I tested the twin-threshold model, a risk-sensitive foraging model incorporating both a starvation threshold and a higher reproductive threshold. The model predicts risk-adverse foraging when an animal's energy state is close to the starvation threshold and risk-prone foraging when the animal's energy state is close to the reproductive threshold. Wild rufous hummingbirds (Selasphorus rufus) were presented with a choice of three artificial flower types that had either no, moderate or high variability around a common mean. I manipulated energy state by changing either the mean nectar volume or altering the cost of foraging (long versus short corollas). When the energy state of hummingbirds was close to the reproductive threshold they preferred the variable options. When the energy state of hummingbirds was close to the starvation threshold they preferred the nil option. Hummingbirds responded in a manner consistent with the twin-threshold model. / x, 90 leaves ; 29 cm.

abstract: Colorful ornaments in animals often serve as sexually selected signals of quality. While pigment-based colors are well-studied in these regards, structural colors that result from the interaction of light with photonic nanostructures are comparatively understudied in terms of their consequences in social contexts, their costs of production, and even the best way to measure them. Iridescent colors are some of the most brilliant and conspicuous colors in nature, and I studied the measurement, condition-dependence, and signaling role of iridescence in Anna's hummingbirds (Calypte anna). While most animal colors are easily quantified using well-established spectrophotometric techniques, the unique characteristics of iridescent colors present challenges to measurement and opportunities to quantify novel color metrics. I designed and tested an apparatus for careful control and measurement of viewing geometry and highly repeatable measurements. These measurements could be used to accurately characterize individual variation in iridescent Anna's hummingbirds to examine their condition-dependence and signaling role. Next, I examined the literature published to date for evidence of condition-dependence of structural colors in birds. Using meta-analyses, I found that structural colors of all three types - white, ultra-violet/blue, and iridescence - are significantly condition-dependent, meaning that they can convey information about quality to conspecifics. I then investigated whether iridescent colors were condition-dependent in Anna's hummingbirds both in a field correlational study and in an experimental study. Throughout the year, I found that iridescent feathers in both male and female Anna's hummingbirds become less brilliant as they age. Color was not correlated with body condition in any age/sex group. However, iridescent coloration in male Anna's hummingbirds was significantly affected by experimental protein in the diet during feather growth, indicating that iridescent color may signal diet quality. Finally, I examined how iridescent colors were used to mediate social competitions in male and female Anna's hummingbirds. Surprisingly, males that were less colorful won significantly more contests than more colorful males, and colorful males received more aggression. Less colorful males may be attempting to drive away colorful neighbors that may be preferred mates. Female iridescent ornament size and color was highly variable, but did not influence contest outcomes or aggression. / Dissertation/Thesis / Ph.D. Biology 2012

Diversity within a habitat is determined largely by ecology and species interactions. Studies to date, however, rarely examined the role of intraspecific aggression in promoting coexistence and diversity. This is especially true in cities, where community ecology is poorly understood. This knowledge is important for basic understanding of how ecological principals come into play in our newly created habitats, as well as for reconciling human-dominated areas for wildlife.I studied the effect of human-made habitats on hummingbird abundance and diversity in Tucson, Arizona. To do that, I examined community organization and competitive interactions among four hummingbird species. I answer the questions: What is the community organization of hummingbirds in Tucson? How do characteristics of human habitats (e.g., landscaping and artificial resources) affect diversity? What mechanism underlies this pattern? And how can we apply this knowledge to conservation?To perform this study, I established a citizen science project - the Tucson Hummingbird Project (http://hummingbirds.arizona.edu). Trained participants reported abundance and behavior of hummingbirds in their backyards. Landscaping and resources (feeders and nectar plants) varied between yards.Results show that the distribution of hummingbirds in Tucson varies by species. Diversity, rather than merely abundance, increased with higher habitat heterogeneity and with more resources. Competitive interactions differ between species. Notably, intraspecific competition takes precedence over interspecific competition in the dominant and most common species, Anna's hummingbird.Based on the data, I suggest that Aggressive Resource Neglect (ARN) promotes coexistence and results in higher diversity when resources are augmented. When there are more feeders, they are distributed over a larger area. This reduces the ability of a territory-owner to defend these resources. While the territory-owner chases intruders, other individuals gain access to feeding opportunities. When dominant individuals prefer chasing conspecifics (as with Anna's hummingbird), this results in higher diversity.Besides discussing theoretical aspects, I apply this knowledge to conservation. Information on the community ecology enabled me to suggest ecologically-based ways to reconcile the city for native hummingbirds. By adding resources following an ecological protocol, we can promote biodiversity and surround ourselves with native wildlife, such as hummingbirds.

