Divergent natural selection for use of locally abundant resources can lead to diversification within and across species. However, the consequences of divergent selection for phenotypic evolution also depend on the development of variation. Because relationships among traits such as shared developmental timing or common involvement in an organismal function can channel variation generated during development, these relationships strongly influence the direction of evolution.During development of the mammalian mandible multiple tissues of distinct developmental origins interact with inputs from the functioning of attached muscles to produce a cohesive and well integrated trait. In soricid shrews, part of the mandible matures late in ontogeny, coinciding with the onset of foraging. In this case, foraging-linked muscle activity should influence the development of the late maturing mandibular region. Here, I show that variation in this late ossifying region reveals the local functional requirements of the jaw and results in an opportunity to decouple internal and external sources of variation (developmental and environmental respectively) in the mandible. Capitalizing on this feature of the Sorex system, I empirically examined the historical persistence of internal and external patterns of variation, the consequences of variation patterning for ecological and morphological diversification across taxa, and differences between early and late ossifying regions in their contribution to local adaptation in mandible morphology.I found that the functional requirements of diet directed mandible development and determined species similarity in both mandible morphology and function. Timing of bone maturation determined the morphological effects of foraging-linked muscle activity, resulting in differential expression of adaptive variation in the late maturing region. Further, I found higher levels of interspecific variation in the late maturing region of the mandible, and showed that interspecific divergence in foraging morphology occurs along the lines delineated by epigenetic inputs of muscle on bone formation during late ontogeny within species. These findings indicate that differences in functional requirements are critical for divergence among taxa in this system. Further, these results suggest that, when external inputs into trait development are indicative of local functional requirements, the same epigenetic mechanism of development can generate diversity both within and among taxa.

A integração morfológica refere-se à organização modular das relações e conexões entre os caracteres, a qual influencia a direção e velocidade da mudança evolutiva, seja restringindo ou facilitando esta ao longo das diferentes direções do morfoespaço. Desta forma, a descrição de padrões e magnitudes de integração e a análise de suas conseqüências evolutivas são aspectos centrais do estudo da evolução de morfologias complexas. Aqui analisamos a integração morfológica no crânio de diferentes famílias de mamíferos, abordando as seguintes questões. Existem padrões de integração comuns a todos os grupos? Seriam esses padrões compatíveis com hipóteses a priori baseadas em ontogenia e função compartilhadas? Que tipos de respostas evolutivas á seleção poderiam ser produzidas por estes padrões? Para isso, digitalizamos representantes de 20 ordens e 40 famílias de mamíferos e então estimamos as matrizes de correlação e variância/covariância correspondentes, comparando-as entre si. Também comparamos cada um dos padrões de integração estimados a hipóteses a priori baseadas em ontogenia e função compartilhadas. Por fim, analisamos as repostas de cada uma das matrizes V/CV a vetores de seleção simulados. Nossos resultados apontam para um padrão de integração amplamente compartilhado entre todas as famílias, indicando que a diversidade morfológica deste grupo foi produzida usando uma estrutura de covariação compartilhada, a qual se manteve similar durante pelo menos 65 milhões de anos. Comparações com uma matriz V/CV genética de roedores sugerem que esta similaridade se estende aos fatores genéticos subjacentes à variação fenotípica. Diversos módulos funcionais/ontogenéticos foram detectados nos táxons amostrados. A principal diferença entre os grupos foram observadas nas magnitudes de integração: as famílias de metatérios e duas das famílias de roedores apresentaram alto nível de integração geral e módulos pouco distintos, enquanto as famílias de primatas e quirópteros apresentaram o padrão de inverso. Nossos dados fornecem evidência de que a evolução da morfologia craniana em mamíferos pode ser vista como marcada por alterações no nível de integração entre caracteres, na qual os módulos ficaram mais evidentes. A consequência evolutiva retirada destas observações foi a de que as linhagens e famílias com menor integração são menos restritas, do ponto de vista evolutivo, e capazes de lidar com pressões seletivas com maior flexibilidade. / Morphological integration refers to the modular structuring of intertrait relationships in an organism, which could bias the direction and rate of morphological change, either constraining or facilitating evolution along certain dimensions of the morphospace. Therefore, the description of morphological integration patterns and its magnitude and the analysis of their evolutionary consequences are central to understand the evolution of complex traits. Here we analyze morphological integration in the skull of several mammalian orders, addressing the following questions: are there common patterns of inter-trait relationships? Are these patterns compatible with hypotheses based on shared development and function? What kind of responses to evolutionary forces could be generated by these patterns? We digitized more than 2000 specimens in 20 mammalian orders and 40 families. We then estimated the correspondent correlation and covariance matrices among traits and compared those matrices among the families. We also compared observed patterns of integration to theoretical expectations based on common development and function. Finally, we analyzed