• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 12
  • 6
  • 4
  • 2
  • Tagged with
  • 27
  • 7
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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.
11

Aspects of the biology of the pink-billed lark (Spizocorys conirostris) in the Limpopo Province, South Africa

Mathonsi, Mandlenkosi Habile Thabo January 2013 (has links)
Thesis (M.Sc. ( Zoology)) --University of Limpopo, 2013 / The fieldwork for this study was carried out from October 2008 to October 2010, under the supervision of Professor D. Engelbrecht of the Department of Biodiversity at the University of Limpopo. Professor Engelbrecht kindly agreed to provide me with raw breeding data of the same population collected during 2008. This study represents original work by the author and where work of other authors has been used; they are duly acknowledged in the text and listed as references. Chapter 1 is a general introduction to the family Alaudidae in which their characteristics and taxonomy are discussed. This is followed by a brief overview of the general biology and ecology of larks of the world in general, followed by a more specific emphasis on the genus Spizocorys, and finally the Pink-billed Lark. In this section, gaps in the available knowledge of Pink-billed Larks are highlighted. This chapter culminates in the aim and objectives of this study. In Chapter 2 the various aspects of the breeding biology of the Pink-billed Lark are reported. This includes, amongst others, aspects such as breeding seasonality, clutch sizes, roles of the sexes during the breeding cycle and breeding success. Chapter 3 provides the results of a morphometric study of museum study skins from across the species range. This includes an analysis of sexual size dimorphism and geographical variation of the different subspecies. This chapter also provides a brief description of the timing and pattern of moult and the various vocalizations of the Pink-billed Lark. Chapter 4 concludes the dissertation with a summary of the results of this study and highlights avenues for future research on the species and the family. The format of Chapters 2 and 3 takes the form of research papers that can be submitted for publication with minimum editing. Chapter 2 has been published in the Journal of African Zoology (see below). Chapter 3 is in preparation for submission to a peer-reviewed journal. As such, there is some repetition in the introductory paragraphs and concluding remarks of chapters 2, 3 and 4. To give this manuscript a degree of uniformity, the literature cited in all chapters has been formatted according to the manuscript requirements of the Journal of African Zoology, and a reference list appears at the end of the dissertation. Tables and figures are arranged at the end of each chapter.
12

Genomic Context, Sequence Evolution, and Evolutionary Ecology of Major Histocompatibility Complex (MHC) Genes in the Red-billed Gull (Larus scopulinus)

Cloutier, Alison J. 26 March 2012 (has links)
Genomic organization of the major histocompatibility complex (MHC) can profoundly influence gene function and multigene family evolution. Situated at the interface of individual genetic variation and the adaptive immune response, MHC class I and II loci are intensively studied for disease associations and used as markers of adaptive genetic variation in evolutionary ecology research. Genomic sequence of MHC-containing cosmid clones from the red-billed gull (Larus scopulinus, Charadriiformes: shorebirds, gulls, and allies) was obtained for comparative analysis of avian MHC evolution. MHCI polymorphism was further investigated using cDNA library screening and locus-specific genotyping protocols. This first information regarding MHC organization and MHCI variation in charadriiforms suggests a complex evolutionary history to MHC architecture in birds. Duplication of MHCIIα loci in tandem MHCIIα/β pairs and their proximity to MHC-region gene COL11A2 are similar to arrangements in nonavian vertebrates, and contrast with the “minimal essential” MHC of the chicken (Gallus gallus, Galliformes: gamebirds). MHCI–TAP2 organization is shared with Galloanserae (gamebirds + waterfowl), as is a proposed major classical function for this MHCI gene. In contrast, the placement of MHCI genes adjacent to sequence from chromosomes 3, 5, and 22 of the chicken and zebra finch (Taeniopygia guttata, Passeriformes: perching birds) indicates interchromosomal rearrangements in birds and the possible genomic dispersal of nonclassical MHCI genes in the red-billed gull. Screening for avian malaria, genetic parentage tests, and field data from red-billed gulls at Kaikoura Peninsula, New Zealand were combined with MHCI genotypes to investigate relationships with disease and reproduction. Plasmodium infection was confirmed in red-billed gulls, and breeding condition was negatively associated with malarial infection and positively related to variation at the putative major MHCI locus. A low rate of extrapair paternity was identified across thirteen breeding seasons. Partners without extrapair young (EPY) had greater MHCI dissimilarity than was expected by chance, whereas lower individual MHCI variation and elevated hatching failure existed for pairs with EPY. In addition to contributing to studies of MHC evolution, sexual selection, and disease dynamics in the New Zealand avifauna, this research will facilitate studies of MHC genes in related charadriiforms, many of which are of conservation concern.
13