A heterogeneidade comum aos sistemas biológicos, sua influência na interação planta-polinizador e demografia de uma arvoreta tropical são os temas centrais desta tese. Utilizando uma abordagem hierárquica de estrutura de manchas de recursos florais: 1. caracterizamos a variação espaço-temporal na disponibilidade de recursos florais aos morcegos e beija-flores, polinizadores de Abutilon rufinerve. 2. avaliamos a existência de indícios de efeitos positivos ou negativos da densidade de A. rufinerve na atração de visitantes florais, em seu comportamento e possíveis conseqüências para a produção de sementes; e 3. discutimos a importância relativa da variação na produção de sementes para a demografia de A. rufinerve em diferentes condições ambientais caracterizadas por média e alta densidade de coespecíficos. A disponibilidade de recursos florais não diferiu entre dia e noite contrariando as expectativas de maior produção de néctar no período noturno em função de uma maior eficiência dos morcegos como polinizadores. As variações mais importantes na distribuição de recursos e na resposta dos visitantes florais foram observadas nas menores escalas. O aumento na densidade de recursos incrementou a visitação das flores por morcegos, porém diminuiu a visitação por beija-flores. A demografia de A. rufinerve indica que, atualmente e para esta população, os polinizadores parecem ter pouca influência em diferenças naaptidão dos indivíduos, e exercem pouca pressão seletiva sobre as plantas. Isto parece ocorrer devido à sobrevivência e crescimento das plântulas ser a etapa mais crítica do ciclo de vida desta população. No entanto é importante enfatizar que estes dados refletem um momento da população desta espécie vegetal, e que os processos evolutivos apresentam variação espaço-temporal, gerando os mosaicos geográficos. / Heterogeneity is a remarkable characteristic of biological systems. This thesis is about the influence of heterogeneity on plant-pollinator interaction and on demography of a tropical treelet Abutilon rufinerve. With an approach of hierarchical scales of patch structure we: 1. characterized the spatio-temporal variation on the availability of floral resources to bats and hummingbirds, the main pollinators of this species; 2. evaluated the occurrence of positive or negative density effects of A. rufinerve on pollinator attraction and seed production; and 3. elucidated the relative importance of variation in seed production to A. rufinerve\'s demography in different environmental conditions, characterized by medium and high conspecific density. The availability of resources did not differ between day and night, against our expectations of higher nectar production by night as a result of selective pressures made by bats, the most efficient pollinators. The greatest variation in floral resources and in the response of floral visitor was observed at fine spatial scales. Abutilon rufinerve\'s demography indicated that in this population, pollinators seem to pose no selective pressure on plants. Seed production has few effects on fitness because seedling survival and growth is the critical stage in life-cycle. However it is important to emphasize that this study reflects a short period of this population existence, and that evolutionary process vary spatio-temporaly creating geographic mosaics.

While producing the highest power output of any vertebrate, hovering hummingbirds must also precisely modulate the activity of their primary flight muscles to vary wingbeat kinematics and modulate lift production. By examining how electromyograms (EMGs) and wingbeat kinematics of hummingbirds change in response to varying aerodynamic power requirements during load lifting trials and air density reduction trials, we can better understand how aerodynamic power output is modulated via neuromuscular control. During both treatments increased lift was achieved through increased stroke amplitude, but wingbeat frequency only increased during air density reduction trials. These changes in wingbeat kinematics were matched by increased EMG intensities as aerodynamic power output requirements increased. Despite the relative symmetry of the hovering downstroke and upstroke, the timing of activation and number of spikes per EMG burst were consistently different in the supracoracoideus compared to the pectoralis, likely reflecting differences in muscle morphology.

While producing the highest power output of any vertebrate, hovering hummingbirds must also precisely modulate the activity of their primary flight muscles to vary wingbeat kinematics and modulate lift production. By examining how electromyograms (EMGs) and wingbeat kinematics of hummingbirds change in response to varying aerodynamic power requirements during load lifting trials and air density reduction trials, we can better understand how aerodynamic power output is modulated via neuromuscular control. During both treatments increased lift was achieved through increased stroke amplitude, but wingbeat frequency only increased during air density reduction trials. These changes in wingbeat kinematics were matched by increased EMG intensities as aerodynamic power output requirements increased. Despite the relative symmetry of the hovering downstroke and upstroke, the timing of activation and number of spikes per EMG burst were consistently different in the supracoracoideus compared to the pectoralis, likely reflecting differences in muscle morphology.

