analysis of the behavioral and traditional parameter estimation techniques. I then provide in Chapter IV practical recommendations for applying this framework to management programs along with general guidelines for the development of rapid behavioral assessment. / Dissertation/Thesis / M.S. Biology 2012
43

Life history trade-offs in growth and immune function: The behavioral and immunological ecology of the Shuar of Amazonian Ecuador, an indigenous population in the midst of rapid economic and ecological change / Behavioral and immunological ecology of the Shuar of Amazonian Ecuador, an indigenous population in the midst of rapid economic and ecological change

Blackwell, Aaron D., 1978- 12 1900 (has links)
xxi, 234 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Life history theory examines the allocation of resources among competing demands, including growth, immune function, and reproduction. Immune function can itself be divided into innate, cell mediated, and humoral responses. For humans, factors like economic condition, disease exposure. and social milieu are all hypothesized to affect life history allocations. For the Shuar of Amazonian Ecuador these factors are rapidly changing as traditional subsistence hunting and horticulture give way to wage labor and Western medicine. This dissertation presents fieldwork conducted amongst the Shuar between 2005 and 2009. It is among the first studies to test for life history trade-offs between different branches of immunity and growth across market conditions. Shuar data include anthropometrics (n=1,547), biomarkers (n=163), and household compositions (n=292). Comparison samples include the Shiwiar of Ecuador (n=42), non-indigenous Ecuadorian colono children (n=570), the Tsimane of Bolivia (n=329), and the 2005-2006 U.S. NHANES (n=8,336). The dissertation finds significant differences between both populations and Shuar villages in growth and immunity. Increasing market integration is associated with poorer growth, but household factors mediate these changes. Adult males have positive effects on child growth in acculturated areas with wage labor and in distant areas where fishing and hunting remain important but not in intermediate areas. Children have consistent negative effects on one another's growth, suggesting competition for resources. Poorer growth is also associated with higher levels of immunoglobulin E (IgE), a humoral response to helminths. In contrast, C-reactive protein, an inflammatory marker, has a positive association with growth. This divergence between humoral and innate immunity is consistent with a lasting reallocation of immune resources towards a T H 2 response in helminth infected individuals. The age-profile of IgE also varies across market conditions: comparing the Shuar with samples from the U.S. and Bolivia, the age of peak IgE is correlated with the level of peak IgE in each population, providing some of the first evidence for a "peak shift" in immune response. Overall, these results support the hypothesis that local conditions lead to the adaptive "tuning" of trade-offs between branches of immunity and growth. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Lawrence Sugiyama, Chairperson, Anthropology; James Snodgrass, Member, Anthropology; Frances White, Member, Anthropology; John Orbell, Outside Member, Political Science
44

The Influence of Body Size on the Ecology of Coastal Fish Predators in The Bahamas

Hammerschlag-Peyer, Caroline M 02 November 2011 (has links)
Body size is a fundamental structural characteristic of organisms, determining critical life history and physiological traits, and influencing population dynamics, community structure, and ecosystem function. For my dissertation, I focused on effects of body size on habitat use and diet of important coastal fish predators, as well as their influence on faunal communities in Bahamian wetlands. First, using acoustic telemetry and stable isotope analysis, I identified high variability in movement patterns and habitat use among individuals within a gray snapper (Lutjanus griseus) and schoolmaster snapper (L. apodus) population. This intrapopulation variation was not explained by body size, but by individual behavior in habitat use. Isotope values differed between individuals that moved further distances and individuals that stayed close to their home sites, suggesting movement differences were related to specific patterns of foraging behavior. Subsequently, while investigating diet of schoolmaster snapper over a two-year period using stomach content and stable isotope analyses, I also found intrapopulation diet variation, mostly explained by differences in size class, individual behavior and temporal variability. I then developed a hypothesis-testing framework examining intrapopulation niche variation between size classes using stable isotopes. This framework can serve as baseline to categorize taxonomic or functional groupings into specific niche shift scenarios, as well as to help elucidate underlying mechanisms causing niche shifts in certain size classes. Finally, I examined the effect of different-sized fish predators on epifaunal community structure in shallow seagrass beds using exclusion experiments at two spatial scales. Overall, I found that predator effects were rather weak, with predator size and spatial scale having no impact on the community. Yet, I also found some evidence of strong interactions on particular common snapper prey. As Bahamian wetlands are increasingly threatened by human activities (e.g., overexploitation, habitat degradation), an enhanced knowledge of the ecology of organisms inhabiting these systems is crucial for developing appropriate conservation and management strategies. My dissertation research contributed to this effort by providing critical information about the resource use of important Bahamian fish predators, as well as their effect on faunal seagrass communities.
45