the responses of each covariance matrix to simulated selection vectors. Our results pointed to a largely shared pattern of inter-trait correlations, implying that mammalian skull diversity has been produced using a common covariance structure that remained similar for at least 65 million years. Comparisons with a rodent genetic variance/covariance matrix suggest that this broad similarity extends also to the genetic factors underlying phenotypic variation. Several morphological modules expected from shared development and function were detected in the mammalian taxa studied. The main differences among groups were found for the magnitudes of integration: metatherians and two rodent families presented higher overall levels of integration and reduced modular distinctiveness ,while primates and chiropterans exhibited the opposite pattern. Our data constitute evidence that the broad picture of mammalian skull evolution could be regarded as a history of inter-module disintegration, while the modules themselves became more clearly marked. The evolutionary implication of these findings is that groups with lower overall integration are less evolutionarily constrained, and are able to cope with selection with more flexibility.

Understanding the processes that have affected the diversification of herbaceous plants is fundamental to understand how flowering plants evolve, how ecosystems form and to predict the effect of climate change and geological events in plant communities. Aiming to create a strong phylogenetic framework where biogeographic and morphological hypothesis can be tested a higher level dated phylogeny of Gesneriaceae was produced. Gesneriaceae is a good study group as it has variable floral morphology, a broad distribution throughout the tropics and subtropics - represented in all non-arid tropical and subtropical hotspots of biodiversity. There are evident differences between lineages in the numbers of species, and it is comparatively well studied compared with other asterid families. In this study a consolidated taxonomic hypothesis of Gesneriaceae is suggested based on a genus level phylogeny, the ages of the main lineages of the family are presented, the effect of geological events are explored, the geographic origin of lineages are suggested and an insight into the effect of floral morphology on the evolution of the family is given. Limiting the taxonomic scope and focusing on a single family should help us better understand how flowering plants diversify.

The plant family Gesneriaceae is represented in Sri Lanka by six genera: Aeschynanthus, Epithema, Championia, Henckelia, Rhynchoglossum and Rhynchotechum, with 13 species (plus one subspecies/variety) of which ten are endemic including the monotypic genus Championia, according to the last revision in 1981. They are exclusively distributed in undisturbed habitats, and some have high ornamental value. The species are morphologically diverse, but face a problem of taxonomic delineation, which is further complicated by the presence of putative hybrids. Sri Lanka and Indian Peninsula, represent the Deccan plate of the ancient Gondwanan supercontinent. The presence of a relict flora may indicate the significance of the geological history of the Deccan plate for the evolution of angiosperms. The high degree of endemism here, along with their affinities to the global angiosperm flora paints a complex picture, but its biogeographic history is still unclear. The pantropical family Gesneriaceae distributed in Sri Lanka and South India is therefore an appropriate study group in this context. Besides, the family itself has a complex but largely unresolved biogeographical history especially concerning the origin and diversification of Old World Gesneriaceae. Modern approaches for the taxonomic studies were applied, integrating morphological and molecular data. Multiple samples were collected for each species across their geographical distribution. Nuclear ITS and chloroplast trnL-F sequences for the taxa from Sri Lanka were used to generate regional genus phylogenies of all six genera, using maximum parsimony. The rate of evolution of the nuclear ITS region versus chloroplast trnL-F was varied greatly across the six genera studied. Molecular delimitations were mostly congruent with the classical taxonomy. Over 65 taxonomic characters were studied in detail to recognize synapomorphies for clades and taxa. A complete taxonomic revision of Gesneriaceae in Sri Lanka, including lectotypification, was conducted based on both, the molecular and morphological data. This resulted in the recognition of 14 species in the six genera, including one newly described species H. wijesundarae Ranasinghe and Mich. Möller. Henckelia communis and H. angusta were not supported molecularly as two separate entities but are recognized as two species because of consistent morphological differences between them. Henckelia humboldtiana is proposed to represent a species complex due to its highly variable and inconsistent molecular and morphological diversity and overlap with H. incana and H. floccosa; more research is needed here. National conservation assessments were conducted, and all 14 species were recognized as threatened. Biogeographic affinities of Sri Lankan Gesneriaceae were elucidated, generating a dated phylogeny using an existing matrix of four plastid gene regions; trnL-F, matK, rps16 and ndhF, amended by sequences generated in this study. The final combined matrix included 175 taxa including newly generated sequences for the 13 Sri Lankan taxa. Phylogenetic trees were generated using parsimony, maximum likelihood and Bayesian inference. Molecular dating was carried out using BEAST and ancestral area reconstruction using BioGeoBears. These analyses indicated that the six genera of Gesneriaceae arrived in Sri Lanka separately and sometimes different time periods. One lineage dated back to the early diversification of the subfamily Didymocarpoideae (generally regarded as the Old World Gesneriaceae), which occurred around the KT boundary, before the Deccan plate was connected to Asia.