Genomic Context, Sequence Evolution, and Evolutionary Ecology of Major Histocompatibility Complex (MHC) Genes in the Red-billed Gull (Larus scopulinus)

Cloutier, Alison J. 26 March 2012 (has links)
Genomic organization of the major histocompatibility complex (MHC) can profoundly influence gene function and multigene family evolution. Situated at the interface of individual genetic variation and the adaptive immune response, MHC class I and II loci are intensively studied for disease associations and used as markers of adaptive genetic variation in evolutionary ecology research. Genomic sequence of MHC-containing cosmid clones from the red-billed gull (Larus scopulinus, Charadriiformes: shorebirds, gulls, and allies) was obtained for comparative analysis of avian MHC evolution. MHCI polymorphism was further investigated using cDNA library screening and locus-specific genotyping protocols. This first information regarding MHC organization and MHCI variation in charadriiforms suggests a complex evolutionary history to MHC architecture in birds. Duplication of MHCIIα loci in tandem MHCIIα/β pairs and their proximity to MHC-region gene COL11A2 are similar to arrangements in nonavian vertebrates, and contrast with the “minimal essential” MHC of the chicken (Gallus gallus, Galliformes: gamebirds). MHCI–TAP2 organization is shared with Galloanserae (gamebirds + waterfowl), as is a proposed major classical function for this MHCI gene. In contrast, the placement of MHCI genes adjacent to sequence from chromosomes 3, 5, and 22 of the chicken and zebra finch (Taeniopygia guttata, Passeriformes: perching birds) indicates interchromosomal rearrangements in birds and the possible genomic dispersal of nonclassical MHCI genes in the red-billed gull. Screening for avian malaria, genetic parentage tests, and field data from red-billed gulls at Kaikoura Peninsula, New Zealand were combined with MHCI genotypes to investigate relationships with disease and reproduction. Plasmodium infection was confirmed in red-billed gulls, and breeding condition was negatively associated with malarial infection and positively related to variation at the putative major MHCI locus. A low rate of extrapair paternity was identified across thirteen breeding seasons. Partners without extrapair young (EPY) had greater MHCI dissimilarity than was expected by chance, whereas lower individual MHCI variation and elevated hatching failure existed for pairs with EPY. In addition to contributing to studies of MHC evolution, sexual selection, and disease dynamics in the New Zealand avifauna, this research will facilitate studies of MHC genes in related charadriiforms, many of which are of conservation concern.
14

Sex-specific growth and pre-and post-hatching patterns of sex allocation in murres (Uria spp.) and Atlantic puffins (Fratercula arctica) /

Cameron, Maureen L., January 2003 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 2003. / Restricted until October 2004. Includes bibliographical references.
15

The Influence of Winter Social Behavior on the Habitat Selection and Reproductive Success of the Black-billed Magpie

Reese, Kerry P. 01 May 1982 (has links)
This study examined the influence of winter social behavior, particularly dominance relationships, on the subsequent nesting habitat selection and reproductive success of Black-billed Magpies (Pica ~ hudsonia) on 2 areas in northern Utah. Hierarchical cluster analysis ordinated the habitats available to breeding birds and Chi-square and Bonferoni-z statistics were used to determine those habitat types the magpies seemed to prefer. Social status was determined by observing color-banded birds engaged in agonistic encounters at winter bait stations. Social dominance was evaluated by% dyads won, not by total % victories. Relationships between winter social status of magpies and their subsequent breeding habitat use and reproductive performance was tested by Kenda 11 's Tau. Winter foraging flocks were comprised primarily of juvenile (1st year) birds while adults tended to remain as isolates or in pairs. Social status within flocks was correlated with age and sex; males dominated females and juvenile males dominated adult males. This was caused by differences in the social organization of adults and juveniles which created asymmetric views of winter food resources between male age classes. Breeding territories were densely packed in all habitats with a mean size of 0.5 ha. Date of clutch initiation was significantly correlated with clutch size and number of fledglings, with earlier nests more successful. Juveniles occupied marginal habitats and produced fewer offspring than adults. Within a dominance hierarchy of juvenile males, no significant differences in reproductive variables were detected except date of clutch initiation and weight of nestlings. Nestlings of dominant parents fledged earlier and were heavier than those of subordinates, which should increase post-fledging survival. This study has documented, for the first time in a free-living population, relationships between characteristics of nestlings and their future dominance status. Two characteristics, fledging date and rank (by weight) in the brood, were correlated with future winter dominance of juvenile males. The dominance status of male magpies is associated with many factors related to relative fitness, with hereditary components moderated by environmental and social factors.
16