Costly Signaling and Prey Choice: the Signaling Value of Hunted Game

January 2019 (has links)
abstract: For most of human history hunting has been the primary economic activity of men. Hunted animals are valued for their food energy and nutrients, however, hunting is associated with a high risk of failure. Additionally, large animals cannot be consumed entirely by the nuclear family, so much of the harvest may be shared to others. This has led some researchers to ask why men hunt large and difficult game. The “costly signaling” and “show-off” hypotheses propose that large prey are hunted because the difficulty of finding and killing them is a reliable costly signal of the phenotypic quality of the hunter. These hypotheses were tested using original interview data from Aché (hunter gatherer; n=52, age range 50-76, 46% female) and Tsimané (horticulturalist; n=40, age range 15-77, 45% female) informants. Ranking tasks and paired comparison tasks were used to determine the association between the costs of killing an animal and its value as a signal of hunter phenotypic quality for attracting mates and allies. Additional tasks compared individual large animals to groups of smaller animals to determine whether assessments of hunters’ phenotypes and preferred status were more impacted by the signal value of the species or by the weight and number of animals killed. Aché informants perceived hunters who killed larger or harder to kill animals as having greater provisioning ability, strength, fighting ability, and disease susceptibility, and preferred them as mates and allies. Tsimané informants held a similar preference for hunters who killed large game, but not for hunters targeting hard to kill species. When total biomass harvested was controlled, both populations considered harvesting more animals in a given time period to be a better signal of preferred phenotypes than killing a single large and impressive species. Male and female informants both preferred hunters who consistently brought back small game over hunters who sometimes killed large animals and sometimes killed nothing. No evidence was found that hunters should forgo overall food return rates in order to signal phenotypic qualities by specializing on large game. Nutrient provisioning rather than costly phenotypic signaling was the strategy preferred by potential mates and allies. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2019
46

Forest Edge Effects on the Behavioral Ecology of L'Hoest's Monkey (Cercopithecus lhoesti) in Bwindi Impenetrable National Park, Uganda

Ukizintambara, Tharcisse 26 February 2010 (has links)
No description available.
47

Composição, estrutura e sazonalidade dos bandos mistos de aves em um remanescente de floresta paludosa no sul do Brasil