Submitted by FABIANA DA SILVA FRANÇA (fabiana21franca@gmail.com) on 2017-12-07T14:56:55Z No. of bitstreams: 1 ArquivoTotal.pdf: 2620143 bytes, checksum: c51d9011e9a0d81c6c8cb5241c91e599 (MD5) / Made available in DSpace on 2017-12-07T14:56:55Z (GMT). No. of bitstreams: 1 ArquivoTotal.pdf: 2620143 bytes, checksum: c51d9011e9a0d81c6c8cb5241c91e599 (MD5) Previous issue date: 2015-06-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Biogeographic studies try to understand the distribution patterns of the biologic groups, considering historic and biologic factors. At Brazil’s Northwest, there are few studies in this sphere. In this area, there are three species of hummingbirds: A. leucogaster, A. versicolor and A. fimbriata, wich have a genetic proximity – belong to the same gender – and are sympatric, and because of that can turn out to be potential competitors and don’t co-occur. But in case they do co-occur, they can be syntopic due to a divergence in some niche dimension. In order to comprehend wich historic and ecologic factors mold the distribution of these species, we reviewed the occurrences of the three of them, analized potencial distribution based on the niche aspects and revised the phylogenies of the group. Therefore, we used QGis 2.9, R 3.0.1 (Maxent), bioclimatic variables of the WorldClim, Statistic 7.0 (ANOVA one way) and the recently published phylogenies. We’ve registered 232 points of occurrence, (94%) of the points are associated to forest areas, and only 15 (6%) occurred in open environments. The co-occurrence between A. leucogaster and A. fimbriata can be easily explained by the phylogenetic distance and by the niche divergence, once they were the species with the most different data when observed by these factors. There is no sympatry of A. leucogaster and A. versicolor. The performances of the models and test of the ANOVA indicate that A. fimbriata and A. versicolor show themselves more similar in the fundamental niche, while the A. leucogaster niche is influenced in a differentiated way by the variables. A. leucogaster, the most recent of the three, has the history of lineage linked to environments of the Quaternário, related to the coastal forests. A. versicolor have a history based on the expansion of humid forests of the Mioceno Superior and Plioceno. When it comes to the A. fimbriata, it has a history that goes from the Mioceno Superior to the Pleistoceno Médio, also related to the expansion of the forests. Because Amazilia is not a monophyletic group and A. fimbriata presents ecologic and historic data that represent an evolutive divergence, we sugest a different taxonomic representation, at the gender level, to this species. / Estudos biogeográficos buscam compreender os padrões de distribuição dos grupos biológicos, levando em consideração fatores históricos e ecológicos. No nordeste oriental do Brasil, poucos são os estudos realizados nesse âmbito. Nessa região ocorrem três espécies de beija-flores, A. leucogaster, A. versicolor e A. fimbriata, que, por possuírem proximidade filogenética -pertencerem ao mesmo gênero -, e serem simpatricas, podem ser potenciais competidoras e não co-ocorrerem. Mas, caso co-ocorram, podem ser sintópicas, devido à divergência em alguma dimensão de nicho. No intuito de compreender que fatores históricos e ecológicos moldam a distribuição dessas espécies, revisamos as ocorrências das três espécies, analisamos distribuição potencial com base em aspectos do nicho e revisamos as filogenias do grupo. Para tal, utilizamos QGis 2.9, R 3.0.1 (Maxent), variáveis bioclimáticas do WorldClim, Statistic 7.0 (ANOVA one way) e as filogenias recentemente publicadas. Registramos 232 pontos de ocorrência, (94%) dos pontos estão associados a áreas florestais, e apenas 15 (6%) ocorreram em ambientes abertos. A co-ocorrência entre A. leucogaster e A. fimbriata pode ser facilmente explicada tanto pela distância filogenética como pela divergência de nicho, visto que foram as espécies com dados mais distintos, quando observados esses fatores. Não existe simpatria de A. leucogaster e A. versicolor. As performances dos modelos e teste o ANOVA indicam que A. fimbriata e A. versicolor mostram-se mais similares no nicho fundamental, enquanto o nicho de A. leucogaster é influenciado de forma diferenciada pelas variáveis. A. leucogaster, a mais recente dentre as três, tem a história da linhagem ligada a ambientes do Quaternário, relacionadas às florestas costeiras. A. versicolor possuem história baseada na expansão de matas úmidas do Mioceno Superior e Plioceno. Já A. fimbriata possui uma história que vai desde o Mioceno Superior até o Pleistoceno Médio, também relacionada à expansão das florestas. Tanto por Amazilia não ser um grupo monofilético quanto por A. fimbriata apresentar dados ecológicos e históricos que representam uma divergência evolutiva, sugerimos uma representação taxonômica distinta, a nível de gênero, para essa espécie.

