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  • 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.
1

Seasonality and trade-offs in equatorial rufous-collared sparrows (Zonotrichia capensis)

Class, Alexandra Morgan 23 December 2009 (has links)
The majority of vertebrates are tropical, existing in an environment with low temperature seasonality. However, there is a strong research bias towards temperate-zone studies of seasonality. I investigated the timing of life history stages and trade-offs in tropical rufous-collared sparrows (Zonotrichia capensis) in the humid Andes of Ecuador, then compared my data to temperate-zone Zonotrichia. In Chapter II, I investigated the function of male territorial aggression. Males had peak territorial aggression scores during pre-breeding and nesting, suggesting that paternity protection and food resource defense are the primary selective forces shaping male territorial behavior. Territorial aggression responses depended on the life history stage of males, which were not synchronized within the general population. In Chapter III, I tested for a trade-off between male territorial aggression scores and paternal provisioning rate. Males with higher provisioning rates had nestlings with larger body size, but contrary to the findings of previous studies, there was no direct relationship between aggression and paternal provisioning. In Chapter IV, I investigated how Z. capensis allocated supplemental food. Previous studies (mainly in temperate-zone breeding birds) found food supplements were allocated to reproduction. We supplemented fed birds in both non-breeding and feeding fledglings life history stages; both groups molted (replaced feathers) in response to supplementation, thus invested in their own maintenance over immediate reproduction. In Chapter V, I tested whether latitude and/or altitude are good predictors of reproductive synchrony in Zonotrichia. Reproductive synchrony indices overlapped among tropical and temperate populations. The high altitude, temperate-zone Zonotrichia population had the highest synchrony index, but there was only a weak relationship of altitude in a comparison of tropical populations. Cumulatively I found that tropical humid-forest resident Z. capensis time life history stages according to individual condition and history and not by overarching climatic cues. / Ph. D.
2

Ecología trófica comparativa de Zonotrichia capensis (Müller, 1776) y Passer domesticus (Linnaeus, 1758) en un agroecosistema de Ica – Perú

Menacho Julca, Katherine Eva January 2014 (has links)
Publicación a texto completo no autorizada por el autor / El “gorrión europeo,” Passer domesticus, ingresó a nuestro país proveniente de Chile durante la década del 50, desde entonces ha logrado colonizar con éxito la costa del Perú como lo ha hecho antes en muchos otros países. Esta pequeña ave es considerada una especie invasora capaz de desplazar especies nativas, pues compite con ellas por los recursos, especialmente por el alimento. Sin embargo, en el Perú todavía no se ha estudiado en qué medida afecta la avifauna local. En la costa central del Perú, en los agroecosistemas de Ica, esta especie introducida convive con el gorrión Zonotrichia capensis, y compite con él por el alimento, debido a que ambos se alimentan de semillas e insectos. La dieta de Z. capensis se compone de 21 ítems con un índice de diversidad H’= 2.07 y la de P. domesticus, de 20 ítems con H’=1.63. Al comparar la composición de sus dietas se demuestra que existe similitud entre los ítems que las componen y la proporción en que son consumidos (Dmax=0.15, p>0.05). Las medidas morfológicas de ambas especies, también son semejantes, tanto en la longitud, altura, ancho y amplitud de abertura de pico, así como la longitud del intestino. Finalmente las pruebas de solapamiento, donde se emplean valores de porcentaje de volumen total, mostraron valores significativos, tanto el Índice Simétrico de Solapamiento de Pianka (ɸ=0.87), como con el Índice de Solapamiento de Schoener (ɸ=0.73). Estos resultados permiten concluir que existe un alto grado de solapamiento en la dieta de ambos gorriones. / Tesis
3

Breeding Ecology and Migratory Connectivity of Passerines in the World's Southernmost Forests

Jara Millar, Rocio Fernanda 05 1900 (has links)
In the extensive and remote sub-Antarctic forests of South America, birds are the dominant terrestrial vertebrates. Despite considerable efforts to understand the ecology of birds breeding in these forests, our current knowledge for many species is still incomplete. During three breeding seasons (2014 – 2017), I studied the breeding ecology of the five most abundant open-cup forest-dwelling passerines in the sub-Antarctic forest of Navarino Island, Chile (55°04′S, 67°40′W). There were differences in some of the breeding strategies used by birds breeding on Navarino Island versus conspecific populations breeding at lower latitudes. Milvago chimango was the main nest predator of open-cup nesting forest passerines, and the main cause of nest failure. In addition, I found that species built their nests in sites with higher density and taller understory; however, these two factors decreased their nest survival. This mismatch could be due to a change in depredation risk on Navarino Island, and thus, passerines breeding there may be in an ecological trap. In addition, using light-level geolocators, I determined that the migratory connectivity of Elaenia albiceps is weak as a result of the large spatial spread of individuals on the wintering ground, and that the distances among individuals on the breeding grounds are not maintained in the wintering grounds. My study opens further questions about the mechanisms driving differences in breeding strategies among populations. In addition, further research is needed to assess hypotheses that could explain the mismatch between nest-site selection and nest survival and to understand what drives elaenias' movements, not only during winter but throughout their annual cycle.
4

The role of cultural divergence in reproductive isolation in a tropical bird, the rufous-collared sparrow (Zonotrichia capensis)