Silveira, André Barcellos January 2006 (has links)
Analisou-se a composição, estrutura e padrão sazonal de formação dos bandos mistos de aves em um remanescente de floresta paludosa na planície costeira do Rio Grande do Sul, sul do Brasil. Efetuaram-se amostragens mensais de fevereiro de 2005 a janeiro de 2006, com observações ocasionais em 2004 e janeiro de 2005. Pontos de contagem foram utilizados para estimar a abundância relativa das espécies integrantes dos bandos, e transecções foram efetuadas para as observações dos bandos mistos. Quarenta e sete espécies foram registradas como participantes em 92 bandos amostrados. O número de indivíduos foi positivamente correlacionado com o número de espécies dentro dos bandos. O pool dos não-passeriformes foi pobremente representado nos bandos, enquanto passeriformes suboscines e oscines foram igualmente representados na riqueza dos bandos. Onívoros e insetívoros foram bem representados, mas os nectarívoros tiveram apenas uma espécie integrante; frugívoros e granívoros foram ausentes nos bandos mistos.Espécies migratórias foram pouco representadas nos bandos, como havia sido verificado para outras áreas de Floresta Atlântica. A regularidade de uma espécie em integrar bandos mistos foi uma função de sua abundância relativa, e as espécies mais conspícuas tenderam a ser os integrantes mais regulares. Detectaram-se quinze co-ocorrências significativas em 153 combinações possíveis (10%), onze delas positivas e quatro negativas. Nenhum tipo estrutural de bandos foi distinguido por meio de análise de agrupamento. Associações positivas e negativas talvez estejam relacionadas a similaridades e dissimilaridades na distribuição vertical de cada par de espécies. Os atributos de freqüência, tamanho e riqueza dos bandos foram os menores encontrados em qualquer outro estudo na Floresta Atlântica. Os bandos formaram-se o ano inteiro no Faxinal, mas a freqüência, o tamanho e a riqueza dos bandos diferiram significativamente entre os meses e entre as estações. Osvalores máximos destes três atributos foram encontrados na estação não-reprodutiva, lembrando os padrões encontrados em outros locais da Floresta Atlântica. A combinação de um pequeno grupo de espécies abundantes e bem distribuídas, junto com uma baixa riqueza local talvez torne a estrutura dos bandos mistos no Faxinal menos variável do que em outros locais da Floresta Atlântica. / The composition, structure and seasonal pattern of formation of mixed-species bird flocks were analyzed in a swamp forest remnant in the coastal plain of Rio Grande do Sul state, southern Brazil. Field work was carried out monthly from February 2005 to January 2006, plus occasional observations in 2004 and January 2005. Point counts estimated the relative abundance of flocking species, and transects were performed to access data relative to the flocks. Forty seven species were recorded as participants in 92 flocks sampled. The number of individuals was positively correlated with the number of species within the flocks. Non-passerines pool is less represented in the flocks, while suboscines and oscines were equally represented in the flock richness. Omnivores and insectivores were well represented, but nectarivores had only one flocking species while frugivores and granivores were absent in flocks. Migrants had low representation on the composition and structure of flocks, as predicted for lowland Atlantic Forest areas. The regularity of a given species in to integrate flocks was a function of its relative abundance, and the species more conspicuous tended to be the more regular flock joiners. Fifteen significant co-occurrences of 153 possible pairs (10%) were detected, eleven positively and four negatively associated. None structural type of flocks was recognized through cluster analyses. Positive and negative associations were better explained by similarities or dissimilarities on vertical distribution of each species pair. The attributes of frequency, flock size and flock richness were the lowest found in any study on Atlantic Forest. Flocks were formed throughout the year at Faxinal, but frequency, flock size and flock richness differed significantly between months and between seasons. Higher values of these three attributes were found in non-breeding season, reaching the pattern found elsewhere in Atlantic Forest. The combination of a little set of abundant and well distributed speciesand low richness perhaps makes the flock structure at Faxinal less variable than that of Atlantic Forest elsewhere.
48

O competidor interespecífico pode alterar a agressividade intraespecífica? um estudo com caranguejos do gênero Uca / An interspecific competitor can change the intraspecific aggressivity? a study with crabs of the genus Uca

Jimenez, Pedro Julião [UNESP] 29 February 2016 (has links)
Submitted by PEDRO JULIÃO JIMENEZ null (p_j_jimenez@hotmail.com) on 2016-04-18T20:29:32Z No. of bitstreams: 1 Dissertação-de-mestrado_Pedro_Jimenez_2016 - repositório.pdf: 1264368 bytes, checksum: 9cba2282085ba20e62c6d3e74cb23964 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-04-19T17:47:28Z (GMT) No. of bitstreams: 1 jimenez_pj_me_bot.pdf: 1264368 bytes, checksum: 9cba2282085ba20e62c6d3e74cb23964 (MD5) / Made available in DSpace on 2016-04-19T17:47:28Z (GMT). No. of bitstreams: 1 jimenez_pj_me_bot.pdf: 1264368 bytes, checksum: 9cba2282085ba20e62c6d3e74cb23964 (MD5) Previous issue date: 2016-02-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Experimentalmente, em campo e em laboratório, usando como modelo as espécies Uca leptodactyla e U. uruguayensis, avaliamos como o estímulo direto e o estímulo visual de um competidor interespecífico pode alterar a agressividade e os comportamentos agonísticos durante as lutas intraespecíficas. Vimos que o comportamento de estender o quelípodo (ameaça), que é um comportamento pouco escalado, ocorre em menos lutas na presença do estímulo do competidor interespecífico nos experimentos em laboratório. Em U. leptodactyla, o comportamento de entrelaçar/agarrar os quelípodos, que indica combates mais escalados, esteve presente em mais lutas com o estímulo direto do interespecífico, diferindo das lutas na presença do estímulo do intraespecífico. Nos experimentos com estímulo visual, em U. uruguayensis, houve mais comportamento de entrelaçar no grupo experimental sem a presença do estímulo, diferindo do grupo experimental com estímulo intraespecífico. Nos experimentos em campo, em U. uruguayensis houve maior número do comportamento arremessar, o mais escalado analisado neste estudo, nas lutas com ausência do estímulo de competidores. Os resultados sugerem que na presença de interespecíficos ocorrem diferenças nas lutas, em que menos comportamentos de ameaça são utilizados. Parece haver identidade mal interpretada do estímulo visual dos competidores, pois não ocorrem diferenças entre os grupos com estímulo visual intra- e interespecífico. Os dados sugerem existir diferenças na ameaça oferecida pelo interespecífico para as diferentes espécies, e a avaliação que os indivíduos fazem dos adversários pode ter levado a respostas diferentes pelas espécies. / Experimentally, in field and laboratory, using as models the species Uca leptodactyla e U. uruguayensis, we evaluated how the direct and the visual stimulus of an interspecific competitor can alter the aggressivity and agonistic behaviors in intraspecific fights. The cheliped extend (threat behavior), a less scalated behavior, occurred in less fights in the presence of the interspecific competitor, in the laboratory experiments. In U. leptodactyla, the interlace/grapple behavior, that indicate more escalated combats, occurred in more fights when in the presence of the direct stimulus of the interspecific, differing of the fights in the presence of the intraspecific stimulus. In the field experiments, there was a bigger number of the flick behavior, the most escalated in this study, in the fights of U. uruguayensis when in the absence of competitor’s stimulus. The results suggest that differences occur in the fights when interspecific competitors are present, occurring less threat behaviors. It seems that occur a misidentification of the specie identity when only exposed to visual cues of the competitors, not occurring differences between the groups with the intra- and interspecific stimulus. The data suggests differences in the offered threat by the interspecific between the species, and the assessment that the individuals do about their adversaries can lead to different response by the species.
49