abstract: Animals have evolved a diversity of signaling traits, and in some species, they co-occur and are used simultaneously to communicate. Although much work has been done to understand why animals possess multiple signals, studies do not typically address the role of inter-signal interactions, which may vary intra- and inter-specifically and help drive the evolutionary diversity in signals. For my dissertation, I tested how angle-dependent structural coloration, courtship displays, and the display environment interact and co-evolved in hummingbird species from the “bee” tribe (Mellisugini). Most “bee” hummingbird species possess an angle-dependent structurally colored throat patch and stereotyped courtship (shuttle) display. For 6 U.S. “bee” hummingbird species, I filmed male shuttle displays and mapped out the orientation- and-position-specific movements during the displays. With such display paths, I was able to then recreate each shuttle display in the field by moving plucked feathers from each male in space and time, as if they were naturally displaying, in order to measure each male’s color appearance during their display (i.e. the interactions between male hummingbird plumage, shuttle displays, and environment) from full-spectrum photographs. I tested how these interactions varied intra- and inter-specifically, and which of these originating traits might explain that variation. I first found that the solar-positional environment played a significant role in explaining variation in male color appearance within two species (Selasphorus platycercus and Calypte costae), and that different combinations of color-behavior-environment interactions made some males (in both species) appear bright, colorful, and flashy (i.e. their color appearance changes throughout a display), while other males maintained a consistent (non-flashing) color display. Among species, I found that plumage flashiness positively co-varied with male display behaviors, while another measure of male color appearance (average brightness/colorfulness) co-varied with the feather reflectance characteristics themselves. Additionally, species that had more exaggerated plumage features had less exaggerated shuttle displays. Altogether, my dissertation work illustrates the complexity of multiple signal evolution and how color-behavior-environment interactions are vital to understanding the evolution of colorful and behavioral display traits in animals. / Dissertation/Thesis / Doctoral Dissertation Biology 2018

A heterogeneidade comum aos sistemas biológicos, sua influência na interação planta-polinizador e demografia de uma arvoreta tropical são os temas centrais desta tese. Utilizando uma abordagem hierárquica de estrutura de manchas de recursos florais: 1. caracterizamos a variação espaço-temporal na disponibilidade de recursos florais aos morcegos e beija-flores, polinizadores de Abutilon rufinerve. 2. avaliamos a existência de indícios de efeitos positivos ou negativos da densidade de A. rufinerve na atração de visitantes florais, em seu comportamento e possíveis conseqüências para a produção de sementes; e 3. discutimos a importância relativa da variação na produção de sementes para a demografia de A. rufinerve em diferentes condições ambientais caracterizadas por média e alta densidade de coespecíficos. A disponibilidade de recursos florais não diferiu entre dia e noite contrariando as expectativas de maior produção de néctar no período noturno em função de uma maior eficiência dos morcegos como polinizadores. As variações mais importantes na distribuição de recursos e na resposta dos visitantes florais foram observadas nas menores escalas. O aumento na densidade de recursos incrementou a visitação das flores por morcegos, porém diminuiu a visitação por beija-flores. A demografia de A. rufinerve indica que, atualmente e para esta população, os polinizadores parecem ter pouca influência em diferenças naaptidão dos indivíduos, e exercem pouca pressão seletiva sobre as plantas. Isto parece ocorrer devido à sobrevivência e crescimento das plântulas ser a etapa mais crítica do ciclo de vida desta população. No entanto é importante enfatizar que estes dados refletem um momento da população desta espécie vegetal, e que os processos evolutivos apresentam variação espaço-temporal, gerando os mosaicos geográficos. / Heterogeneity is a remarkable characteristic of biological systems. This thesis is about the influence of heterogeneity on plant-pollinator interaction and on demography of a tropical treelet Abutilon rufinerve. With an approach of hierarchical scales of patch structure we: 1. characterized the spatio-temporal variation on the availability of floral resources to bats and hummingbirds, the main pollinators of this species; 2. evaluated the occurrence of positive or negative density effects of A. rufinerve on pollinator attraction and seed production; and 3. elucidated the relative importance of variation in seed production to A. rufinerve\'s demography in different environmental conditions, characterized by medium and high conspecific density. The availability of resources did not differ between day and night, against our expectations of higher nectar production by night as a result of selective pressures made by bats, the most efficient pollinators. The greatest variation in floral resources and in the response of floral visitor was observed at fine spatial scales. Abutilon rufinerve\'s demography indicated that in this population, pollinators seem to pose no selective pressure on plants. Seed production has few effects on fitness because seedling survival and growth is the critical stage in life-cycle. However it is important to emphasize that this study reflects a short period of this population existence, and that evolutionary process vary spatio-temporaly creating geographic mosaics.

No description available.