Microsatellite DNA Analysis of the Communal Breeding System of the Smooth-billed Ani (Crotophaga ani) in Southwest Puerto Rico

Startek, Jennifer Melissa 05 1900 (has links)
The communal breeding system of the smooth-billed ani (Crotophaga ani) was studied at two wildlife refuges in southwest Puerto Rico. Groups ranged in size from 2 to 9 adults, and communal clutches ranged in size from 11 to more than 25 eggs. Microsatellite DNA loci were isolated and used to examine the mating system and the extent of reproductive skew in individual groups. Loci were also screened in guira cuckoos (Guira guira) to examine the relationships suggested by Quinn et al. (1994). In the four focal smooth-billed ani groups, I found suggestions of monogamy, polygamy, and incidents of intraspecific brood parasitism. In all groups, incubated clutch size and microsatellite data indicate that subordinate females are gaining some reproductive success. At one nest, evidence suggested a decrease in the intensity of reproductive skew between successive nests. Although the data are limited, they suggest that alternative strategies to monogamy may be more prevalent than previously believed, and that reproductive skew may be affected by the availability of limiting resources within the breeding season. / Thesis / Master of Science (MS)
17

Sexual Dimorphism in a Joint-Nesting Plural Breeder, the Smooth-Billed Ani (Crotophaga ani) / Sexual Dimorphism in Smooth-Billed Anis / Sexual Selection in a Joint-Nesting Plural Breeder, the Smooth-Billed Ani (Crotophaga ani)

Barclay, Megan 09 1900 (has links)
Sexual selection has been investigated in many different systems but information is lacking in joint-nesting species. Both sexual dimorphism and possible signals of quality were explored in this study for a joint-nesting plural breeder, the smooth-billed ani (Crotophaga ani). Sexual dimorphism can be examined for a species in an attempt to reveal particular traits that might be under sexual selection and the strength of sexual selection on them. In mate choice decisions, sexually selected traits may be used by the choosy individual to assess the quality of potential mates. These honest traits need to reveal the condition and genetic quality of the individual accurately. For example, it has been proposed that plumage colour reveals condition, and more specifically parasite resistance in birds. This study explores sexual size dimorphism and dichromatism in smooth-billed anis, as well as the ability of their feather colour to reveal body condition (measured as residuals from a regression of mass versus body size), body size, and parasite numbers. Additionally, because anis are group living birds, this study investigated whether group size had an effect on parasite numbers. Anis from a population in southwestern Puerto Rico were measured for size, their feathers were collected and analyzed using a spectrometer, and ectoparasites were collected by dustruffling. For all size traits measured, males were significantly larger than females. Males also had more exaggerated bill depths (relative to body size) than females. There were no differences between the sexes for all colour morphometries, except tail saturation; females had more saturated tails than males. While no decisive conclusions can be drawn as to why the dimorphic traits are different between males and females, sexual selection may have played a role. The relationship between log10 average lice numbers per group and group size was positive, but not significant. In male smooth-billed anis, plumage colour was not related to lice or mite numbers, or body size and body condition. Plumage colour was also not related to body condition and size in females. Additionally, ectoparasites did not have an effect on male body condition. Plumage may not only be an inaccurate signal of parasite resistance or body size and body condition in the smooth-billed ani, but ectoparasites may not even have a negative effect on their host. The inability to find significant results may have been affected by other factors, such as feather wear and the age of individuals. These results warrant a more detailed look into the social behaviour of the group-living smooth-billed ani. / Thesis / Master of Science (MSc)
18

O gerenciamento do planejamento de mercado nas distribuidoras de energia elétrica: do racionamento ao ambiente regulado e livre de contratação de energia / The Management of Market Planning in the Utilities: From the Rationing to the Regulated Environment and Free Costumers.