Composição, estrutura e sazonalidade dos bandos mistos de aves em um remanescente de floresta paludosa no sul do Brasil

Silveira, André Barcellos January 2006 (has links)
Analisou-se a composição, estrutura e padrão sazonal de formação dos bandos mistos de aves em um remanescente de floresta paludosa na planície costeira do Rio Grande do Sul, sul do Brasil. Efetuaram-se amostragens mensais de fevereiro de 2005 a janeiro de 2006, com observações ocasionais em 2004 e janeiro de 2005. Pontos de contagem foram utilizados para estimar a abundância relativa das espécies integrantes dos bandos, e transecções foram efetuadas para as observações dos bandos mistos. Quarenta e sete espécies foram registradas como participantes em 92 bandos amostrados. O número de indivíduos foi positivamente correlacionado com o número de espécies dentro dos bandos. O pool dos não-passeriformes foi pobremente representado nos bandos, enquanto passeriformes suboscines e oscines foram igualmente representados na riqueza dos bandos. Onívoros e insetívoros foram bem representados, mas os nectarívoros tiveram apenas uma espécie integrante; frugívoros e granívoros foram ausentes nos bandos mistos.Espécies migratórias foram pouco representadas nos bandos, como havia sido verificado para outras áreas de Floresta Atlântica. A regularidade de uma espécie em integrar bandos mistos foi uma função de sua abundância relativa, e as espécies mais conspícuas tenderam a ser os integrantes mais regulares. Detectaram-se quinze co-ocorrências significativas em 153 combinações possíveis (10%), onze delas positivas e quatro negativas. Nenhum tipo estrutural de bandos foi distinguido por meio de análise de agrupamento. Associações positivas e negativas talvez estejam relacionadas a similaridades e dissimilaridades na distribuição vertical de cada par de espécies. Os atributos de freqüência, tamanho e riqueza dos bandos foram os menores encontrados em qualquer outro estudo na Floresta Atlântica. Os bandos formaram-se o ano inteiro no Faxinal, mas a freqüência, o tamanho e a riqueza dos bandos diferiram significativamente entre os meses e entre as estações. Osvalores máximos destes três atributos foram encontrados na estação não-reprodutiva, lembrando os padrões encontrados em outros locais da Floresta Atlântica. A combinação de um pequeno grupo de espécies abundantes e bem distribuídas, junto com uma baixa riqueza local talvez torne a estrutura dos bandos mistos no Faxinal menos variável do que em outros locais da Floresta Atlântica. / The composition, structure and seasonal pattern of formation of mixed-species bird flocks were analyzed in a swamp forest remnant in the coastal plain of Rio Grande do Sul state, southern Brazil. Field work was carried out monthly from February 2005 to January 2006, plus occasional observations in 2004 and January 2005. Point counts estimated the relative abundance of flocking species, and transects were performed to access data relative to the flocks. Forty seven species were recorded as participants in 92 flocks sampled. The number of individuals was positively correlated with the number of species within the flocks. Non-passerines pool is less represented in the flocks, while suboscines and oscines were equally represented in the flock richness. Omnivores and insectivores were well represented, but nectarivores had only one flocking species while frugivores and granivores were absent in flocks. Migrants had low representation on the composition and structure of flocks, as predicted for lowland Atlantic Forest areas. The regularity of a given species in to integrate flocks was a function of its relative abundance, and the species more conspicuous tended to be the more regular flock joiners. Fifteen significant co-occurrences of 153 possible pairs (10%) were detected, eleven positively and four negatively associated. None structural type of flocks was recognized through cluster analyses. Positive and negative associations were better explained by similarities or dissimilarities on vertical distribution of each species pair. The attributes of frequency, flock size and flock richness were the lowest found in any study on Atlantic Forest. Flocks were formed throughout the year at Faxinal, but frequency, flock size and flock richness differed significantly between months and between seasons. Higher values of these three attributes were found in non-breeding season, reaching the pattern found elsewhere in Atlantic Forest. The combination of a little set of abundant and well distributed speciesand low richness perhaps makes the flock structure at Faxinal less variable than that of Atlantic Forest elsewhere.
50