Danner, Julie Elizabeth 31 May 2012 (has links)
In birds, song can evolve quickly through cultural transmission and due to errors in the learning process may result in regional dialects. A lack of dialectal recognition may be a critical component of reproductive isolation through female mate preference. I investigated the role of cultural divergence in reproductive isolation in a widespread Neotropical passerine the rufous-collared sparrow (Zonotrichia capensis). In Chapter II, I investigated, the role of female preference for and male territorial response towards, local and non-local dialects in two allopatric populations. Females in both populations preferred their local dialect to the dialect of an allopatric population only 25 km away. In contrast, males showed similar territorial response to all conspecific dialects. Premating reproductive isolation based on culture may exist among the study populations. In chapter III, I investigated if cultural divergence can drive population divergence by examining dialects and variable microsatellite loci among eight populations of Z. capensis. I investigated the presence of population divergence and then identified the mechanism that may be driving the pattern. Apart from culture, a geographic barrier (the Andean ridge), elevation, and geographic distance were potential mechanisms of population divergence that I considered. All sites exhibited localized dialects, except for two closest neighboring populations. Populations exhibited genetic differentiation with support for the presence of five genetic clusters. Culture does not appear to be driving population divergence because song dialects and genetic population structure were not correlated. Populations separated by an Andean ridge did not display higher genetic or song differences than distance would predict, suggesting that the ridge is not driving population divergence. Elevation was not correlated to song or genetic differentiation. Both song divergence and microsatellite allele frequency differentiation were correlated with geographic distance suggesting a pattern of isolation by distance. Overall, geographic distance is the best predictor of population divergence in this system. Cumulatively, I found that culture might promote assortative mating via female mate choice, perhaps generating partial reproductive isolation; however, song dialect differences among contiguous populations is not currently driving population divergence in this species. / Ph. D.
5

Campylobacter spp., Salmonella enterica e Yersinia enterocolitica em aves silvestres e frangos de corte / Campylobacter spp., Salmonella enterica and Yersinia enterocolitica in wild birds and broilers

Dias, Priscila Alves 27 February 2015 (has links)
Submitted by Ubirajara Cruz (ubirajara.cruz@gmail.com) on 2017-03-29T15:43:44Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_Priscila_Dias.pdf: 621590 bytes, checksum: 4374c0a0e561b72bdead1ccfab73ac46 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-05T17:55:36Z (GMT) No. of bitstreams: 2 Tese_Priscila_Dias.pdf: 621590 bytes, checksum: 4374c0a0e561b72bdead1ccfab73ac46 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-04-05T17:55:36Z (GMT). No. of bitstreams: 2 Tese_Priscila_Dias.pdf: 621590 bytes, checksum: 4374c0a0e561b72bdead1ccfab73ac46 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-02-27 / Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul - FAPERGS / Campylobacter jejuni, Salmonella enterica e Yersinia enterocolitica estão entre os micro-organismos mais comumente associados a toxinfecções alimentares envolvendo o consumo de produtos de origem animal. As aves têm sido identificadas como reservatórios, atuando como possíveis propagadoras desses micro-organismos. Neste contexto, o trabalho teve como objetivo verificar a ocorrência de Campylobacter spp., Y. enterocolitica e S. enterica em frangos de corte e em aves silvestres, identificar as espécies de aves silvestres presentes na região sul do Brasil e quais podem ser portadoras de patógenos, pesquisar a presença dos genes cdtA, cdtB e cdtC nos isolados de Campylobacter e identificar os sorotipos de Salmonella encontrados. As aves silvestres foram capturadas próximas a lavouras de arroz e aviários com redes de neblina e soltas após a coleta. Amostras de fezes, 200 de frangos e 214 de aves silvestres de várias espécies, foram coletadas diretamente da cloaca com uso de zaragatoas e processadas para pesquisa de Campylobacter spp., S. enterica e Y. enterocolitica. Campylobacter spp. foi isolado de Chrysomus ruficapillus (Garibaldi) e Zonotrichia capensis (Tico-tico), e Salmonella isolada de Sicalis flaveola (Canário-da-terra). De frangos foram isolados Campylobacter spp., S. enterica e Y. enterololitica. Os mesmos micro-organismos foram isolados de fezes de frangos e aves silvestres capturadas no entorno dos mesmos aviários, sugerindo que ocorra uma contaminação mutua entre os dois grupos de animais. / Campylobacter jejuni, Salmonella enterica and Yersinia enterocolitica are among the most commonly microorganisms associated with food intoxication involving the consumption of animal products. The birds have been identified as reservoirs, acting like possible propagators of these microorganisms. In this context, the study aimed to verify the occurrence of Campylobacter spp., Y. enterocolitica and S. enterica in broilers and wild birds, identify the species of wild birds present in south Brazil and which may harbor pathogens, search the presence of genes cdtA, cdtB and cdtC in isolated Campylobacter and identify serotypes Salmonella found. Wild birds were captured near rice fields and aviaries with mist nets and released after collection. Faeces samples, 200 of broilers and 214 of wild birds, were collected directly from the cloaca using swabs and processed for Campylobacter spp., S. enterica and Y. enterocolitica research. Campylobacter spp. was isolated from Chrysomus ruficapillus (Garibaldi) and Zonotrichia capensis (Tico-tico), and Salmonella isolated from Sicalis flaveola (Canário-da-terra). Campylobacter spp., S. enterica and Y. enterololitica were isolated from broilers. The same microorganisms were isolated from broilers and wild birds faeces captured in the vicinity of the same aviaries, suggesting a mutual contamination between the two groups of animals.

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