Savoia, Ricardo 27 March 2009 (has links)
Este trabalho tem por objetivo quantificar as relações entre a demanda de energia elétrica e suas principais relações com os indicadores econômicos, socioeconômicos e comportamentais do País, busca a relação do consumo de eletricidade com o PIB - Produto Interno Bruto, seus agregados econômicos e o consumo de eletricidade do Brasil, Região Sudeste e o Estado de São Paulo, com suas principais classes de consumo residencial, comercial e Industrial, no período de 1984 a 2007. Para análise estatística, foi utilizado o E-Views como suporte e avanços para obtenção de melhores coeficientes estatísticos e tratamento dos dados. Os resultados encontrados foram condizentes com o esperado. A demanda nacional mostrou-se elástica ao comportamento do Produto Interno Bruto do País, para o período de 2003 2007, sendo constatada uma forte correlação aos indicadores econômicos. A Região Sudeste, denominada a locomotiva do crescimento nacional por sua maior predominância de indústria e comércio na região, mostrou-se elástica ao PIB, mas ligeiramente menor comparada ao comportamento do consumo nacional, reflexo de mudanças e incentivos governamentais para expansão e criação de pólos industriais em regiões pioneiras e em plena expansão demográfica. Com relação à classe residencial do Estado de São Paulo, o consumo mostrou-se inelástico com as taxas de crescimento da renda, isto é, o crescimento do consumo residencial é inferior ao crescimento da renda, mas com fracos resultados estatísticos nas variações apresentadas por este indicador econômico; necessitando porém, de estudos mais avançados incluindo outras variáveis de controle como o preço e outros fatores que são apresentados ao decorrer do trabalho. Para a classe comercial do Estado de São Paulo, encontrou-se a melhor relação com PIB Serviços Brasil e para a demanda industrial, sua aderência ao PIB Industrial Brasileiro. / The objective of this work is to quantify the relations between the demand of electric energy and its main relations with the economic, socio-economic and behavioral indicators of the Country, searching the relation of electricity consumption with the GDP Gross Domestic Product, its economic aggregates and the consumption of electricity of Brazil, Southeast region and the State of São Paulo, with its main classes of residential, commercial and Industrial consumption, in the period between 1984 to 2007. For statistical analysis, the E-Views were used as a support and advances to obtain the best statistical coefficients and data processing. The results obtained were compatible with those expected. The national demand proved to be flexible to the behavior of the Gross Domestic Product of the Country for the period of 2003 - 2008, being evidenced the strong relation to the economic indicators. The Southeast Region called the locomotive of the national growth for its bigger predominance of industry and commerce in the region, proved to be elastic to the GDP, but slightly lower compared with the behavior of the national consumption, reflexion of changes and government incentives for expansion and the creation of industrial areas in pioneer regions with booming population. Regarding to the residential classes of the State of São Paulo, the consumption proved to be inelastic with the growth rates of the income, that is, the growth of the residential consumption is inferior to the growth of the income, but with small statistics relations in the variations presented for this economic indicator, needing however, more advanced studies including other control variables as the price and other things presented in the work. For the commercial class of the State of São Paulo, the relation with the Services GDP Brazil was better and for the industrial demand its adhesion to the Brazilian Industrial GDP.
19

Distribution and habitat of the least bittern and other marsh bird species in southern Manitoba