A integração morfológica refere-se à organização modular das relações e conexões entre os caracteres, a qual influencia a direção e velocidade da mudança evolutiva, seja restringindo ou facilitando esta ao longo das diferentes direções do morfoespaço. Desta forma, a descrição de padrões e magnitudes de integração e a análise de suas conseqüências evolutivas são aspectos centrais do estudo da evolução de morfologias complexas. Aqui analisamos a integração morfológica no crânio de diferentes famílias de mamíferos, abordando as seguintes questões. Existem padrões de integração comuns a todos os grupos? Seriam esses padrões compatíveis com hipóteses a priori baseadas em ontogenia e função compartilhadas? Que tipos de respostas evolutivas á seleção poderiam ser produzidas por estes padrões? Para isso, digitalizamos representantes de 20 ordens e 40 famílias de mamíferos e então estimamos as matrizes de correlação e variância/covariância correspondentes, comparando-as entre si. Também comparamos cada um dos padrões de integração estimados a hipóteses a priori baseadas em ontogenia e função compartilhadas. Por fim, analisamos as repostas de cada uma das matrizes V/CV a vetores de seleção simulados. Nossos resultados apontam para um padrão de integração amplamente compartilhado entre todas as famílias, indicando que a diversidade morfológica deste grupo foi produzida usando uma estrutura de covariação compartilhada, a qual se manteve similar durante pelo menos 65 milhões de anos. Comparações com uma matriz V/CV genética de roedores sugerem que esta similaridade se estende aos fatores genéticos subjacentes à variação fenotípica. Diversos módulos funcionais/ontogenéticos foram detectados nos táxons amostrados. A principal diferença entre os grupos foram observadas nas magnitudes de integração: as famílias de metatérios e duas das famílias de roedores apresentaram alto nível de integração geral e módulos pouco distintos, enquanto as famílias de primatas e quirópteros apresentaram o padrão de inverso. Nossos dados fornecem evidência de que a evolução da morfologia craniana em mamíferos pode ser vista como marcada por alterações no nível de integração entre caracteres, na qual os módulos ficaram mais evidentes. A consequência evolutiva retirada destas observações foi a de que as linhagens e famílias com menor integração são menos restritas, do ponto de vista evolutivo, e capazes de lidar com pressões seletivas com maior flexibilidade. / Morphological integration refers to the modular structuring of intertrait relationships in an organism, which could bias the direction and rate of morphological change, either constraining or facilitating evolution along certain dimensions of the morphospace. Therefore, the description of morphological integration patterns and its magnitude and the analysis of their evolutionary consequences are central to understand the evolution of complex traits. Here we analyze morphological integration in the skull of several mammalian orders, addressing the following questions: are there common patterns of inter-trait relationships? Are these patterns compatible with hypotheses based on shared development and function? What kind of responses to evolutionary forces could be generated by these patterns? We digitized more than 2000 specimens in 20 mammalian orders and 40 families. We then estimated the correspondent correlation and covariance matrices among traits and compared those matrices among the families. We also compared observed patterns of integration to theoretical expectations based on common development and function. Finally, we analyzed the responses of each covariance matrix to simulated selection vectors. Our results pointed to a largely shared pattern of inter-trait correlations, implying that mammalian skull diversity has been produced using a common covariance structure that remained similar for at least 65 million years. Comparisons with a rodent genetic variance/covariance matrix suggest that this broad similarity extends also to the genetic factors underlying phenotypic variation. Several morphological modules expected from shared development and function were detected in the mammalian taxa studied. The main differences among groups were found for the magnitudes of integration: metatherians and two rodent families presented higher overall levels of integration and reduced modular distinctiveness ,while primates and chiropterans exhibited the opposite pattern. Our data constitute evidence that the broad picture of mammalian skull evolution could be regarded as a history of inter-module disintegration, while the modules themselves became more clearly marked. The evolutionary implication of these findings is that groups with lower overall integration are less evolutionarily constrained, and are able to cope with selection with more flexibility.