O competidor interespecífico pode alterar a agressividade intraespecífica? um estudo com caranguejos do gênero Uca

Jimenez, Pedro Julião. January 2016 (has links)
Orientador: Rodrigo Egydio Barreto / Resumo: Experimentalmente, em campo e em laboratório, usando como modelo as espécies Uca leptodactyla e U. uruguayensis, avaliamos como o estímulo direto e o estímulo visual de um competidor interespecífico pode alterar a agressividade e os comportamentos agonísticos durante as lutas intraespecíficas. Vimos que o comportamento de estender o quelípodo (ameaça), que é um comportamento pouco escalado, ocorre em menos lutas na presença do estímulo do competidor interespecífico nos experimentos em laboratório. Em U. leptodactyla, o comportamento de entrelaçar/agarrar os quelípodos, que indica combates mais escalados, esteve presente em mais lutas com o estímulo direto do interespecífico, diferindo das lutas na presença do estímulo do intraespecífico. Nos experimentos com estímulo visual, em U. uruguayensis, houve mais comportamento de entrelaçar no grupo experimental sem a presença do estímulo, diferindo do grupo experimental com estímulo intraespecífico. Nos experimentos em campo, em U. uruguayensis houve maior número do comportamento arremessar, o mais escalado analisado neste estudo, nas lutas com ausência do estímulo de competidores. Os resultados sugerem que na presença de interespecíficos ocorrem diferenças nas lutas, em que menos comportamentos de ameaça são utilizados. Parece haver identidade mal interpretada do estímulo visual dos competidores, pois não ocorrem diferenças entre os grupos com estímulo visual intra- e interespecífico. Os dados sugerem existir diferenças na ameaça o... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Experimentally, in field and laboratory, using as models the species Uca leptodactyla e U. uruguayensis, we evaluated how the direct and the visual stimulus of an interspecific competitor can alter the aggressivity and agonistic behaviors in intraspecific fights. The cheliped extend (threat behavior), a less scalated behavior, occurred in less fights in the presence of the interspecific competitor, in the laboratory experiments. In U. leptodactyla, the interlace/grapple behavior, that indicate more escalated combats, occurred in more fights when in the presence of the direct stimulus of the interspecific, differing of the fights in the presence of the intraspecific stimulus. In the field experiments, there was a bigger number of the flick behavior, the most escalated in this study, in the fights of U. uruguayensis when in the absence of competitor’s stimulus. The results suggest that differences occur in the fights when interspecific competitors are present, occurring less threat behaviors. It seems that occur a misidentification of the specie identity when only exposed to visual cues of the competitors, not occurring differences between the groups with the intra- and interspecific stimulus. The data suggests differences in the offered threat by the interspecific between the species, and the assessment that the individuals do about their adversaries can lead to different response by the species. / Mestre

Page generated in 0.4461 seconds