Hay, Stacey 28 March 2006 (has links)
Call-response surveys were conducted to better delineate and estimate the population of the nationally threatened least bittern and their habitat requirements in southern Manitoba, Canada. Other marsh bird species whose populations are believed to be declining due to wetland loss throughout, or in parts of, their range were also surveyed including the American bittern, pied-billed grebe, sora, Virginia rail and yellow rail. Surveys were conducted during the 2003 and 2004 breeding seasons within 46 different wetlands. Least bitterns were encountered on 26 occasions at 15 sites within 5 wetlands. The sora was the most abundant and widely distributed target species and was encountered on 330 occasions in 39 of the 46 surveyed wetlands. Yellow rails were not detected during either survey year due to survey methodology. Use of the call-response survey protocol led to an increase in the numbers of all target species detected. This increase was more significant for the least bittern, sora and Virginia rail. Habitat was assessed as percent vegetation cover within a 50-m radius around the calling sites, and forest resource inventory data were used in a Geographic Information System to determine the landscape composition within a 500-m radius around the sites and within a 5-km radius around the wetlands surveyed. Logistic regression analyses were used to evaluate the relationship between the presence of the target species and the site and landscape characteristics. The target species responded differently to different site and landscape characteristics. Least bittern and pied-billed grebe selected areas with higher proportions of Typha spp. and tall shrubs; American bittern also selected areas with higher proportions of tall shrubs. At the 5-km scale, the American bittern responded positively to the amount of wetland and some positive trends were also detected for the pied-billed grebe. Sora and Virginia rail were not associated with any of the measured landscape characteristics. One of the most important steps towards the conservation of marsh bird species in Manitoba and elsewhere is the development, adoption, and implementation of a standardized survey protocol. Based on the results of the present study, I recommend that future surveys include both a passive and call-broadcast period for marsh bird species. Future surveys should be conducted in both the morning and evening and sites should be visited 3 times each during the breeding season. In southern Manitoba, call-response surveys should begin as early as the beginning of May to ensure the survey incorporates the period of peak vocalization. I recommend that future yellow rail surveys be conducted after dark. In this study many of the target species selected sites that had a greater area of wetland habitat surrounding them. Future wetland conservation efforts should focus on the protection and/or restoration of wetland complexes to ensure that remaining wetlands do not become smaller and increasingly isolated from one another. In addition, the Rat River Swamp was found to be the most productive marsh complex for least bittern in southern Manitoba. Measures should be taken to protect this area from future development and alteration. / May 2006
20

Distribution and habitat of the least bittern and other marsh bird species in southern Manitoba

Hay, Stacey 28 March 2006 (has links)
Call-response surveys were conducted to better delineate and estimate the population of the nationally threatened least bittern and their habitat requirements in southern Manitoba, Canada. Other marsh bird species whose populations are believed to be declining due to wetland loss throughout, or in parts of, their range were also surveyed including the American bittern, pied-billed grebe, sora, Virginia rail and yellow rail. Surveys were conducted during the 2003 and 2004 breeding seasons within 46 different wetlands. Least bitterns were encountered on 26 occasions at 15 sites within 5 wetlands. The sora was the most abundant and widely distributed target species and was encountered on 330 occasions in 39 of the 46 surveyed wetlands. Yellow rails were not detected during either survey year due to survey methodology. Use of the call-response survey protocol led to an increase in the numbers of all target species detected. This increase was more significant for the least bittern, sora and Virginia rail. Habitat was assessed as percent vegetation cover within a 50-m radius around the calling sites, and forest resource inventory data were used in a Geographic Information System to determine the landscape composition within a 500-m radius around the sites and within a 5-km radius around the wetlands surveyed. Logistic regression analyses were used to evaluate the relationship between the presence of the target species and the site and landscape characteristics. The target species responded differently to different site and landscape characteristics. Least bittern and pied-billed grebe selected areas with higher proportions of Typha spp. and tall shrubs; American bittern also selected areas with higher proportions of tall shrubs. At the 5-km scale, the American bittern responded positively to the amount of wetland and some positive trends were also detected for the pied-billed grebe. Sora and Virginia rail were not associated with any of the measured landscape characteristics. One of the most important steps towards the conservation of marsh bird species in Manitoba and elsewhere is the development, adoption, and implementation of a standardized survey protocol. Based on the results of the present study, I recommend that future surveys include both a passive and call-broadcast period for marsh bird species. Future surveys should be conducted in both the morning and evening and sites should be visited 3 times each during the breeding season. In southern Manitoba, call-response surveys should begin as early as the beginning of May to ensure the survey incorporates the period of peak vocalization. I recommend that future yellow rail surveys be conducted after dark. In this study many of the target species selected sites that had a greater area of wetland habitat surrounding them. Future wetland conservation efforts should focus on the protection and/or restoration of wetland complexes to ensure that remaining wetlands do not become smaller and increasingly isolated from one another. In addition, the Rat River Swamp was found to be the most productive marsh complex for least bittern in southern Manitoba. Measures should be taken to protect this area from future development and alteration.

Page generated in 0.0506 seconds