The sex comb an array of specialized bristles on the foreleg, is a highly variable male trait of Drosophila that provides an ideal system for integrative studies of morphological evolution. Here, studies of the genetic and developmental architecture of sex comb bristle number variation in Drosophila melanogaster are described. Analysis of the response to twenty-four generations of divergent artificial selection indicated high genetic variance underlying this trait, and demonstrated a weak relationship with other, developmentally related non-sex bristle systems. I also present evidence showing bristle number is associated with mating success. Manipulation of diet in full-sib families confirmed that this trait is condition dependent, and that there is a genetic basis for condition dependence. Further partitioning of variance components using a half-sib mating design revealed a strong maternal, dominance and/or X chromosome effect on sex comb bristle number variation. Finally, sex comb bristle number was not correlated with comb orientation in wild type, High and Low artificial selection lines, or the mutant strain bric a brac PR72. Analysis of patterns of variation in comb orientation over ontogeny in these lines showed that this aspect of the sex comb phenotype is highly canalized. This body of work provides important insight into D. melanogaster sex comb evolvability, and represents a timely approach to bridging the gap between population genetics and development in studies of phenotypic evolution. / Thesis / Doctor of Philosophy (PhD)

The growing need for high-performance electrode materials in electrochemical conversion and storage applications requires further fundamental investigation on the working and degradation mechanisms of these materials. Among various functional materials, transition metal oxides are still one of the main choices due to their tunable chemical compositions and diverse crystal structures in most aqueous and organic electrolytes. The charge transfer process mainly occurs at the electrode-electrolyte interface, and controlling the electrochemical interfacial stability represents a key challenge in developing sustainable and cost-effective electrochromic materials. The present thesis focuses on classical tungsten trioxide (WO3) materials as the platform to uncover the previously unknown interrelationship between phase transformation, morphological evolution, nanoscale color heterogeneity, and performance degradation in these materials during 3,000 cyclic voltammetry cycles. Through the application of novel cell design, synchrotron/electron spectroscopic, and imaging analyses, we observe that the interface between the WO3 electrode and 0.5 M sulfuric acid electrolyte undergoes constant changes due to the tungsten oxide dissolution and redeposition. The redeposition of dissolved tungsten species provokes in situ crystal growth, which ultimately leads to phase transformation from the semicrystalline WO3 to a nanoflake-shaped, proton-trapped tungsten trioxide dihydrate (HxWO3·2H2O). The multidimensional (surface and bulk) quantification of the electronic structure with X-ray measurements reveals that the tungsten reduction caused by proton trapping is heterogeneous at the nanometric scale and is responsible for the nanoscale color heterogeneity. The Coulombic efficiency, optical modulation, apparent diffusion coefficients, and switching kinetics are gradually diminished during 3,000 cyclic voltammetry cycles, resulting from the structural and chemical changes of the WO3 electrode. We hypothesize that the high interfacial reactivity in the electrode-electrolyte interfacial region could be the universal underlying mechanism leading to undesired bulk structural changes of inorganic electrochromic materials. / M.S. / With the rapid development of human society, the research of new energy-saving materials has become a focus of attention. Among them, electrochromic devices can effectively adjust their color through a controllable electrochemical reaction and have a wide range of uses in our daily life. For example, smart windows can reduce glare and heat without blocking the natural light, thereby providing buildings and vehicles with better thermal and visual comfort. Electrochromic optical displays can lower energy consumption. Variable reflectance mirrors such as anti-glare car rear-view mirrors can ensure the safety of driving. Lastly, wearable apparel such as electrochromic lenses for spectacles and sunglasses can protect users from ultraviolet radiation. Although electrochromic materials and devices have not expanded from the niche market, the enormous potential that they hold cannot be ignored and wide-scale commercialization should be sought after. Tungsten oxides electrochromic devices have proved to utilize the full spectrum of the incident light through structure design. These devices can also be configured with solar cells as a state-of-art integrated self-powered system with satisfactory optical modulation that can be obtained without any external electrical energy input. Moreover, WO3-based devices have also been combined with electrodeposition technology to achieve fast color-switching kinetics. However, the long-term durability in the acidic electrolyte under electrochemical cycling conditions needs to be further improved, and the road of full commercialization is still unpaved. To design high-performance electrochromic materials, it is imperative to study the degradation mechanism under long-term electrochemical cycling conditions. In the present thesis, the performance degradation of the WO3 electrode in acid electrolytes involves chemical changes. Through a better understanding of the fundamental degradation process, the design of high- performance electrochromic metal oxides can be developed.

