Thesis (Ph. D.)--University of Chicago, Dept. of Anthropology, August 2000. / Includes bibliographical references. Also available on the Internet.

Thesis (doctoral)--Rijksuniversiteit te Utrecht. / Pocket inside back cover contains 20 plates.

Thesis (M.A.)--Abilene Christian University, 2007. / Includes bibliographical references (leaves 88-90).

Thesis--Copenhagen. / Bibliography: p. 289-294.

Inaug.-Diss.--Freie Universität Berlin. / Bibliography: p. [247]-271.

Thesis (Ph. D.)--Ohio State University, 1969. / Vita. Description based on print version record. Includes bibliographical references (leaves 506-511).

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Little is known about the evolution and ecology of crassulacean acid metabolism (CAM) in the genus Puya Molina. CAM is a photosynthetic pathway typified by nocturnal CO2 fixation and is regarded as a water-saving mechanism. Puya is one of the largest genera in the pineapple family (Bromeliaceae), with 226 species distributed across the Andes to Costa Rica and the Guiana Shield, and from sea level to 5000 m. About 21% of Puya species are CAM and at least 10 of these CAM species occur above 3000 m. The main aim of this thesis was to uncover new evidence to understand the ecophysiology and evolution of CAM in the montane genus Puya. The prevalence of CAM and C₃ species in Puya was estimated from carbon isotope values of 161 species. The climatic niche of constitutive CAM species and C₃ species of Puya was modelled using georeferenced herbarium records and climatic variables to evaluate the differences between their niches. The evolution of CAM in Puya was investigated by reconstructing the ancestral photosynthetic pathway on an AFLP phylogeny and by studying positive selection in the genes encoding the key enzyme phosphoenolpyruvate carboxylase (PEPC). The coldresistance and the thermal lability of PEPC was investigated for high- and low- elevation CAM species of Puya to explore the potential molecular adaptations of CAM plants in high-elevation environments. The present study concludes that the common ancestor of Puya was a cold-resistant plant. This is suggested to explain the prevalence of Puya at highelevations. The evolution of CAM was correlated with changes in the climatic niche, and occurred multiple times in Puya. These multiple origins were not independent because the common ancestor of Puya was likely to be a weak CAM plant (based on a diagnostic Arg679 residue in the PEPC sequence). It is likely that populations of P. chilensis gained CAM by introgression with P. alpestris ssp. zoellneri. Weak CAM photosynthesis and coldxv resistance allowed Puya to colonise the Andes from the south to the north; and, in the process, constitutive CAM and C₃ evolved. The later-evolving species in the genus are suggested to have lost their capacity for CAM as they radiated into more mesic habitats during their colonisation of the northern Andes.

A estruturação em comunidades biológicas sugere que há fatores que determinam quais espécies poderão ocorrer juntas. Os pequenos mamíferos sul-americanos (marsupiais e roedores cricetídeos) apresentam um padrão de dispersão no continente sul-americano bastante distinto. Os marsupiais chegaram ao continente há cerca de 100 milhões de anos e os roedores cricetídeos o colonizaram apenas na formação do Istmo do Panamá em aproximadamente 2,5 milhões de anos. Atualmente esses dois grupos ocupam nichos bastante diversos e também específicos. O objetivo geral desta dissertação é explorar padrões funcionais entre pequenos mamíferos sul-americanos, apresentando uma nova métrica de análise e discriminando os principais mecanismos que estruturam esses padrões. Assim, ela está dividida em dois capítulos: o primeiro apresenta uma nova abordagem analítica para o cálculo de divergência funcional entre clados coocorrentes na mesma comunidade; o segundo trata de avaliar os principais determinantes da divergência funcional entre marsupiais e roedores cricetídeos sul-americanos. A métrica desenvolvida no primeiro capítulo foi adaptada da abordagem de diversidade beta funcional, entretanto, ao invés de compararmos pares de comunidades, comparamos pares de clados que coocorrem na mesma comunidade, distinguindo o quanto similiar ou diferente funcionalmente esses clados são. No segundo capítulo, verificamos que fatores ambientais, funcionais, históricos e evolutivos influenciam a divergência funcional entre os dois clados aqui estudados. Além disso, nós encontramos uma tendência de aumento da diferenciação de nicho entre marsupiais e roedores cricetídeos em direção ao norte do continente sul-americano. Nós podemos inferir que a porta de entrada da colonização dos roedores cricetídeos no continente determina, ainda hoje, padrões de funcionalidade dos ambientes, além de outros fatores importantes como o clima. / The existence of structure in biological communities suggests that there are factors that determine which species may occur together. Small mammals of South America (marsupials and cricetid rodents) show a pattern of dispersal in this continent quite different and interesting. Marsupials arrived on South American continent about 100 million years and cricetid rodents only colonized it in the formation of the Isthmus of Panama, approximately 2.5 million years. Currently, these two groups occupy several and specific niches. The major goal of this thesis is to explore functional patterns among small mammals in South America, presenting an analytical novelty and discriminating mechanisms that driving these patterns. Thus it is divided into two chapters: the first presents a new functional approach for the calculation of functional divergence among clades co-occurring in the same community; the second evaluates the main drivers of functional divergence between marsupials and cricetid rodents in South America. The metric developed in the first chapter was adapted from the approach of functional beta diversity, however, instead of comparing pairs of communities, we compared pairs of clades co-occurring in the same community, discriminating how functionally similar or different these clades are. In the second chapter, we found that environmental, functional, evolutionary and historical factors determine the functional divergence among two clades studied here. Furthermore, we found a trend of increased niche differentiation between marsupials and cricetid rodents northward South American continent. We may infer that the gateway of cricetid rodents already determines patterns of functionality in environments nowadays, beyond other important factors, like climate.