A major goal of evolutionary biology and ecology is to understand why species richness varies among clades. Previous studies have suggested that variation in richness among clades might be related to variation in rates of morphological evolution among clades (e.g., body size and shape). Other studies have suggested that richness patterns might be related to variation in rates of climatic-niche evolution. However, few studies, if any, have tested the relative importance of these variables in explaining patterns of richness among clades. Here, we test their relative importance among major clades of Plethodontidae, the most species-rich family of salamanders. Earlier studies have suggested that climatic-niche evolution explains patterns of diversification among plethodontid clades, whereas rates of morphological evolution do not. A subsequent study stated that rates of morphological evolution instead explained patterns of species richness among plethodontid clades (along with "ecological limits" on richness of clades, leading to saturation of clades with species, given limited resources). However, they did not consider climatic-niche evolution. Using phylogenetic multiple regression, we show that rates of climatic-niche evolution explain most variation in richness among plethodontid clades, whereas rates of morphological evolution do not. We find little evidence that ecological limits explain patterns of richness among plethodontid clades. We also test whether rates of morphological and climatic-niche evolution are correlated, and find that they are not. Overall, our results help explain richness patterns in a major amphibian group and provide possibly the first test of the relative importance of climatic niches and morphological evolution in explaining diversity patterns.

Este trabalho busca entender a diversificação craniana dos macacos do Velho Mundo (Catarrhini) integrando duas abordagens para o estudo da evolução de caracteres complexos: a genética quantitativa e a integração morfológica. A investigação tem três objetivos principais: 1) comparar a magnitude e o padrão das relações entre os caracteres cranianos entre todos os Catarrhini; 2) testar a hipótese de que deriva genética é o único agente responsável pela diversificação craniana; 3) explorar as conseqüências evolutivas da associação entre caracteres. De posse de um banco de dados bastante representativo da diversidade dos macacos do Velho Mundo (39 medidas cranianas de cerca de 6.000 crânios de mais de 130 espécies), gerei as matrizes de correlação e de variância/covariância, que resumem as relações entre os caracteres, e comparei-as entre vários grupos. Comparei-as também a expectativas derivadas de modelos teóricos de evolução por deriva genética, além de simular a ação de seleção natural sobre essas matrizes para observar o comportamento evolutivo dos diversos padrões de associação entre caracteres. De maneira geral, o padrão das relações é o mesmo entre todos os Catarrhini, mas a magnitude com que os caracteres estão associados varia bastante. Isso tem conseqüências evolutivas importantíssimas, pois grupos com baixas magnitudes tendem a responder na mesma direção em que a seleção atua (alta flexibilidade evolutiva), enquanto que altas magnitudes estão associadas, independentemente da direção da seleção, a respostas ao longo do eixo de maior variação, que no caso dos Catarrhini corresponde à variação no tamanho (baixa flexibilidade evolutiva). A diversificação inicial do grupo parece ter sido gerada por seleção natural, mas nos níveis de gênero e espécie, deriva genética é o processo predominante; a exceção são os cercopitecíneos, onde há evidência de seleção também nesses níveis. Com base nesses resultados, proponho um modelo que associa a magnitude geral da correlação entre caracteres aos possíveis caminhos evolutivos que uma população pode seguir. Apesar de este trabalho estar empiricamente restrito aos macacos do Velho Mundo, esse modelo é válido para os mamíferos como um todo e pode ser testado em outros grupos, aumentando nossa compreensão de como a associação entre caracteres afeta a evolução dos seres vivos. / This is a study on the cranial diversification of the Catarrhini, a large group of primates that includes all Old World monkeys and apes, bringing together two approaches to investigate the evolution of complex characters: quantitative genetics and morphological integration. It has three main goals: 1) to compare magnitudes and patterns of inter-trait relationships in the skull among catarrhines; 2) to test the null hypothesis that genetic drift is the sole agent responsible for cranial diversification; 3) to explore the evolutionary consequences of inter-trait associations. With a large and representative cranial database of Old World monkeys and apes (39 measurements of around 6,000 skulls from more than 130 species), I generated and compared correlation and variance/covariance matrices, which summarize inter-trait relationships, among several Catarrhini groups. I compared some of those matrices to expectations derived from theoretical models of evolution through genetic drift, and simulated natural selection to observe the evolutionary behavior of each matrix. From a broad perspective, the patterns of relationships are the same among all catarrhines, but the magnitudes are quite variable. This has very important evolutionary consequences, because groups with low overall magnitudes tend to respond in the same direction of selection (high evolutionary flexibility), while higher magnitudes, regardless of the direction of selection, are associated to responses along the axis of highest variation, which in this case corresponds to size variation (low evolutionary flexibility). The initial diversification of catarrhines seems to have been generated by natural selection, but drift probably played a major role at the genus and species level; the exception are the cercopithecines, for which there is evidence for selection also in those levels. Based on these results, I propose a model that links the overall magnitude of inter-trait correlations to the possible evolutionary paths of a given population. This study is empirically restricted to Old World monkeys and apes, but the model has been proved valid to a broader sample of mammals and can be tested for other groups, contributing for our understanding of how complex characters evolve.

No presente trabalho utilizo as abordagens de genética quantitativa e integração morfológica para compreender a evolução do crânio em morcegos da Família Phyllostomidae. Esses morcegos exibem uma diversidade de especializações alimentares que não encontra precedentes dentre os demais mamíferos, havendo atualmente formas envolvidas na insetivoria, hematofagia, nectarivoria, carnivoria, omnivoria e frugivoria. Neste trabalho comparo as matrizes de correlação e covariância fenotípicas que quantificam a associação entre caracteres que descrevem o crânio entre espécies de filostomídeos, com o objetivo de investigar se há similaridade estrutural entre elas. Além disso, exploro possíveis fatores que podem afetar a sua estabilidade, como a história evolutiva (filogenia), dieta e as associações funcionais e de desenvolvimento entre os caracteres cranianos. Por fim, investigo a presença de módulos nos crânios dos filostomídeos e avalio as consequências evolutivas dos padrões e das magnitudes de integração na evolução desse grupo. A base de dados compreende 35 medidas cranianas de 2665 indivíduos, abrangendo todas a subfamílias, e representando ao todo 48 espécies e 45 gêneros. Os resultados indicam que após um período de diversificação evolutiva de aproximadamente 33.9 milhões de anos, a estrutura fenótipica de variância/covariância se manteve até certo ponto similar entre as espécies de morcegos filostomídeos. Enquanto os padrões estruturais das matrizes de correlação e covariação permaneceram relativamente similares, a magnitude geral de integração se mostrou evolutivamente mais plástica entre as espécies. Os caracteres cranianos que mais divergiram entre as matrizes estão relacionados às regiões do crânio que expressam grande variação morfológica qualitativa e estão diretamente relacionadas aos hábitos alimentares das espécies. A independência entre a distância filogenética e a similaridade estrutural das matrizes de variância/covariância indica que as mudanças e as manutenções dos padrões de covariância são, até certo ponto, dissociados da história evolutiva do grupo. Por outro lado, mudanças nas estruturas de correlação e covariância fenotípicas estão associadas à dieta do grupo. Embora dieta e filogenia estejam relacionadas, estes fatores diferem quanto a sua associação (e potencial causalidade) com a evolução tanto do fenótipo médio quanto da estrutura de correlação entre os caracteres do crânio. A dieta mostrou um ajuste melhor do que a filogenia para as matrizes de correlação, e para as matrizes de distância morfológica. Além disso, os resultados demonstram que os filostomídeos compartilham padrão de modularidade craniana relacionado à função e desenvolvimento, e os resultados corroboram a organização modular encontrada em outras linhagens de mamíferos. Em geral, as subregiões oral, nasal e a abóbada craniana aparecem como módulos dominantes nos crânios destes morcegos, e um olhar para aspectos funcionais e de história evolutiva ajudam a compreender os padrões de integração morfológica desse grupo tão diverso e intrigante. Nem todas as espécies de filostomídeos estudadas aqui apresentaram variação associada ao tamanho no primeiro componente principal da matriz de covariância. Mesmo não sendo tamanho, esse componente ainda assim age como uma restrição à evolução. Esse resultado é evidente nos valores de correlação altos e significativos entre os índices de magnitude geral de integração e o primeiro componente principal, e das correlações entre o primeiro CP e os índices de flexibilidade e restrição. Espécies que apresentaram alta magnitude geral de integração entre os caracteres do crânio possuem menor capacidade de evoluir na direção da seleção, sendo portanto mais restritas evolutivamente. Espécies de filostomídeos que apresentam asssociações mais baixas nos caracteres cranianos apresentam maior flexibilidade evolutiva, ou seja, maior capacidade em responder na direção em que a seleção está atuando / Here I use a quantitative genetics and morphological integration approaches to understand the evolution of bat skulls of the Phyllostomidae family. These bats display an unprecedented diversity in terms of dietary specialization that is unique in mammals, with insectivorous, hematophagous, nectarivorous, carnivorous, omnivorous and frugivorous species. In this thesis, I compare the covariance and correlation phenotypic matrices, which are a quantification of the relationship among skull traits, in order to investigate whether there is structural similarity between them. Furthermore, I explore possible factors that may affect its stability, such as evolutionary history (phylogeny), dietary habits and functional and developmental associations between cranial traits. Finally, I investigate the presence of modules in the skulls of phyllostomids and assess the evolutionary consequences of the patterns and magnitudes of morphological integration in the evolution of this group. The database comprises 35 cranial measurements of 2665 specimens, including all the subfamilies, representing 45 genera and 48 species. The results indicate that after an approximately 33.9 million years period of evolutionary diversification, the phenotypic variance/covariance structure remained, to some extent, similar among species of phyllostomid bats. While the patterns of covariance and correlation matrices remained relatively similar, the overall magnitude of integration presented considerable variation between species. The cranial traits that diverged the most between the matrices are related to the regions of the skull that display great qualitative morphological variation and are directly related to the dietary habits of the species. The independence between the phylogenetic distance and the structural similarity of variance/covariance matrices indicates that changes and stasis in covariance patterns are, to some extent, decoupled from the evolutionary history of the group. On the other hand, changes in the phenotypic correlation and covariance structure are associated with the dietary habits of the group. While diet and phylogeny are related, these factors differ regarding their association (and potential causality) with evolution, both concerning the average phenotype divergence, as well as the correlation structure between cranial traits. The diet showed a better adjustment than the phylogeny for correlation matrices, as well as for the morphological distance matrices. Furthermore, the results demonstrate that the phyllostomids share the same patterns of cranial modularity for functional and developmental hypothesis, and confirm the modular structure found in other lineages of mammals. Generally speaking, the oral, nasal and cranial vault subregions appear as dominant modules in the skulls of these bats, and focusing on functional and evolutionary history aspects help to better understand the patterns of morphological integration of this group that is so diverse and intriguing. Not all species of bats that were included in this study showed size variation in the first principal component of the covariance matrix. Even if this first principal component is not size related, this component still acts as an evolutionary constrain. This result is evident in the high and significant correlation values between the overall integration indexes and the first principal component, and regarding the correlation between the first PC and the flexibility and constraint indexes. Species with high overall magnitude of integration between the skull traits have less ability to evolve in the direction of the selection and, therefore, are more evolutionary constrained. Species of bats that exhibit lower associations of cranial traits show greater evolutionary flexibility, i.e., greater capacity to respond in the direction in which selection is acting